NBSIR 77-1226

Intermediate Minimum

Property Standards for Solar

Heating and Domestic Hot

Water Systems

Solar Energy Program

Office of Housing and Building Technology

Center for Building Technology, IAT

National Bureau of Standards

Washington, D.C. 20234

March 1977

Final Report

Prepared for Department of Housing and Urban Development

Office of Policy Development and Research

Division of Energy, Building Technology and Standards

Washington, D.C. 20410

NBSIR 77-1226

INTERMEDIATE MINIMUM

PROPERTY STANDARDS FOR SOLAR

HEATING AND DOMESTIC HOT

WATER SYSTEMS

Solar Energy Program

Office of Housing and Building Technology

Center for Building Technology, IAT

National Bureau of Standards

Washington, D C. 20234

March 1 977

Final Report

This publication, NBSIR 77-1226, supersedes

NBSIR 76-1059 published in April 1976.

Prepared for Department of Housing and Urban Development

Office of Policy Development and Research

Division of Energy, Building Technology and Standards

Washington, D.C. 20410

U.S. DEPARTMENT OF COMMERCE, Juanita M. Kreps, Secretary

Dr. Betsy Ancker-Johnson, Assistant Secretary for Science and Technology

NATIONAL BUREAU OF STANDARDS, Ernest Ambler, Acting Director

ACKNOWLEDGEMENTS

The preparation of this document has been a joint effort of members of the Solar Energy

Program Team *at the National Bureau of Standards, Center for Building Technology.

Team members include:

Office of Housing and Building Technology

Robert Dikkers

David Waksman

John Holton

Kenneth DeCorte

William Niessing

Thermal Engineering Section

Elmer Streed

James Hill

John Jenkins

Dennis Jones

Michael McCabe

Materials and Composite Section

Larry Masters

Leopold Skoda

Elizabeth Clark

Paul Brown

Jean-Noel Andre

McClure Godette

Mechanical System Section

James Kao

Building Services Section

Robert Beausoliel

Grover Sherlin

Structures Section

William Greene

Architectural Research Section

Richard Crenshaw

Office of Building Standards and Codes Services

James Harris

Robert Eisenhard

Program for Fire Control - Construction

(Center for Fire Research)

Daniel Gross

William Walton

Edward Budnick

Typing, Editing, and Preparation by

Rita Whalen

Mary Lou Miller

Leslie Suddueth
Preparation of Appendix C, Illustrated Definitions, was done by

the AIA Research Corporation

Invaluable critique and guidance has been given by:

Department of Housing and Urban Development

Joseph Sherman

David Moore

William Freeborne

Mervin Dizenfeld

Consultant Review Panel

William Beckman

John Bowen

John Duffie

Mel Green

Michael Holtz

Alwin Newton,

Andrew Parker

Richard Rittelmann

Daniel Talbott

Gordon Tulley

Ed Wachter

Edgar Weisman

Professor, University of Wisconsin - Madison

Chairman, Standards Committee, Solar Energy Industries

Association (AMETEK Corporation)

Professor, University of Wisconsin - Madison

International Conference of Building Officials

AIA Research Corporation

American Society of Heating, Refrigerating and

Air Conditioning Engineers

Mueller Associates (AIA/RC consultant)

Burt, Hill fc Associates

(formerly) National Association of Hone Builders

Massdesign (AIA/RC consultant)

International Conference of Building Officials

Falcon Construction Co., Inc.

ii
PREFACE

The "Minimum Property Standards for One and Two Family Dwellings" 4900 and the "Minimum

Property Standards for Multifamily Housing" 4910 were developed to provide a sound

technical basis for the planning and design of housing under numerous programs of the Department of Housing and Urban Development (HUD) . These "Intermediate Minimum Property

Standards for Solar Heating and Domestic Hot Water Systems" are intended to provide a companion technical basis for the planning and design of solar heating and domestic hot

water systems.

These standards have been prepared as a supplement to the MPS and consider only aspects

of planning and design that are different from conventional housing by reason of the

solar systems under consideration. To the greatest extent possible, they are based on current state-of-the-art practice and on nationally recognized standards including the

MPS and the HUD "Interim Performance Criteria for Solar Heating and Combined Heating/

Cooling Systems and Dwellings."

This document considers requirements and standards applicable to both one and two family

dwellings and multifamily housing and references made in the text to the MPS refer

to the same section in both the "Minimum Property Standards for One and Two Family

Dwellings" 4900.1 and the "Minimum Property Standards for Multifamily Housing" 4910.1

unless otherwise noted.

In general, the Chapters and Divisions in this document are organized to parallel the

Chapters and Divisions contained in the MPS. Within Divisions, however, these standards

do not follow the numbering of the MPS, but rather list the solar topics sequentially.

It has been found that this method allows the presentation of these new topics in a manner that is clearly related to the MPS and yet is not made cumbersome. Not all Chapters

or Divisions in the MPS have topics of solar concern; for example, there are no such topics

in Chapter 2, General Acceptability Criteria, nor in Division 512, Furnishings.

An example will help to illustrate the organization of this document:

Consider hail loads to be applied to solar collectors. Hail loads

are not a subject in the MPS, but would be covered in Chapters 6,

Division 1, General Structural Requirements if they were. In these

standards they are located in Chapter 6, Division 1, Section S-601-7.

For comparison, plumbing construction is covered in Chapters 6,

Division 15, Section 615-5 of the MPS. In these standards it is also

located in Chapter 6, Division 15, but in Section S-615-12.

MPS MPS Solar Supplement

Hail loads none S-601-7

Plumbing 615-5 S-615-12

It has frequently been found useful to include a commentary on a particular standard.

The commentaries are not mandatory, but are intended to give further explanation and

guidance to users of the standards on topics which may have special consequences in

solar installations. Several appendices are included which give additional information

for assistance in use of the standards. Appendix A presents the calculation procedures for

determining the thermal performance of solar heating and domestic hot water systems and

Appendix C presents graphic illustrations of terms used in the standard.

iii
The format developed for these standards has been structured to convey information in a number of categories as follows:

S - the prefix used on all sections (for solar) to distinguish them from

existent MPS section

BOLD FACE TYPE - to present standards and commentaries applicable to

MULTIFAMILY HOUSING ONLY

Conventional type - to present standards applicable to one and two family

dwellings and multifamily housing

Italics - to present commentaries applicable to one and two family dwellings

and multifamily housing

SI CONVERSION UNITS

In view of the present accepted practice in this country for building technology, common

U.S. units of measurement have been used throughout this document. In recognition of the

position of the United States as a signatory to the General Conference of Weights and

Measures, which gave official status to the metric SI system of units in 1960, assistance

is given to the reader interested in making use of the coherent system of SI units by

giving conversion factors applicable to U.S. units used in this document.

Length

1 in 1 0.0254 meter (exactly)

1 ft = 0.3048 meter (exactly)

Area

1 in 2 = 6.45 x 10~^ meter2

1 ft 2 = 0.09290 meter2

Volume

1 in^ = 1.639 x 10

-

^ meter 2

1 gal (U.S. liquid) = 3.785 x 10“ 2 meter 2

Mass

1 ounce-mass (avoirdupois) = 2.834 x 10“ 2 kilogram

1 pound-mass (avoirdupois) = 0.4536 kilogram

Pressure or Stress (Force/Area)

1 inch of mercury (60°F) => 3.377 x 10 2 pascal

1 pound-force/inch2 (psi) = 6.895 x 10 2 pascal

Energy

1 foot-pound-force (ft-lbf) = 1.356 joule

1 Btu (International Table) = 1.055 x 10 2 joule

Power

1 watt * 1 x 10 7 erg/second

1 Btu/hr = 0.2929 watt

Temperature

t°c * 5/9 (t«p - 32)

Heat

1 Btu-in/h-f

t

2 -°F = 1.442 x 10-2 W/m-K (thermal conductivity)

1 Btu/lbm-°F = 4.184 x 10 2 J/kg-K (specific heat)

1 langley = 4.184 x 10^ J/m2 = 1 cal/cm2 = 3.69 Btu/ft 2

iv
GENERAL TABLE OF CONTENTS

Chapter 1 General Use. . . 1-1

Chapter 2 General Acceptability Criteria (Not used) 2-1

Chapter 3 Site Design 3-1

Chapter 4 Building Design 4-1

Chapter 5 Materials 5-1

Chapter 6 Construction 6-1

Appendix A Calculation Procedures for Determining the Thermal

Performance of Solar Domestic Hot Water and Space

Heating Systems A-l

Appendix B Materials Tables B-l

Appendix C Illustrated Definitions C-l

Appendix D Definitions D-l

Appendix E Referenced Standards E-l

Appendix F Abbreviations F-l
'
CHAPTER 1

S-100

S-101

S-101-1

S-102

APPLICATION

General Use

These "Intermediate Minimum Property Standards for Solar Heating and Domestic

Hot Water Systems" are a supplement to MPS 4900.1, "Minimum Property Standards

for One and Two Family Dwellings," and MPS 4910.1, "Minimum Property Standards

for Multifamily Housing," and shall be used in conjunction with MPS 4900.1 and

MPS 4910.1. Furthermore, the solar components must provide for the collection

of solar energy, conversion of the solar energy to thermal energy, and distribution, storage and control of the thermal energy so obtained. Insofar as applicable, these standards apply to active and passive solar energy systems

that utilize building elements, mechanical subsystems or combinations thereof.

Commentary: MPS 4900. 1, and MPS 4910.1 are available from HUD Regional Offices.

VARIATIONS TO STANDARDS

NEW MATERIALS AND TECHNOLOGIES

These standards are intended to encourage the use of new or innovative

designs, technologies, methods or materials in solar applications. These

features include designs, methods of construction, systems, subsystems,

components, materials and processes which do not comply with the MPS and

this document, and whose acceptance cannot be determined by other provisions

of these standards. Alternatives, nonconventional or innovative designs, methods,

and materials shall demonstrate, however, equivalent quality to these standards

in operating effectiveness, structural soundness, durability, economy of maintenance or operation, and usability. Variations shall be made in accordance

with Section 101-4 of MPS.

Commentary: One basis for design, fabrication, construction, and acceptance of

new and innovative solar systems, subsystems, components, materials , and processes is the "Interim Performance Criteria for Solar Heating and Combined

Heating/Cooling Systems and Dwellings , " January , 1975, available from GPO.

PRODUCT AND DESIGN MODIFICATIONS

Variations from approved designs shall be submitted to HUD for review.

Commentary: It is recognized that product or design changes may occur. These

changes may affect the performance of the system or its components.

CHAPTER 2

GENERAL ACCEPTABILITY CRITERIA

(not used)

2-1

TABLE OF CONTENTS

Page

CHAPTER 3 - SITE DESIGN

S-300 GENERAL 3-2

S-301 PROPOSED SITE 3-2

S-301-1 Site Surroundings 3-2

S-303 LAND USE 3-2

S-303-1 Solar Equipment Location and Arrangement 3-2

S-303-2 Site Hazards 3-3

S-304 LOTS, YARDS AND BUILDING SETBACK DISTANCE 3-3

S-304-1 Projection into Yard Area 3-3

S-304-2 Usable Outdoor Area 3-3

S-304-3 Snow and Ice 3-3

S-309 SERVICES 3-3

S-309-1 Maintenance 3-3

S-311 DRAINAGE 3-4

S-311-5 Drainage Swales and Gutters 3-4

S-311-7 Downspouts 3-4

S-312 PLANTING DESIGN 3-4

S-312-3 New Plant Material 3-4

3-1
CHAPTER 3

S-300

S-301

S-301-1

S-303

S-303-1

SITE DESIGN

GENERAL

The provisions of this chapter are applicable to solar energy systems

including heating (H) and domestic hot water (DHW) systems. This chapter

is a supplement to the Minimum Property Standards (MPS) Chapter 3.

PROPOSED SITE

SITE SURROUNDINGS

Solar buildings and solar system components shall be located and designed in

such a manner as to harmonize with the surrounding community.

Commentary : Solar system oorrrponents may include elements which are large

and visually dominant when viewed from off-site. If not carefully designed

and located, such elements can produce a detrimental effect on the overall

quality of a residential area.

LAND USE

SOLAR EQUIPMENT LOCATION AND ARRANGEMENT

Solar buildings and site located solar equipment shall be arranged and

located to relate well to:

a. The natural topography.

Commentary : The location of the solar collector should be planned to avoid

pockets where frost can collect or unprotected ridges where winds can be more

extreme in order to avoid heat losses due to low temperatures and high winds.

b. The climate.

Commentary : The location of the solar collector should be planned to take

into account prevailing winds in order to avoid excessive heat losses due to wind and to drifting snow which impair the collection of solar energy. For

specific requirements on tilt and orientation see S-615-2. 1 . 2 and C-8} C-9 in

Appendix.

c. Attractive on-site and off-site views.

Commentary : Components of the solar system may be large and could block

attractive views from the building.

d. Existing and proposed site elements such as vegetation, fences, landforms

and buildings

.

Commentary : Proper relationship of a solar collector to site elements can minimize the shading of the collector and reduce air flow over the collector

.

Location of the solar building in the northern portion of the site can help

to minimize the possibility of shading solar collector surfaces by future

off-site development.

e. Existing and proposed pedestrian and vehicular circulation systems.

Commentary : Proper location of solar equipment in relation to pedestrian

circulation may reduce tampering and vandalism.

3-2
S-303-2

S-304

S-304-1

S-304-2

S-304-3

S-309

S-309-1

f. Existing and proposed surrounding buildings and facilities.

Commentary: The location and orientation of the solar collector should

consider 'physical and chemical air home waste from nearby facilities such

as incinerators and factories which might have an impact on the efficiency

of the solar collector. (See S-S15-1 . 5)

SITE HAZARDS

Special considerations must be given to assure that elements of the solar

system do not create unnecessary safety hazards to users.

Commentary : Hazards which require special attention include the reflection

of sunlight which creates visual distraction, the projection of sharp edges

which influence the movement of people near free-standing collectors, and the

proximity of solar components to recognized architectural hazards such as exterior overhangs, stairs, ramps, landings, doors, etc.

LOTS, YARDS AND BUILDING SETBACK DISTANCE

PROJECTION INTO YARD AREA

The projection of solar collectors into yards shall conform to those restrictions placed on open balconies, bay windows and uncovered porches in Section

304-2 of MPS.

USABLE OUTDOOR AREA

Components of the solar system shall not unnecessarily impinge on the

requirements of Section 304-3 of MPS.

Commentary : Reasonable outdoor open space must be maintained for livability

service, emergency access, isolation of fire and protection of adjacent

property

.

SNOW AND ICE

In areas which have a snow load of 20 pounds per square foot or greater

required by local codes, provisions should be made over entrances and locations

of pedestrian and vehicular ways to restrain or deflect sliding snow and ice masses which may slide off elevated solar system components.

Commentary : Solar system components may often include smooth slippery

surfaces located in elevated positions at steep angles. These elements

may heat up rapidly and loosen masses of snow or ice which may slide-off.

Means should be provided to prevent a hazard to people or property . Methods

such as deflectors, restraints, low friction materials, or design of "safe

fall" areas (pedestrian or vehicular ways spaced away from the building)

should be considered.

SERVICES

MAINTENANCE

Solar energy components located on the site should be accessible for cleaning,

adjusting, servicing, examination, replacement or repair without trespassing

on adjoining property.

Commentary: Components should not be located unnecessarily under buildings

or roads or in other places which are difficult to reach. Storage tanks in

particular are large and may need periodic replacement or inspection.

3-3
Solar collectors on roofs over 3 stories must have access provided

FOR CLEANING AND MAINTENANCE.

Commentary: The use of portable ladders is not considered to be

ADEQUATE UNDER THESE CIRCUMSTANCES,

S-311 DRAINAGE

S-311-5 DRAINAGE SWALES AND GUTTERS

Gutters or other means of controlling runoff shall be provided on solar collectors when the soil is of such a nature that excessive erosion or expansion may occur as a result of increased runoff.

S-311-

7

DOWNSPOUTS

S-311-7 .

1

In addition to method of disposal of 311-7.1 of the MPS, downspouts may

be discharged into an acceptable non-potable water storage tank if it is

part of the solar system.

Commentary: Current MPS requires that the water from a downspout empty into

available storm sewer or on a splash block. When downspouts are used as part

of a solar system, it is acceptable for it to empty into a storage tank

provided consideration has been given the quality of the water and its effect

on the solar system. (See S-515-2. 3)

S-312 PLANTING DESIGN

S-312-3 NEW PLANT MATERIAL

S-312-3.

9

Plant material should be selected and located to prevent the unwanted reduction

of thermal output of a solar collector from shading, sap or other by-products

of plants.

3-4
TABLE OF CONTENTS

Page

CHAPTER 4 - BUILDING DESIGN

S-400 GENERAL 4-2

S-401 SPACE PLANNING 4-2

S-401-1 Passive Solar Systems 4-2

S-402 ACCESS AND CIRCULATION 4-2

S-402-1 General 4-2

S-402-10 Solar Energy Equipment 4-2

S-403 LIGHT AND VENTILATION 4-2

S-403-3 Ventilation 4-2

S-405 FIRE PROTECTION 4-2

S-405-1 General 4-2

S-405-4 Fire Resistance Requirements 4-3

S-405-6 Exits 4-3

S-405-7 Firestopping 4-3

S-405-12 Roof Coverings 4-3

4-1
CHAPTER 4

BUILDING DESIGN

S-400 GENERAL

The provisions of this chapter are applicable to solar energy systems including

heating (H) and domestic hot water (DHW) systems. This chapter is a supplement to the Minimum Property Standards (MPS) Chapter 4.

S-401 SPACE PLANNING

S-401-1 PASSIVE SOLAR SYSTEMS

Where normal building spaces are designed to also be part of passive solar

energy collection, storage, distribution or control, provisions shall be made

so that this use does not interfere with the intended use of these spaces.

S-402 ACCESS AND CIRCULATION

S-402-1 GENERAL

S-402-1 .

1

The design and installation of the solar heating and domestic hot water systems

shall not impair the normal movement of occupants of the building or emergency

personnel.

Commentary; Special consideration should be given to the effect of the

CONFIGURATION OF ROOF-MOUNTED COLLECTORS ON FIRE EXITING, FIRE FIGHTING OR

EMERGENCY RESCUE,

S-402-10 SOLAR ENERGY EQUIPMENT

Solar energy equipment shall be accessible for routine maintenance without

disassembling any major structural or mechanical element. Sufficient space

or clearance shall be provided based upon solar equipment sizes and potential maintenance equipment sizes to permit examination, replacement,

adjusting, servicing and/or maintenance. See Section S-600-5.

Commentary: Accessibility for repair and maintenance should reflect the

expected life of the equipment and the frequency of routine maintenance

required. An element with a shorter maintenance cycle or life expectancy

should be more accessible than one with a long maintenance cycle or life

expectancy

.

S-403 LIGHT AND VENTILATION

S-403-3 VENTILATION

When attics or structural spaces are used as part of a passive solar system,

attic or structural space ventilation may be omitted if other means are provided to control condensation. See Section 403-3 of MPS.

S-405 FIRE PROTECTION

S-405-1 GENERAL

S-405-1.

1

The incorporation of solar systems into the living unit shall not increase

the fire hazard or interfere with the means of safe egress in the event of

a fire.

4-2
S-405-4 FIRE RESISTANCE REQUIREMENTS

S-405-4 .

1

Integrated Construction

The incorporation of solar subsystems shall not reduce the fire resistance

ratings required by 405-4 of the MPS.

Commentary : Roof-mounted collectors which are an integral part of the roof

construction shall not reduce the required fire resistance rating of the

roof assembly

.

S-405-4.

2

Penetrations

Penetrations through fire-rated assemblies shall not reduce the fire

resistance ratings required by 405-4 of the MPS.

S-405-6 EXITS

Components of the solar system shall not be located in such a way as to interfere with the primary or secondary means of occupant egress.

Commentary : The location of solar equipment on a roof shall not reduce

the usability of that roof for access or egress. Solar system components

located remote from the building but near a means of egress shall not block

the means of egress if a fire occurs in the solar system component

.

S-405-7 FIRESTOPPING

Major solar system components that are integral parts of assemblies which

normally require firestopping shall be firestopped on all sides. Firestopping shall be wood blocking of minimum 2 inch nominal thickness or of

noncombustible materials providing equivalent protection. Firestopping

may be included as an integral part of the component where the component as installed provides equivalent protection.

Commentary: It is the intent of the section to prevent solar system components from reducing the effectiveness of firestopping. For example, in the case where a solar collector is an integral part of a wood framed wall which

would normally be firestopped between studs, firestopping shall be required

in the wall above and below the solar collector

.

S-405-12 ROOF COVERINGS

Installation of solar collectors or system components on or as an integral

part of the roof shall not reduce the fire retardant characteristics of the

roof covering below the level specified in 405-12 of the MPS.

4-3
.
TABLE OF CONTENTS

Page

CHAPTER 5 - MATERIALS

S-500 GENERAL 5-2

S-500-1 Applicable Standards 5-2

S-500-2 Exceptions and Re-Statements 5-2

S-500-3 Suitability of Alternate or Special Materials 5-2

S-501 GENERAL REQUIREMENTS 5-3

S-501-1 General 5-3

S-501-2 Labeling 5-3

S-501-3 Safety 5-3

S-501-4 Documentation of Performance 5-3

S-508 DOORS, WINDOWS, GLAZING PANELS 5-4

S-508-7 Hardware 5-4

S-515 MECHANICAL - SOLAR POWERED EQUIPMENT 5-5

S-515-1 General Provisions 5-5

S-515-2 Collectors 5-6

S-515-3 Energy Transport System 5-22

S-515-4 Mechanical Supporting Devices . 5-23

S-515-5 Valves 5-24

S-515-6 Pumps and Fans 5-24

S-515-7 Thermal Storage Units 5-25

S-515-8 Heat Transfer Fluids 5-26

S-515-9 Heat Exchangers 5-28

S-515-10 Gaskets and Sealants 5-29

S-515-11 Insulation/Thermal and Moisture Protection 5-30

S-515-12 Catch Basins 5-31

S-515-13 Organic Coupling Hoses 5-32

5-1
CHAPTER 5

MATERIALS

S-500 GENERAL

The provisions in this chapter are applicable to solar energy systems

including heating (H) , and domestic hot water (DHW) systems. This chapter

is a supplement to the Minimum Property Standards (MPS) . Materials provisions (Chapter 5) of the MPS are applicable in addition to the items

explicitly discussed in this document.

Commentary : Conditions of -potentially deleterious exposure of materials

used in solar systems and particularly in solar collectors vary widely with

the design and operating characteristics of the system and collectors. The

performance of materials in the context of the overall normal and no-flow

characteristics of system and collectors should he considered as primary

factors in material selection.

S-500-1 APPLICABLE STANDARDS

Except as modified herein, materials, equipment and installation shall

be in accordance with the standards and nationally recognized model codes

cited within the body of this document; the current applicable editions

and titles of referenced standards and codes are contained in Appendix E. State and local codes which deviate from nationally recognized codes or standards in order to satisfy local conditions may be accepted by HUD if

such deviations are identified and substantiated with satisfactory engineering data.

S-500-2 EXCEPTIONS AND RE- STATEMENTS

S-500-2 .

1

Exceptions

Exceptions to the cited standards are included in this document where

deemed appropriate by HUD.

S-500-2.

2

Re-statements

Certain requirements that are already covered in the referenced standards

are re-stated in this document to emphasize the need for implementing these

requirements in HUD construction.

S-500-3 SUITABILITY OF ALTERNATE OR SPECIAL MATERIALS

Alternate or special materials or products, other than those contained

herein may be used when found acceptable by established HUD procedures

and Division 513 of MPS and Section S-101 of this document.

Commentary: Documentation of satisfactory long-term performance under

in-use conditions may be used to demonstrate compliance with many of the

requirements in this chapter.

5-2
DIVISION 1

S-501

S-501-1

S-501-2

S-501-3

S-501-3 .

1

S-501-4

GENERAL REQUIREMENTS

GENERAL

Materials installed shall be of such kind and quality as to assure that

the solar energy system will provide a) adequate structural strength,

b) adequate resistance to weather, moisture, corrosion and fire, c) ac- ceptable durability and economy of maintenance and market acceptance.

LABELING

Mandatory labeling requirements, where applicable, are contained herein

for specific materials and products.

Commentary: Installation, operation and maintenance information re- quirements are specified in S-600-3.

SAFETY

Protection of potable water and circulated air

No material, form of construction, fixture, appurtenance or item of

equipment shall be employed that will introduce toxic substances, impurities , bacteria or toxic chemicals into potable water and air circulation systems in quantities sufficient to cause disease or harmful

physiological effects.

Commentary: This situation is of concern not only as it pertains to ducts,

piping, filters and joints but also to storage areas, such as rock beds.

In addition, the growth of fungus, mold and mildew is possible when collectors are applied to a roof surface over the water tight membrane. If

the collectors are in contact with the membrane or held away from the membrane to allow for drainage, the shaded membrane area can support the

growth of mildew and other fungus in some warm, moist climates . Special

design considerations should be included to avoid this problem in climates

where it can occur.

DOCUMENTATION OF PERFORMANCE

Documentation of satisfactory long term performance of systems, components,

or materials may be used to demonstrate compliance with the standards

listed in this chapter.

5-3
DIVISION 8

S-508

S-508-7

S-508-7 .

3

DOORS, WINDOWS, GLAZING PANELS

HARDWARE

Screening

Solar control insect screening for windows and doors shall provide insect

protection equivalent to 16 by 18 mesh insect screen,

Cormentary : There cere louvered solar control insect screens which have

elongated openings. These vary from the traditional square openings of

screens and are effective in limiting incident solar radiation as well

as keeping out insects.

5-4
DIVISION 15

S-515

S-515-1

S-515-1 .

1

S-515-1.

2

S-515-1.

3

S-515-1 .

4

S-515-1.

5

S-515-1.

6

S-515-1.

7

S-515-1.

8

MECHANICAL - SOLAR POWERED EQUIPMENT

GENERAL PROVISIONS

Fire Safety

Assemblies and materials used in the solar systems shall comply with the

nationally recognized codes for fire safety under all anticipated operating

and no flow conditions.

Effects of external environment

The systems for heating (H) and for domestic hot water (DHW) and their

various subassemblies shall not be affected by external environmental

factors prevalent at the site to an extent that will significantly impair

their function during their intended design life.

Temperature and Pressure Resistance

Components shall be capable of performing their functions for their intended design life when exposed to the maximum and minimum temperatures

and pressures that can be developed in the system.

Materials Compatibility

All materials which are joined directly to or in contact with other materials

shall have sufficient chemical compatibility with those materials to prevent

deterioration that will significantly impair their function during their

intended design life. Provisions shall be made to allow for differences

in the expansion and contraction of joined materials due to expected

temperature fluctuations

.

Airborne Pollutants

Materials exposed to airborne pollutants while in service, such as ozone,

salt spray, sulfur dioxide, oxides of nitrogen and/or hydrogen chloride,

shall not be affected by those pollutants to an extent that will significantly impair their function during their intended design life.

Chemical Decomposition Products

Materials shall not be affected by chemical decomposition products ex- pelled from components under in-use conditions to an extent that will

significantly impair their function during their intended design life.

Abrasive Wear

Exterior materials shall not be affected by abrasive wear caused either

by cleaning or by natural factors such as wind blown sand to an extent

that will significantly impair their function during their intended

design life.

Soil Corrosion

Materials installed in corrosive soil shall be either of a material unaffected

by such soil or shall be isolated from it by a protective coating. The

coating and its application shall conform to AWWA C-203.

5-5
S-515-1.

9

Corrosion by Leachable Substances

Substances that can be leached by moisture from any of the materials within

the system which may be exposed to mositure shall not cause corrosive deterioration of any other materials to an extent that will significantly

impair their function during their intended design life.

S-515-1. 10 Leakage

Leakage from assemblies or subassemblies which contain heat transfer fluids

shall not significantly impair the function of other components which may

come in contact with the leaking heat transfer fluid or create a safety

hazard.

S-515-2 COLLECTORS

S-515-2.1 General

Collectors shall perform their function for their intended design life.

- Commentary: In addition to their primary function of collecting solar

energy, collector panels can he used as the roofing membrane. They can also

he mounted over a roofing membrane or mounted remotely. The primary function

of a roofing membrane is to prevent the entrance of water into the structure.

When collector panels are designed to fulfill this function, leakage at joints

must be considered in the design.

When collectors are mounted over a roofing membrane, consideration should

be given to the growth of fungus, mold, and mildew between the roofing

membrane and the collector and to potential problems in reroofing under

collectors. Also, it is possible, due to extreme temperature differentials,

to cause the formation of ice dams which could in turn back water under

shingles or other roofing materials, causing rapid deterioration. Consideration should be given to the methods of applying non-integral collectors to roof structures and to the choice of waterproofing membrane.

S-515-2. 1.1 Labeling and Technical Data Sheets

Collectors shall be labeled to show the manufacturer's name and address,

model number, serial number , and collector weight (dry). Technical data

sheets shall also be provided which include collector efficiency as measured

according to S-615-2.2, maximum allowable operating and no-flow temperatures

and pressures, minimum allowable temperatures, and the types of fluids which

can and cannot be used.

Commentary: Other data related to the installation and operating conditions

or characteristics is desirable such as the pressure drop across the

collector.

S-515-2. 1.2 Thermal Stability

Collectors shall not exhibit a change in the product of FR

ra (intercept) or

FR Ul (slope) that would result in a 10% or greater decrease in thermal

efficiency for the proposed system design operating conditions when evaluated

in accordance with the following testing procedure.

Testing Procedure :

The parameters FR

to and Fr Ul shall be determined in accordance with the test procedure described in ASHRAE Standard 93 both before and after exposing

the collector panel assembly to the Exposure Test described below. Both the

before and after collector thermal performance tests (ASHRAE Standard 93)

shall be performed utilizing the same test facility under similar climatic

conditions

.

5-6
Exposure Test:

A. Test specimen shall consist of a complete air or liquid collector panel

assembly.

B. Pre-exposure preparation :

(1) Air collectors shall be sealed and capped with a pressure relief

device set to a value within 10% of the collector manufacturer's

maximum recommended operating pressure. The inlet shall be equipped

with a check valve and desiccant to allow the admission of dry air

if internal pressures of less than one (1) atmosphere occur.

(2) Liquid collectors intended for use in all systems (with or without

draindown) shall be completely filled with clean tap water, following

which the inlet shall be sealed and the outlet provided with a pressure

relief valve set to a value of within 10% of the manufacturer's

recommended maximum operating pressure.

(3) Liquid collectors limited to use in systems that draindown when not

operating shall be completely filled with clean tap water, following

which the water shall be allowed to gravity drain for 15 minutes with

the collector mounted at a 45° tilt angle. The collector inlet

shall then be sealed and the outlet provided with a pressure relief

valve set to a value of within 10% of the manufacturer's recommended

operating pressure.

C . Exposure conditions

Exposure conditions shall consist of 30 days of cumulative exposure to a minimum daily incident solar radiation flux of 1500 Btu/ft^.day as measured in the plane of the collector aperture. The exposure conditions

shall include at least one consecutive four-hour period with a minimum

flux of 300Btu/ft^ *hr . In water filled specimens, this must occur after

water boilout has occurred. The average ambient temperature shall be 80 °F or higher during the 300Btu/ft^ •hr exposure time. The collector shall

be mounted to a rack at a tilt angle such that the incident solar radiation during solar noon is within + 10° of the normal to the plane of the

aperture

.

D. Data records

(1) The exposure conditions including insolation, ambient temperature,

wind velocity, and precipitation shall be recorded to enable determination of the average daily values . Values shall be recorded every

30 minutes during the 300 Btu/ft^-hr exposure.

(2) A regularly scheduled weekly visual inspection shall be made and a record of changes in the physical construction or appearance of the

collector kept.

(3) The results of the pre-test and post-test thermal performance shall

be plotted on the same graph for comparison purposes.

Commentary: The purpose of the "no-flow" test is to identify , in a short

period of time, potential problems with collector materials or construction.

The 30 days do not necessarily have to be consecutive but the test should be

performed on a continuous basis until the solar radiation levels have been

achieved for 30 cumulative days. It is recognized that other heat transfer

fluid materials exist which may be preferred by the manufacturer or designer.

If the test is conducted in a manner other than that prescribed, the collector

specification shall state the specific conditions used during the test and

identify the pertinent limitations regarding collector array installation

5-7
S-515-2 .1.3

and operation. The test procedure is based upon draft versions of a test

method in preparation by ASTM and will be superceded by a consensus test

method as soon as possible.

Outgassing of Materials

Outgassing products or condensates on the cover plate surfaces shall not

contribute to a decrease in thermal performance greater than that specified

after exposure as described in S-515-2. 1.2.

Commentary: Outgassing from components inside the collector could lead to condensation on the underside of the collector cover plate (s) which may

reduce the transmittance of the cover plate (s).

S-515-2 .1.4 Flashing

a. Flashing for collector panel supports that penetrate the primary roof

membrane shall be designed to prevent the penetration of water or melting snow for the life of the roof system.

b. Flashing systems shall be designed to permit minor repairs without

disturbing the roof membrane, collector supports, or collector panels.

c. In general, flashing for roof penetrations shall comply with applicable

Sections of 507-5 and 507-8 of the MPS.

Commentary: Suggested practices for flashing used on no-slope or low slope

roofs and roof penetrations are provided in the National Roofing Contractors

Association's "A Manual of Roofing Practice," 1970.

S-515-2.

2

Cover Plates

S-515-2. 2.1 General

The materials used as glazing for cover plates must meet the following

requirements based on materials properties as well as safety considerations.

The safety requirements are made with respect to the physical location of

the glazing and the exposure risk of persons nearby.

S-515-2. 2.1.1

Commentary : Appendix table B-l lists properties of a number of materials

that have been used for cover plates.

Structural Requirements

All glazing materials shall be of adequate strength and durability to withstand the loads and forces required by Section S-601 of this document.

S-515-2 . 2 J. . 2 Types of Applications

Applications include windows which act as cover plates for solar collectors,

both integral with dwelling construction and freestanding components.

a. Glazing materials other than those specified in b or c below, shall

meet the intent of the requirements for glazing in MPS Section 508-8.3.

Commentary: Consumer Product Safety Act, Part 1201 , was published in

the Federal Register January 6, 1977 and will become effective on July 6, 1977 (except for fire retardant glazing required by ordinance

for which the effective date is January 6, 1980). This standard contains

mandatory safety standards for architectural glazing materials.

5-8
Film-type glazing materials for the outermost cover plate, if unsupported,

may he unacceptable if they can he deflected under load, e.g., a person's

hand pushing against the glazing, may present an opportunity for

exposure of the film (and the person's hand) to hot surfaces such as

the absorber plate. Also, there is a probability of exposure to impact

which may result in tearing of the film.

b. Glazing materials with slopes less than 45° which extend below 6' 0"

(from ground level) shall be safety glazed or otherwise protected

against impact of falling bodies.

Commentary: This commonly refers to glazing on which children may

climb or against which a passerby may fall.

c. Glazing panels which are an integral part of a roof or rack-mounted

system on a roof, not routinely accessible by the occupant, shall meet

the requirements of Section S-601.

Commentary : Annealed, glass or films may be acceptable.

S-515-2.2.2 Codes and Standards

Materials used as glazing for cover plates shall comply with MPS Section

508, Section S-601 of this document and applicable sections of local

building codes and national standards.

S-515-2.2.3 Materials Performance

S-515-2 . 2 . 3 . 1 Thermal Stability

After testing as described in S-515-2. 1.2, there shall be no cracking,

crazing, warping, sagging, or buckling of the cover plate (s) that will

result in premature failure or degradation in collector performance greater

than the design limits.

S-515-2 . 2 . 3 . 2 Ultraviolet Stability

Documentation shall be provided that the cover plate (s) is resistant to degradation by UV radiation that would significantly impair its function

during its design life. In lieu of other documentation, the transmittance of

the cover plate(s) as measured by ASTM E 424-71 shall not significantly

change after exposure using any one of the three aging procedures described

below. The computation of solar transmittance based on the spectrophotometric method in E 424 shall be standarized on air mass 2.

For collectors with multiple covers, the tests below shall be performed with

the cover plates in their design configuration.

Aging Procedure 1

Expose components or materials to simulated solar radiation (such as xenon

arc radiation) for a period of 2000 equivalent sun hours. The exterior

surfaces of components which are exposed to rainfall in service shall be

subjected to a water spray for a period of 5 minutes during each 60 minutes

of the light exposure. For components not exposed to rainfall under normal

operating conditions, the water spray shall not be included in the procedure.

5-9
Aging Procedure 2

S-515-2 .

2

S -515-2.

2

S-515-2.

3

S-515-2.

S-515-2.

3

S-515-2.

S-515-2.

Expose components or materials to concentrated natural solar radiation using

machines such as those referenced in ANSI Z97. 1-1975, paragraph 4.3.2 for a period of 2000 equivalent sun hours. The exterior surfaces of components

which are exposed to rainfall in service shall be subjected to a water spray

for a period of 8 minutes during each 60 minutes of sunlight exposure. For

components not exposed to rainfall under normal operating conditions, the

water spray shall not be included in the procedure.

Aging Procedure 3

Expose components and materials to solar radiation outdoors for twelve

months. The average daily flux of the solar radiation, as obtained by

averaging the daily fluxes over the twelve month period of outdoor exposure,

shall be at least 1,500 Btu/ft^.

3.3 Glass

Where tempered glass is used, it shall meet the requirements of ANSI-Z97.1-

1975 and MPS, Section 508, as specified in S-515-2 . 2 . 1 . 2 of this document.

Other glass cover plates shall meet the requirements for glass as specified

in Federal Specification DD-G-451C (June 15, 1972).

Commentary : Appendix Table B-l contains solar transmittance data and rec- ommended maximum operating temperature for a number of types of cover plate

materials .

3.4 Other Materials

Cover plate materials other than glass shall conform to the requirements

of MPS, Section 513 and the intent of S-515-2 . 2 . 3 . 3. Appendix Table B-l

lists a number of materials that have been used for cover plates.

Absorber Plate

1 General

Materials used for absorber plates shall not degrade to an extent that

collector performance would be reduced below allowable design limits.

2 Materials Performance

2.1 Thermal Stability

Any deformation that occurs in the test described in S-515-2. 1.2 shall not

result in premature failure or degradation in collector performance greater

than the design limits.

Commentary : In addition to buckling, sagging, and warping that can be produced

in the thermal stability test3 consideration should be given to the possibility

that repeated boilout cycles can lead to deformation or rupture of the

absorber plate.

2.2 Erosion/Corrosion

Flow rates shall be maintained below the values listed in Tables S-515-2. 3.2

and 2.3.3 to prevent erosive wear.

5-10
Commentary: The variables which have an important impact on the rate of

erosion/corrosion are:

1) the quantity and size distribution of solids in suspension

2) the flow rate

3) the pipe diameter

4) the oxygen content of the fluid

5) the angle of the change of flow direction

6) the internal surface condition of the pipe

7) the temperature

8) partial obstructions in flow passages which create localized areas of

highly turbulent fluid flow

S-515-2 . 3 . 2 . 3 Compatibility with Transfer Medium

a. The absorber plate or flow conduits shall not be pitted, corroded, or otherwise degraded by the heat transfer medium to an extent that will

result in failure during its design life. In lieu of other documentation

for metals, modifications of tests listed in Table S-515-2. 3.1 shall be

used to demonstrate compliance with this requirement. For materials

other than metals, documentation shall be provided to demonstrate compliance

with S-515-1.4 and this requirement.

Commentary: Two types of heat transfer liquid, aqueous and anhydrous nonaqueous, may be used in the collector system. Generally, corrosion is

associated with aqueous transfer media. However, corrosion could also occur in non-aqueous media under one or more of the following conditions:

1) if the liquid is initially agressive to the containment material

2) if liquid decomposition generates corrosive products

3) if water is initially present in the liquid or contaminates the liquid

once in use.

b. Metallic absorber plates or flow conduits in direct contact with heat

transfer liquids in open systems should generally be used in accordance

with the acceptable conditions listed in Table S-515-2. 3. 2 where

applicable. Generally unacceptable conditions listed in this table should

be avoided. Documentation shall be provided to demonstrate that materials

applications not explicitly covered in Table S-515-2. 3. 3 meet the intent

of S-515-1.4 and S-515-2 . 3 . 2 . 3a.

Metallic absorber plates or flow conduits in direct contact with heat

transfer liquids in closed systems should generally be used in accordance with the acceptable conditions listed in Table S-515-2. 3. 3 where

applicable. Generally unacceptable conditions listed in this table should

be avoided. Documentation shall be provided to demonstrate that materials

applications not explicitly covered in Table S-515-2. 3. 3 meet the intent

of S-515-1.4 and S-515-2. 3. 2. 3a.

Commentary: Tables S-515-2. 3 . 2 and S-515-2. 3. 3 are intended to provide

general guidelines for the selection of metals or alloys for use in

solar collectors . Various alloys of the same base metal may be expected

to show significant variability in resistance to corrosion. Small

concentration changes in a number of chemical species may significantly

change the corrosion behavior of a given material at a given temperature

.

A complete description of this behavior is not possible in this context.

Therefore, generally unacceptable use conditions as stated should be

avoided unless it has been demonstrated that the metal or alloy performs

suitably in the anticipated use condition. Adequate performance is

anticipated for normal operation in generally acceptable use conditions.

The stated generally acceptable use conditions are directed toward normal

operation. Under the conditions of stagnation, where high temperatures

may be encountered, different behavior may occur. It is recommended that

specific tests be carried out to ensure adequate materials performance

in these conditions.

5-11
SAE Report J447a (1964) , Prevention of Corrosion of Metals, provides

guidance in preventing corrosion in aqueous media, but its application

should be tempered by consideration of the special operating characteristics

of solar collectors, e.g., no-flow temperature effects.

Table S-515-2.3.1: Corrosion Test Methods*

Number Title Comment

NACE TM-01-7

1

Autoclave Corrosion Testing

of Metals in High Temperature

Water

Modify to reflect conditions

present in solar system

NACE TM-02-74 Dynamic Corrosion Testing of

Metals in High Temperature

Water

Modify to reflect conditions

present in solar system

NACE TM-02-70 Conducting Controlled Velocity

Laboratory Corrosion Tests

Modify to reflect conditions

present in solar system

NACE TM-01-69 (1972) Laboratory Corrosion Testing

of Metals for the Process

Industries

Describes factors to consider in corrosion testing

ASTM D1384-70 (1975) Corrosion Test for Engine

Antifreeze in Glassware

Modify to reflect conditions

present in solar system

ASTM D2570-73 Simulated Corrosion Testing

of Engine Coolants

Modify to reflect conditions

present in solar system

ASTM D2776-72 Corrosivity of Water in the

Absence of Heat Transfer

* Modification of test procedures developed for purposes other than

collector material testing should adequately reflect all expected

collector conditions including no-flow conditions.

Commentary: Open and Closed Systems

Open systems are those in which air, in addition to that initially in the

transfer liquid, can be absorbed into the liquid by contact with the atmosphere or air entrapped in the system.

Closed systems are those in which the air initially absorbed in the transfer

liquid is not replaced to a significant extent. In a closed system, there

is no exposure of the liquid to the atmosphere except above the expansion

tank (in some cases a nitrogen blanket above the liquid in the expansion

tank may be used); there is no entrapped air in the piping or storage

systems and the expansion tank is isolated from the flow path between the

collector and storage. In addition, liquid leakage requiring frequent make

up is avoided.

5-12
TABLE S-515-2 .3.2 Generally Acceptable and Unacceptable Use Conditions for Metals

In Direct Contact with Heat Transfer Liquids In Open Systems

Generally Unacceptable Use Conditions Generally Acceptable Use Conditions —

Aluminum

1.

When in direct contact with untreated

tap water with pH <5 or > 9

.

2.

When in direct contact with aqueous

liquid containing less electro positive

metal ions, such as Copper or iron or halide ions

.

3. When specific data regarding the

behavior of a particular alloy are not

available, the velocity of aqueous liquid shall not exceed 4 ft/sec.

4. When in direct contact with a liquid

which is in contact with corrosive fluxes

.

1. When in direct contact with distilled

or deionized water which contains

appropriate inhibitors and does not

contact copper or iron.

2. When in direct contact with distilled

or deionized water which contains

appropriate inhibitors and a means of

removing heavy metal ions obtained

from contact with copper or iron.

3. When in direct contact with stable

anhydrous organic liquids

.

Copper

1. When in direct contact with aqueous

liquid containing high concentrations

of chlorides, sulfates or liquid which

contains hydrogen sulfide.

2. When in direct contact with chemicals

that can form copper complexes such as ammonium compounds.

3.

1. When in direct contact with distilled,

deionized or low chloride, low sulfate

and low sulfide tap water.

2. When in direct contact with stable

anhydrous organic liquids

.

When in direct contact with an aqueous liq-

^

j

uid having a velocity greater than 4 ft/sec.—

4.

When in direct contact with a liquid

which is in contact with corrosive fluxes

.

5. When in contact with an aqueous liquid

with a pH lower than 5.

6. When the copper surface is initially

locally covered with a copper oxide film

or a carbonasceous film.

7. When operating under conditions conducive

to water line corrosion.

Steel

1. When in direct contact with untreated

tap, distilled or deionized water with

pH <5 or >12.

1. When in direct contact with distilled,

deionized or low salt content water

which contains appropriate corrosion

inhibitors

.

5-13
TABLE S-515-2 .3.2 (Contd.)

Generally Unacceptable Use Conditions Generally Acceptable Use Conditions 1 /

2. When in direct contact with a liquid

which is in contact with corrosive fluxes.

3. When in direct contact with an aqueous

liquid having a velocity greater than

6 ft/sec. 2/

4. When operating under conditions conducive

to water line corrosion.

2. When in direct contact with stable

anhydrous organic liquids

.

3. When adequate cathodic protection of

the steel is used (practical only for

storage tanks)

.

Stainless Steel

1.

When the grade of stainless steel selected is not corrosion resistant in the

anticipated heat transfer liquid.

2.

When in direct contact with a liquid

which is in contact with corrosive

fluxes

.

1. When the grade of stainless steel se- lected is resistant to pitting, crevice

corrosion, intergranular attack and

stress corrosion cracking in the

anticipated use conditions.

2. When in direct contact with stable

anhydrous organic liquids

.

Galvanized Steel

1. When in direct contact with aqueous

liquid containing copper ions.

2. When in direct contact with aqueous

liquid with pH <7 or >12.

3. When in direct contact with aqueous

liquid with a temperature >55 °C.

1. When adequate cathodic protection of

the galvanized parts is used (practical

only for storage tanks)

.

2. When in contact with stable anhydrous

organic liquids

.

Brass and Other Copper Alloys

Binary copper-zinc brass alloys (CDA 2XXX series) exhibit generally the same behavior

as copper when exposed to the same conditions. However, the brass selected should

resist dezincification in the operating conditions anticipated. At zinc contents of

15% and greater, these alloys become increasingly susceptible to stress corrosion.

Selection of brass with a zinc content below 15% is advised. There are a variety of

other copper alloys available, notably copper-nickel alloys, which have been developed

to provide improved corrosion performance in aqueous environments

.

“The use of suitable antifreeze agents and buffers is acceptable provided they do not promote

corrosion of the metallic liquid containment system. The use of suitable corrosion inhibitors for specific metals is acceptable provided they do not promote corrosion of other

metals present in the system. If thermal or chemical degradation of these compounds occurs,

the degradation products should not promote corrosion.

2 /

The flow rates at which erosion/corrosion becomes significant will vary with the conditions

of operation. Accordingly, the value listed is approximate.

5-14
TABLE S-515-2.3.3 Generally Acceptable and Unacceptable Use Conditions for Metals

In Direct Contact with Heat Transfer Liquids in Closed Systems

Generally Unacceptable Use Conditions Generally Acceptable Use Conditions 1 /

Aluminum

1. When in direct contact with untreated

tap water with pH <5 or >9.

2. When in direct contact with liquid

containing copper, iron or halide ions.

1. When in direct contact with distilled

or deionized water which contains

appropriate corrosion inhibitors.

2. When in direct contact with stable

anhydrous organic liquids.

3.

When specified data regarding the behavior

of a particular alloy are not available,

the velocity of aqueous liguids shall not

exceed 4 ft/sec.

Copper

1.

When in direct contact with an aqueous liq^/l.

uid having a velocity greater than 4 ft/s ecr

When in direct contact with untreated

tap, distilled or deionized water.

2.

When in contact with chemicals that can form copper complexes such as ammonium compounds

.

2. When in direct contact with stable

anhydrous organic liquids.

3.

When in direct contact with aqueous

liquids which do not form complexes

with copper.

Steel

1. When in direct contact with liquid

2 having a velocity greater than 6 ft/sec.—

2. When in direct contact with untreated

tap, distilled or deionized water with

pH <5 or >12.

1. When in direct contact with untreated

tap, distilled or deionized water.

2. When in direct contact with stable

anhydrous organic liquids.

3.

When in direct contact with aqueous

liquids of 5< pH <12.

Stainless Steel

1. When the grade of stainless steel selected

is not corrosion resistant in the anticipated heat transfer liquid.

2. When in direct contact with a liquid

which is in contact with corrosive fluxes.

1. When the grade of stainless steel

selected is resistant to pitting,

crevice corrosion, intergranular attack

and stress corrosion cracking in the

anticipated use conditions.

2. When in direct contact with stable

anhydrous organic liquids.

5-15
TABLE S-515-2 .3.3 (Contd.)

Generally Unacceptable Use Conditions Generally Acceptable Use Conditions —

Galvanized Steel

1. When in direct contact with water with

pH <7 or >12.

1. When in contact with water of pH >7 but <12.

2. When in direct contact with an aqueous

liquid with a temperature >55°C.

Brass and Other Copper Alloys

Binary copper-zinc brass alloys (CDA 2XXX series) exhibit generally the same behavior

as copper when exposed to the same conditions. However, the brass selected should

resist dezincification in the operating conditions anticipated. At zinc contents of

15% and greater, these alloys become increasingly susceptible to stress corrosion.

Selection of brass with a zinc content below 15% is advised. There are a variety of

other copper alloys available, notably copper-nickel alloys, which have been developed

to provide improved corrosion performance in aqueous environments.

The use of suitable antifreeze agents and buffers is acceptable provided they do not

promote corrosion of the metallic liquid containment system. The use of suitable corrosion

inhibitors for specific metals is acceptable provided they do not promote corrosion of

other metals present in the system. If thermal or chemical degradation of these compounds

occurs, the degradation products should not promote corrosion.

The flow rates at which erosion/corrosion becomes significant will vary with the conditions

of operation. Accordingly, the value listed is approximate.

1 /

2 /

5-16
Commentary : Corrosion

Corrosion is a very complex phenomenon in which many parameters are of

importance . In the case of the corrosion of metals likely to he used in

the liquid containment system, parameters of importance are:

the composition of the metals or alloys

the composition of the water, i.e. the concentrations of salts and

dissolved gases and heavy metal ions

the temperature

- the flow rate and the possibility of erosion-corrosion

- system design factors , particularly the presence of galvanic cells or differential aeration cells

- the presence of additives or their decomposition products

Galvanic cells result from contact between dissimilar metals while differential aeration cells are areas where a metal is in contact with the

liquid which has a variable dissolved oxygen content.

1. Water Composition

Water composition has an important effect on corrosion. The composition

of tap water varies substantially from one geographic area to another.

Even within a given area, water composition will vary depending on its source (surface vs. well water) and the time of year. The major variables

include: pH, gas content (Og, COg) , chloride content, sulfate content,

solids content (organic matter) , and conductivity. Because of variation

in water, similar variations in the type and severity of corrosion may

be expected.

la. pH

The pH of the transfer liquid will have an important impact on cor- rosion rates. However, the optimum pH range to achieve minimum cor- rosion of a given material will chanae with termoerature [1 1. Because

varying temperatures occur within a solar heating system and the tem- perature at a given point will change with time, care must be taken

to optimize the pH range. It should be noted that the pH of a system

immediately after filling is not necessarily the equilibrium pH.

lb. O

2 Content of Aqueous Media

Generally, corrosion of metals such as Cu and carbon steel will de- crease with a decreasing amount of Og in aqueous media. In the

absence of Og, measurable corrosion of Cu and steel does not occur. In a closed system, where O

2 will be depleted, the corrosion rate

will become negligible . Corrosion inhibitors should not be necessary

in a completely closed containment system composed of Cu or steel,

if the proper pH is maintained. However, the probability of a closed

system remaining closed is uncertain since the eventual intrusion

of oxygen cannot be discounted. Therefore, the use of corrosion

inhibitors or oxygen scavengers should be considered.

Oxidizing species such as dissolved oxygen act to stabilize the

passivity of the protective film on stainless steel. When stainless

steel is used in the absence of such species, it may be necessary to specify a grade which will provide adequate resistance to corrosion

attack under these conditions.

LI] R. M. Diamant, "The Prevention of Corrosion," Business Books Ltd.,

London, 1971.

5-17
The corrosion of Al may continue even in the absence of oxygen since

an alternative corrosion process can occur. In this process, anodic

dissolution of Al is accompanied lay the evolution of molecular

hydrogen. However, this reaction is expected to he negligible if the

pH is maintained between 5 and 7 in the absence of aggressive ions.

lc. Chlorides

Chloride concentration should be kept to a minimum since the presence

of chlorides in water accelerates corrosion of most metals. Therefore, the metallic collector components selected should be compatible

with the chloride level anticipated in the heat transfer liquid. Aside

from its initial presence in water, there are several potential sources of chloride in a solar unit:

- Residual chloride from pickling treatment of metallic components

.

This may also be a source of sulfate ; while this is a rather unlikely source of these ions, care should be taken that the components

of the system are thoroughly cleaned before assembly.

Chloride from the decomposition of nan-metallic components in the

system.

Chloride from flux used in soldering or brazing components during

installation.

2 . Temperature

The temperature is an important consideration with regard to selection of

containment materials . Corrosion in aqueous media generally increases

rapidly with temperature until the boiling point is approached. In systems

open to the atmosphere, the corrosion rate will tend to decrease due to a sharp decrease in the solubility of oxygen in water at these temperatures.

However, in a pressurized system, from which the dissolved oxygen cannot

escape, corrosion may continue at an accelerated rate.

3. Copper in a Recirculating System

In "once through" systems, copper pipe is usually only connected downstream from iron pipe. Residential plumbing is an example of this. This

practice is carried out because small amounts of copper tend to go into

solution . When these copper ions contact more active metals such as Zn or Al, and to a lesser extent, Fe, they are reduced to copper metal which

subsequently deposits on the metal surface. No such effect is anticipated

for systems utilizing copper and stainless steel. When this occurs, a galvanic cell is set up and rapid corrosion initiates . The presence of

a dielectric pipe joint between Cu and Al or Fe will not alleviate this

problem. Similar action may be expected if Fe deposits on Al.

4. Galvanizing

Galvanizing has long been used to protect iron or steel from corrosion.

Zinc is more active than iron and, when the two are in electrical contact,

will corrode preferentially. Thus, the iron is cathodically protected.

The rate of corrosion of zinc is generally lower than that of iron, so a relatively thin coating may last for quite a long time. However,

there are data indicating that at elevated temperatures approaching 158*F

(70°C), this effect is reversed and the iron corrodes rather than the

zinc. [2]

[2] G. Butler and H. C. K. Ison, "Corrosion and its Prevention in Waters,"

Reinhold Publishing, N.Y., l 966.

5-18
In addition, the corrosion rate of zinc itself increases rapidly in the

temperature range between 131 and 194°F (55 and 90° C). Accordingly, the use of galvanized steel above 13l°F (55°C) should be considered with care.

5. Stainless Steel

While stainless steel is generally regarded as corrosion resistant, it may

be susceptible to intergranular attack, pitting, crevice corrosion or stress corrosion cracking. The corrosion resistance of stainless steel

varies greatly with the grade used and the thermal treatment. Therefore

,

the grade of stainless steel selected should be resistant to corrosion

when exposed to the anticipated heat transfer liquid.

6. Galvanic Coupling

Contact between dissimilar metals in the liquid containment system should

be avoided when aqueous heat transfer media are to be used. However,

physical separation of dissimilar metals may not always ensure against

galvanic corrosion (see commentary on copper in a recirculation system).

7 . Stress Corrosion

Collector components may be subject to substantial residual stresses re- sulting from their fabrication. In addition, thermal cycling during operation may introduce applied stresses. Typical collector designs and

operating conditions may be such that it is virtually impossible to avoid

residual or applied stresses.

Some metals and alloys are susceptible to stress corrosion when stressed

in the presence of contaminants commonly present in water, aqueous fluids,

or in the atmosphere. Therefore, the metals used in collectors should be

limited to those which are not susceptible to stress corrosion when in

contact with the anticipated heat transfer liquid.

8. Expression of the Results of Corrosion Measurements

Corrosion may be localized in the form of pitting, crevice corrosion,

intergranular attack, stress corrosion, or erosion corrosion or it may

be uniform. Localized corrosion is generally more destructive since it

results in perforation in far shorter periods. Therefore, the type of

attack observed should be reported. The measurement technique used in

evaluating the severity of attack should also be consistent with the type

of attack observed. For example, weight loss measurement would not be

completely adequate to assess the degree of damage caused by localized

corrosion. Weight loss measurement may be meaningful when the degree of

localization of attack is described. However, results should also include

pit density, maximum depth of penetration or rate of penetration measurement where appropriate.

ASTM standards G 1-72, G1 6-71, and G 46-76 provide recommended practices

relating to corrosion test evaluation.

S-515-2 . 3 . 2 . 4 Ultraviolet Stability

Organic absorber plates shall not degrade to an extent that will significantly impair their function during their design life when exposed to UV

radiation.

Commentary: Organic absorber plates can crack, embrittle, soften, fade, or undergo other changes that could result in premature failure.

5-19
S-515-2.4 Absorptive Coatings

S-515-2.4.1 General

Materials used for absorptive coatings shall not degrade to an extent that

collector performance will be reduced below allowable design limits.

Cormentary : Appendix Table B-2 lists some characteristics of absorptive

coatings currently in use. Absorptive coatings are generally of two types 3 selective or nonselective . A nonselective coating has an absorptance to emittance ratio near unity whereas in a selective coating3 the ratio is

higher. A selective coating has a high absorptance (a) over the solar

spectrum (.3 to 2.0 \im) with low emittance (z) to reduce thermal radiative

heat losses.

For coatings applied by an electroplating process, as are many selective

coatings, the substrate finish3 plating geometry 3 bath composition, and

current density may influence the properties necessary for optimum solar

applications

.

S-515-2.4. 2 Materials Performance

S-515-2.4. 2.1 Thermal Stability

After testing as described in S-515-2.1.2, there shall be no evidence of

checking, cracking, blistering or flaking of the absorptive coating that

will significantly Impair its function. ASTM methods D 660-44 (1970),

D661-44 (1975), D714-56 (1974) and D772-47 (1975) shall be used to evaluate the above properties.

S-515-2.4. 2. 2 Ultraviolet Stability

Documentation shall be provided that the absorptive coating is not adversely

affected by UV radiation to an extent that will significantly impair its

function during its intended design life. In lieu of other documentation,

the absorptive coating shall not exhibit checking, cracking, blistering or flaking after testing using any one of the three aging procedures described

in S-515-2.2.3.2 in its design configuration.

Comnentary : The above tests shall be performed with a cover plate between

the absorptive coating and the light source (if so designed) to simulate

in-service conditions. The cover plate shall be of the same type and con- figuration as used in an actual collector

.

S-515-2.4. 2. 3 Moisture Stability

Documentation shall be provided that the absorptive coating is not adversely

affected by moisture with which it comes in contact to an extent that will

significantly impair its function during its intended design life. In lieu

of other documentation, the absorptive coating shall not exhibit checking,

cracking, blistering or flaking after testing for 30 days according to ASTM D 2247-68 (1973).

Commentary: Moisture is not expected to come in contact with absorptive

coating in collectors which have a desiccant or in evacuated tube collectors

.

S-515-2.4. 2. 4 Compatibility With Heat Transfer Medium

When absorptive coatings are in direct contact with the heat transfer

medium documentation shall be provided to show that they are not affected

by the medium to an extent that would significantly impair their function

during their design lives. In lieu of other documentation, the absorptive

coating shall exhibit no checking, cracking, blistering or flaking or signs

of erosion after immersion in the fluid transfer medium for 100 hours at the

maximum service temperature according to ASTM D1308-57 (1973)

.

5-20
S-515-2 .

5

Collector Enclosure

S-515-2 .5.1 General

Collector enclosure materials shall be in accordance with applicable

sections of Division 5 and 6 of the MPS.

Protective coatings, where used, shall be in accordance with Section 509-7

of the MPS.

S-515-2. 5.

2

Materials Performance

S-515-2. 5. 2.1 Thermal StabilityAfter testing as described in S-515-2. 1.2, there shall be no cracking or warping of the collector enclosure materials to an extent that would

result in premature failure or degradation in collector performance

greater than the design limits.

S-515-2.

6

Reflective and Antireflective Surfaces

S-515-2. 6.1 General

Changes in reflective and antireflective surfaces due to in-use exposure

shall not result in a decrease in collector performance below the design

limits

.

S-515-2. 6.

2

Materials Performance

S-515-2. 6. 2.1 Thermal Stability

After testing as in S-515-2. 1.2, there shall be no cracking, crazing,

delamination or change in reflectance properties of the surfaces to an extent that would result in premature failure or degradation in collector

performance greater than the design limits.

S-515-2. 6. 2.

2

Ultraviolet Stability

Documentation shall be provided that the reflectance properties of the

surfaces will not be adversely affected by UV radiation to an extent that

will significantly impair their function during their design life.

In lieu of other documentation, the reflectance, as measured for air mass 2 by ASTM E 424-71, method A, shall not decrease by more than 10%

after exposure using any one of the three aging procedures described

in S-515-2. 2. 3. 2.

5-21
S-515-3 ENERGY TRANSPORT SYSTEM

This section includes materials used to transport the heat transfer

medium to a heat exchanger or storage facility and also those necessary

components used to return the heat transfer medium from the heat exchnager

or storage facility to the collector subsystem.

S-515-3 .

1

Applicable Standards for Liquid Systems

3-515-3.1.1 Compliance with MPS

Materials used in the transport system shall be in accordance with Sections

515-3.2, 515-5.1, 515-5.2 and 515-6.4 of the MPS where applicable.

S-515-3. 1.2 Other Standards

Materials used for transporting liquids shall be shown to be in compliance

with applicable standards. Examples of some standards that may be useful

are given in Appendix Table B-4. The standards and specifications for each

component of the piping system shall also be given on plans or specifications.

Commentary: Most of the standards for piping shown in Appendix Table B-4

are the standards normally considered by the model plumbing codes. Designers

may use other ANSI} ASTM, or Federal Standards or Specifications that may

be more appropriate to their particular design.

S-515-3.

2

Materials Performance for Liquid Systems

S-515-3. 2.1 Thermal Stability

Components comprising the transport system shall not be damaged by normal

thermal expansion and contraction of piping materials under in-use con- ditions. Proper pipe hangers and supports and fittings shall be used to allow normal movement of piping. See Appendix Table B-4.

S-515-3. 2.

2

Chemical and Physical Compatibility

a. Materials comprising the transport system shall have sufficient chemical

and physical compatibility with organic materials in the system, such

as sealants and gaskets, to which they are joined or in contact to prevent significant deterioration.

b. Materials comprising the piping or transport system shall have sufficient

chemical and physical compatibility with the heat transfer liquid to prevent significant corrosive wear and deterioration. (For metals,

see S-515-3. 2. 5)

S-515-3. 2.

3

Erosion/Corrosion

Materials comprising the transport system shall be in conformance with

S-515-2 .3.2.2.

S-515-3. 2.

4

Joints Between Dissimilar Metals

Dissimilar materials joined to form the transport system shall be electrically

isolated from each other unless documentation is provided to demonstrate

that the joints are sufficiently compatible to prevent corrosive wear and

deterioration during their design lives.

5-22
Commentary: Care must be taken to avoid short circuiting of dielectric

couplings . For example - dielectric couplings used to isolate dissimilar

metals which are buried in soil may be ineffective because of contact of

the metals with ground water, or dielectric couplings may be short circuited

through pipe supports connected to metal structures .

S-515-3 .25 Metals

S-515-3.

3

Metals used in the transport system which are in direct contact with heat

transfer liquids shall be used in accordance with the generally acceptable

conditions listed in Tables S-515-2.3.2 or S-515-2.3.3 where applicable.

Generally unacceptable conditions listed in these tables shall not be used.

Documentation shall be provided to demonstrate that material usages not

covered in the tables meet the intent of S-515-1.4 and S-515-3. 2. 3.

Applicable Standards for Air Systems

Design of all warm air heating systems shall be in accordance with the

recommendations of the ASHRAE Guide or applicable manuals of NESCA,

SMACNA, and ARI . Installation shall comply with NFPA Standards 31 and

54 and either NFPA 90A or 90B, as applicable and 515-3.1 of MPS.

S-515-3. 3.1 Size

Air distribution equipment shall be adequately sized to fulfill the heating requirements of the system.

S-515-3. 3. 2 Air filters shall conform to the requirements of UL 900 (ANSI B124 . 1-1971)

.

S-515-3. 3. 3 Heating supply and return air ducts in unconditioned spaces shall be insulated

with materials or have thermal characteristics as specified in 515-3.1 of

MPS.

S-515-4 MECHANICAL SUPPORTING DEVICES

S-515-4.1 General

Mechanical supporting devices including support devices for roof, wall, or remote mounted collectors shall be designed and constructed of materials in

accordance with Section 500 of MPS.

S-515-4. 2 Applicable Standards

Materials used in mechanical supporting devices shall be in accordance with

the following sections of MPS.

Wood Section 506

Wood subject to termite

damage

Section 502

Concrete Section 503

Masonry Section 504

Metals Section 505

Coatings Section 509-7

5-23
S-515-4~3 Pipe and Duct Hangers

Pipe and duct hangers, used to support insulated pipes or ducts, shall

be designed to avoid damaging the insulation material.

Commentary: If pipe or duct hangers are installed over the insulation

material, metal surface plates should he used to avoid damaging the

insulation.

S-515-5 VALVES

S-515-5 .

1

S-515-5.

2

S-515-6

Applicable Standards

Valves shall be shown to be in compliance with applicable standards.

Examples of standards that may be useful are given in Appendix Table B-4.

Valves manufactured to other standards not listed but fulfilling the re- quirements of a particular solar heating system design may be acceptable.

Commentary: Standards for valves usually present pressure-temperature

ratings. Appendix Table B-S presents these ratings as an example for ball

valves, Federal Specification WW-V-Z5a-l975. National standards do not cover all valves useful to solar heating system design. Valves not covered

by standards may be acceptable to HUD if a history of successful usage can

be demonstrated by the valve manufacturer or solar heating system designer.

Material Performance

Valve materials shall be compatible with the heat transfer liquid as re- quired in S-515-1.4 and S-515-3.2.

PUMPS AND FANS

S-515-6. 1 Applicable Standards

a. Centrifugal, rotary and reciprocating pumps shall be in compliance with

the requirements of the Hydraulic Institute [1].

Commentary: A Hydraulic Institute Standard defines the product, material, process or procedure with reference to one or more of the following : nomenclature3 composition, construction, dimensions, tolerance, safety, operating characteristics, performance, quality, rating, testing and service for which designed [1].

b. Fans shall comply with the applicable standards of the AMCA or HVI and

shall be tested, rated and labeled accordingly.

S-515-6. 2 Material Performance

Pump materials shall be compatible with the heat transfer liquid as re- quired in S-515-1.4 and S-515-3.2.

[1] Hydraulic Institute, 1230 Keith Building, Cleveland, Ohio 44115

HYDRAULIC INSTITUTE STANDARDS FOR CENTRIFUGAL, ROTARY & RECIPROCATING PUMPS,

thirteenth edition, 1975. Library of Congress Card No. A56-4036

5-24
S-515-7

S-515-7 .

1

S-515-7.

2

S-515-7.

3

S-515-7.

4

S-515-7. 4.

S-515-7. 4.

THERMAL STORAGE UNITS

Thermal storage units are defined as any container, space or device which

has the capacity to store thermal energy or transfer media (liquid or solid) containing thermal energy for later use.

General

Thermal storage units shall be of sufficiently durable material to fulfill

the heating storage requirements of the system for the intended design

life of the storage unit.

Applicable Standards

Applicable standards for thermal storage materials are presented in Appendix

Table B-6. The thermal performance of storage units can be evaluated using

ASHRAE 94.

Labeling

Pressurized thermal storage containers shall be labeled in accordance with

515-1.2 of the MPS. In addition, labels shall list the maximum operating

pressure and temperature and minimum operating temperature.

Materials Performance

1 Contamination

Thermal storage tank materials, including any interior protective coatings

and the heat storage medium used, shall not impart toxicity, undesirable

tastes, or odors to either air or water intended for human consumption.

For liquid system, the requirements of the U. S. Public Health Service

Drinking Water Standards shall apply.

2 Materials Compatibility

a. Materials comprising the thermal storage system shall not cause corrosive wear and deterioration which results in premature failure or degradation in storage performance greater than the design limits.

b. Metals used in the thermal storage system which are in direct contact

with heat transfer liquid shall be in accordance with the generally

acceptable conditions listed in Tables S-515-2.3.2 or S-515-2.3.3,

where applicable. Generally unacceptable conditions listed in these

tables shall not be used. Documentation shall be provided to demonstrate that material usages not covered in the tables meet the intent

of S-515-1 . 4 and S-515-7. 4. 2a.

5-25
S-515-8

S-515-8 .

1

S-515-8. 1.

S-515-8.

2

S-515-8. 2.

S-515-8. 2.

HEAT TRANSFER FLUIDS

General

The heat transfer fluid shall be of sufficient stability to perform its

intended heat transfer functions for the intended life of the fluid. The

heat transfer fluid shall not cause premature failure or degradation in a system performance exceeding the design limit for those parts of the

solar energy system with which it comes into contact.

Commentary: Appendix Table B-7 presents a partial listing of properties

of several types of heat transfer liquids .

1 Labeling

The provisions of the Federal Hazardous Substances Act (1971) shall apply

to heat transfer fluids. In addition, heat transfer media classified

as combustible shall be labeled as such.

Emergency first aid instructions shall be included on the label of toxic

heat transfer fluid containers. A technical data sheet shall be provided

with all heat transfer fluids which contains the following information.

Service temperature range

Viscosity over service temperature range

Freezing point

Boiling point

Flash point

Auto ignition temperature

Specific heat

Vapor pressure over service temperature range

Instructions for inspection, treatment and disposal of fluid

Emergency first aid instructions.

For toxic fluids, a list of the chemical components of the fluid shall be

available expressed in mg. /liter. This list shall include any substances

which comprise more than 0.10% of the medium.

Toxic and Combustible Fluids

1 General

Heat transfer fluids which require special handling (e.g., toxic, com- bustible, corrosive, explosive, etc.) shall not be used unless the systems

in which they are used are designed to avoid unnecessary or unreasonable

hazards; see Section S-615-10.1.

2 Flash point

Temperatures attained by fluids in solar systems under operating and no flow conditions shall not exceed a temperature which is 100°F below the

flash point of the fluid. In no case shall a liquid with a flash point

below 100°F or a flammable gas be used. Flash point shall be determined

by the methods described in NFPA No. 321, Basic Classification of Flammable

and Combustible Liquids.

5-26
S-515-8 . 2

.

S-515-8 .

3

S-515-8. 3.

S-515-8. 3.

S-515-8. 3.

Commentary: NFPA No. 321 (1973) defines Flammable Liquids as those with

flash points below 1002F and Combustible Liquids as those with flash points

at or above 100°F. This seation prohibits the use of flammable liquids

(flash point below 100°F) and permits the use of combustible liquids

(flash point at or above 100°F) under prescribed conditions. In common, non-technical usage, the term flammable liquid frequently refers to any

liquid with a flash point, including liquids classified as combustible.

3 Atmospheric Concentration of Toxic Materials

The concentration of the vapor of the heat transfer medium in the building's

interior atmospheric environment shall not exceed l/10th the threshold

limit value (TLV) for that particular medium in an 8-hour period.

Commentary: The TLV is primarily concerned with industrial exposures

.

Because routine household exposure could be for much longer time periods,

the l/10th value of the TLV is recommended. TLV's are under continuous

review; a list of currently adpoted values is published by the American

Conference of Government Industrial hygienists

.

Materials Performance

1 Changes in the Heat Transfer Fluid

Except when such changes are allowed by the design of the system, the

heat transfer fluid shall not freeze, give rise to excessive precipitation,

give rise to sludge, asphaltic or resinous deposits or coatings, otherwise

lose its homogeneity, boil, change pH or undergo changes in viscosity outside the design range when exposed to its intended service temperature and

pressure range and other intended operating conditions.

Commentary : Some organic fluids may degrade by oarldation in open systems

and thereby be unacceptable for use in such systems while providing

satisfactory service in closed systems.

2 Chemical Compatibility

Heat transfer fluids designed to be used in contact with component

materials shall not cause deterioration which results in premature

failure or degradation in system performance greater than the design

limits . Inhibitors in the concentration used shall be compatible with

all components in the system with which they come in contact.

3 Thermal Stability

The heat transfer fluid shall not degrade at temperatures up to the

maximum service temperature or cause deterioration of the system components

which results in premature failure or degradation in system performance

greater than the design limits.

Commentary: This maximum temperature will generally be reached under

"no-flow" conditions. Appendix Table B-7 includes data for a number of

typical transfer liquids. Some fluids may decompose somewhat at elevated

temperatures . For example, ethylene glycol can degrade to form organic

acids. Buffers are usually included with such liquids to control the

pH. It may be desirable, if fluids decompose with time, to change the

fluids periodically

.

5-27
S-515-9 HEAT EXCHANGERS

S-515-9 .

1

General

When nonpotable liquid is used in a solar energy system to transfer

heat to domestic (potable) hot water, the design of the heat exchanger

shall be such that either a minimum of two walls or interfaces are maintained between the non-potable liquid and the potable water supply or protection is provided in such a manner that equivalent safety is provided

Commentary : Double wall heat exohanger designs are one way of meeting

the intent of this criterion. When double wall heat exohanger designs

consisting of two single wall heat exohangers in combination with an intermediary potable heat transfer liquid are used, leakage through one of the walls would result in a single wall configuration. Although this

design is considered to meet the intent of this criterion} there are several other designs that avoid this problem.

The use of single wall configurations which solely rely upon potable

water pressure to prevent contamination is not considered to be an acceptable solution. Similarly} extra thick single walls are not

considered to meet the intent of this criterion.

For approval of other than double wall designs, the procedures described

in S-101 should be utilized.

S-515-9.

2

Applicable Standards

Heat exchangers shall be in compliance with the applicable standards

given in S-515-9. 2.1 and S-515-9. 2. 2. Exchangers manufactured to other

standards not listed but fulfilling the requirements of a particular

solar heating system design may be acceptable.

S-515-9. 2.1 Tubular Heat Exchangers

Tubular heat exchangers shall be in compliance with the appropriate

requirements of TEMA.

S-515-9. 2.

2

Heating Coils

Forced circulation air-heating coils shall be in compliance with the

requirements of ARI Standard 410.

S-515-9.

3

Material Performance

Heat exchanger material shall be compatible with the heat transfer fluid

as required in S-515-1.4 and S-515-3.2.

5-28
S-515-10 GASKETS AND SEALANTS

S-515-10 .

1

Applicable Standards

Caulking and sealants shall be in accordance with 507-6 of the MPS, where

applicable. Gaskets which seal pressurized systems , shall withstand the

maximum service pressure when tested in accordance with ASTM D 1081-60 (1974).

Commentary: Since gaskets and. sealants used in solar systems may not be

adequately covered by existing specifications. Appendix Table B-8 is

included to serve as a guide in selecting specific sealing materials.

S-515-10.

2

Materials Performance

S-515-10. 2.1 Thermal Stability

Gaskets and sealants included in the test described in S-515-2.1.2 shall

not exhibit cracking, loss of elasticity, outgassing, or loss of adhesion

sufficient to impair their function at the completion of the test.

Commentary: A potential problem with sealants and gaskets used in collectors

is that during no-flow conditions outgassing may occur with the outgassing

products being deposited on the interior surface of the cover plate. Such

deposits can reduce the transmittance of the cover plate.

S-515-10. 2.

2

Chemical and Physical Compatibility

a. Gaskets and sealants shall be chemically and physically compatible

with the substrates to which they are joined.

Commentary : Compatibility of gaskets and sealants with substrates may

be evaluated in the process of testing materials for compliance with

the Federal Specifications listed in Appendix Table B-8.

b. Documentation shall be provided to show that gaskets and sealants in

direct contact with the heat transfer fluid are not degraded by the

fluid. In lieu of other documentation, gaskets and sealants which

are in direct contact with heat transfer fluid shall not exhibit significant expansion, cracking, loss of elasticity or loss of adhesion

when immersed for 100 hours in the heat transfer fluid at the maximum

service terperature. ASTM D 471-75 or F 146-72 shall be used as a guide in performing these tests.

S-515-10. 2.

3

Ultraviolet Stability

Gaskets and sealants that are normally exposed to UV radiation in service

shall not be adversely affected by such radiation. Documentation shall

be provided demonstrating that such materials are capable of withstanding

exposure to sunlight for their design lives without functional impairment.

Commentary : Data obtained under ambient environmental exposure conditions

will be accepted if data obtained under in service conditions is unavailable

.

Gaskets of ethylene propylene diene monomer (EPDM) rubber or silicone

rubber are examples of materials that may be appropriate for these

applications

.

5-29
S-515-11 INSULATION/THERMAL AND MOISTURE PROTECTION

S-515-11. 1 General

These requirements apply to both fixed and movable insulation installed

in conjunction with or as an integral part of the solar system. Materials

used for insulation shall be of sufficient proven effectiveness and durability under the expected operating conditions to assure that required

design conditions concerning heat losses, sound control and fire rating

are attained. Insulation in contact with the ground shall not be adversely

affected by soil, vermin or water. Insulating materials shall be in accordance with 507-3 of the MPS and S^OI-S. Insulating materials for air

ducts shall be in accordance with S-515-3.1. Materials used for waterproofing shall be in accordance with Section 507-1 of the MPS. Materials

used for vapor barriers shall be in accordance with Section 507-2 of the

MPS.

Commentary: When movable insulation is used in passive systems, design

considerations should be given to ensure protection of the insulation

from structural damage, degradation due to weather or other degrading

factors .

S-515-11. 1.1 Flame Spread Classification

The flame spread classification index for all insulation materials shall

not exceed the following values:

Plastic Foam 25

Loose Fill Insulation 50

Other Insulation Material 150

The ASTM E84 flame spread test method shall be the basis for evaluating

the surface burning characteristics of the insulation materials. Where

fibrous blankets with facings are to be used, the surface burning characteristics of the complete faced insulation blanket shall be measured.

Commentary: No single test is sufficient to provide a full estimate of

performance of a product in a fire. Plastic foams and loose fill insulation are difficult to evaluate in ASTM E -84. The requirement of

Flame spread classification of 25 maximum for plastic foams and 50 for

loose fill insulation will provide as much safety assurance as is possible

with current test methods. Such a classification shall not be construed

as the equivalent of "noncombustible . " Many insulation materials, including those consisting of cellulose, plastic foam and fibrous glass

(containing organic binder) are combustible materials which will bum and

release heat, especially when exposed to continuous large fire sources.

S-515-11. 1.2 Flame Resistance Permanency

Chemical retardant insulations shall retain their flame resistance throughout their service lifetime. The procedures and equipment specified in

ASTM C739-73, Section 10.4, "Flame Resistance Permanency" shall be used

in judging the effect of aging on the permanence of any flame retardants

used during manufacture.

5-30
S-515-11 .

2

Materials Performance

S-515-11 .2.1 Collector Insulation

S-515-11. 2. 1.1 Thermal Stability

Collector insulation shall not degrade at the maximum service temperature

to an extent which results in premature failure or degradation in

collector performance greater than the design limits.

After testing as described in S-515-2.1.2, there shall be no swelling

or other dimensional changes in the collector insulation, outgassing or physical changes resulting in the decrease in thermal performance in excess of that permitted in the test.

Commentary: Organic materials found in insulation have been known to evolve from collector insulation during system operation, leaving a coating on the cover plates which impairs collector performance . Normally,

the insulation nearest the absorber plate is exposed to temperatures

higher than insulation near other parts of the collector. It may be

possible to use one type of insulation adjacent to the absorber plate and

another type in areas of the collector which wilt not be exposed to extreme temperatures . Fiberglass insulation with binders can be preheated to expel volatiles prior to use in collectors . If such pretreatment is used, the upper temperature limit becomes somewhat higher.

S-515-11. 2.

2

Pipe or Duct Insulation

Pipe or duct insulation shall be sufficiently stable at the maximum

temperature to which it will be exposed in service.

Commentary : General practice for the use and protection of pipe

insulation is described in the ASHRAE Handbook of Fundamentals

.

S-515-11. 2.

3

Storage Subsystem Insulation

If insulation whose thermal properties are affected by water is used,

the insulation shall be protected in accordance with S-515-11. 1.

S-515-12 CATCH BASINS

S-515-12 .

1

General

Catch basins shall be of adequate size and construction to fulfill their

intended functions and be constructed of materials in accordance with

Section 515-5 of MPS.

S-515-12.

2

Materials Performance

S-515-12. 2.1 Materials Compatibility

Catch basin materials which are jointed to or in contact with other

materials shall have sufficient chemical and physical compatibility

with those materials to prevent deterioration.

S-515-12. 2.

2

Coating

The catch basin coating, when used, shall not be significantly deteriorated

during its design life by weathering or by the transfer medium with

which it comes in contact.

5-31
S-515-13 ORGANIC COUPLING HOSES

S-515-13 .

1

Materials Performance

S-515-13. 1.1 Thermal Stability

Organic coupling hoses included in the test described in S-515-2.1.2

shall not exhibit cracking, loss of elasticity, or embrittlement at the

completion of the test that will significantly impair their function.

Commentary: The selection of coupling hoses and clamps is quite critical.

Many failures have been noted due to the clamping of hoses with screw or spring-type clamps, exposing the hose to high temperatures which tend to vulcanize the area beneath the clamp, causing it to lose resiliency and

begin to leak. Further tightening of the clamps will temporarily stop

leakage but further vulcanizing will occur with the end result being a hard non-resilient ring under the clamp which can no longer be tightened

to prevent leakage. Silicone rubber hose is one of the few materials

which have been tested and tend to maintain their resiliency with no tendency to take a thermal set. The silicone rubber hoses, however,

tend to be so pliable that screw-type clamps with perforated bands should

not be used as it is possible to extrude the material through the perforations in the band. If this material is used, smooth band clamps

should be utilized.

S-515-13. 1.2 Ultraviolet Stability

Organic coupling hoses which are exposed in service to UV radiation shall

not be adversely affected by the radiation. In lieu of other documentation,

organic coupling hoses shall not exhibit significant cracking, loss of

elasticity or embrittlement after 500 hours exposure as described in

ASTM D750-68 (1974)

.

S-515-13. 1.3 Compatibility with Heat Transfer Fluid

Documentation shall be provided to demonstrate that organic coupling

hoses which are in direct contact with heat transfer fluids are not

significantly degraded by the fluids. In lieu of other documentation,

the hoses shall not exhibit cracking, loss of elasticity or embrittlement that will significantly impair their function when tested for 100

hours at the maximum service temperature according to ASTM D471-75 or F146-72

.

Commentary: SAE Standard J20e (1974) covers coolant system hoses for

automobiles. For solar systems using glycol liquids, this SAE Standard

may be applicable for demonstrating compliance with S-515-13. 1 . 3. It

is expected, however, that hoses in solar systems will be exposed to more strenuous conditions than automobile hoses.

S-515-13. 1.4 Compatibility with Piping Materials

Organic coupling hoses which are used to join piping shall be compatible

with the piping.

S-515-13. 1.5 Ozone Degradation

Documentation shall be provided to demonstrate that organic coupling

hoses which are exposed in service to the environment are not significantly

degraded by ozone in the air. In lieu of other documentation, the hoses

shall exhibit no cracking or loss of elasticity that will significantly

impair their function when tested for 100 hours to an ozone atmosphere

of 50 + 5 pphm/volume at 23° according to ASTM D1149-64 (1970)

.

5-32
TABLE OF CONTENTS

Page

CHAPTER 6 CONSTRUCTION

S-600 GENERAL 6-3

S-600-1 Labeling 6-3

S-600-2 Alternate Construction 6-3

S-600-3 Installation, Operation and Maintenance Manual 6-3

S-600-4 Replacement Parts 6-4

S-600-5 Maintainability of Systems and Subsystems 6-4

S-600-6 Safety and Health Requirements 6-5

S-601 GENERAL STRUCTURAL REQUIREMENTS 6-7

S-601-1 General 6-7

S-601-2 Design Dead Loads 6-7

S-601-3 Design Live Loads 6-7

S-601-4 Wind Loads 6-8

S-601-5 Snow Loads 6-9

S-601-6 Seismic Loads 6-9

S-601-7 Hail Loads 6-11

S-601-8 Dynamic Loads 6-14

S-601-9 Thermal Distortion 6-14

S-601-10 Collector Cover Plates 6-14

S-601-11 Connections of Collector Frames and/or Other Support Structures . . . 6-14

S-601-12 Storage Tanks 6-14

S-604 MASONRY 6-16

S-604-1 General 6-16

S-607 THERMAL AND MOISTURE PROTECTION 6-17

S-607-2 Waterproofing, Dampproofing and Vapor Barriers 6-17

S-607-3 Building Insulation 6-17

S-615 MECHANICAL 6-19

S-615-1 Thermal Design 6-19

S-615-2 Collectors 6-24

6-1
S-615-3 Mechanical Supporting Devices 6-29

S-615-4 Valves 6-29

S-615-5 Pumps and Fans 6-30

S-615-6 Mechanical Vibration Isolation 6-30

S-615-7 Thermal Storage , 6-30

S-615-8 Heat Transfer Fluids 6-33

S-615-9 Waste Disposal 6-33

S-615-10 Plumbing 6-34

S-615-11 Auxiliary Energy System 6-38

S-615-12 Heat Exchangers 6-39

S-615-13 Air Distribution 6-40

S-615-14 Controls and Instrumentation 6-41

S-615-15 Chimneys and Vents 6-42

S-615-16 Mechanical Ventilation 6’"42

6-2
I CHAPTER 6

CONSTRUCTION

S-600 GENERAL

The provisions of this chapter are applicable to solar energy systems

including heating (H) and domestic hot water (DHW) systems. This chapter

is a supplement to the Minimum Property Standards (MPS) . Building

construction provisions (Chapter 6) of the MPS are applicable in addition

to the items explicitly discussed in this document.

S-600-1 LABELING

Solar heating (H) and/or domestic hot water (DHW) systems, subsystems,

and components shall be labeled or given clear indication of their operating temperatures, pressures, flow direction and filled weight as appropriate in accordance with 515-1.2 of the MPS.

Commentary: Labeling requirements for specific material and products are given in Chapter 5 of this document.

S-600-2 ALTERNATE CONSTRUCTION

Alternate or special methods of construction other than those contained

herein, may be used when found acceptable by established HUD procedures

and Division 613 of MPS and Section S-101 of this ducument.

S-600-3 INSTALLATION, OPERATION AND MAINTENANCE MANUAL

Manuals shall be provided to describe the installation, operation and

maintenance of the H and/or DHW systems.

A complete manual as described in S-600-3. 1, 3.2, and 3.3 shall be provided to the installer or maintenance contractor. A simplified owners manual shall be provided to the building occupant which shall include

as a minimum: system description including a schematic diagram; owner maintenance procedures; and a tabulation of appropriate pressure, temperature and flow information that is indicative of system performance.

The owners manual shall also include the names and addresses of manufacturers of all the primary components of the system.

Commentary : It is suggested that each manufacturer of a subsystem should

provide installation, operating and maintenance manuals for each subsystem

he provides, and that he show typical systems using his and other subsystems to complete the whole. The installer, who is responsible for the

complete installation and therefore for the complete system should assemble

all the manuals from the subsystem manufacturers into a complete manual

pertinent to the system. He should add any other information needed for

an understanding of the complete system and its functioning. Control

sequences are determined almost entirely in the field and should be described for the specific installation.

S-600-3 .

1

Installation Instructions

The manual shall include physical, functional and procedural instructions

describing how the subassemblies of the H and/or DHW systems are to be

installed.

6-3
S-600-3 .

2

S-600-3.

3

S-600-4

S-600-5

S-600-5 .

1

S-600-5.

2

These instructions shall include descriptions of both system interconnections

and connections with the dwelling and site.

Ifaintenance and Operation Instructions

The manual shall completely describe the H and/or DHW systems, their

breakdown into subsystems, their relationship to external systems and

elements, their performance characteristics and their required parts

and procedures for meeting specified capabilities.

The manual shall list all parts of the systems, by subsystem, describing

as necessary for clear understanding of operation, maintenance, repair

and replacement, such characteristics as shapes, dimensions, materials,

weights, functions, and performance characteristics. The manual shall

include a tabulation of those specific performance requirements which are dependent upon specific maintenance procedures. The maintenance procedures

including ordinary, preventive and minor repairs, shall be cross-referenced

for all subsystems and organized into a maintenance cycle. The manual shall

fully describe operating procedures for all parts of the system including

those required for implementation of specified planned changes in mode of

operation. The instructions shall provide warning against hazards that could

arise in the maintenance of the system and shall fullv describe precautions

that shall be taken to avoid these hazards.

Maintenance Plan

The manual shall include a comprehensive plan for maintaining the specified

performance of the H and/or DHW systems for their design service lives.

The plan shall include all the necessary ordinary maintenance, preventive

maintenance and minor repair work, and projections for equipment replacement, and should include important pressure, temperature and flow information as checkpoints throughout the system to assist in troubleshooting.

REPLACEMENT PARTS

Parts, components, special tools and test equipment required for service,

repair or replacement shall be commercially available or available from

the system or subsystem manufacturer or supplier.

Commentary: This provision is intended to preclude long periods of system

down-time due to the need for the repair or replacement of parts.

MAINTAINABILITY OF SYSTEMS AND SUBSYSTEMS

Service Complexity

The H and DHW systems and subsystems shall be capable of being serviced

with a minimum amount of special equipment by a trained service technician

using a maintenance manual and common tools.

Commentary: On larger collector installations it may be desirable to make

PROVISIONS FOR SUPPLYING ELECTRICAL POWER AND WATER FOR MAINTENANCE PURPOSES,

Access for System Maintenance

All individual items of equipment and components of the DHW systems which

may require periodic examination, adjusting, servicing and/or maintenance

shall be accessible for inspection, service, repair, removal or replacement

without dismantling of any adjoining major piece of equipment or subsystem.

6-4
S-600-6

S-600-6 .

1

S-600-6.

2

S-600-6.

3

S-600-6.

4

S-600-6.

5

S-600-6.

6

Corrmentary : It is recommended that individual collectors in an array be

replaceable or repairable without disturbing non-adjacent collectors in

the array.

Accessibility as a function of component life is an important consideration.

Some manufactured collector systems and many individually designed systems

are done in such a way that sequential installation is necessary . This can make it very difficult to replace an individual collector without disturbing

the entire array.

SAFETY AND HEALTH REQUIREMENTS

General

The incorporation of solar systems into the living unit shall not create

an environment which is more hazardous to the occupants than that of a conventional living unit. Materials and the construction used in installation of solar systems shall be in accordance with the fire protection

provisions of S-405.

Combustible Liquids

The storage, piping and handling of combustible liquids shall be in

accordance with the Flammable and Combustible liquids code NFPA No. 30.

Protection From Heated Components

Components of solar systems which are accessible, located in areas normally

subjected to occupant traffic and which are maintained at elevated temperatures shall either be insulated to maintain their surface temperatures at

or below 140°F at all times during their operation or suitably isolated.

Any other exposed accessible components that are maintained at temperatures above 140° shall be identified with appropriate warnings.

System Component Clearances

Combustible solids adjacent to solar equipment or an integral part of a solar component shall not be exposed to elevated temperatures which may

cause ignition.

Commentary : Heating of cellulosic materials as well as other combustible

materials over an extended period of time may result in the material reaching and surpassing its autoignition temperature . The most commonly accepted

ignition temperature of wood is 292°F. However, studies hare indicated

that wood may ingite when exposed to a temperature of 212°F for prolonged

periods of time. The ignition temperature of plastics may be above or below those of cellulosic materials. Clearances for HVAC equipment, ducting and piping are discussed in NFPA No. 89M. Where applicable , clearances

specified by a nationally recognized testing laboratory may be used.

Protection Against Over-Pressure and Over-Temperature

The total system shall be protected against excessive pressures and temperatures. Pressures shall be limited as specified in S-615-14.

Personal Safety

Where access for service of cleaning of solar subsystems requires a person

to balance on a narrow or (steeply) sloping surface, provisions shall be

made for securing a life-line, guard-rail or other personal protective

device.

6-5
S-600-6 .

7

S-600-6 .

8

S-600-6.

9

Growth of Fungi , Mold or Mildew

Compoments and materials used in the H and DHW systems shall not promote

the growth of fungi, mold or mildew in accordance with applicable codes,

the test specification of Section 10, UL 181-74 and MPS , Appendix D,

Section E.

Commentary: Special consideration should he given to the presence of

fungi in air handling systems since such micro-organisms are frequently

allergenic.

Protection Against Vermin or Rodents

Solar energy systems (including piping, fixtures, appliances and other

equipment) should not contribute to the entry or growth of vermin of

rodents. Maintenance of physical barriers, minimization of concealed

spaces conducive to harboring vermin or rodents, provisions of access for

cleaning shall be in accordance with applicable codes such as Section 2.13

of the National Standard Plumbing Code .

Protection of Potable Water Supply

The design and installation of the solar system its subsystems and components shall be accomplished in such a manner as to provide complete protection ot the potable water supply. Such installations shall be in

accordance with Chapter 10 of the National Standard Plumbing Code and

other applicable codes (see Section S-615-10)

.

6-6
DIVISION 1

S-601 GENERAL STRUCTURAL REQUIREMENTS

S-601-1 GENERAL

This section contains those supplemental requirements to Chapter 6 of the MPS

needed to cover solar systems which utilize conventional structural materials

(materials covered by the current MPS edition) . Unless specifically

modified herein, the requirements of MPS Chapter 6, apply in addition to the supplemental requirements in this section.

All structural design for solar systems and their mounting structures shall

be based on generally accepted engineering practice. All loading shall be

in accordance with ANSI A58.1 except as shown otherwise in this document

or MPS.

S-601-2 DESIGN DEAD LOADS

In calculating the dead loads for solar systems, the weights of the transfer

liquid in the collector, liquid in storage tank, and liquid in other subsystems and components shall be included, except when using dead load to resist uplift or overturning.

Commentary : Liquids are normally present in systems in which they are the

heat transfer medium and thus are a long term sustained Load where oreep

is a consideration. They aiso effect seismic forces in a fashion simitar

to any other dead load. However, it is possible to remove liquid, thus

they should no be counted on to resist uplift.

S-601-3 DESIGN LIVE LOADS

S-601-3 .

1

Roof Mounted Solar Systems

Resistance to design live roof loads prescribed in Table 6-1.2 of MPS 4900.1

shall not be required for collector panels that are mounted on roofs but

not form an integral part of the roof if adequate access is provided for

service and maintenance personnel. For collectors which form an integral

part of the roof, resistance to the design live roof loads listed in Table

6-1.2 shall be required.

Commentary: The design live loads contained in Table 6-1.2 of MPS 4900.1

constitute minimum loading requirements needed primarily for human safety.

The roof will need to be repaired from time to time; therefore , it must

support the workman making the repairs , regardless of the wind and snow

loading requirements. This is not the case for accessible roof-mounted

collectors; they do not need to support workmen when being repaired. Hence

,

they need only to sustain the required environmental loading (wind, snow

and hail).

S-601-3.

2

Maintenance Loads

All components of the solar energy systems which must support maintenance

personnel shall resist a single concentrated load of 250 lbs. distributed

over a 4 sq. in. area, acting on the installed component in the most critical locations. Special allowance shall also be made for heavy maintenance

equipment, if used.

6-7
S-601-4

S-601-4.1

S-601.4.1.

S-601-4.1.

S-601-4.1.

S-601-4.1.

S-601-4.

2

S-601-4.

3

S-601-4.

4

S-601-4.

5

WIND LOADS

Flat Plate Collectors Mounted on Roofs and Walls

Wind loads on flat plate solar collectors shall be those specified for

roofs and walls in Section 601-6 of the MPS or as modified in paragraphs

S-601-4. 1.1, .2, .3, and .4 below.

1 Flat plate collectors that are mounted with their cover plates and back

surfaces flush with the surface of the roof shall resist the wind loads

that would have been imposed on those areas of the roof covered by the

collectors

.

2 Flat plate collectors mounted at an angle or parallel to the surface of

the roof on open racks shall resist any uplift load caused by the impingement of wind on the underside of the collector. This wind load is in

addition to the equivalent roof area wind pressure and suction loads, and

shall be determined by utilizing accepted engineering procedures which

may include wind tunnel testing. Equivalent roof area wind loads are those wind loads that would have been applied to the areas of the roof

occupied by the collectors. Equivalent roof area wind loads shall be

applied to the outer cover plate of the collectors.

3 In calculating design wind loads for flat plate collectors mounted on roofs,

the internal pressure coefficients, C listed in Table 11, ANSI A58.1

shall be taken as zero for the wind pressure within a collector. Collectors

that form an integral part of the roof structure shall resist the internal

pressures from the inside of the building just as any other roof member.

4 Wind loads on flat plate collectors mounted at an angle to a vertical wall

shall be the same as those required for equivalent roof eave area as stipulated in section 6. 5. 3. 2. 4 of ANSI A58.1. Wind loads on flat plate

collectors mounted parallel to, or integral with vertical walls shall be

the same as those required for exterior walls.

Other Types of Solar Collectors Mounted on Roofs and Walls

Wind loading on other types of solar collectors shall be determined using

the results of accepted engineering procedures including the MPS and ANSI

A58.1 or physical simulation which may include wind tunnel testing.

Roof Wind Loads

Roof loading due to wind effects on flat plate collector and concentrating

collector support structures and/or enclosures must be included not only

in the design of the roof support framing, but also in the design of all

structural elements influenced by these loads.

Ground Mounted Collectors

Wind loading on ground-mounted flat plate collectors and their support

structures shall be determined in the same manner as that for roof-mounted

flat plate collectors. Where flat plate collectors are mounted on open

racks, equivalent roof area wind loads shall be those given for nonenclosed structures as given in section 6. 6, ANSI A58.1, taking into

account local terrain characteristics.

Exposed Storage Tanks

Wind loads on exposed storage tanks shall be determined in accordance with

ANSI A58.1.

6-8
S-601-5

S-601-5 .

1

S-601-5. 1.

S-601-5. 1.

S-601-5. 1.

S-601-5.

2

S-601-5.

3

S-601-6

S-601-6 .

1

S-601-6.

2

SNOW LOADS

Flat Plate Solar Collectors Mounted on Roofs and Walls

Snow loads acting on flat plate solar collectors or caused by their installation shall be those required for roofs as specified in Section 601-5 of MPS

or as modified in paragraphs S-601-5. 1.1, .2, and .3 below.

1 Flat plate collectors that are mounted with their cover plates and back

surfaces parallel to the surface of a roof, and those that are mounted at an angle to the surface of a roof, on open or closed racks in a saw-tooth

arrangement shall support the snow loads that would otherwise have been

imposed on areas of the roof covered by the collectors. Where collectors

are mounted with their cover plates forming steep slopes, shedding of snow from the collector may cause snow to accumulate at the base of the collector

or other hazardous conditions which shall be considered in the design of

the roof.

2 Flat plate collectors mounted at an angle to the surface of a wall, and

supported by the wall, shall be designed to support the same snow loads

as an equivalent roof eave area.

3 Consideration shall be given to the potential local accumulation of snow under flat plate collectors.

Roof Loading

A single or multiple saw-tooth array of collectors may cause severe drifting between each mounted collectors (and under open racks) in addition to the snow load on the cover plates. These unusual snow loads must be determined on the basis of local snow conditions.

Other Types of Solar Collectors

Snow loads on other types of solar collectors shall be determined as specified in the applicable portions of ANSI A58.1 and by accepted

engineering procedures.

SEISMIC LOADS

General

Seismic design requirements for the mechanical and electrical components

of solar energy systems are covered in this section. Architectural and

structural components shall be designed in accord with MPS Sec. 601-9.

The requirements of this section shall apply to the erection, installation,

relocation, or replacement of, or addition to, any mechanical or electrical

component of, a solar system. If elements of the solar energy system are attached to any existing structural element, or if parts of any existing

structural element are modified or replaced with parts different in size

and weight, the element, as well as its connections to the building shall

be re-designed to comply with the seismic design requirements of Section

601-9 of MPS.

Mechanical and Electrical Components

For those buildings required to be designed for earthquake by section 601-9

of the MPS, mechanical and electrical components of solar energy systems

shall resist seismic forces as specified for parts and portions of buildings

in the latest edition of the Uniform Building Code (UBC) [1]. The value of

C

p used in the UBC to establish the seismic force shall be taken from table

S-601-6.

[1] The Uniform Building Code is published by the International Conference

of Building Officials, Whittier, California.

6-9
The design of all connections between the mechanical or electrical com- ponents and the structural frame shall allow for anticipated movements of

the structure. The details of the connections shall be made a part of the

contract documents.

Commentary: Mechanical or electrical components of a solar system are subjected to seismic forces generated by their mass and may also be influenced by interaction with elements of the structural system.

TABLE S-601-6

Part of System Direction of

Force

Value of C —

P 2/

Storage tanks, pressure vessels 0.12 when resting on boilers, furnaces, absorption ground

air conditioners, other equipment 0.20 when connected to. using combustible or high temper- or housed, elsewhere

ature energy sources, electrical in the building.

motors and motor control devides, any

storage tanks, heat exchangers,

pressure vessels

direction

Flat plate and concentrating any 0.20

solar collectors direction

Tranfer liquid pipes larger any horizontal

than 2 l/2 in. in diameter direction 0.12

— For flexible and flexibly mounted equipment and machinery, appropriate values of C shall be determined by a properly documented dynamic analysis, or by dynamic testiRg,

using appropriate excitation spectra approved by HUD. Consideration shall be given

to both the dynamic properties of the equipment and machinery and to the building or structure in which it is placed.

2/ When located in the upper portion of any building where the H^/D ratio is 5:1 or GREATER THE CP VALUE SHALL BE INCREASED BY 50%

Where Hw = height in ft. of the part of the system above the base level of

N THE BUILDING

D = The dimension of the structure in feet in a direction parallel to

THE APPLIED FORCE

6-10
S-601-7 HAIL LOADS

The cover plates, lenses, and reflector surfaces of solar collectors shall

be protected against or resist the perpendicular impact of a single hailstone of the magnitude stipulated below falling at its terminal velocity.

Hail size: D= 0.3d

in which D = hail stone diameter, inches

d = means annual number of days with hail taken from Figure

S-601-7 [1],

Terminal velocities for various hail sizes are given in Table S-601-7. [2],

Compliance with this provision shall be based on documented past hail loading performance or testing using the procedures described in NBS Building

Science Series BSS 23 [3] or analytical procedures acceptable to HUD.

Commentary : The correlation of hail size with mean annual number of days

with hail was determined using data relating the probability of occurrence of hail particle size to the number of days with hail (tabulated in

Ref- [4], and limited statistical information relating the local area covered by a hailstorm3 and the regional area for which statistical data

is compiled. The hail size indicated has a 5% probability of being ex- ceeded in any one year (estimated 20 year recurrence interval) . The hail

requirements in this section are based on available information which does

not contain physical test data. Therefore, local hailstone loading performance should be considered in implementing the requirements of this

section.

The impact from the vertical terminal velocity is used as a measure of the

effect of hail falling with or without horizontal wind. It is possible

that a larger impact could occur on surfaces sloped from 30° to 60° if the

maximum particle diameter occurred simultaneously with a high horizontal

wind velocity perpendicular to the surface. It may be overly conservative

for particles over 1.5" impacting on near vertical surfaces. However} due

to the lack of information on this phenomenon and the low probability of

its occurrence, it is assumed that the terminal velocity gives the best

measure of -impact force consistent with the present state of the art.

The loadings specified in this section to determine collector performance

closely parallel those that conventional asphalt shingles and built up

roofing are expected to withstand for all but the mid-continent hail belt.

[1] Baldwin, J. L., Climates of the United States , U.S. Dept, of Commerce,

Washington, D.C. (1973).

[2] Mathey, R. C., Hail Resistance Tests of Aluminum Skin Honeycomb Panels

for the Relocatable Lewis Building, Phase II , NBS Report 10193,

National Bureau of Standards, Washington, D.C. (1970).

[3] Greenfield, H. , Hail Resistance of Roofing Products , Building Science

Series 23, National Bureau of Standards, Washington, D.C. (August 1969).

[4] Storm Data , U.S. Dept, of Commerce, National Oceanic and Atmosphere

Administration, Environmental Data Service (monthly periodical).

6-11
6-12

from:

Baldwin,

J.

L.,

Climates

of

the

United

States

,

U.S.

Department

of

Commerce,

Washington,

D.C.,

1973.
TABLE S-601-7

Values of weight and terminal velocity in free fall computed for smooth ice spheres.

Diameter Weight Terminal

in gm lb Velocity

f t/sec

1/2 0.98 0.002 51

3/4 3.30 0.007 62

1 7.85 0.017 73

1 1/4 15.33 0.034 82

1 1/2 26.50 0.058 90

1 3/4 42.08 0.093 97

2 62.81 0.138 105

2 1/4 89.43 0.197 111

2 1/2 122.67 0.270 117

2 3/4 163.28 0.360 124

3 211.98 0.467 130

from: Mathey, R. C., Hail Resistance Tests of Aluminum Skin Honeycomb Panels for the

Relocatable Lewis Building, Phase II , NBS Report 10193, National Bureau of

Standards, Washington, D.C., 1970.

6-13
S-601-8 DYNAMIC LOADS

Dynamic Loads resulting from sun tracking solar collectors or other moving

equipment shall be taken into account in the design of the dwelling frame.

S-601-9 THERMAL DISTORTION

Thermal distortion of the mechanical or structural components of the solar

system shall not cause premature failure or degradation in system performance

greater than the design limits.

Thermal distortion of the solar system, including that occurring during

periods of stagnation, shall not cause damage to the system or the supporting

dwelling structure.

Commentary : Expansion coefficient data for cover and absorber plate materials

is listed in Appendix Tables B-l andB-3.

S-601-10 COLLECTOR COVER PLATES

Deflection or local distress of cover plates resulting from the maximum design

loading shall not allow the cover plate to become separated from the unit nor result in degradation in collector performance greater than the design limits.

This shall be demonstrated by analysis or physical simulation.

Commentary: Since wind can come from any direction, there will be maximum

pressure (inward) loading for units mounted on the windward side of an installation and maximum suction (outward) loading for those mounted on the

leeward side (unless shielding is provided). Depending on the installation,

suction loading can, and often does, exceed pressure loading; hence, cover plate retainers must be adequately designed to prevent them from being

separated from the collector frame or induce failure of the cover plate by

suction loading.

S-601-11 CONNECTIONS OF COLLECTOR FRAMES AND/OR OTHER SUPPORT STRUCTURES

When collector frames and/or other support structures are mounted on walls,

roofs, or other weather resistant surfaces, distortion of the frame from

imposed loading shall not cause penetrations or separations of these surfaces such that moisture leaks occur through the weather resistant surfaces.

S-601-12 STORAGE TANKS

S-601-12 .

1

Design and Fabrication

Storage tanks shall be designed and fabricated to standards embodying

principles recognized as good engineering design and fabrication practice

for the materials used. These standards shall include those listed in

appendices C and E of the MPS and others as approved by HUD.

Tanks containing soil or rock like materials shall be designed for lateral

pressures in accordance with accepted principles of soil mechanics.

S-601-12.

2

Testing

Each liquid storage tank shall be tested in accordance with section S-615-10.10

to prove that leakage does not occur. Storage tanks designed to contain

only dry heat storage material need not be leak tested unless a safety hazard

can result from a storage tank failure.

S-601-12.

3

Environmental and Vehicular Loading

In addition to meeting the design, fabrication and test requirements, stipulated in the preceeding paragraphs of this section, storage tanks shall

meet the following loading requirements.

6-14
S-601-12 .3.1 Above Ground

Unsheltered storage tanks shall resist loads resulting from snow, wind, hail,

thermal, and seismic loading. Sheltered (completely enclosed) tanks need

only resist seismic loading.

S-601-12. 3. 2 Underground

Underground tanks shall resist soil and hydrostatic loads and foundation

loads transmitted to them; and they shall be anchored to prevent flotation

resulting from flooding or high ground water level when the tanks are empty.

For sites subject to commercial traffic or heavy truck traffic, storage tanks

shall resist the wheel loads transmitted to them as specified in AASHTO H20-44,

with no impact. For areas subject to other vehicular or human traffic, the

pertinent loads stipulated in the MPS, section 601-4.3 shall be resisted.

Commentary : The criterion specifies the level of vehicular traffic for

which buried components should be designed in cases where heavy vehicular

traffic is anticipated to occur in service for purposes of access. The

H20-44 truck is considered to be representative of load levels associated

with heavy vehicles such as trucks for repair, maintenance, moving, and

delivery of fuel.

6-15
DIVISION 4

S-604 MASONRY

S-604-1 GENERAL

S-604-1 .

1

Termination Height of Masonry Chimneys

Termination height of masonry chimneys shall be in accordance with NEPA 211.

Commentary: The presence of solar equipment may introduce building components

that are elevated above the roof surface more than is usually required, thus

producing wind disturbance at a higher level. The standard of NFPA 211

provides for proper clearance and separation.

6-16
DIVISION 7

S-607

S-607-2

S-607-2.1

S-6U7-3

S-607-3 .

1

S-607-3 •

2

THERMAL AND MOISTURE PROTECTION

WATERPROOFING, DAMPPROOFING AND VAPOR BARRIERS

Waterproofing of Storage Tanks and Reservoirs

Underground thermal storage tanks and unsheltered above ground thermal

storage tanks shall be waterproofed to stop water seepage into the tanks

and tank insulation. See Section 607-2 of MPS

.

BUILDING INSULATION

Areas of Application

Materials used for thermal insulation shall be in accordance with

S-515-11 and may be applied to the following areas: walls, roofs,

ceilings, floors, pipes, ducts, vessels and equipment exposed to the

external environment.

Exposed plastic foam (untreated or fire-retardant treated) , Kraftasphaltic vapor barrier on mineral and organic fiber insulations, and

non-fire-retardant treated loose fill insulation shall not be permitted

in habitable areas unless fully protected from the interior of the

building by a thermal barrier of 1/2 inch gypsum wallboard having a finish

rating of not less than 15 minutes or other approved material having an equivalent finish rating as determined at ASTM E-119. Thermal barriers

shall be installed in a manner such that they will remain in place for a minimum of 15 minutes under the same test conditions.

Installed insulation and vapor barriers shall not make contact with re- cessed light fixtures, motors, fans, blowers, heaters, flues, and chimneys.

Thermal insulation shall not be installed within 24 inches of the top or within 3 inches of the side of a recessed electrical fixture enclosure,

wiring compartment or ballast unless labeled for the purpose. To retain

loose fill insulation from making contact with other energy-dissipating

objects, a minimum of 2 inches of air space should be provided and assured

by the use of blocking.

Commentary: Although a degree of material combustibility is allowed, the

intent is to allow insulating materials which are not more combustible

(or flammable) than existing construction and insulation materials, and

to preclude any increased fire hazard due to the retention of heat from

energy dissipating objects. In areas where occupants are likely to be

engaged in normal activities, the insulation should perform its intended

function without the increased risk of ignition, rapid flame spread, and

heat and smoke generation. Insulation in concealed spaces may be a particular fire problem due to its susceptibility to smoldering and its

inaccessibility for fire fighting.

Insulation Values

Insulation values may vary where they can be shown to improve the overall

energy balance of the building.

Commentary : Section 607-3 of MPS was originally written to conserve energy or minimize the JJ-value of the exterior enclosure. For some solar systems

it may be desirable to vary the U-value in order to collect useful energy

and prevent it from escaping or, at least, to provide a compromise U-value

between the collection and loss of useful energy. An example might be a

6-17
shuttered window which has single glazing. When the shutters are open

the window collects energy and its U-value can he lower than those stated

in 607-3. When the shutters are closed the window conserves energy and

the U-value would fall at or higher than those stated in 607-3.

6-18
DIVISION 15

S-615 MECHANICAL

S-615-1 THERMAL DESIGN

S-615-1.

1

General

The solar energy system shall be capable of collecting and converting solar

energy into thermal energy. Solar thermal energy shall be used, in combinaation with a conventional auxiliary energy source and other components such

as thermal storage or heat pumps to augment the system effectiveness to meet the standards and requirements for space heating and domestic hot water

set forth in Section 615 of MPS. The system shall be capable of dissipating

thermal energy where this function is included in the design.

Commentary: The prediction of system performance should reflect the cumulative degradation in components resulting from environmental or system wear and deterioration. Solar energy systems for residential applications generally

are capable of storing and providing thermal energy to meet at least the

average 24 hour heating load for the peak heating month. The residential

domestic hot water load is generally considered constant throughout the year

for purposes of system design.

S-615-1.

2

Back-up

The thermal energy contribution provided by solar energy shall be backed

up 100 percent with an auxiliary thermal energy subsystem which will provide

the same degree of reliability and performance as a conventional system.

Commentary : The uncertainty in the availability of solar energy during inclement

weather requires complete back-up of the solar energy contribution to meet

comfort and hot water standards.

S-615-1.

3

System Capacity - Space Heating

S-615-1. 3.1 Auxiliary Energy Subsystem

Heat load requirements used to determine the size of the auxiliary energy

subsystems shall be calculated in accordance with the procedures and 97 1/2%

design temperatures described in Section 615-3.1 of MPS.

Commentary: Uncertainties of ±10 percent or more in the calculated heating

load are tolerated in sizing the auxiliary energy subsystem. Thermal load

programs should reflect the energy conserving features of the building

construction and operation such as insulation, thermal windows, actual indoor

temperature and night-time set-back. There are benefits if the back-up method

is designed to minimize the use of a utility supplied, on-line, auxiliary

energy during peak load conditions.

S-615-1. 3.

2

Solar Energy System

a. The solar energy system size shall be based upon monthly average heat

loads determined by a degree-day method using average monthly design

temperature and conditions as the maximum analytical time interval.

Hourly or daily simulation times may be used if detailed local solar

radiation is available. Calculations of building heat loss for use

in sizing the solar energy subsystem shall be performed for the full

heating season using a method at least as sophisticated as described

in Appendix A.

6-19
Commentary: Sinoe the methods of calculating heat losses and heat gain

specified in 615-3.1 and 615-4.2 of MPS may not he detailed enough to predict the performance of the heating and cooling systems for buildings

using passive solar systems other approved methods may be used for making

calculations for passive solar buildings . An example of the considerations

and level of detailed analysis are presented in ASHRAE Standard 90-75

Energy Conservation in New Building Design .

b. The solar energy contribution shall be determined as a percentage of the

dwelling average annual space heating energy requirements. Analytical

simulations or correlations based upon simulations combining the building

heating load, solar system performance and climatic conditions shall be

utilized to predict the average monthly and annual energy contribution

to be provided by solar energy, auxiliary energy and electrical operating

energy as illustrated in Appendix A.

Commentary: Parametric studies have shown that a solar energy contribution of between 30 to 70% for an active system is generally optimum when

cost benefits have been considered. Passive systems may contribute from

5 to l007o depending upon the relationship between the demand/building/

climate.

S-615-1.4 System Capacity - Domestic Hot Water Heating

S-615-1.4.1 Auxiliary Energy Subsystem

The auxiliary energy domestic hot water heating subsystem shall meet the

minimum requirements for storage, draw and recovery shown in Tables 6-15.2

or 6-15.3 of MPS.

Commentary : There are benefits if the back-up method is designed to minimize

the use of a utility supplied, on-line, auxiliary energy service during peak

load conditions . The minimum acceptable hot water storage is listed in the

MPS but generally solar energy DEW systems have a larger storage capacity

than the MPS requirements.

S-615-1.4. 2 Solar Energy System

a. Determination of the average annual energy requirements for solar hot

water heating applications shall be based on average monthly conditions

as the maximum analytical simulation time interval to compare solar

energy system performance with the load.

b. Minimum daily usage shall be as indicated in Table S-615-1.

Commentary: The design shall allow for the higher requirement where the

potential increase in use exists.

c. An average hot water temperature of 140°F and an average source water

temperature of 55°F shall be used for design purposes, if local temperatures are unknown

.

Commentary : A residential DEW design temperature of 140°F is required

by the MPS and is necessary to meet some appliance operating temperatures.

Local source water temperature can vary from 45 to 75°F with climate region

and season.

6-20
Table S-615-1 Daily Hot Water Usage (140°F) for Solar System Design

Category One

and

and Two Family Units ^

Apartments up to 20 Units

Apts, of 7J

20-200 Units

Apts, of 2J

over 200 Units

No. of People 2 3 4 5 6 — —

No. of Bedrooms 1 2 3 4 5 — —

Hot Water /Unit

(gal/day)

40 55 70 85 100 40 35

_!/ Assumes 20 gal. per person for first 2 people and 15 gal. per person for additional

family members*

2/ From: R. G. Werden and L. G. Spielvogel: "Part II Sizing of Servic Water Heating

Equipment in Commercial and Institutional Buildings," ASHRAE Transactions, Vol. 75,

PII, 1969 p. iv.1.1.
d. The solar energy contribution shall be determined as a percentage of

the dwelling average annual DHW energy requirements . Analytical

simulation or correlations based upon simulations including the load,

solar system performance and climatic conditions shall be utilized to predict the average monthly and annual energy contribution to be provided

by solar energy and auxiliary energy as illustrated in Appendix A.

Commentary: Parametria studies have shown that a solar energy contribution

of between 50 and 80% of the DHW load is generally optimum when cost

benefits have been considered.

S-615-1.5 System Capacity Combined Space and Domestic Hot Water Heating Systems

a. The solar energy contribution shall be determined as a percentage of the

combined dwelling average annual space heating and average annual DHW

energy requirements. Analytical simulations or correlations based upon

simulations combining the space and DHW loads, solar system performance

and climatic conditions shall be utilized to predict the average monthly

and annual energy contributions to be provided by solar energy, electrical

operation energy and auxiliary energy as illustrated in Appendix A.

S-615-1.6 Environmental Conditions - Passive Systems

Where normal building spaces are designed to be part of a solar energy

collection, storage, distribution or control system, indoor design conditions

can vary as long as they do not interfere with the normal use of a space.

S-615-1.6.1 Design Air Temperature for Passive System

The air temperature in areas that can be thermally isolated such as halls

and storage, can be designed for fluctuations from 57°F to 83°F [1], Other

areas can be designed for fluctuation from 62 °F to 78°F [1] provided there are provisions for bringing the air temperature up to design conditions

required in section 615-3.1 of MPS when the space is in use.

Commentary : The operation of a passive system is dependent upon temperature

gradiants to get energy into and out of storage and to transport energy

from one location to another. To accomplish this temperature differences

of at least 4°F to 6°F should be allowed in a completely passive system.

Temperature fluctuations are permitted during non-use periods such as night

hours.

S-615-1.6. 2 Radiant Temperatures

The temperatures of various surfaces in a living space, used as part of a passive solar system, shall not exceed the following values:

Floor 78° [1]

Walls up to 6'- 8” 84° [1]

Ceiling and walls up to 6'- 8" 115° [2]

Commentary: When a living space is used as a solar collector, occupants of

that space may experience discomfort from direct solar radiation, from the

longwave radiation emitted by the solar heated glass or from the floor or walls of the space. To achieve the required conditions, means of control may

be necessary such as shutters, draperies or louvered screens.

[1] Grandjean, Etienne, 1973 Ergonomics of the Home , New York, Halstead Press.

[2] Flynn, John E. and Segil, Arthur W. , 1970. Architectural Interior Systems , New York: Van Nostrand Reinhold Co.

6-22
S-615-1 .6.3 Draft

The movement of air through a living space used to transport solar heated

air in a passive system shall not exceed 70 FPM measured in the occupant

zone

.

Commentary : See ASHRAE Standard 55-74.

S-615-1.

7

Protection Against Blockage of Fluid Flow

The entire heat transport system shall be protected to prevent contamination

by foreign substances that could impair the flow and quality of the heat

transfer fluid beyond acceptable limits.

Commentary : The heat transfer fluid passages in solar collectors and some heat exchangers may have small cross sections in which blockage by dirt,

scale, pieces of gasket material, pieces of packing or other foreign matter

in the heat transfer fluid could occur.

S-615-1,

8

System Shutdown

The SHITTDOWN OF THE SOLAR HEATING OR DOMESTIC HOT WATER SYSTEM IN ONE UNIT

OF A MULTI-FAMILY DWELLING SHALL NOT INTERFERE WITH THE FUNCTION OF THESE

SYSTEMS IN ANY OTHER UNIT.

Commentary: This is to permit the shutdown of equipment in an individual

DWELLING UNIT FOR REPAIRS WITHOUT IMPAIRING THE OPERATION OF THE EQUIPMENT

IN OTHER DWELLING UNITS THAT ARE CONNECTED TO THE SAME CENTRAL SYSTEM.

S-615-1.

9

Excess Collected Energy

Provisions for dumping excess thermal energy shall be provided during the

off-peak heating season when required for safe operation of the system.

Commentary: For systems in which it is not practical to shut the collection

system down, the excess energy can be transfered to the external environment

using a heat exchanger or alternate methods.

6-23
S-615-2 COLLECTORS

S-615-2. 1 General Provisions

S-615-2. 1.1 Design Flow Rates

When an array of solar collectors is connected by manifolds, the design

shall assure, or provision shall be incorporated in the manifolds and/or

collectors to balance the flow rate through each collector. The variation

shall not exceed + 20% of the design flow range.

Commentary: An available method of balancing air and liquid HVAC equipment

is described in the National Standards for Field Measurement and Instrumentation: Total System Balance, Vol. 2, No.12173 (Associated Air

Balance Council 2146 Sunset Blvd. , Los Angeles, California 90026). The

method describes procedures and measurements , but does not establish

standard balance values.

S-615-2. 1.2 Tilt and Orientation

The collector shall be installed in a mount capable of maintaining tilt

and orientation to within + 10 degrees of design conditions.

Commentary: A collector tilt angle equal to the latitude plus 10 to 1 5 degrees from the horizontal is generally used to provide maximum collection

during the winter season for space heating applications. However, deviations of + 10 degrees from this value, when using conventional flat plate

collectors, will have little effect as illustrated in Figure S-615-2. 1 which

shows, for a particular example, the effect on annual performance of var- iations of tilt angles for a collector facing south.

A fixed collector tilt angle equal to the latitude or latitude +15 degrees

for domestic hot water applications is typically used to favor winter

heating requirements . This angle will tend to maximize the year-round

performance of domestic hot water heaters.

Conventional flat plate collector orientation should be such that the

effective aperature generally faces south. However, deviations to the

east or west by up to 20° may not result in a significant decrease in

incident radiation as indicated by the example of the influence of air

collector orientation on the solar fraction of total load shown in

Figure S-615-2. 2. Other weather conditions such as morning or evening fog

may influence the deviation from south.

If the optimum tilt angle will seriously interfere with building design

requirements , or will impose extensive additional structural provisions,

tradeoffs for less optimum tilt angles or relocation of the collector where

the optimum tilt angle can be utilized should be considered.

The orientation of concentrating type collectors is a function of the collector acceptance angle design and may require tracking within specific limits.

S-615-2. 1.3 Shading

Shading of collectors shall be considered during the design so that shading

by trees, adjacent collectors or other obstructions is accounted for.

Commentary: On east and west exposures during the entire year, and on south exposures during the winter, the solar altitude may be low enough

to cause direct shading and a resultant loss in collection capability

.

A practical design goal is to limit the reduction in collected useful

thermal energy during the month of peak load to less than 5%.

6-24
Figure S-615-2.1 An example of the effect of Collector Tilt for

a particular System/Climate Combination. 1_/

Figure S-615-2.2 An example of the effect of Collector Orientation

(45° Tilt) for a particular Collector/Climate

Combination. jL/

1/ Balcomb, J.D. , J.C. Hedstrom, B.T. Rogers, "Design Considerations of Air Cooled/

Collector Rock-Bin Storage Solar Heating Systems," presented at the 1975 ISES

Congress, Los Angeles, California, 1 Aug. 1975.

6-25
S-615-2 .

1

S-615-2. 1.

S-615-2 . 1.

S-615-2. 1.

S-615-2. 1.

,4 Dirt Retention

The cover plate(s) shall not collect or retain dirt to an extent that would

significantly reduce its ability to transmit sunlight.

Commentary: The possible collection and retention of dirt by the cover plate

and the effect of retained dirt on collector performance may be significant.

The retention of dirt may depend on the surface characteristics and tilt angle

of the collector. Rainfall and snow melt are generally sufficient to keep

the collector cover plates clean. If periodic scrubbing is necessary for

cleaning, the cover plates should be resistant to damage by abrasion re- sulting from the scrubbing. If the collector is ventilated, provisions should

be made for exclusion of dust by appropriate filters.

5 Cleaning

In designs where the interior surfaces of collector glazing and cover plates or absorber surfaces are not protected against accumulation of

dust or dirt, provisions shall be made to allow cleaning of these surfaces

as frequently as necessary to prevent a significant deterioration of collector performance.

Commentary: On active collectors that are not hermetically sealed or provided with air filters and in passive installations which may hare

large air plenums behind glazed surfaces or combine solar collection with

view provisions, accessability for periodic cleaning is essential to con- tinued high solar transmittance. Selective absorber surfaces must be

kept clean as dust accumulations can change their emittance characteristics.

6 Ice Dams and Snow Build Up

The design of solar buildings and systems shall provide for the possibility

of formation of ice dams and snow build up.

Commentary : In very cold climates, water flowing off a warm collector

may freeze on cold surfaces immediately below it (such as exposed eaves),

thereby forming an ice dam which can cause water to back up under roofing

or into the collector itself. This may be moderated by methods such as elimination of the cold surface or provision of an impervious surface such

as continuous flashing. Snow sliding off a collector may pile up at the

bottom and cover part of the collector . This would have a tendency to reduce the efficiency of the collector and increase the possibility of

thermal breakage of glass in the collector. This may be moderated by

methods such as the provision of space below the collector for snow pile

up or by the installation of heating cables.

7 Mud Splash

The design of solar buildings and systems shall minimize the possibility

of mud splash on collector surfaces.

Commentary: Water running off collectors located close to the ground can

cause mud splashing to coat portions of the collector and reduce its efficiency. Remedies to this include: easy access for cleaning, position of

collectors elevated sufficiently to avoid splashing, or provisions of

gutters or splash free material at the base of the collector.

8 Protection Against Thermal Shock and Pressure

Collectors shall not be damaged or adversely affected by extreme temperature

and pressure that could occur by thermal shock resulting from sudden environmental or fluid flow changes.

6-26
S-615-2

S-615-2

S-615-2,

S-615-2.

S-615-2.

S-615-2.

Commentary: Thermal shook oould result from the passage of hot fluid through

a oold collector or cold fluid through a hot collector during start-up. The

designer should either assure that the materials used in the collector can withstand the extreme temperatures and pressures or provide temperature and

pressure relief from thermal cycling or shock. See S-615-14.

,1.9 Moisture Build-up Control

Means shall be provided to prevent moisture build-up in collectors to an extent that would reduce collector performance below allowable design limits.

Commentary: Moisture build-up in the collector can soak insulation and reduce its effectiveness , leach alkalies out of fiberglass insulation and hasten

its degradation, lead to chemical attack on absorber plates and cause con- densation on cover plates.

Depending on the design, the likelihood of condensate forming on the interior

surface (s) of the cover plate (s) may be high. Desiccants in breather tubes or breather plugs can be used to maintain a dry environment . The desiccants

should be located in such a way that they are not in contact with the collector plate and it is desirable that they be capable of regeneration by

solar energy as the collector builds temperature

.

One additional potential problem with collectors is that, in industrial

atmospheres, the introduction of pollutants in condensate solution may cause permanent etching of the underside of the cover plate (s) or chemical attack

of the absorber over a period of time. Such etching can permanently reduce

the transmittance. Then this possible condition exists, design considerations

must be given to avoid the problem.

,1.10 Access to Components

If routine maintenance or repair of collector components is anticipated,

the collector shall be designed to permit easy access to those components.

Commentary: Some materials such as rubber hoses, joint sealants, exterior

coatings, etc. may have to be replaced periodically . Also, in some geographic locations, the cover plates may have to be cleaned occasionally

.

If materials in the collector are likely to be replaced, repaired or maintained within the design life of the collector, it is important to provide

easy access to those materials.

,1.11 Openings

All openings in the collector enclosure shall be protected to prevent the

entry of insects and vermin.

2 Collector Thermal Performance

2.1 General

This section is intended to cover component and integral collectors which

can be flat plate, concentrating, reflector aided, fixed or tracking types.

2.2 Collector: Component

This type collector can be characterized as a component for an active

solar system requiring the use of powered mechanical equipment to move the

heat transfer fluid (liquid or gas) through the collector. The collector

thermal performance shall be based upon the slope-intercept method of

expressing efficiency for the range of operating conditions including

solar power density, heat transfer fluid temperature, ambient temperature,

wind, solar radiation incident angle, and flow rates, to be used in the

design.

6-27
Commentary : The collector performance characteristics can be measured

using the ASHRAE test method 93-77* for rating solar collectors or

any other method demonstrated to have an overall limit-of-error of less

than +5%. This method provides sufficient efficiency versus operating

condition data to construct a curve normalized for insolation and temperature difference between ambient and heat transfer fluid temperature.

Curves for typical flat black and selective coated absorber panels with

one and two covers are shown in Appendix A for air and water collectors.

Collectors with other geometric, optical or thermal characteristics may

require additional tests to fully describe their thermal performance for

all environmental and operating conditions. The operating electrical

power is recorded and reported during all tests.

S-615-2.2.3 Collector: Combined With Storage

This type of combined component system can be characterized as an active

system with integral construction and operation of the components such

that the solar radiation collection and storage phenomena cannot be measured separately in terms of flow rate and temperature changes. The

system thermal performance is determined by the short term (1 to 3 days)

collection and storage of thermal energy obtained from solar radiation and

the amount of useful energy delivered to the load from storage for part

and full load conditions. Experimental performance data, in terms of heat

collected and stored or delivered to load, shall be provided for the design

conditions including solar power density, heat transfer fluid temperature,

ambient temperature, wind, solar radiation incident angle, and flow rates. The daily and average test period electrical operating requirements are reported with system performance.

Commentary: Although a consensus test method to rate and evaluate these

systems does not exist, the efficiency in terms of converting incident

solar energy into useful thermal energy can be measured and reported as

a function of the specified operating conditions

.

S-615-2.2.4 Passive: Integral Collector, Storage and Building System

A passive integral collector system can be characterized as one in which

the collector and storage components are an integral part of the building.

Auxiliary energy may be used for control purposes but heating is generally

achieved by natural heat transfer phenomena. The thermal performance of a passive, integral collector system can be obtained from a detailed simulation

analysis of the climate, building thermal properties and occupancy thermal

influence

,

Commentary: Roof ponds, modified walls , roof sections with sky lights, or similar applications where solar energy is used to supply a significant

fraction of the building heating requirements, are examples of passive integral

collectors

.

A more detailed simulation of solar heating, building thermal capacitance

and thermal energy control must be included in the traditional building

load determination programs for the design and evaluation of a passive,

integral solar system. Experimental evaluation of the system performance

includes measurement of the climatic conditions, auxiliary energy use and

comfort level for sufficient periods to account for building thermal

capacitance effects (minimum of 7 days and, preferably , monthly or seasonal)

.

*ASHRAE Standard 93-77, "Methods of Testing Solar Collectors

Based on Thermal Performance," American Society of Heating, Refrigerating

and Air-conditioning Engineers, Inc., 345 East 47th Street, New York, N.Y. 10017

6-28
S-615-2 .2.5 Passive: Component (Thermosyphon) Systems

This type collector can be characterized as one in which the collector is

a separate component to collect, convert and transfer the thermal energy.

The thermal performance of individual collector panels can be obtained

from procedures described inSection S-615-2. 2. 2 for active collectors.

System performance is obtained from measurements of incident solar energy

and hot water delivered to the load for extended periods to determine

monthly averages.

Commentary: A thermosyphon water heating system is an example of the application of a passive component type collector where the hot water circulation

results from the change in density of the fluid with temperature.

The movement of a heat transfer fluid by natural convection is achieved by

relatively low pressure differentials . Therefore , it is necessary that pipe

or duct size , shape, distance and elevations are considered in predicting

the performance based upon individual collector panel test data.

S-615-3 MECHANICAL SUPPORTING DEVICES

S-615-3 .

1

Pipe Hangers and Supports

Pipe hangers and supports shall be installed in accordance with the prevailing model plumbing code having jurisdiction in the area.

S-615-4 VALVES

Gate valves or similar valves that open to nearly full pipe bore shall be

used for shut off valves. Globe ball or similar valves shall be used for

flow control.

6-29
S-615-5 PUMPS & FANS

S-615-5 .

1

Applicable Standards

a. Pumps shall be installed in accordance with the requirements of the

Hydraulic Institute. [1]

b. Fans shall be installed in accordance with the recommendations of the

ASHRAE Guide or applicable manuals of NESCA and SMACNA.

c. All moving machinery shall be protected and guarded to comply with the

current safety standards of ANSI B15.1 if such machinery is exposed to other than maintenance personnel.

S-615-6 MECHANICAL VIBRATION ISOLATION

S-615-6 .

1

General Requirements

All operating mechanical equipment shall be isolated by suitable piping

or duct connections and where necessary by isolation pads or foundations

to prevent transmission of noise or vibration. The dwelling shall be

free of objectionable sound as required in HUD circular 1390.2, Noise

Abatement and Control.

Equipment conforming to other sound level criteria referenced in these

standards shall also be acceptable.

S-615-7 THERMAL STORAGE

S-615-7 .

1

General

This section applies to sensible and latent heat type thermal energy

storage devices using gas or liquid as the heat transfer fluid and liquid

or solid as the heat storage medium. The storage medium can be contained

in a separate enclosure, stored at more than one temperature, or can be

a part of the building structure. Some typical storage subsystem arrangements are shown in Appendix C.

Commentary: The interaction between storage temperature and collector

operating efficiency must be considered in the location and operation of

the auxiliary energy source . Auxiliary energy supplied to the storage

medium directly can result in decreased system efficiency . Designs which

enhance normal storage temperature gradients and control the heat transfer

fluid mixing, which use utility supplied, on-line, energy during peak load

conditions or which use solar assisted heat pumps may influence storage

temperature or operation.

S-615-7.

2

Applicable Standards

Thermal storage shall comply with the design standards of MPS Section 615

and the applicable recognized standards given in MPS Appendicies C and E.

Hydraulic Institute Standards for Centrifugal , Rotary and Reciprocating

Pumps , Thirteenth Edition, 1975. The Hydraulic Institute, 1230 Keith

Building, Cleveland, Ohio 44115.
S-615-7 .

3

Thermal Storage Requirements

S-615-7. 3.1 Space Heating

The thermal energy storage capacity for space heating shall not be less

than 500 Btu per square foot of solar collector area for an active system.

The thermal energy storage capacity for space heating shall be not less

than 1000 Btu per square foot of collector area for a passive system. (The

capacity shall be based upon a temperature difference determined from the

lowest temperature that useful heat can be extracted from storage and the

highest practical storage temperature.)

Commentary: A relationship between the load fraction supplied by solar

energy to the storage capacity for liquid and air applications is presented

in Appendix A. Since system efficiency is affected by storage temperature

and capacity_, storage capacity requirements less than those stated may be

justified in terms of the effect on system efficiency . The storage heat

capacity for integral (passive) systems is a function of the thermal coupling

between storage and the load but} because of usual lower storage temperatures

,

a larger heat capacity is desired

,

S-615-7. 3. 2 Domestic Hot Water Heating

The solar thermal energy storage for preheating domestic hot water shall

have a volume capacity not less than the number of gallons shown in

Tables 6-15.2 or 6-15.3 of MPS.

Commentary: Although it is possible to design a hot water storage container

with large temperature gradients permitting the auxiliary energy source to be incorporated in the same container , it is preferred to add the auxiliary

energy after the water has been removed from the solar heated container.

S-615-7. 3. 3 Combined Space and Domestic Hot Water Heating

The thermal energy storage capacity for a solar energy system providing

thermal energy for both space and domestic hot water shall not be less than

500 Btu per square foot of solar collector area.

Commentary : Since system efficiency is affected by storage temperature and

capacityy storage capacity requirements less than those stated may be justified in terms of the effect on system efficiency

.

S-615-7. 3. 4 Thermal Energy Loss

The thermal energy loss from storage containers located outside the

heated dwelling shall not exceed 10 percent of the maximum operating

thermal energy capacity over an average 24 hour winter design day.

Commentary: Thermal energy losses within the heated, dwelling will con- tribute to the heating requirements. However, losses during the summer operation could add to cooling requirements and should be accounted for

in the design. Calculations of the thermal loss from tanks 3 piping3 and

valves can be performed using average fluid and ambient temperatures and

thermal insulation conductivity values with procedures described in the

ASHRAE Handbook of Fundamentals

.

S-615-7. 4 Tank Drainage

Each tank shall be provided with means of emptying the liquid. Each tank

located above grade or floor level shall be provided with a valved pipe

at its lowest point to permit emptying the tank. Each buried tank, including

tanks with a solid storage medium, shall have provisions for utilizing a pump or siphon or other means to allow emptying.

6-31
S-615-7 .

5

S-615-7 .

6

S-615-7.

7

S-615-7.

8

S-615-7.

9

Commentary: Buried storage tanks containing solid storage media may be

subject to leakage or flooding; means should be provided to remove this

water.

Tank Filling

Tanks of large capacity should have an indicator or other means for determining that the tank is full. Tanks should have overflows with outlets

located so that spillage will not run into the building structure or damage the premises. Tanks that do not contain potable water but require

make up water from the potable water system shall be filled by way of an

air gap or other means acceptable to the administrative authority having

jurisdiction

.

Inlet and Outlet Location

The inlet and outlet piping or ducts for thermal storage shall be located

in the container to prevent thermal "short circuiting" of the fluid flow.

Commentary: The collector performance is a function of the fluid temperature, therefore , the storage-to-collectox1 fluid outlet should be

located in the coldest portion of the container such as the lower 5% of

a vertical liquid tank. The inlet should be located in the warmest

storage volume such as the upper 5% of the tank. Inlets and outlets of

liquid containers should be installed to provide flow parallel to the top

and bottom of the tank, respectively, to minimize mixing.

Auxiliary Energy Location

Auxiliary energy heating elements or the inlet of heat transferred from

auxiliary energy sources to the inside of storage devices shall be located

in the warmest practical area of the container.

Commentary : In designs where it is possible to add auxiliary energy to storage, the configuration should be designed to maintain the collector

inlet temperature as low as possible.

Pebble Bed Storage Design

The size, shape and cleanliness of pebbles, when used for storage, shall

be considered in designing the thermal performance and pressure drop.

Commentary : The effectiveness of pebble bed storage is related to the

specific heat and thermal conductivity of the pebbles and the configuration

of the container to achieve a temperature gradient through the bed. Clean,

smooth pebbles are desired to facilitate the passage of air and minimize

maintenance. Additional design considerations and typical performance data

has been reported. *

Protection Against Maximum Temperature, Pressure and Vacuum

Thermal storage shall be protected against maximum temperature, pressure

and vacuum in accordance with the provisions of S-615-14.1.

*ASHRAE Publication, "Applications of Solar Energy for Heating and Cooling

of Buildings," GRP 170.

6-32
S-615-8 HEAT TRANSFER FLUIDS

S-615-8 .

1

Toxic and/or Combustible Fluids

S-615-8. 1.1 General

Requirements for handling non-potable heat transfer fluids are discussed

in Sections S-615-9, Waste Disposal; S-615-10, Plumbing; and S-615-12,

Heat Exchangers, of this document.

S-615-8. 1.2 Detection of Toxic and/or Combustible Fluids

If toxic or combustible heat transfer fluids are used, means shall be provided

for the recognition of leaks and thus the warning of occupants when leaks occur.

Commentary: These substances may be treated in a manner similar to antifreeze

and gases when providing for tell-tale indicators. For instance, antifreeze

agents, such as ethylene glycol, may be treated with non-toxic dyes which distinguish them clearly. Furthermore, if any such materials are to be stored

on the premises, they should be stored in containers which are labeled in

accordance with the Federal Hazardous Substances Act and be protected from easy

opening by children e.g., childproof lids. Safe storage locations should be

provided.

S-615-8. 1.3 Identification

Drains and other designated fluid discharge or fill points in solar systems

at which toxic, combustible, high temperature or high pressure fluids may

be discharged shall be labeled with a warning describing the identification

and hazardous properties of the fluid, instructions concerning the safe

handling of the fluid, and emergency first aid procedures.

Commentary : The original fluid containers will frequently be discarded after

the system is charged which could result in no record of the fluid's properties being retained. The system drain is the point at which the owner or

service personnel are most likely to contact the heat transfer fluid and

permanent labeling should be retained at that point. Identification may be

provided by attaching a tag containing the required information such as may

be supplied by the heat transfer fluid manufacturer

.

S-615-9 WASTE DISPOSAL

S-615-9 .

1

Catchment

Systems utilizing other than air or potable water as a heat transfer fluid

shall provide for the catchment and/or harmless removal of these fluids

from vents, drains or re-charge points as approved by local administrative

code authority. Potable water shall be discharged to suitable drainage

systems connected to the building or site drains. See MPS Section 615-9.

S-615-9.

2

Provision of Containment for Discharge Treatment of Toxic and/or Combustible

Fluids

Adequately sized and protected receptacles shall be provided when toxic and/or

combustible fluids are used in order to collect and store the overflow from:

pressure relief valves, liquids drained from the system when it is being ser- viced, and identifiable leakage. Provisions of MPS Section 615-4.4 shall be

applied

.

Commentary: When a toxic heat transfer fluid is used (see Section S-515-8 . 2)

,

a catch basin must be provided. It must be sufficiently large to accept dilution as required by MPS Section 515-9 before disposal.

6-33
S-615-10

S-615-10.1

S-615-10. 1.

S-615-10. 1.2

S-615-10. 1.3

If the diluted medium is biodegradable through conventional sewage treatment, the diluted medium is to be flushed into the sanitary sewer system

(not the storm sewer system). Consideration should be given to the effect

of flushing solar systems on the "Basic Design Loading" for sewage treatment, Section CS 603, HUD Handbook 4940. 3, Minimum Design Standards for

Community Sewage Systems.

PLUMBING

Handling of Nonpotable Substances

Potable water supply shall be protected against contamination in accordance

with the prevailing model plumbing code having jurisdiction in the area.

Separation of Circulation Loops

Circulation loops of subsystems utilizing non-potable heat transfer fluids

shall either be separated from the potable water system in such a manner that

a minimum of two walls or interfaces is maintained between the non-potable

liquid and the potable water supply or otherwise protected in such a manner

that equivalent safety is provided.

Commentary : Double wall heat exchanger designs are one way of meeting the

intent of this criterion. When double wall heat exchanger designs consisting

of two single wall heat exchangers in combination with an intermediary potable

heat transfer liquid are used, leakage through one of the walls would result

in a single wall configuration . Although this design is considered to meet

the intent of this criterion, there are several other designs that avoid this

problem.

The use of single wall configurations which solely rely upon potable water

pressure to prevent contamination is not considered to be an acceptable

solution. Similarly, extra thick single walls are not considered to meet

the intent of this criterion

For approval of other than double wall designs, the procedures described

in S-101 should be utilized.

Identification of Nonpotable and Potable Water

In buildings where dual fluid systems, one potable water and the other

non-potable fluid, are installed each system may be identified either by

color marking or metal tags as required in ANSI A13. 1-1956 [1] or other

appropriate method as may be approved by the local administrative code

authority. Such identification may not be required in all cases.

Backflow Prevention

Backflow of nonpotable heat transfer fluids into the potable water system

shall be prevented in a manner approved by the local administrative code

authority.

Commentary: The use of air gaps and/or mechanical backflow preventers

are two possible solutions to this problem. The following are some recognized

standards that may be acceptable to the local administrative code authority

Complete titles are given in Appendix E.

[1] Scheme for the Identification of Piping Systems, ANSI A13 . 1 - 1956.

6-34
S-615-10 .

2

S-615-10.

3

S-615-10.

4

S-615-10.

5

S-615-10.

6

S-615-10.

7

S-615-10. 7.1

S-615-10. 7.

2

S-615-10. 7.3

Air gaps

Backflow preventers

- ANSI-A112. 1 .

2

- FCCCtiR Chapter 10

IAPMO PS 31-74

AWWA C506-69

A.S.S.E. 1011

A.S.S.E. 1012

A.S.S.E. 1013

A.S.S.E. 1015

A.S.S.E. 1020

ANSI-All 2. 1.1

Pipe Sizing

Pipe sizing shall be in accordance with recognized methods.

Expansion and Contraction

Provisions for expansion and contraction without undue strain or distortion

shall be made as required by means of offset branches, expansion compensators,

or flexible pipes. Piping shall be adequately supported to prevent undue

strain on the flexible pipes and branches.

Protection Against Maximum Temperature, Pressure and Vacuum

Systems shall be protected against maximum temperature, pressure and vacuum

in accordance with the provisions of S-615-14.1.

System Drainage

Liquid systems shall be designed so that complete isolation and drainage

of all system components, piping, or storage tanks can take place in a reasonable length of time for maintenance purposes. See S-615-7.4, Tank

Drainage

.

Protection from Scalding

All domestic hot water systems shall be equipped with means for limiting

temperature of the hot water for personal use at fixtures to 140° F.

Provision of Valves and Fittings

Shutoffs

All domestic water heaters and water heating systems shall be va-lved to provide shutoff from the cold water supply systems.

Water Hammer Arresters

When a liquid is used as the transfer fluid in a solar energy system and

quick-closing valves are employed in the design, the piping system shall be

able to control or withstand potential "water hammer". Water hammer

arresters shall be in compliance with local codes.

Air Bleeds

When liquid heat transfer fluids are used in solar heating systems, the

systems shall be provided with suitable means for air removal.

6-35
S-615-10 .

8

System Cleaning

After completion of piping tests and after all equipment has been installed,

the entire liquid systems shall be thoroughly flushed to remove sediment,

dirt and loose scale, etc. Strainers shall be cleaned or replaced. During

the flushing of the system, the collectors must be disconnected or bypassed

to preclude passage of debris through, the collectors.

S-615-10. 9 Expansion Tanks

Adequate provisions for the thermal expansion of solar heat transfer and

storage liquids that would occur over the service temperature range shall

be incorporated into the solar heating system design.

Expansion tanks shall be sized in accordance with the recommendations of

ASHRAE Guide and Data Book.

S-615-10. 10 Leak Testing

S-615-10. 10 . 1 Pressurized Tanks and Systems

Those portions of heating systems which contain liquid heat transfer fluids

and are not directly connected to the potable water supply shall not leak

when pressures of not less than 1-1/2 times their design pressure are imposed for a minimum of 15 minutes [1] . The pressure shall be gradually

applied and sustained for a sufficient length of time to permit examination

of all pipe joints for leakage. Those portions of the system using

domestic hot water shall not leak when tested in accordance with the code

having jurisdiction in the area where the system is used. In areas having

no building code, a nationally recognized model code shall be used [1].

S-615-10 . 10 . 2 Non-Pressurized Tanks

Non-pressurized tanks shall be tested visually for leaks by filling tanks

with water.

Commentary: A hydrostatic test pressure of 2 -l/2 times design pressure

is considered a standard test pressure for pressurized system [2], For

most applications, clear water is used. The temperature of the water

should be no lower than that of the ambient atmosphere. Otherwise, sweating will result and proper examination will be difficult. In environments

where freezing may occur, antifreeze or hydrocarbons may be added to keep

the water from freezing. Bleeder valves or petcocks should be provided

at the highest point or points in the system to permit venting of all air

in the piping during the filling operation [2]. Automatic vents must be

protected from freezing

.

S-615-10. 11 Discharge of Liquids

Relief valves shall be piped to discharge to locations acceptable to the

local administrative code authority having jurisdiction.

S-615-10. 12 Location of Exposed Piping

Piping and equipment shall be located so as not to interfere with normal

operation of windows, doors, or other exit openings and so as to prevent

damage to piping, equipment, or injury to persons.

[1] The BOCA Basic Plumbing Code, Southern Standard Plumbing Code, The

Uniform Plumbing Code, and The National Plumbing Code.

[2] Piping Handbook, Remo C. King and Sabin Crocker, McGraw-Hill Book

Company, 5th Edition.

6-36
S-615-10.13 Underground Piping

Underground water service piping shall be installed in accordance with

the provisions of Section 615-5.3 of MPS. Underground heat distribution

piping shall be installed in accordance with Section 615-3.5 (k) of MPS.

S-615-10.14 Treatment of Water

When make-up water is of such a quality that excessive corrosion or scaling is known to exist, a suitable water treatment system as recommended

by the Water Quality Foundation shall be provided.

Commentary : The use of small water passages in collectors and heat ex- changers makes them susceptible to plugging and any size water passage

may be subject to reduction in heat transfer from the precipitation of

salts or corrosion products

.

S-615-10.15 Freeze Protection

For systems subject to freezing of the heat transfer fluid, freeze protection by draining, circulation of an anti-freeze agent or other means

shall be provided.

S-615-10 . 15 . 1 Draindown Freeze Protection

In draindown systems, if drainage of heat transfer fluid to the thermal

storage tank is intended, the storage tank shall be sized adequately to accommodate it. See S-615-7.3.1 and S-615-10. 2. System designs incorporating automatic drainage of heat transfer fluid to storage to prevent

freezing of the fluid in solar collectors shall not be constructed of

materials which corrode in the presence of air or shall be suitably protected .

Commentary : One means of preventing corrosion during system drainage would

be by introducing an inert gas such as nitrogen.

S-615-10 . 15 . 2 Draindown Venting

In draindown systems, provisions for venting of collector panels and manifold

lines shall be provided as required to allow refill of the collector system

without air entrapment

.

Commentary : Operation and maintenance of draindown venting must be com- patible with venting for normal operations . Draindown venting may employ

either venting to the atmosphere or pressurized methods with valves and

holding tanks which automatically accomplish the refilling and venting.

6-37
S-615-11 AUXILIARY ENERGY SYSTEMS

Commentary: The auxiliary energy subsystem may be integrated directly into

the solar energy system, or it may be completely separate from it, and contain its own means for delivery of heat and/or hot water to the building.

S-615-11.

1

Applicable Standards

S-615-11. 1.1 Heating and domestic hot water systems shall comply with the design standards

of MPS Section 615 and the applicable recognized standards given in MPS

Appendices C and E.

S-615-11. 1.2 Heat pumps shall be installed in compliance with the requirements of ANSI

B 9.1-1971, "Safety Code for Mechanical Refrigeration" (ASHRAE) ; ANSI

B 191.1-1976, "Standard for Heat Pumps" (UL 559); ARI Standard 240,

"Standard for Unitary Heat Pump Equipment" (1975); ARI Standard 260,

"Standard for Application, Installation, and Servicing of Unitary Systems"

(1967) ; and tested in accordance with the procedure outlined, in ASHRAE

Standard 37-69, "Method of Testing for Unitary Air Conditioning and Heat

Pump Equipment".

S-615-11.

2

System Interconnection

The interconnections of the auxiliary energy system to the solar energy

system shall be made in a manner which will not result in excessive temperature or pressure in the auxiliary system or in bypassing of safety

devices of the auxiliary system.

6-38
S-615-12 HEAT EXCHANGERS

S-615-12.

1

S-615-12.

2

Sizing

a. A heat exchanger when used in conjunction with the solar collector and

storage shall be evaluated for its effectiveness in transferring heat

from the collector to storage. The heat exchanger effectiveness is

expressed by:

e c where

(me ) P c (t - t . ) / (me ) . (t

o i p min o

t)

= (me ) . = the minimum fluid capacitance rate of collector (C ) p min / ~ n c or storage (C ) (me ) = fluid capacitance rate in the flow circuit between

p

s

(tit ) P c

storage and the collector heat exchanger

= fluid capacitance rate in the flow circuit between

collector and the collector heat exchanger

storage temperature (°F)

collector outlet temperature (°E)

collector inlet temperature (°F)

effectiveness of the collector - storage heat exchanger

flow rate of the working fluid (lb/h)

fluid specific heat (Btu/lb-°F)

Commentary : Diagrams of typical locations and a discussion of heat

exchangers are presented in Appendix A and C. Calculation methods

for heat exchanger performance are described in the ASHRAE Handbook

of Fundamentals. A minimum effectiveness value of 0.7 is a typical

value that is used. This value was used in the correlation studies

which provide the basis for the Appendix A calculation method.

b. The load heat exchanger heat transfer rate shall be selected such that

the ratio of the heat exchanger effectiveness times the minimum capacitance rate to the total heating load is between a value of 1 and 3

.

This dimensionless parameter and relationship is expressed by:

e T (m c ) . 1 TL L P mxn <_ ^ UA

where

= Effectiveness of load heat exchanger

UA = Building heat loss factor (Btu/h °F)

Commentary : The load heat exchanger effectiveness can degrade the

system performance if the heat transfer rate is not sufficiently

large. Oversizing the heat exchanger results in unused cccpacity.

Protection Against Maximum Temperature, Pressure and Vacuum

Heat exchanger shall be protected against maximum temperature, pressure

and vacuum in accordance with the provisions of S-615-14.1.

6-39
S-615-13

S-615-13 .

1

S-615-13.

2

AIR DISTRIBUTION

Applicable Standards

Design of all warm air heating systems shall be in accordance with applicable recommendations of the ASHRAE Guide, and manuals of NESCA and ARI. Installation shall comply with NFPA Standards 90B, 31 and 54.

Commentary : Duct work should he designed for the shortest practical run and elbows should he kept to a minimum. Constrictions should he avoided.

Dust and Dirt Prevention

Duct and fan systems shall be protected against accumulation of deposits

of dust or dirt that could reduce flow and efficiency in addition to creating a potential health hazard when admitted into occupied spaces.

Air filters are required on the outlet side of rockbed storage in active systems.

Commentary: The gravel used for rockbed storage with air systems is

selected for size and freedom from dirt and dust. Therefore, smooth and

washed material combined with the use of filtered air is desirable to provide a maintenance free, clean distribution system. Fan grilles should

be removable or hinged to permit access to the fan and motor for cleaning,

servicing, replacement, or repair.

6-40
S-615-14 CONTROLS AND INSTRUMENTATION

S-615-14. 1 Fail-Safe Controls

The control subsystem shall be designed so that in the event of a power

failure, or a failure of any of the components in the subsystem, the temperatures and/or pressures developed in the H and DHW systems will not

be damaging to any of the components of the systems and the building or present a danger to the occupants. The safety devices shall meet the re- quirements of Section 515-6.4 of MPS and be demonstrated to be adequately

safe and protected for the intended application.

S-615-14. 1.1 Automatic Pressure Relief Devices

Adequately sized and responsive pressure relief devices shall be provided

in those parts of the energy transport subsystem containing pressurized

fluids. A pressure release device shall be provided in each portion of

the system where excessive pressures can develop. Each section of the system

shall have a pressure relief device so that no section can be valved off or otherwise isolated from a relief device. Automatic pressure relief devices

shall be set to open at not more than the maximum pressure for which the subsystem is designed.

Relief devices shall drain to locations in accordance with Section S-615-9.1.

Commentary: Care should be taken in the design and layout of the fluid

transport system to prevent conditions in which locally excessive pressures

are developed as a result of flow restrictions. Precautions must be taken

to assure that heat transfer liquids do not discharge on asphalt base roofing materials or other types of roofing or locations which may be hazardous

,

cause structural damage, building finish discoloration, or damage to plant

materials .

S-615-14. 1.2 Vacuum Relief

The solar energy system, including collectors, pipes, tanks, and heat

exchangers shall be protected against possible collapse by design or by

provision of vacuum relief valves.

Commentary : System components may be subjected to collapse if heating

system leakage were to occur or if the system were drained without venting.

S-615-14. 1.3 Collector Thermal Shock

Automatic flow control valves shall be provided for collectors unable to withstand temperature shock.

S-615-14. 2 Identification and Location of Controls

Main shutoff valves and switches shall be conspicuously marked and placed

in a readily accessible location, in the same manner as electrical ser- vice panels, in accordance with Section 240.24 of NFPA 70, and MPS, Section

616.

S-615-14. 3 Indirect Water Heaters

Indirect domestic water heater installations shall include operating

controls for the heat source, of the type recommended by the boiler

manufacturer. The installation shall be made in accordance with the

boiler manufacturer's instructions.

6-41
S-615-14.4

S-615-15

S-615-15 .

1

S-615-16

S-615-16 .

1

Efficient Operation (Active Systems)

Automatic control of the heat transfer fluid circulation between the

collector and storage or load shall be used to limit operations to con- ditions when useful energy can be collected. Designs utilizing collector

flow as a fail-safe method shall employ override controls as required.

Commentary: The collector circulation in liquid systems is normally

limited to conditions when the absorber plate temperature is greater

than the storage or load temperature by a At of 10°F for start-up and

a At of 3°F for shut-down. A larger At may be used for air systems

depending upon the oireulating fan electrical power requirements.

CHIMNEYS AND VENTS

Termination Height of Chimneys and Vents

Termination height of chimneys and vents shall be in accordance with

NFPA 211.

Commentary: The presence of solar equipment may introduce building com- ponents that are elevated above the roof surface, thus producing wind

disturbance at a higher level. The standards of NFPA 211 will provide for

proper clearance and separation.

MECHANICAL VENTILATION

Air Discharge Openings

Air discharge openings through roofs or exterior walls shall not be

located such that their exhaust will cause the deposition of grease, lint,

condensation or other deleterious materials on solar optical components.

6-42
APPENDIX A

CALCULATION PROCEDURES FOR

DETERMINING THE THERMAL

PERFORMANCE OF ACTIVE, SOLAR

SPACE HEATING AND DOMESTIC

HOT WATER SYSTEMS

A-l
PREFACE

The system performance calculation procedure for determining the thermal performance of

active solar space heating and domestic hot water systems is presented in five sections

for clarity and ease of use.

The Introduction provides background information on the applicability of the method and

the systems modeling research from which it has been derived.

Section two. Basis of the Calculation Method, gives a concise description of the procedure's

steps, lists the assumptions on which it is based, provides schematic drawings of the systems

for which it is applicable and indicates the scope of data which 'is required in order to perform the calculation.

Section three presents the Procedure arranged in six steps each including a description of

the calculations required and worksheets on which to carry out and tabulate the calculations.

Also included in this section is a procedure for determining heat exchanger effectiveness,

and important ancillary calculation that may be required if information on heat exchangers

is not provided in the required form.

Section four, Typical Examples, carries out a set of calculations for each of three typical

solar energy systems; a liquid heating and domestic hot water system, an air heating and

domestic hot water system, and a liquid domestic hot water only system. Typical data is

provided for these and worksheets have been completed for each.

Section five, Ref erence Materials , provides a table of nomenclature, lists references, includes reference tables required to carry out the calculations and provides a set of blank

worksheets which may be reproduced for individual calculation.
TABLE OF CONTENTS

PREFACE A2

1. INTRODUCTION A4

2. BASIS OF THE CALCULATION METHOD A-6

1. Description A-6

2. Assumptions A-7

3. Schematic Drawings of Basic Systems A8

4. Project Data Sheet A9

3. PROCEDURE A-10

1. Portion of Total Load Supplied by Solar Energy (F^nnual) A-10

2. System Performance Parameters (Dp, D 2

) A-14

3. Total Building Heating and Domestic Hot Water Load (L) A-16

4. Solar Energy Available (S) A-21

5. Collector Combined Performance Characteristics (Fjp(ToT) , FrU^) A-24

6 . Correction Factors (Kp, K2

, K3 , K4 ) A-30

7. Heat Exchanger Effectiveness A-34

4. TYPICAL EXAMPLES OF SYSTEM THERMAL PERFORMANCE CALCULATION A_40

1. Liquid H and DHW System A-40

2. Air H and DHW System A-54

3. Liquid DHW System A-69

5. REFERENCE MATERIAL A“ 82

1. Nomenclature A-83

2. References Cited A-85

3. Tables and Graphs A-87

4. Blank Worksheets A-114
1. . INTRODUCTION

The performance of any solar energy system is directly related to the amount of solar

radiation available, the outdoor conditions, the heat load thermal characteristics,

and the solar energy system characteristics. The energy flow diagram for one type

of a simplified active solar energy system (using a flat plate collector) is shown in

the figure below. Specific systems for providing heat and/or hot water using air and

liquid collectors are illustrated in Figure A-4.

Collector losses

Figure A-l Energy Flow Diagram for a Typical Active Solar Energy System

Starting on the left side of the figure, solar energy is incident on the solar collector.

Some energy is lost from the collector due to reflection from the collector and heat

transfer to the ambient surroundings. The amount of energy actually collected by a solar collector is termed useful energy and is directly proportional to the collector

area.

Useful energy is transferred directly to the heated space, hot water load or thermal

storage device (TSD) by a working fluid. The TSD is necessary due to the intermittent

nature of solar energy and is characterized by the TSD heat capacity.

Energy from the TSD to the heated space or hot water load is transferred as needed to meet the load. If the TSD cannot meet the load, auxiliary energy from other sources

is necessary. Heat exchangers and pumping systems must be properly sized to meet

energy flow requirements.

Precise prediction of performance of solar heating systems is difficult because of the

random variation in climatic conditions and the mathematically complex relationships

between the system components.

The procedure for estimating performance of a solar energy system used in this document

is called the "f-chart" method and was developed by Klein, Beckman, and Duffie of the

University of Wisconsin. [1, 17, 18] Their approach was to use a detailed hour by hour

computer simulation for several typical solar energy systems covering a wide range of

system parameters at several geographic locations in order to develop a generalized

correlation (''f-chart") which is useful in evaluating long term system performance.

A-4
Of the methods presently in use, this method is widely accepted and offers flexibility

in the range of design parameters that can be evaluated.

Although differences were found between the simulated and estimated performance using

the generalized chart for specific monthly periods, the correlation, determined by a least squares fit, was found to be quite satisfactory in most cases for predicting

year-long performance, as shown in Figure A-2. It should be emphasized, however, that

the "f-chart" procedure is not intended to provide an accurate estimate of system

performance for any particular month, but rather for the long-term. The difference

between the simulated and estimated yearly performance of systems in different locations were also found to be small. The standard deviation in the fraction of load to be met

by solar predicted for four different cities was 0.018, an error judged to be substantially lower than the errors inherent in the simulation model and the recorded data.

The "f-chart" procedure has been checked using the data obtained from existing solar

heating systems and the difference between estimated and actual performance is small.

For example, for M.I.T Solar House IV [2], the difference between actual performance

and estimated performance using the "f-chart" procedure over two complete heating

seasons was about eight percent.

The procedure can accommodate various non-tracking flat plate collector designs when

the thermal performance is available in terms of the effective collection and conversion

of solar radiation into useful thermal energy for a range of operating conditions.

Simulations used to derive the "f-chart" correlation include typical ranges for heat

transfer fluid flow rates, heat exchangers, thermal storage capacity and configuration,

auxiliary energy integration and control modes. Methods of estimating the performance

of systems having characteristics other than those used to generate the "f-chart"

are included in some instances. The procedure does not apply to passive systems and

is generally limited to geographic regions below sixty degrees latitude. Preliminary

design considerations for passive systems have been studied [3] but no procedure is

currently available. The method does not apply to systems using heat pumps.

s

m T Trrri i i

|

i it: : » ; i r, ; t i ivn i

|

1 1 . i n v

:

E

b -too *«ob *i5C

X > X

5*

iJ-LJ

••60

• H

A

i-oec

Figure A-2 Comparison of System Performance

Between f-chart and Detailed Simulation

The procedure is intended for use in the evaluation of the capability of a solar energy

system to provide a portion of the heating and hot water requirements for a residential

dwelling. The method is not intended to perform the thermal design of a unique system

or to optimize the solar energy system performance for a unique thermal load profile.

The calculation can be performed using a slide rule, hand calculator or simplified

computerized program. Another method is available to size collectors for a specific

type system using hand calculations [4] and a somewhat more detailed method has been

described using a computer [5]. Each of these methods can be used to estimate the cost

and fuel savings for local environments and conditions.

A-5
2 BASIS OF THE CALCULATION METHOD

2.1 DESCRIPTION

The procedure for calculating the performance of solar heating and/or hot water system

allows the estimation of long-term solar heating system performance applicable for

space heating and domestic hot water systems, either individually or combined. The

method is applicable to those air and liquid heat transfer systems in which solar

energy and auxiliary energy are added directly to the heating and/or hot water loads.

Solar energy systems using heat pumps are not covered. Examples of each application

are presented in section 4 of this appendix. The system evaluation procedure is not

intended to provide an accurate prediction of system performance for any particular

month, but rather for the long-term average.

The procedure is based on a computer simulated systems analysis. Solar energy

system performance is characterized by the term f, which denotes the monthly fraction

of the total heating load supplied by the solar energy system and is determined from

a single parametric chart, the "f-chart," Figure A-5 and A-6 . The systems analysis

has shown the performance of the system to be well correlated to two systems performance parameters D-^ and I> 2

, the coordinates used on the "f-chart." D-^ is a function

of solar insolation and system heat load and D2 is a function of solar collector

heat losses and system heat load. Several other design parameters were found to have

only a small effect on system performance and thus, the method can be used for a wide

range of these design parameters by means of correction factors, K^, K2 , K3

, and K^.

The calculation method is applicable to systems schematically identical to Figure A-4

or similar simplified models. The basis of the calculation procedure is the "f-chart"

and the two equations which define D^ and D2

. The equations, given below, have been

labeled with the section numbers that describe the indicated elements. These sections

are further listed in the order in which they appear in the text. 3.2 3.2 3.5 3.4 3.6.4

D _ energy absorbed by collector plate

1 total heating load

3.3

3.2

: _ reference collector plate energy losses

2 total heating load

the portion of the total heating load supplied by solar energy

the System Performance Parameters (D^, D^)

the total building heating and/or domestic hot water load (L)

solar energy available to satisfy the heating requirements (S)

the collector combined performance characteristics [F^ (fa), F^U^]

the correction factors (K^, K^, K^, K^)

3.7 Heat Exchanger Effectiveness (e uv) rLA Project Data Worksheet A, is provided at the end of this section to record the basic

information necessary to carry out the calculation procedure.

3.1 Determination of

(f and F ) 1 Annual

3.2 Determination of

3.3 Determination of

3.4 Determination of

3.5 Determination of

3.6 Determination of

3.2 3.5 3.2 3.6.1 3.6.3

A

c FR

UL(tref

“ t o )4tlme

l .. z J

x

1 3.3

x K

2 x K

3 3.6.2

A F' (ta) S c R

x K,
2.2 ASSUMPTIONS

The following assumptions were made in developing the procedure:

1) Thermal storage is contained within the heated structure and all storage heat losses

are considered to supplement the space heating load.

2) Auxiliary heat sources are provided to supply energy for both the space and water

heating when the energy in storage is depleted, or the rate at which solar energy

can be supplied in less than the total heating load.

3) For heating systems utilizing a liquid heat transfer fluid, a heat exchanger can be used between the collector and the storage tank. When an anti-freeze solution

is circulated through the collector to avoid the problems of freezing and corrosion,

the use of a heat exchanger in conjunction with water storage may be more economical

than using the anti-freeze solution as the energy storage medium.

4) The heat transfer fluid is circulated through the collector whenever a positive

energy gain can be achieved. During periods of low radiation (when the energy gain

becomes zero or negative), the collector pump or blower is turned off.

5) For the space heating load determination, the energy per degree day method is

adequate. Load calculations are provided using the "Manual J" method but any

procedure that reasonably predicts the building thermal load is acceptable.

6) The average domestic hot water demand as a function of the time of day and family

size was established in the development of the procedure. In general, hot water

consumption is highly dependent upon the habits of the occupants, however, it has

been determined that the actual time distribution of the water heating load will

have only a small effect upon the long-term performance for solar heating systems

combining domestic hot water and space heating.

7) For those solar energy systems used only for hot water heating, the procedure has

been developed using an assumed hourly hot water consumption pattern that Is re- peated every day, Figure A-3. It is not known how deviations from this consumption

pattern effect the performance of the hot water system.

8) Since in most instances flat plate collectors are utilized for heating buildings,

the collector component parameters are only valid for modeling flat plate collectors.

Concentrating collectors or tracking collectors cannot be incorporated into the

solar heating system evaluation as it is presently written in this Appendix.

Figure A-3 Assumed Hourly Hot Water Consumption
2.3 SCHEMATIC DRAWINGS OF BASIC SYSTEMS

Supply Loop

Loop Pump Loop Pump Building

Supply Fan

a) Liquid System: Space Heating and Domestic Hot Water

Collector Hot. Water

Loop Pump Loop Pump

b) Liquid System: Domestic Hot Water Only

c) Air System: Space Heating and Domestic Hot Water

Figure A-4
2.4 PROJECT DATA SHEET

WORKSHEET A PROJECT DATA

PROJECT

Location Latitude

Building Heating and/or Hot Water Load

Design Heat Loss Rate, qg

= Btu/h

Winter Design Temperature (97 1/2%)

,

°F Average Hot Water Consumption = (may vary on a monthly basis)

gal /day

Average Cold Water Supply (main) Temp., tm

(may vary on a monthly basis)

°F

Hot Water Supply Temp., t g Collector Subsystem Data

Collector Type: ,

°F

Selective or non-selective , no. cov r plates

Collector Area, Ac = ft

2

Tilt Angle O

Azimuth Angle = Collector Shading (av. % month of Dec.) =

O

%

Collector Efficiency Data

(from manufacture): F„(Ta) = k n

fr

ul

t in + t Reference Temp. Basis: t. , —— , t xn 2 out

Fluid : Composition

Btu/h-ft 2

- °F

Specific Heat, Cp Btu/lb • °F

Specific Gravity (if applicable) = Volumetric Flow Rate =

lb /lb

3 gal/min or ft /min

Storage Subsystem Data

Volume = Storage Medium

3 gal or ft

Specific Heat, c^ = Specific Gravity/or Density = Circulation Loop Volumetric Flow Rate =

Btu/lb- °F

lb/lb or lb/ft 3

3 gal/min or ft /min

Collector/Storage Heat Exchange Effectiveness, e =

Hot Water Preheat Storage Volume = Load Subsystem Data

Load Heat Exchanger Effectiveness, =

gal

Supply Loop Volumetric Flow Rate = Building Air Supply Volumetric Flow Rate =

gal/min

f

t

3 /min

A9
3 . PROCEDURE

3.1 FRACTION OF TOTAL HEATING LOAD SUPPLIED BY SOLAR ENERGY, fAnnual

The fraction of the heating load supplied by solar energy is the measure of system performance that is calculated. The solar contribution is calculated first on a monthly

basis and then summed to provide the yearly total.

3.1.1 Monthly Fraction (f)

The monthly fraction of the heating load supplied by solar energy is determined from

the "f-charts", figure A-5 for air systems and figure A-6 for liquid systems. Worksheet B has been provided for tabulating monthly values of (f) and calculating FAnnual.

On figure A-5 or A-6 locate the two system parameters Di and D2 for each month and read

off the corresponding value of f. Di and D2 are determined by the procedure described

in section 3.2.

3.1.2 Annual Fraction (F^nnual)

As previously mentioned, the procedure is not intended to provide an accurate estimate

of system performance for a particular month but will provide a relatively good estimate

for long-term performance such as a year, f is calculated on a yearly basis in the

following steps:

3. 1.2.1 The actual solar energy supplied for each month is calculated as follows:

EJan ~ f Jan EJan

EFeb " f Feb LFeb

( 1 )

EDec ~ EDec EDec

The total solar energy supplied for the year is calculated by summing the contributions from each month.

ETotal = E Jan + EFeb • • + EDec ( 2 )

3. 1.2.2 The total heating load for the year is calculated by summing the contributions for

each month.

LTotal = LJan + LFeb • • • + LDec (3)

3.1. 2.3 Knowing the total annual solar energy supplied by the heating system (Ex0 tal) and

the total annual heating load (Lxotal) » determine FAnnual for the entire year as follows:

E Total

FAnnua! =

[ (4)

A-10
CD o O O o

o 10 o ID o o a 9 a a a • LQ a

cf0 CM CM •

CO

T—

oa CD

O

rroI CM

*-4 o

o

oa CO

o

oA

oc CM

TTTTJTTTTpirrpriTf

O')

fnn |in i|

00 N- c O O C

II II V~- »

TmjmT

o iD'Jr

)do' n ii it 4— **— 111

jrnTiTnri rinpui

- OII H- -

- -

- V f=0.3-

- TO\ \ CVI

\ \ O

\ \ n

“

\ \

\ \

5—-

ii -4 s—

-

- \\\l \ \ “

iiiiimiillllllllll llllllllllliiuiLuu m\lim JiM

00

o

CO

o

o9 CM

oa o

o0 - 00

o

CO

oa

CN

Q

"a a Q o o o o

a 10 o IQ o uo a

• a « e a & 9 CM CM v=3

o9

O

I

a

A-ll

Figure

A-5

f

-

Chart

for

Solar

Air

Heating

Systems
60

=

l

a

A-12

Figure

A-6

f

-

Chart

for

Solar

Liquid

Heating

Systeas
WORKSHEET

B

FRACTION

OF

TOTAL

HEATING

LOAD

SUPPLIED

BY

SOLAR

ENERGY,

F

Ann

ual

PROJECT

m Actual Solar en/mo E Btu/mo

.

Solar

Fraction/ mo

.

f

m

System

Parameters d2

CN

System

Parameters D

1

»-

H

Tot.

Mo.

Htg.

Load L Btu/mo

.

Month Jan. Feb.

March April

May

June July

Aug. Sept

.

Oct

.

Nov. Dec

.

Q CJ

<u

0) —

C/5 u

o3

s

ou

u,

*—» CM

u

un

A-13

From

Worksheet
3.2 SYSTEM PERFORMANCE PARAMETERS, D , T> 2

The system performance parameters Dj and D 2 characterize the entire solar energy system

thermal performance. Worksheet C is included for tabulating the system performance

parameters. The two parameters are calculated for each month using the following

equations

_ energy absorbed by collector , plate

total heating load

Ac Fp (Tot) S =

7 x K4 (5)

ref, collector plate energy losses

total heating load

Ac F R

U L( tref-t0 )Atime

x Ki x K2 x K3 ( 6 )

where

Ac = collector aperture area ( f

t

^ ) . This must be consistent with the collector manufacturers performance data and in most instances equals Aa used in the collector

thermal performance test, ASHRAE 93-P.

S = total incident solar radiation normal to the surface of the collector for an average month (Btu/month • ft^), (a detailed calculation procedure and data are provided in section 3.4, sample calculations are in section 4 and worksheets are

in section 5)

.

L = total heating and hot water load for the particular month (Btu/month) . In hot water

only systems this term equals Qw (a detailed calculation procedure is provided in

section 3.3, sample calculations are in section 4 and worksheets are in section 5).

F^ (roT) and F^ Ul = collector combined performance characteristics that are obtained

from the experimentally determined efficiency plot for the collector combined with

heat exchanger performance data. The F^ (rcT) product is dimensionless and the

FR product has units (Btu/h* °F- f t^) , (a detailed calculation procedure and data

are provided in section 3.5, sample calculations are in section 4 and worksheets

are in section 5)

.

t re f = 212°F, reference temperature (arbitrarily chosen).

t D = monthly average day-time temperature (°F) , (table A-4 in section 5 provides tables

of these temperatures for many locations)

.

Atime = total number of hours for the particular month.

Ki = air collector flow capacitance rate factor.

K2 = storage mass capacitance factor, for liquid and air heating and hot water systems

(dimensionless)

.

K3 = hot water factor, for liquid hot water only systems (dimensionless).

K4 = load heat exchanger factor, for liquid heating systems (dimensionless).

(A detailed calculation procedure for , K 0 , , and is provided in section

3.6, sample calculations are in section 4 and worksheets are in section 5).

A-14
WORKSHEET

C

SYSTEM

PERFORMANCE

PARAMETERS

D

1

, D

2

PROJECT

C3

P-, G

AJ AJ AJ

ro 0) 0) TD cd CD jr X c co CO

CD> »j •H o o o

o o o

AJ AJ AJ

CD CD <D

CD Cl) cd x X X CO (A CO X X

H u >J o o o

J2

II II II

CN <3“

X CN Q

uO

co

Tot.

Hrs

in

Mo

.

A

time hr. <r<r 672 <3" 720 <r

<3" 720 <r

NT

r-

<r 720 744 720 NT

NjO

AJ

1 Uh CN O rH

CN

Mo

.

Av

.

Day

Time

Temp

.

to °F

CO i—1 Q

S/L

CN Total

Heating Load L Btu/Mo

.

r—

1

Tot.

Monthly

Radiation

on

Tilt

Surf.

S

Btu/

(Mo

>ft^)

Month Jan

.

Feb.

March April

May

June July

Aug.

Sept

.

Oct

.

Nov. Dec

.

IIro X

x

CDB

•H

AJ <1

1

T3Ou

ClCN G

< T3 U_i

r

- “1 C a) 3

CO X Cl) cn H X

w Q o H AJ o

/-S u X <r Jj AJ AJ

1 0 CL CC rH Cl

CD CD 1 H H 1 3

CD CD rH <C G CN

C! X Q UO Q

CO CO -cd 31 d) as 3 3 pJ rH Pj u H O X

o o u CD Cl) cn u <D 3 3 < H CO H < CD CD E E o o 1 12 O O n 3

H u —

1

U H CN X X Q U, P-. Q

r—

1

CN CO <3- U0 vO

A-15
3.3 TOTAL BUILDING HEATING AND DOMESTIC HOT WATER LOAD, L

The total heating load is determined on a monthly basis for both space and domestic

hot water heating.

The space heating and domestic hot water heating loads are calculated separately and

for combined systems the monthly individual loads are added to get a monthly total

load

.

Worksheet D is included for tabulating the heating load calculation.

3.3.1 Space Heating Load

It is recommended that the space heating load for each month be calculated using

the degree-day method. It is based on the assumption that over the long-term, solar

and internal heat gains will offset the residential heat los6 when the mean daily

outdoor air temperature is 65 °F and that the long-term heating load will be proportional to the difference between the mean daily temperature and 65°F. Tables

of degree-days with a base of 65 °F have been constructed and are published for a large number of cities in Chapter 43 of the 1976 ASHRAE Systems Handbook [9].

However, in many current buildings larger internal heat gains coupled with the

increased insulation levels are sufficient to offset a home's heat loss to a mean

daily temperature as low as 56°F (reported in Reference [9]). Therefore, a modified

degree day procedure is suggested. It consists of the use of proportionality factor

(PF) . This factor can range in value from 0.60 to 0.80 depending on the insulation

level, weather patterns, internal gains, etc. However, it is recommended that a value of 0.75 be used unless practical experience in the particular locality would

dictate the use of a different value.

The ASHRAE Handbook of Fundamentals [8] describes the basic method for calculating

heat losses in a chapter entitled Heating Load. In addition, NESCA Manual J, [14]

IBR Guide H-21, [15] and ARI Standard 230 present slightly different methods,

including examples, tables, and pre-printed calculation forms which simplify the

calculating process. For multi-family installations NESCA Manual M may be used

instead of Manual J. Although the various methods differ somewhat in format and

details, the principles and the overall approach are essentially the same.

3. 3. 1.1 Calculate the Building Design Heat Loss Rate (q^)

.

The following outline of the main steps in calculation are adopted from ASHRAE 's Fundamentals [8] and a typical calculation form. Figure A- 7 is shown from NESCA

Manual J. Note that the Manual J form also contains spaces for use only in cooling

load calculation notably the columns labeled C19 and lines 7 and 16-21.

Select the design outdoor weather conditions. The data on winter climatic con- ditions are given in the ASHRAE Handbook of Fundamentals (select from the 97 1/2

column) or Table A-3 in section 5.

Select 70 F for family and 75 F for care-type and elderly housing as the indoor

air temperature to be maintained in living spaces during winter.

Estimate temperatures in adjacent unheated spaces. Consult ASHRAE' s Fundamentals

for formulae, examples, and tables.

Select or compute the heat transmission coefficients for outside walls and glass,

and for inside walls, nonbasement floors, and ceilings, if these are next to unheated spaces; include roof if next to heated space. On the Manual J form, a HTM (heat transfer multiplier) is used which equals the heat transmission coefficient multiplied by the temperature difference.

Determine net area of outside wall, glass, and roof next to heated spaces, aa well as any cold walls, floors, or ceilings next to unheated space. Such measurements are made from building plans, using inside dimensions.

A-16
3. 3. 1.2

Compute the heat transmission losses for each kind of wall, glass, floor, ceiling,

and roof in the building by multiplying the heat transmission coefficient in each

case by the area of the surface in square feet and the temperature difference

between the indoor and the unheated space or outdoor air. Note: In the Manual J form heat transmission coefficient x temperature difference is replaced by the.HTM.

Compute heat losses from floors over crawl space or basement floors or grade-level

slab floors.

Estimate infiltration rate (number of air changes per hour) and compute the

heat equivalent of the infiltration of cold air taking place around outside doors

and windows. The infiltration rate depends on the type of or width of cracks, wind

speed, and the temperature difference between the indoor and outdoor air; the

result expresses the heat required to warm the cold air infiltrating into the

building. Refer to ASHRAE's Fundamentals.

The sum of the transmission losses or heat transmitted through the confining walls,

floor, ceiling, glass, and other surfaces, plus the heat equivalent of the cold

air entering by infiltration represents the total heating load. Since these are

for the design heat loss conditions and are expressed as an hourly rate, this

value represents q^ the building design heat loss rate.

Obtain the monthly total Degree Days from the ASHRAE Systems Handbook [9], Climatic

Atlas of the U.S. [13], or Table A-3 in section 5 for the particular location

for each month.

3. 3. 1.3 Calculate the monthly space heating load using the equation:

Qs = (PF) (24) (UA) (Degree Days)

where

PF = 0.75 (or more appropriate value)

(7)

UA =

At,

Design Heat Loss Rate (Btu/h)

Temperature difference between inside

and outside for design conditions (°F)

( 8 ) 70-t

Select the 97 1/2% winter design temperature (t^) from Table A-3, section 5 or from ASHRAE Handbook of Fundamentals [8] or from available weather data.

3.3.2 Domestic Hot Water Heating Load

3. 3. 2.1 Determine the volume of domestic hot water (Gal) required on a monthly basis from

known consumption figures or sources such as the ASHRAE Guide or Table S-615-1

(in section 6 of this MPS)

3. 3. 2. 2 Determine the water main temperature (t ) or assume t = 55 °F (see S-615-1. 4 in

this MPS). Figure A- 8 gives typical values for a number of major cities and shows

the monthly variations, particularly pronounced in those cities which rely on surface water sources.

3. 3. 2. 3 Determine the domestic hot water supply temperature (t s ) or assume t s - 140°F

(see S-615-1. 4 in this MPS).

A-17
3. 3. 2. 4 Calculate the monthly domestic hot water heating load using the following equation

where: m (mass of water) = volume of water (gal) x 8.33 lb /gal

c (water) = 1 Btu/(lb'°F)

P

3.3.3 Total Heating Load

The monthly total heating and hot water load is the sum of the space heating and

domestic hot water load for each month. Where only domestic hot water or space

heating is provided, the appropriate single load is used.

Monthly Total Heating and Hot Water Load, L = Q

g + (10)

A-18
1 Name of Room Entire House 1 2 3 4 5

2 Running Ft Expo—d Wall

S Room Dimension*, Ft

4 Ceiling Ht, Ft Directions Room Faces fm

Of

EXPOSURE

Const. HTIf Area Btuh Area Btuh Area Btuh Area Btuh Area

length

Btuh Ana

length

Btuh

No. Ht* Cl! Length Htf Clf length Htf Clf length Htf Ci« Length Ht. Cl, Ht, Cl, Htg Cl,

s Gross Exposed

Walls and

Partitions

a

b

e

d

• Windows

and Glass Doors(Htg)

a

b

c

7 Windows

and Glass Doors (Clg)

North E AW or NE A NW

South or SE A SW

8 Other Doors

• Net

Exposed

Walls and

Partitions

a

b

c

d

18 Ceilings a

b

11 Floors

b

12 Ventilation

12 Sub Total Btuh Loss

14 Duet Btuh Loss

IS Total Btuh Loan

If People (f> 300 and Appliances 1200 . '

17 Sensible Btuh Gain (Structure)

1^ Duet Btuh Gain

1» Sum of Lines 17 and 18 (Clg)

l» Total Btuh Gain (Line 19 x 1.3) 1.3

21 Btuh for Air Quantities Figure A- 7 Building Design Heat Loss Calculations Form

from: Load Calculations for Residential Winter and Summer Air Conditioning, Manual J, NESCA [14]

City Source^ Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

1 . Phoenix Ri, Re, W 48 48 50 52 57 59 63 75 79 69 59 54

2. Miami W 70 70 70 70 70 70 70 70 70 70 70 70

3. Los Angeles Ri, W 50 50 54 63 68 73 74 76 75 69 61 55

4. Albuquerque W 72 72 72 72 72 72 72 72 72 72 72 72

5. Las Vegas W 73 73 73 73 73 73 73 73 73 73 73 73

6. Denver Ri 39 40 43 49 55 60 63 64 63 56 45 37

7. Ft. Worth L 56 49 57 70 75 81 79 83 81 72 56 46

8. Nashville Ri 46 46 53 66 63 69 71 75 75 71 58 53

9. Washington, DC Ri 42 42 52 56 63 67 67 78 79 68 55 46

10. Salt Lake City W, C 35 37 38 41 43 47 53 52 48 43 38 37 11. Seattle Ri 39 37 43 45 48 57 60 68 66 57 48 43

12. Boston Re 32 36 39 52 58 71 74 67 60 56 48 45

13. Chicago L 32 32 34 42 51 57 65 67 62 57 45 35

14. New York City Re 36 35 36 39 47 54 58 60 61 57 48 45

1. Data from Handbook of Air Conditioning System Design , p. 5-41 through 5-46 McGraw Hill Book Company, New York (1965). Abbreviations: C-creek, L-lake,

Re-reservoir, Ri-river, W-well.

Figure A-8 Monthly Temperature (tp) in °F at Source for City Water in 14 Selected Cities

A-19
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Monthly Space

Htg

Load Qs

Btu/Mo. i—1

Monthly

Degree Days DD

°Fdays

Month Jan.

Feb.

March April

June July

Aug.

Sept.

Oct. >oXDec.

>•> PQ

a)

a)M

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A-20
3.4 SOLAR ENERGY AVAILABLE (INCIDENT SOLAR RADIATION), S

The solar radiation incident on the collector is determined for a particular collector

tilt and orientation, on a monthly basis, by modifying known insolation values for a given geographic location with factors which relate this to the specific collector

geometry.

The relationship between the various solar radiation variables is presented in

figure A-9. Terminology and methods developed by Liu and Jordan [10] are used.

Figure A-9 Relationship Between Insolation Variables

Worksheet E is included for tabulating the incident solar radiation calculation.

3.4.1

Monthly Average of the Daily Radiation Incident on a Horizontal Surface, (I)

.

H

For cases where local_detailed horizontal insolation is available, this data should

be used to calculate 1^. Where detailed horizontal radiation is not available, an estimate of Ig can be made using the values listed for 80 cities in section 5,

Table A-4 or the mean daily insolation maps shown in section 5, figure A-29. [11]

3.4.2

Ratio of the Monthly Averages of the_Daily Radiation on a Horizontal Surface

to the Extraterrestrial Radiation, (K

t

)

.

Values of for each month are listed in section 5, Table A-4. Intermediate values

can be calculated by interpolation between cities. Alternatively using the

extraterrestrial insolation, _I , for the given location (listed in section 5, Table

A-5 for various latitudes), K can be obtained from the relationship:

f

H

" K = -p (ID

o

3.4.3

Ratio of the Monthly Average Daily Radiation on a Tilted Surface to that on a Horizontal Surface for Collectors Facing Due South, (R)

.

The factor R accounts for the three components of radiation included on the collector

surface, beam, sky diffuse, and ground reflected. In accounting for ground reflected

radiation, a diffuse reflectance of 0.2 has been used for ground surface conditions.

If it is desired to use other values a computer procedure such as reference [19] should

be used.

A-21
R is determined from Table A-6 in section 5 by entering with the known latitude of

the installation (<j>) , tilt of the collector (0) (expressed in relation to the latitude),

and ratio of extraterrestrial to terrestrial radiation (K

t

) (calculated in the

preceeding step). For tilt angles other than those listed values may be interpolated.

These tables assume the collector is oriented due south (y = 180°)

.

For exact evaluation of the effects of collector azimuth angle (y) on incident

radiation, a computer procedure such as reference [19] should be used. However, for

collector tilt angles approximately equal to the lattitude and for lattitudes of 45° or less, reference [16] states that the total annual beam radiation will not vary

by more than 2% for collectors oriented up to 22 1/2 degrees east or west of due

south.

For graphic illustration of collector tilt and orientation angles, see page C-ll.

3.4.4 Monthly Average Daily Radiation on a Tilted Surface, (I )

.

is calculated by multiplying 1^ (for a horizontal surface) by R (ratio of the

horizontal to tilted)

.

IT

= (iR

) (R) (12)

3.4.5 Total Monthly Radiation on a Tilted Surface, (S)

ITM, the monthly average daily radiation on a tilted surface, must be multiplied

by the total days in each month, (N) to obtain total insolation for each month.

s = (i T

) (N)

( 13) 3.4.6 Shading

Shading should not be neglected in calculating the incident solar radiation on a particular collector array. The amount of shading is strongly dependent on the

collector site and orientation; thus, each case must be analyzed separately.

Calculation of the collector array shaded for the month of largest energy requirement

and lowest solar altitude (i.e., December) will provide a useful correction factor,

reducing the amount of available solar radiation. For graphic illustration of

collector shading, see page C8-12.

A-22
WORKSHEET E

TOTAL

MONTHLY

SOLAR

RADIATION

AVAILABLE, S

PROJECT

vO

Tot.

Monthly

Radiation

on

Tilt

Surf. S

Btu/

(Mo• f

t^)

No.

of

Days

in

Month

N 31 00

CM 1

31 30 31 30 31 31 30 31 30 31

m

Monthly

Avg.

Daily

Rad.

on

Tilt

Surf.

It

Btu/

(Day f

t^)

<r Ratio

Horizontal

to

Tilt

R

co Ratio

Horizontal

to

Extra- terrestrial

Kt

CM

Extraterrestrial

Insolation To

Btu/

(Day •f

t^]

1—1

Horizontal Insolation #2

Btu/

(Day •f

ty

Month Jan. Feb.

March April

May

June July

Aug.

Sept.

Oct.

Nov. Dec. I osZ z +. H

II in cr

a)Eo

tier

CDEoh

Pu. * H 4-» 0 4—1

ctf "O 1 g . CD rH 'TD O rH 3 c 4—1 •H

cr 4->

>-4 CD 0 II rH u0 ,—s

no in CM C

N-'

C rH O »H rH CD •» *H c T3 0

4-1 0 • O O cr 4-1 CD no (D H

CO CD 4-1 CO nj 3 O rH

oc

*H

Ex-Ho

'd' <

CD »—I

x>

ctf HEo

V-I fx- 0

(DCO m1 <HEouf Eoh

tt, E -n o AJ M *h

tx- s

A-23

Table

A-4

section
3.5 COLLECTOR COMBINED PERFORMANCE CHARACTERISTICS. F ' (TcQ , F'lL

K K L

In this section, the procedure for calculating the collector combined performance

characteristics Fr (To) and Fp Up used in equations 5 and 6 is developed. The procedure

is developed for a liquid system containing a collector /storage heat exchanger which is

the most complex case. The simplified steps for air of liquid systems which do not con- tain a collector /s torage heat exchanger are also explained.

To calculate the combined performance characteristics, it is necessary to first establish

the performance characteristics for the collector alone, Fp(ia) n and FrUr. (xct) n is

corrected by the incident angle modifier which modifies test data taken with the sun normal to the collector to the performance that can be expected from the average (varying

angle) radiation. This gives Fr(xcT). Both of the characteristics are then corrected for. the effects of the collector/storage heat exchanger by the heat exchanger modifier factor, ^ which includes corrections for both the heat exchanger effectiveness and capacitance

rates. This step gives Fr (tcT) and Fp Ur.

Worksheet F is provided for these calculations.

3.5.1 Collector Performance Characteristics, FR(xa) n , FrUr

The performance characteristics for the collector alone are determined from manufacturers

data (which may be presented in any of several forms) or if this is not available from

typical characteristics curves such as those included. 1/

3. 5. 1.1 Collector Efficiency Data Available From Test

Determine the FR(xa) n and FrU^ factors from the thermal performance efficiency curves provided by the manufacturer covering the appropriate range of operational temperature,

insolation, tilt angle and fluid flow rates. The collector performance efficiency

curve must be plotted such that the y axis is the thermal ef f iciency ( q ) and the x axis is the temperature difference between a reference fluid temperature (t*) and the

ambient temperature divided by the incident solar radiation [(t*-ta )/l t ] as shown in

figure A-10.

l.o —

Thermal Efficiency 1

0.9 -

0.8 —

0.7 —

-Straight line fit of experimental data

for near normal incident solar radiation

and for collector capacitance rate = C c

tf -t

Figure A-10 Example Collector Thermal Performance Efficiency Chart

1/ ASHRAE 93-77 defines the collector efficiency using the gross collector area whereas

previous data was generally reported using aperture area. Figure A-27a and A-27b

present data for several liquid collector types with the efficiency based upon gross area and aperture area, respectively' . Calculations for this procedure can be performed with either definition, however, the efficiency and area must be consistent

in all portions of the calculation.

A-2 4
The equation of the straight line fit of the experimental data is given by:

y

= -mx + b (14)

where:

-m = the slope of the straight line

b = the y axis intercept (value of y when x-o)

Usually, the reference temperature t* in the plot of experimental data is the fluid

inlet temperature, in which cases the collector characteristics FR

(xa) n and FR

UL are obtained directly from the efficiency graph. However, in some cases the data

is based on other reference temperatures. The following procedure describes the

determination of FR

(ta) n and FRU^ for three different values of reference temperature.

case 1 t* = tin (fluid inlet temperature)

then FR("ra) n = b (the y axis intercept of the data line)

case 2

then

and

frU;L = m (the magnitude of the data line slope)

t* = -- -I’—°Ut (average of inlet and exit temperature)

FR(Tot) n

frUl

= b x

= m x

mA r 1 + —

2C c

- 1mA r* 1 + "rTT"

(15)

(16)

case 3

then

where C ct*

FR(ta) n

FRUL

= collector fluid capacitance rate (mCp) Btu/h-°F

= t ou t (fluid exit temperature)

= b x

= m x

r

i i

jl +

n^c

^c

1 1 + ^c

^c

(17)

(18)

It should be noted that the fluid mass flow rate of air collectors can significantly

influence the performance of the collector. Therefore, the efficiency data used for

air collectors in this procedure must have been obtained for the specific range of

flow rates anticipated for collector operation.

3.5. 1.2 No Measured Efficiency Data For Collector

When collector efficiency data are not available for the specific collector, performance characteristics may be estimated from the data provided in figures A-27

and A-28 in section 5 for liquid and air systems respectively. Note that in figure

A-27 for liquid collectors, the primary parameters affecting performance are the

number of cover glass sheets and the radiative properties of the absorber coating

(whether selective or non-selective) . Figure A-28 shows that air collectors with

flat black absorbers have performance characteristics that are sensitive to air flow

rate, number of cover glass sheets and to the specific configuration of the absorber.

Alternatively, for flat plate collectors constructed with relatively simple flow

path geometry, the analytical equations described in ref erence [16 ]can be used to estimate performance. For this purpose, the optical properties of several glazing

materials and absorber coatings are provided in tables A-l and A-2 in section 5.

A-25
3.5.2 Incident Angle Modifier /

TCt

?—

(Toi) n

Angular variations in transmittance and absorptance due to changing sun angle during

the day or changing diffuse component affect x and a. Determine the transmittance - absorptance (xa) product angle modifier that relates normal incident radiation to average incident radiation either from manufacturers data obtained during collector

testing or by the following approximate relation:

(xa) _1.91, for two cover plates

(xa) n ) - 93 , for one cover plate

F

' 3.5.3 Collector Loop Heat Exchange Modifiers, K

FR

3. 5. 3.1 Capacitance Rates

Calculate the collector loop and storage loop capacitance rates and determine the

minimum capacitance rate. The loop capacitance rate is the product of the mass flow

rate, m (lb/h) and fluid specific heat, Cp (Btu/lb ,0 F).

C c = (&Cp) c collector loop

C s = (mcp) s storage loop

The minimum capacitance rate Cm^nis the lesser of Cc or C

g

.

3. 5. 3. 2 Heat Exchanger Effectiveness

The effectiveness of the collector /storage heat exchanger, t cs is a function of the

particular heat exchanger design and size and capacitance rate of each loop. If a numerical value of £ cs is not known, section 3.7 describes procedures whereby values

can be calculated or estimated depending on information available from the heat ex- changer manufacturer.

Fr

3. 5. 3. 3 Heat Exchange Modifier Factor. —

fR

( 20 )

( 21 )

The heat exchanger modifier is determined by first calculating the following dimensionless parameters:

= _££

^s Cmin

= ac (frul )

( 22 )

(23)

The heat exchanger modifier is then determined either from the following equation or from figure A-ll.

Frf fr

i

1 + y(x-l) (24)

For air systems and liquid systems without a collector /storage heat exchanger

FR

1.

3.5.4

t Collector Combined Performance Characteristics, FR

(xa), FRUL The values for the combined collector performance characteristics are calculated

as follows:

Fi

Fr

(xa) FR (xa) n x

"Fr"

t (xa) "Fr'

(xa) n X Fr

UL = FrUl

(25)

(26)

A-26
(FrUl)

I

1

X =

'CS ^min

Figure A-ll Relationship Used to Determine the Ratio of

A-27
WORKSHEET F COLLECTOR COMBINED PERFORMANCE CHARACTERISTICS, Fl (to), F'

U

R R L

PROJECT:

(3.5.1) Collector Efficiency Data From Test

intercept, b = F (xa) = R n slope, m = F U = R L Reference Temperature Basis: 1. t , 2.

t, + t . in out

2 • 3. t'out

Collector area, A

c Collector volumetric flow rate

Correction to t. basis:

rn Case 1: (no correction) F (xa) R n

f

r

u

l

Case 2: F (xa) = b x

R n

Vl x

C = me =

c

(

volumetric) /, , ^ \ /time \ /specific^

flow rate / ( 6nS t ^/ \conversion/ (heat /

where: for liquids, density =(8.33 lb/gal^ x

( gravity

0

) 3 for air, density = 0.75 lb/ft , at 70° and 1 atm. specific heat = 0.24 Btu/lb-°F

Case 3: F (xa) = b x R n

fru

l

= m x

(3.5.2) Incident Angle Modifier, (xa) .91, for two cover plates

.93, for one cover plate

A-28
WORKSHEET F (Continued)

(3.5.3) Collector Loop Heat Exchanger Modifier, —fr for air systems and liquid systems without a collector/storage heat exchanger,

Capacitance Rate

C = (from above) =

c C = (calc, as for C above) =

s c C . = (lesser of C of C ) = mm c s

Collector Storage Heat Exchanger Effectiveness, e cs =

C c

E cs Cmin

ac (frul )

—— = from figure A-ll or = q— 7—r-r Fr

6

1 + y(x-l)

(3.5.4) Fr

(to) = FR

(xa) n

x

FA = fr

u

l

x

(ia)

[

fr 1

(xa) n x

_ Fr

_

A-29
3.6 CORRECTION FACTORS, K , K , K , K

4

This section develops the correction factors to be applied to Dq and D2 in equation 5 and 6 to account for the effect of variation of several design parameters. The validity

of the procedure for values outside of the ranges indicated on accompanying figures A-12

through A-15 is not known, therefore evaluation of systems outside this range is not

recommended. Worksheet G is provided for these calculations.

3.6.1 Air Collector Flow Capacitance Rate Factor, Kl

Ki modifies D 2 in equation 6 and accounts for the effect of flow capacitance rate on

the performance of air collectors. For liquid collectors K3 = 1. Figure A-12 presents

a plot of Ki as a function of the ratio of collector flow capacitance rate C c to collector area for the range of values noted. C c is calculated using equation 20.

3.6.2 Storage Mass Capacitance Factor, K2

K2 modifies D 2 in equation 6 and accounts for the effect of storage thermal capacitance

on the performance of liquid and air systems. Figure A-13 presents a plot of K2 as a function of the ratio of storage mass capacitance, (Mcp)

s to collector area, Ac for

the range of values noted. Separate curves are used for air and liquid systems. The

storage mass capacitance (Mcp) s is the product of the storage mass M (lb) times the

specific heat of the storage medium, Cp (Btu/lb , 0 F).

3.6.3 Hot Water Factor, K3

K3 modifies D 2 in equation 6 and permits the use of the correlations originally developed for combined heating and hot water systems to be used for systems that provide

domestic hot water only. For liquid systems that provide heating only or combined

heating and hot water and for all air systems K3 = 1. Figure A-14 presents a plot of

K3 as a function of average day-time temperature t Q . t Q may be read from table A-4

in section 5. In this plot the cold water supply temperature, tm and the hot water

delivery temperature, t s are parameters that must be supplied.

3.6.4 Load Heat Exchanger Factor, K4

K4 modifies in equation 5 and accounts for the effect of load heat exchanger sizing

on the performance of liquid systems for heating or combined heating and hot water.

In air systems or domestic hot water only systems where there is no load heat exchanger

K4 = 1. Figure A-15 presents a plot of K4 as a function of ^'min/^bldg t where

= load heat exchanger effectiveness.

Cmin

= capacitance rate of the fluid with the minimum mass flow rate - specific

heat product (mcp) and is usually the air side fluid capacitance rate. AUbidg overall heat transfer coefficient for the building calculated in equation 8 .

When information on the load heat exchanger effectiveness is not provided, section 3.7

describes several alternate methods for estimating a value.

A-30
<Mc„) s Ac Btu/h’°F , ft

2

Figure A-13 Storage Capacitance Factor, K2

A-31
Average Day-Time Temperature (t ) f °F

o

Figure A-14 Hot Water Factor, K3

E L^min

( UA)bldg

Figure A-15 Load Heat Exchanger Factor,

A-32
WORKSHEET G CORRECTION FACTORS, ^ , K

2

, K

3

,

PROJECT

Air Collector Flow Capacitance Rate Factor,

for liquid collectors = 1.0

for air collectors: C = (from worksheet F) =

c A = (from worksheet A) =

c

C

c A

c

= (from Figure A-12)

Storage Mass Capacitance Factor,

M = (vol. storage media) x (density) = Note: M includes hot water storage

volume where it is solar heated.

c = (from worksheet A) = P

(MC — t>> ”—s = K

2 = (from Figure A-13)

c

Hot Water Factor,

for liquid systems providing heating only or heating and

hot water, and for all air systems = 1.0

for DHW only systems: t = (from worksheet A) = °F

s

t = (from worksheet A or if variable see worksheet D) = °F m

t is taken from table A-4 section 5 o is taken from figure A-14 and tabulated on a monthly basis on worksheet C

= (tabulated or const.

Load Heat Exchange Factor,

for air systems and DHW only systems, = 1.0

e = (from worksheet A) = L^hot water supply loop

mC

p

C - = me air loop p C . = lesser of C„ or C, = min H A

UA bldg = (from worksheet D) =

= K, = (from Figure A-15)

min e L

A-33
3.7 HEAT EXCHANGER EFFECTIVENESS, e uvHX

In the evaluation of solar energy system performance using the "f-chart" method, there

are two locations in the calculation procedure at which an explicit value for heat

exchanger effectiveness, ejg must be known. This section describes two approaches

to calculation of effectiveness, based on different ways design data may be provided

by a heat exchanger manufacturer. In situations when no manufacturer design data

is available, a method is described to estimate heat exchanger effectiveness.

Definitions

° Overall conductance (AU)^ for a heat exchanger is the product of the overall heat

transfer coefficient U (which depends on the thermal properties of each fluid, the

fluid mass flow rate and the heat exchanger geometry) and the associated heat

transfer surface area.

0 Effectiveness is the ratio of the actual rate of heat transfer in the exchanger

to the theoretical maximum rate of heat transfer that would occur only in a counterflow exchanger with infinite surface area.

° Log-mean temperature difference Atjj^ is the effective temperature difference

between the inlet and outlet fluids such that the product Atj^ and (AU)^ equals

the actual heat transfer rate.

The basic relationships are developed in the following paragraphs.

In the following schematic heat exchanger drawing, the hot stream with capacitance

rate Cjj and inlet temperature t^ -j_ n and the cold stream with capacitance rate Cg and

inlet temperature t c both enter a heat exchanger that has an overall conductance

( au)hxHeat Exchanger with

overall Conductance

(au)hx

Figure A-16 Schematic Heat Exchanger

The actual heat transfer rate is given by

Q C

c (tc, Out t C} in ) (27)

Si ^h, in Si, out^

(28)

= (AU) HX

AtLM

(29)

A-34
The maximum theoretical heat transfer rate would occur if the fluid having the minimum

capacitance rate were heated (or cooled) to the inlet temperature of the maximum

capacitance rate fluid, i.e.

if C . min CH

Then Q = Cu

(t • - t , ) rniax H h , in c , in

Or if C , = C min c

Then Q

= C (t . - t . ) max c h, in c , in

The effectiveness is given by

(30)

(31)

e HX = 2

Qmax

C (t - t , ) c c, out c, in

C

min*'

th, in*" 0 , in^

S^^h , in

t H, out^

C . (t . - t min h > in . c , in

(32)

The log mean temperature difference is a complex function of the hot and cold fluid

inlet and outlet temperatures and depends on the heat exchanger flow arrangement.

The term At^ is defined in terms of a reference log mean temperature difference for

a counterflow heat exchanger (At^M) c £ and a correction factor K as follows:

'LM v “ w LM/ cf

where (t

^ AtLM^cf

h , in

- t out ) - (t

h, out

- t in

log^/

th, in11 c, out out

t c, in

Jjh.

'W,

(33)

(34)

and K depends on the particular heat exchanger flow geometry and two dimensionless

temperature ratios R^ and such that:

R

1

R

2

_ c, out c, in n, in c, in

_ *~h , in *~h , out

t - t c, out c, m

(35)

(36)

Tabular or graphical values of (At^) ^

and K are usually provided by heat exchanger

manufacturers

.

Example 1

Calculate the effectiveness of a counterflow heat exchanger located in the collector/

storage circulation loop. Assume the collector circulation loop flow rate is 2 gpm

and the storage loop flow rate is 6 gpm and that fluid leaves the collector at 120°F

and fluid leaves the storage tank at lOO^F. The heat exchanger manufacturers perfor- mance data for the specific heat exchanger and fluid properties is given in the

following curves:

A-35
Figure A-17 Example Heat Exchanger Performance

Entering the above curve with 2.0 gpm (cold) and 6.0 gpm (hot), with a 120°F - 100° = 20°F At, the actual heat transfer rate is determined to be 11,000 Btu/h. The maximum

rate of heat transfer is:

Q

= C . At = max min

= 2.0 gal x 8.33 lb x 60 min x 1.0 Btu x 20°F = 20,000 Btu/h.

min gal h lb°F

From the definition, the heat exchanger effectiveness is calculated as:

e hx = act

Qm,ax

11,000

20,000 .55

Example 2

Calculate the effectiveness of a two pass shell and tube heat exchanger transferring

heat between water and a heat transfer fluid. Water enters the heat exchanger at 110°F and 10 gpm and the heat transfer fluid enters the heat exchanger at 160°F and

15 gpm. The properties of the heat transfer fluid are c = .65 Btu/lb'°F and

density = 55 lb/ft^. ^

The manufacturers data consist of the following:

0 2 overall heat transfer coefficient U = 150. (Btu/h- °F- ft )

2

° heat transfer surface area A = 30.0 ft

0 a table of factors to convert the performance of a counterflow heat exchanger to the performance of the actual heat exchanger by the log mean temperature difference

correction factor K is shown in Figure A-18.

A-36
R

1

1 :.05 .1 .15 .2 .25 .3 .35 .4 .45 .5 .6 .7 .8 .9 1.0

.2 .999 993 .984 .972 .942 .908 .845 .71 A

No correction re- quired when K &

R fall in thii area.

.994 .983 .971 .959 .922 .855 .70

.6 .992 .980 .965 .948 .923 .840

.8 .995 .981 365 .945 .916 872 he .988 .970 .949 918 .867 .770 2.0 .997 .973 .940 .845 . 740? 3.0 .977 .933 .835 4.0 .993 .950 .850 5.0 .982 .917 6.0 .968 .855 8.0 .930 10.0 .996 .880 12.0 .985 .720 14.0 .972 16.0 .958 18.0 .940 20.0 .915

Figure A-18 Example of Heat Exchanger Log-Mean

Temperature Difference Correction Factor

Since neither of the fluid exit temperatures are known, it is necessary to use a trial and error procedure.

s, -C15 S^M8 - 33 “sr~) *(-£.

The capacitance rate for the heat transfer fluid (hot) is given by:

lb fluid\ (rrs min\ ( rr Btu \ Btu

4 lbH

2o"M60 —

H

65 lbTvk 4295

The capacitance rate for the water (cold) is given by:

lb H.O

C = 10

^ x 8.33 —

c mm g^l

min , „ Btu , Btu

x 60 — x l.Ojpj- 4998

^

Assume the exit temperature of the water t is 130°F.

c, out The actual heat transfer rate is calculated from equation (27) as:

Q

= C

c (t

c, out

- t c, in. ) = 4998 (130-110) = 99960

^

h

t, = t, . - Q = 160 - 99960 = 136. 7°F

h, out h, in ~^295

h

The reference log mean temperature difference for a counter flow heat exchanger is

calculated from equation (34)

(AtLM^cf (160 - 130) - (136.7 - HO)

log / 160 - 130 \ e

y 136.7 - 110

)

28 . 3°F

Since the heat exchanger is not of the counter flow arrangement, a correction factor

K must be determined from the manufacturers supplied data, in this example Figure A-18

based on the computed values of and R^ as follows

A-37
From equation (35)

R 130 - 110

1 “ 160 - 110

' - 4

From equation (36)

R 160 - 136.7

"130 - 110

“ 1.16

K is then determined from the Figure A-18

Then from equations (29) and (33)

Q = (AU)^ x (Atm) cf x K = (150) (30)

and t . = 110 + = 132. 9°F.

c, out 4998

(by extrapolation) as: K = .90

(28.3) (.90) = 114615

h

*

Since the original exit temperature of the water was estimated to be 130 °F, the

procedure is repeated until the estimated water temperature and the calculated water

temperature are the same.

For this problem, the exit water temperature is then calculated to be

t - 131. 2°F

c, out

The actual heat transfer rate is then

Q

= 4988 (131.2 - 110) = 105,960 Btu/h*

The maximum possible heat transfer rate would occur if the minimum capacitance rate

fluid (the hot fluid in this example) were cooled to the cold fluid inlet temperature.

Qm, = C , (fc iax min t - t . ) = 4295 (160 - 110) = 214,750

c , m h

The heat exchanger effectiveness is given by equation (32) as:

= 105,960 = HX 214,750 y

The heat exchanger effectiveness can be assumed to be a constant for a given heat

exchanger and fluid mass flow provided the thermal properties of the fluids do not

vary substantially and provided no change of phase occurs. Thus, the calculated

value of effectiveness based on an assumed set of inlet temperatures would still be

valid over a range of hot fluid and cold fluid inlet conditions usually found in

most solar heating applications.

For the case where there are no performance data available for the particular heat

exchanger, an estimate of effectiveness can be made from the data of reference [7]

for a range of different heat exchanger designs, provided the overall conductance

liquid to air load heat exchangers, C^,-^ is usually the air side capacitance rate and

the parameter Cm£xe(j/Cunin^xe^ shown in Figure A-19 for this arrangement is equivalent

t0 ^min^^max*

(AU)hx known. Figure A-19 shows the effectiveness of counter flow, parallel flow

and cross flow heat exchangers as a function of the ratio (AU) My/C . with the ratio

*-Tnin/ ^max as the parameter. For the cross flow arrangement usually round in the

A-38
If the particular flow arrangement of a heat exchanger is unknown, the effectiveness

can be estimated by taking an average of the calculated effectiveness for the counter

flow and parallel flow arrangements for the given (atO,„,/C . and C . /C design

parameters. HX mm mm max

For situations in which a heat exchanger consists of a coil of tubing submerged in a tank of water, is the capacitance rate of the fluid circulating through the

coil and CmaY is essentially infinite. Thus, the ratio Cmin/Cmax = 0 is used to determine effectiveness from any of the three arrangements shown since for Cmj^/Cma-g = 0,

the expressions for effectiveness as a function of (AU) HX

/Cman

for all flow arrangements reduce to the same expression.

Figure A-19 General Heat Exchanger Performance [7]

A-39
4 TYPICAL EXAMPLES OF SYSTEM THERMAL PERFORMANCE CALCULATION

The following examples demonstrate the utilization of the calculation method for

evaluation of solar heating and hot water systems. Examples using air and water as working fluids were chosen to represent existing typical solar heating systems.

4.1 SOLAR HEATING AND DOMESTIC HOT WATER SYSTEM - LIQUID WORKING FLUID

Our example is a typical liquid working fluid solar heating system shown in Figure A-20.

The system is designed to provide space and domestic hot water heating. A flat plate

collector is used to transform incident solar radiation into thermal energy. This

energy is stored in the form of sensible energy and used as needed to supply the

space and water heating loads. In this case, antifreeze solution is circulated through

the collector to avoid the problems of freezing and corrosion. A heat exchanger is

used between the collector and the tank as it is generally more economical than using

the antifreeze solution as the energy storage medium. A second heat exchanger is used

to transfer energy from the main storage tank to the smaller domestic hot water tank.

Conventional auxiliary heaters are provided to supply energy for both the space and

water heating loads when the energy in the storage tank is depleted. Controllers,

relief valves, pumps and piping make up the remaining equipment. All heat losses

from the solar energy system are assumed to contribute to the building heating load.

The temperature of the fluid entering the collector is assumed equal to the temperature

at the outlet of the collector - storage heat exchanger. The relief valves ensure

that the fluid temperature leaving the collector or heat exchangers does not exceed

the boiling point of water. At night, or during periods of low radiation, a differential temperature controller between the outlet at the bottom of the storage tank

and the collector outlet manifold turns off the pump if this difference is less than

about 9°F. Collected solar energy is stored in two tanks, a large main tank and a smaller domestic water tank. When the temperature of the domestic water tank is less

than the main tank, energy is transferred to it. The model assumes that these two tanks are at the same temperature. No temperature gradients are assumed in the

storage tanks.

Madison, Wisconsin has been selected as the location of the example problem as it

represents a city with major winter heating requirements and reasonable amount of

solar radiation to meet these requirements. Project data for the example are presented

on worksheet A.

Relief Valve Relief Valve Supply Loop

Loop Pump Loop Pump Building

Supply Fan

Figure A-20 Liquid System: Space Heating and Domestic Hot Water

A-40
4.1 (Continued)

WORKSHEET A PROJECT DATA

PROJECT Liquid £*AmPL£; MADtsoH . Wtz .

Location Af^O/SOA»v WtS. Latitude

Building Heating and/or Hot Water Load

Design Heat Loss Rate,

Winter Design Temperature (97 1/2%), t^. Average Hot Water Consumption

(may vary on a monthly basis)

Average Cold Water Supply (main) Temp . , t (may vary on a monthly basis)

Hot Water Supply Temp., t s Collector Subsystem Data

Collector Type: Flat Plate , Selective or^non-selective ,) no . cover plates SL Collector Area, Ac Tilt Angle

Azimuth Angle

Collector Shading (av. % month of Dec.)

Collector Efficiency Data

(from manufacture) FR

(xa) n

FR

UL Reference Temp. Basis

Fluid :

ls: ©~t. + t m .out 'out

Composition : 50 Z EtHYL€V£ 4LYC6l/WAT£A

Specific Heat, Cp

Specific Gravity (if applicable)

Volumetric Flow Rate

Storage Subsystem Data

Volume

Storage Medium WATSA

Specific Heat, -c^ Specific Gravity /or Donoity

Circulation Loop Volumetric Flow Rate

Collector/Storage Heat Exchange Effectiveness, e Hot Water Preheat Storage Volume

Load Subsystem Data

Load Heat Exchanger Effectiveness,

Supply Loop Volumetric Flow Rate

Building Air Supply Volumetric Flow Rate

cs

¥3°

VI, 700 Btu/h - 5

" °P

22.7 gal /day

55 °F

/ fO °F

2Q O ft

3 ¥3 •

o %

.77

25 Btu/h- ft

2 *°F

0.73. Btu/lb • °F 1.05 ib/ib

1.0 Btu/lb -°F

/• O (^Tb/lbl or lb/ft 3

/ iP

^gai/min^or ft

3 /min

.70

gal

.So

/ O gal/min

3 1200 ft /min

A-41
4.1

(Continued)

1. Fraction of Total Heating Load Supplied by Solar Energy, ^Annual

1.1 The values and calculations developed in this section are tabulated on Worksheet B.

Monthly Fraction (f)

By locating the system parameters Di and D2 on figure A-6 , (f) can be determined on

a monthly basis. and D2 are taken from Worksheet C, L is from Worksheet D and S from Worksheet E. For February, the value for (f) was 0.48 and is tabulated in Worksheet B.

1.2

Annual Fraction (F^nnua^)

1.2.1 The solar energy supplied for the example month of February is.

EFeb Feb^ (’ LFeb )

= (.48) (23.5 x 10 6

) = 11.28 x lO^tu

The total solar energy supplied for the entire year is calculated on Worksheet B

1.2.2 The total heating load for the entire year is calculated on Worksheet B

1.2.3 Annual for the entire year is equal to,

F „ .* 10

6 . 0 . 62 Annual L_ _ , , 1 ^ n 6 Total 156.1 x 10

2. System Performance Parameters, D^,

The values and calculations developed in this section are calculated on Worksheet C.

The parameters and are obtained from equations 5 and 6.

For the month of February this is done as follows:

D

1 = Vi S x K. = (D , ) f 4 1 proa L

- ( 860) (.69) (.95) fL

,3 . = (563.7) f

= 563.7 -3-

5

- ' 8 x 10

= .86

23.5 x 10

6 Vt

Pa F'U_ (t j. - t ) Atime

c R L ref o

(860) (.82) (1.0) (1.1)

(212- 5)672

x K

x x K

2 x K

3 = (D2 prod )

(212-t ) Atime

o x K„

(212-t ) Atime

o x K„

= (775.7)

23.5 x 10

x 1.0 = 4.2

A-42
4.1 (Continued)

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A-44
I

4.1 (Continued)

3 Total Building Heating and Domestic Hot Water Load, L

The total heating load is equal to the sum of the space heating load and the domestic hot

water heating load. Worksheet D is used for load calculations.

3.1 Space Heating Load

3.1.1 Knowing the building thermal characteristics (heat transfer coefficients and areas of

surfaces exposed to the outside) and using Manual J, the design temperature difference

(Atd ) and design heat loss (qd ) were found to be 75°F and 71,700 Btu/h respectively.

These are recorded on Worksheet A. An example of the Manual J calculation is presented in the air system example in section 4.2.

3.1.2 Monthly total degree days (DD) for Madison were taken from Table A-3 in section 5. 3.1.3

Monthly space heating load (Q s ) was then calculated using equations 7 and 8. In February for example,

Qs = (PF) (24) (UA) (Degree Days)

where:

PF = 0.75

5d_ = 71 , 7000 Btu/h = Btu_

Atd 75°F 956 h-°F

Qr (F eb) = (0.75) (24) (956) (1274) = 21.9 x 10

6 Btu

3.2 Domestic Hot Water Heating Load

3.2.1 In this example, the hot water requirements are 82.7 gallons per day. Monthly re- quirements are then,

/Mi\ ( n Daxs_\ _ /Mi)

\ Day / V Month J

\ mo /

Values obtained are tabulated in Worksheet D for the example problem. In February

for example,

(82.7) (28) = 2316

gal

month

3.2.2 Water main temperature = 55°F.

3.2.3 Domestic hot water supply temperature (t s ) in accordance with MPS requirements, was assumed to be set at (t s = 140°F)

.

3.2.4 Monthly domestic hot water heating load (Qw) is then,

Qw ^^p (bg bra)

where Cp is the specific heat of water [cp = lBtu/ (lb • °F) ] . Qw is then calculated

on a monthly basis and tabulated in Worksheet D. In February for example,

Qw 2316 gal \

monthJ

Btu \

ib- °Fy (140°F - 55°F) = 1.63 x 10 6 Btu

A-45
4.1 (Continued)

3.3 Total Heating Load (L) is then the sum of space heating (Qs ) and water heating (Qw)

.

l =

Qs -* Qw

f In February for example,

L = 21.9 x 10 6 Btu + 1.63 x 10^ Btu = 23.5 x 10^ Btu

Values of L for each month are tabulated in Worksheet D ,for the example problem.

A-46
WORKSHEET D

HEATING

AND/OR

DOMESTIC

HOT

WATER

LOAD, L

PROJECT

L/QO/D H£

VHW

ExAHPLC.

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A-47
4.1

(Continued)

4 Solar Energy Available (Incident Solar Radiation), S

4.1 Monthly Averages of the Daily Radiation Incident on a Horizontal Surface (IH ) , were

taken from Table A-4, section 5 and are tabulated in Worksheet E for the example

problem.

4.2 Monthly values for Kt were taken from Table A-4, section 5 and are also tabulated in

Worksheet E.

•4.3 Knowing _the collector tilt (0 = 43°), the latitude (<j> = 43°), and monthly Kt values;

monthly R values were taken from Table A-6, section 5 and tabulated in Worksheet E.

For instance, in February, K = .47 Referring to Table A-6 (Kt

_= . 5 ) and determining

the latitude minus tilt difference (<j> - 0_= 43° - 43° = 0°) the R value under the

February column opposite latitude 43° is R = 1.57.

4.4 Monthly Average Daily Radiation on a Tilted Surface (lx) is calculated using equation 12.

IT = (I H) (R)

and tabulated in Worksheet E. For example, in February,

I T = (812) (1.57) = 1284

4.5 Total Average Insolation per Month (S) is calculated using equation 13.

S = (IT ) (N)

where N is the number of days in the month. S is then tabulated in Worksheet E. For

example, in February,

= 35.8 x 103 Btu Month • f t^

4.6 Assume no shading of the collector array in this example.

A-48
WORKSHEET E

TOTAL

MONTHLY

SOLAR

RADIATION

AVAILABLE, S

PROJECT

LlQU/D

UJ

DliW

EkAMPLE

4.1 (Continued) V$X

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A-49

Table

A-4

section
4.1 (Continued)

i i 5 Collector Combined Performance Characteristics Fr(xci), FrUr

5.1The values and calculations developed in this section are tabulated in Worksheet E.

Collector Performance Characteristics, FR(xa) n , FrUr

The collectors are constructed with a double glass cover plate and an aluminum parallel

flow absorber coated with a non-selective flat black paint. Area of collector Ac = 860 ft^

In this case the collector manufacturer has provided a thermal performance

efficiency curve as shown below for the collector, operating with a volumetric

flow rate of 20 gal/min and with the reference temperature equal to the inlet temperature. This corresponds to case 1 in the calculation method and the

performance characteristics are obtained directly as follows:

t i _t

a , °F-hr-ft 2

x IT

Btu

Figure A-21

F U = .85 Btu/h , 0 F-ft determined from the slope of the efficiency curve shown in K L Figure A-21.

F (xct) = .79 as determined from the intercept of the efficiency curve with the y axis.

K n

5.2 Incident Angle Modifier, —

(T0t) n

The incident angle modifier is calculated on Worksheet F. Fr

5.3 Collector Loop Heat Exchanger Modifier, —

fR The collector loop heat exchanger modifier is calculated on Worksheet F.

6 Correction Factors, K^, K2 , K3 , K4 Correction factors Kp , K/? , K3 , K4 are calculated on Worksheet G.

A-50
4.1 (Continued)

WORKSHEET F COLLECTOR COMBINED PERFORMANCE CHARACTERISTICS, F' (to). F'U.

R R L

PROJECT : Liquid H c PHW £xAnpL£ t

(3.5.1) Collector Efficiency Data From Test

. 79

. 85- intercept , b = F (xa) R n slope

,

m = fr

ul

Reference Temperature Basis: 1. Q) 2 -

t. + t. in out

Collector area, A

c Collector volumetric flow rate

3. t'out &UO

2.C ^aI/auaj

Correction to t. basis: m

Case 1: (no correction) F„(xa)

R n

fru

l

Case 2: F (xa) = b x

R n

frul

= m x

_ . /volumetric\

C = me =[ r. c p Iflow rate ) (density) (' tlme

. ) (T

p<T

lflC

)

J \

J ) \conversion/ yneat /

- (*» &*»fcrY'-o*

' gao &

where: for liquids, density =^8.33 lb/gal^ x

( gravity

0

) 3 for air, density = 0.75 lb/ft , at 70° and 1 atm. specific heat = 0.24 Btu/lb*°F

Case 3: F(xa) = b x R n

fru

l

= m x

(3.5.2) Incident Angle Modifier, -)—

f

° (xa)

(xa) f917) for two cover plates

.93, for one cover plate

A-51
4.1 (Continued)

WORKSHEET F (Continued)

fr

(3.5.3) Collector Loop Heat Exchanger Modifier, ——

fr

for air systems and liquid systems without a collector/storage heat exchanger.

a

fr

= i

Capacitance Rate

C = (from above)

&tu

5 &I 0 XT*F

btu

= (calc, as for C above) = ( ICr ^ s ^ # ep

Cmm. = (lesser of C of C ) c s

/h/Ai 2000

Collector Storage Heat Exchanger Effectiveness, E cs = #70

26>to

y

=

e cs ^min ac (frul )

= A 5*3 7

_ _ , o85- #4* I O

fr— = from figure A-ll or =

FR

(3.5.4) (xa) = FR

(ra) n

x

(xa)

[

fr1

X

(Ta) n *

_ Fr

_

FA = fr

u

l

x

fr

1 + y(x-l)

/ +.01*(t. 537-1)

- = . £9

- 6W)6**> = .ga

~

= .96.

A-52
4.1 (Continued)

WORKSHEET G CORRECTION FACTORS , K.12, K„ , K_ , K,

3 4

PROJECT Liquid H f VHM BxAMPLe Mad/soai^/s.

Air Collector Flow Capacitance Rate Factor, K

for air collectors: C = (from worksheet F) =

c A = (from worksheet A) =

c

= (from Figure A-12) = 1.0

Storage Mass Capacitance Factor, K? M = (vol. storage media) x (density) = (lCoo+2 o)£2.33)^ 219b U>

Note: M includes hot water storage

volume where it is solar heated.

, , &~bu

c^ = (from worksheet A) = hO ~j

<McA , (g•nrtOl = /0<+4 2bo

Hot Water Factor,

for liquid systems providing heating only or heating and

hot water, and for all air systems/

K„ = (from Figure A-13) = !• I

me only or

for DHW only systems: t = (from worksheet A)

t = (from worksheet A or if variable see worksheet D) m

t is taken from table A-4 section 5 o

F

°F

is taken from figure A-14 and tabulated on a monthly basis on worksheet C

= (tabulated or const.) = LO

Load Heat Exchange Factor,

for air systems and DHW only systems, = 1.0

e = (from worksheet A) .20

L^hot water supply loop

mC

p C . , = me air loop p

C . = lesser of C„ or C. min H A

UA bldg = (from worksheet D)

UA 1 5C

- «w«

= -Eta.

Ik . *F

15b -8ra —

h-°f

mm e. .9* K. = (from Figure A-15) = .95

4

~~~

A-53
4.2 SOLAR HEATING AND DOMESTIC HOT WATER SYSTEM - AIR WORKING FLUID

Our example is the solar air heating system shown in Figure A-22. The system is designed

to provide space heating and domestic hot water. This system has three modes of operation. Mode 1 occurs when solar energy is available for collection and there is a space

heating load. Then, room temperature air is drawn through the solar collectors, heated,

and returned to the building. The dampers will be in position 1. Mode 2 occurs when

solar energy is available for collection at times when there is no space heating load.

Air from the bottom of the pebble bed is drawn through the solar collectors, heated, and

returned to the top of the storage unit. The hot air moving down through the bed heats

the pebbles resulting in sensible heat storage. The dampers will be in position 2. Mode

3 occurs when no solar energy can be collected but there is a space heating load. Hot

air is drawn from the top of the pebble bed into the house and room temperature air is

returned to the bottom of the bed. The dampers will be in position 3. In modes 1 and 3,

auxiliary energy from a conventional furnace may supplement the solar contribution. The

diagram indicates the dampers in the mode 1 position.

The mode of operation of the solar air heating system is determined by the position of

the dampers. Whenever the collector is operating, damper A is in position 1, 2; otherwise, it is in position 3. The collector operation is controlled by an on-off differential

controller monitoring the temperatures of the air in the collector outlet manifold, t 0 , and in the bottom of the pebble bed, tn , as indicated in Eq. 37,

t Q

- tn <_ At]_ Collector is operating

• t Q

~ t n At2 Collector is off (37)

At^ and At£ are controller deadbands* ideally chosen so that the energy collected is at least equivalent to the energy required to operate the blower. Both At^ and At2 have

been chosen to be 9°F in the examples noted here.

Dampers B and C are controlled by the building thermostat. Whenever the building needs

heat, damper B is in position 1 or 3 and damper C is in position 1, 3, Figure A-22

otherwise they are in position 2. The modeling method used, which is suitable for

long-term simulation, does not follow the system mode changes exactly, but rather assumes

that during any time period, the system operates in whatever modes necessary to maintain

the building temperature at the desired level. Then by comparing energy rates, it is

possible to determine the fraction of the time period in which the system operated in

each mode.

During each time period, the rate of energy collection is compared with the rate of energy

required to meet the heating load. If there is zero energy collection, the system is

assumed to be in mode 3 operation. If the rate of energy collection is non-zero, but

smaller than the rate of energy required by the load, it is assumed that the system is

in mode 1 operation. If the rate of energy collection is greater than the rate at which

energy is required, the fraction of the time period which the system would have to be in

mode 1 operation to just satisfy the load is calculated; the system is assumed to be in

mode 2 operation during the remainder of the period. This method of calculating system

performance allows the simulation to use time steps on the order of an hour without a sacrifice in the accuracy of the calculated long-term system performance.

Grand Junction, Colorado has been selected as the location of the example problem as

it represents a city with major winter heating requirements and a significantly different

set of solar radiation conditions from the previous example. Project data for the ex- ample are presented in Worksheet A.

*Deadband - Temperature range over which the controller does not initiate or terminate

operation of the fan.

A-54
4.2 (Continued)

Figure A-22 Air System: Space Heating and Domestic Hot Water
4.2 (Continued)

WORKSHEET A PROJECT DATA

project Air U* DHU pit . 6ra r\J t Joa c ito*

Location (&r4.r>.cf Jur\c.fiOT't, /6. Latitude

Building Heating and/or Hot Water Load

Design Heat Loss Rate, qy

Winter Design Temperature (97 1/2%), tw Average Hot Water Consumption

(may vary on a monthly basis)

Average Cold Water Supply (main) Temp., tm

(may vary on a monthly basis)

Hot Water Supply Temp., t

s Collector Subsystem Data

Collector Type:_ EIc± PUic ,

Co/o

Selective or^non-s elective^) no. cover plates 2

.

Collector Area, Ac Tilt Angle

Azimuth Angle

Collector Shading (av. % month of Dec.)

Collector Efficiency Data

(from manufacture) FR

(T0°n

FR

UL Reference Temp. Basis: t. . m

t. + t m out

Fluid : Composition

Air

Specific Heat, Cp

Specific Gravity (if applicable)

Volumetric Flow Rate

Storage Subsystem Data

Volume

Storage Medium &>rjc

Specific Heat, cP

-Sfipri fir GV1 ty / © 5T Density

Circulation Loop Volumetric Flow Rate

Collector/Storage Heat Exchange Effectiveness, e Hot Water Preheat Storage Volume

Load Subsystem Data

Load Heat Exchanger Effectiveness,

Supply Loop Volumetric Flow Rate

Building Air Supply Volumetric Flow Rate

cs

= 37 0

= S3,00 0 Btu/h

// °F

= $5~ gal/ day

= SS

= !4o

= 700 ft

s4 °

= Ss /S’O ° o %

= .<.4

= Btu/h • f t 2

• °F

,24 Btu/lb • °F

AJ/A lb /lb

/SDO gal/min or (f

t^

/min^

foo gal or <S>

o, x Btu/lb -°F

/OO lb/lb or /lb/f

t

^ /S&0 gal/min or^t"^/mir

/.O

20 gal

= as/A

= At/A gal/min

3 = / 2>~00 ft /min

A-56
4.2

(Continued)

1. Fraction of Total Heating Load Supplied by Solar Energy, ^Annual

The values and calculations developed in this section are tabulated on Worksheet B.

1.1 Monthly Fraction (f)

By locating the system parameters Di and D 2 on figure A-5, (f) can be determined on

a monthly basis. and D2 are taken from Worksheet C, L is from Worksheet D and S from Worksheet E. For February, the value for (f) was 0.76 and is tabulated in Worksheet B.

1.2 Annual Fraction (F^nnual)

1.2.1 The solar energy supplied for the example month of February is,

EFeb Feb^ <' LFeb )

= (0.76) (16.2 x 10 6

) = 12.31 x lO^tu

The total solar energy supplied for the entire year is calculated on Worksheet B

1.2.2

The total heating load for the entire year is calculated on Worksheet B

1.2.3

F^nrua^ for the entire year is equal to,

=

ETotal =

87 . 17xlQ

6 Annual " LTotal " 112>5xl()

6 = .77

2. System Performance Parameters, D^,

The values and calculations developed in this section are calculated on Worksheet C.

The parameters and D ? are obtained from equations 5 and 6,

For the month of February this is done as follows:

D

i ‘ Vr s * K4

’ ®lprod> I- <700) ( - 48) (1 - 0) !

= 322 f= 322

56 • 3x- 10

= 1.12

L 16.2x10

“it

Fa F’Ut (t c - t ) Atime

c R L ref o'

.05)J

[

1212^351672

]

x 1<Q = |_16.2xl0

(700) (.51) (1.04) (1

= (389.8)

x K

x x K

2 x K3 = (D

2 prod )

(212-t ) Atime

o x K„

(212-t ) Atime

oL

= 2.86

x K„

A-5 7
WORKSHEET

B

FRACTION

OF

TOTAL

HEATING

LOAD

SUPPLIED

BY

SOLAR

ENERGY,

FAnnual

PROJECT

4.2 (Continued)

$

*

ft

0

4

i

N

K ri * x

u

oi3

C

c

<:

4 • ft rH O m

rt n o 6

3 n) e y N

AJ W 3

CJ O £ n) IN i? O N 0- u* *\ 0- 5ft Ob C co a) pq ri Oo V N < ft <

•s \

c M O

03 *H '-i o fsl tH 4J o M-4 0 P

o cj E

rs O' ft ft ft ft a o «« ft

CO CT3 M

* < "C < < •V.

* *

Eh

COH m

E QJ

CD 4-J U 0) N

co e n N

(0 Si 5» r~

y* o»

ft Oo y- 'o

rt

fs. V

v»

ft

pH CT3 CO H

CO

« lo O 4bN V,

ft •x S ft «*> nr

P-.

CO

CNJ

E Qj

a) 4J U CD rH s» cy © *o ft da Cb ‘sO

03 E Q

rt rv o V Ob 0- •ft rs do

CO H

co Cl < < ty V di tv Os Os fti N

• T3 ft O 03 • 0 So o Ny x e V,

i—1

Tot.

Htg.

L

Btu/ «N

><

c

4

si o

6*

fV

•v> v* *0

oi

O'si y-V

rs

fti s

j= X. rH

4-J • • CJ *H CD • 4-J • • • 3 C rO u >> C r—1 6C CL 4-J > CJ o 03 0) 0

3

CL 03 3 0 3 0) CJ O <D 2 pi-. 2 < 2 •o < CO o z Q

$

y

c

e

II

4-» oUW

Nlo

y

U

o

4-» J

Q U U

h (N n sj m

A-58

Worksheet Worksheet
4.2 (Continued)

'l

v55I

,vHUW’“3 o

PS

P-. %

Vw

s:C*4

CM Q | HW

SC

CO

n

to

l-i • <d a o e • X -H M • 4J X

•u e o -h < H I CM

r—1

CM . CL) > E • < n p, HE

O tn . OJ 4-1 O O H S «Q J

CO

60 • i—1 c o

CO *H TD

X 4-1 AJ 03 X 0 CO O 0 H (D .-I 4J cc PQ

<4-4 /-v

r-H CN X c D 4-1

4-J

O C/D <4-1

C -H • C u 4-» o X to i—11

to

X

*H *H • T3 H

—

4-1 rt 2 O CX C 4_» H o eo cOS

to •oc0) >8

N,

IIoC

CDQJ X

U) Xo

\J 5

vc

p*-l *

p<iMO5

<0

II

-os«

**i

0) Xto ps

Pio

3:

<u

0) Xto XL-i O3

CD

CD Xto PS

t-l o3Q

Mt

f". <» \

<0 V

CM

r- >

>-i CD < a

>s

o«

bodo

f“

ft

V)

yv<K

ft

C4D D< H

—

ba

»X VN

vr

vi

V* *

NINI N

*>

<A *< 1 in£

•n o

4-1

T3OU

CD

oo vr

Oomn

too

_i '"v vro

A-59
4.2

(Continued)

3 Total Building Heating and Domestic Hot Water Load, L

The total heating load is equal to the sum of the space heating load and the domestic hot . water heating load. Worksheet D is used for load calculations.

3.1 Space Heating Load

3.1.1 Knowing the building thermal characteristics (heat transfer coefficients and areas of

surfaces exposed to the outside) and using Manual J, the design temperature difference

(Atd ) and design heat loss (qd ) were found to be 59°F and 53,000 Btu/h respectively.

These are recorded on Worksheet A. An example of the Manual J calculation is presented in Figure A-23 for the example house of 1400 sq. ft. floor area.

3.1.2 Monthly total degree days (DD) for Grand Junction were taken from the Table A-3 in

section 5.

3.1.3 Monthly space heating load (Q g

) was then calculated using equations 7 and 8. In February for example,

Qs = (PF) (24) (UA) (Degree Days)

where

PF = 0.75

ha = = 53,000 Btu/hr Btu

Atd 59°F

“ y h-°F

Qs (Feb) = (0.75) (24) (898) (907) - 14.5 x 10 6 Btu

3.2 Domestic Hot Water Heating Load

3.2.1

In this example, the hot water requirements are 85 gallons per day. Monthly re- quirements are then,

85 gal

Day

x N P

ay. s.

.

Month

Values obtained are tabulated in Worksheet D for the example problem. In February

for example.

<85 ) (28) - 2380

3.2.2 Water main temperature = 55 °F.

3.2.3 Domestic hot water supply temperature (t s ) in accordance with MPS requirement, was assumed to be set at (t s = 140°F)

.

3.2.4

Monthly domestic hot water heating load (Qw) is then,

Qw

= mc

p

(t s - tm)

where Cp is the specific heat of water [c p = lBtu/ (lb • °F) ] . is then calculated

on a monthly basis and tabulated in Worksheet D. In February for example,

Qw 2380 ML. \

month J

Btu \

lb-°F/

(140°F - 55°F) - 1.68 x 10 6 Btu

A-60
4.2 (Continued)

3.3 Total Heating Load (L) is then the sum of space heating (Qg ) and water heating (C^)

.

In February for example,

L = 14.5 x 10 6 Btu + 1.68 x 10 6 Btu = 16.2 x 106 Btu

Values of L for each month are tabulated in Worksheet D for the example problem.

4 Solar Energy Available (Incident Solar Radiation) , S

4.1 Monthly Averages of the Daily Radiation Incident on a Horizontal Surface (Ijj), were

taken from Table A-4, section 5 and are tabulated in Worksheet E for the example

problem.

4.2 Monthly values for Kt were taken from Table A-4, section 5 and are also tabulated in

Worksheet E.

4.3 Knowing _the collector tilt (0 = 54°), the latitude (<p = 39°), and monthly Kt values;

monthly R values were taken from Table A-6, section 5 and tabulated in Worksheet E.

For instance, in February, K = .63. Referring to Table A-6 (Kt = .6) and determining

the latitude minus tilt difference (<J> - 0_= 39° -54°= -15°) the R value under the

February column opposite latitude 40° is R - 1.68.

Interpolating for Kt = .63 and <j> = 39° gives a value of R = 1.66.

4.4 Monthly Average Daily Radiation on a Tilted Surface (Iq-) is calculated using equation 12.

^ Qs f Qw

IT = (IH ) (R)

and tabulated in Worksheet E. For example, in February,

I T = (1211) (1.66) = 2010 Da*^t7

4.5

Total Average Insolation per Month (S) is calculated using equation 13.

S = (I T ) (N)

where N is the number of days in the month. S is then tabulated in Worksheet E. For

example, in February,

= 56.3 x 103 Btu Month • f t^

4.6

Assume no shading of the collector array in this example.

A-61
4.2 (Continued)

1 N»m* of Room Entire House i Ull> 2 y/Ul'O'-i DIKI 1 lAOAJ • HAU 'e'e /c/r 5 g#7/4 1 ’

2 Running Fl Exposed Will x

1 2. 4. i 2> // i 7 (< 7

3 Room Dimen«ion*, Ft 14 x -a- 1 7X/S 0 4X4 7X11 xx u t 3 x n <0*8 7 3 r S

4 Ceiling Ht, Ft Direction.* Room Farr* % cj V Alt UJ 8 AJ f £ 8 e IT £ TYPE OF

EXPOSURE

Const. No. HTM Area Btuh Area

or length

Btuh Area

le'ngt h

Btuh Ar.-a

Length

Btuh Ana

length

Btuh Btub

Cl, Length Htg Cl, Ht, Cig Htg Cl, Hr, Cl, Htg Cl, length Htg Cl,

5 Grow

Exposed

Walla and

Partitions

a fUd) S /M /o 4 3-4 n 7

2

b /O'c, (0 <r(«

c li (4) 3(o

d (/«) f

6 Window*

and Glass

Doofs(Htg)

. fc) Of n SCO S' 4oo

b 4(b) /of 4° 3)io 20 /cso

c 3(a) no

7 Windows

and Glass Doo»»(Gg)

North E AW or NE A NW|

South or SE A SW

8 Other Doors l

(bj /go n 2.430

9 Net

Exposed

Walls and

Partitions

a 'ft// S 42? flo $< 330 -5 1 /fO 77 IfO Zb~0

b /Ofi) /a ?o 70 0 Zi 70c

c II (a) JO

d K'il ,r

10 Coiling! a lift) 4 131° ooo 77 JiO /39 050 43 5 00

b

II Floors a n z

b

12 Ventilation 22 -t.fi . Co 3&oo

13 Sub Total Btob Lou 5120 34°° 3C4o /goo 750

14 Duct Btub Laaa

J IS Total Bruh Loss ,53, <5 oo

18 People £ JOO and Appliances 1200

17 Sensible Btub G&h) (Structure)

1ft Duct Btub Gain

19 Sum of Lines 17 and IS (Clj)

20 Total Btub Gain (Line 19 t 1.3) 1J

21 3tuh for Air Quantities

5 6«*3 7 » BATH **2 » Bft 5*! io HAU. ‘A* 2 'B' 11 Rec RM Work a urn_ 1 10 24 5" 2.7 7 82 74 2 to* ti & 3 «£> 10*14 X 2x5* S'- S' H*i%2.»Sli3"6 2.3-26 2 6x 16 19-23 a.s«i2 3 a £ 6 S&t 8 S 6 S iW a | w e.,s. a vs/ W, K 2 £ 1

Ar-a

length

Btuh An .» Btuh Ann Btuh Area Btuh Ana Btuh Ana Btuh Arts* Btuh

Htg Cl, Ht, Cl, l.« ngtli Htg Cl, Length Htg Cl, Li ngrh Ht,

| Cl, la-ngtl' Htg Cl, Lt-ngih Htg Cl, SO 192 40 232 3-<s 5

296 222

4,e 370

2.2. f/+° za IfV* a 4o<? 23 Mil

ft

16 2470 4 (,70

7

20 k&lo t JB .Z'iO <69 32 209 ?|© 36 HO 9

230 71 >0 V*

4iO f^2o 370 mo

123 4/0 /S*o ?#> 24" «|0 238 /|4a /68 7^0 23 1 30 10

772. 1 270 028 ipoo 11

n !W 41770 430 3400 li££ 0 nso 13

14

IS

Ift

17

IS

IS

20

51

Figure A-23 Example Heat Loss Rate Calculation (Manual J)

A-62
WORKSHEET

D

HEATING

AND/OR

DOMESTIC

HOT

WATER

LOAD,

L

PROJECT

Aft H

V

&J<Q

ExG**pl*>

I

1

1

1

1

r

r

-

|

1

1

'

C&/A

4.2 (Continued)

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I u. Uh CD Sr

4-1 CO <Q

si a) • G rH G G ( 4-1 4-» *H cO O 60 X cO c £ 4-1 *H CD

4-> rH CD G IT) CO G « X 1—

1

© CD CD P u CO CN CD E G G P 4-1 rH > JN G cO O 4-> G

CO *H rH P P *H G G G >

0

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0 0 G II cl w rC •H 4-1 cO O E <L V* *« 4-1 9

ff

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CO<

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A-63
WORKSHEET E

TOTAL

MONTHLY

SOLAR

RADIATION

AVAILABLE, S

PROJECT

fijf

Uinku

Ff*

4.2 (Continued) f

v£>

Tot.

Monthly

Radiation

on

Tilt

Surf. S

Btu/

(Mo• f

t^)

©>*\

Vr>

Si 5

>>4 d

A

<*

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A-64
4.2

(Continued)

* i 5 Collector Combined Performance Characteristics FrCtci), FrUl

The values and calculations developed in this section are tabulated in Worksheet E.

5.1 Collector Performance Characteristics, FR(ra) n , FrU^

The collectors are constructed with a double glass cover plate and an aluminum parallel

flow absorber coated with a non-selective flat black paint. Area of collector Ac 700 ft^.

In this case the collector manufacturer has provided a thermal performance

efficiency curve as shown below for the collector, operating with a volumetric

flow rate of 2.1 ft3/min*ft2 and with reference temperature equal to fluid outlet temperature. This corresponds to case 3 in the calculation method and the

performance characteristics are calculated in case 3 on Worksheet F.

K "t a /F-hr-ft2

' I

T

^ Btu ;

Figure A-24

(ta)

5.2

Incident Angle Modifier, —r

(ta) n

The incident angle modifier is calculated on Worksheet F.

5.3

Collector Loop Heat Exchanger Modifier, £r_ Fr

The collector loop heat exchanger modifier is calculated on Worksheet F.

6 Correction Factors, K-j , K2 , K3 , K4

Correction factors K]_, K2 , K3 , are calculated on Worksheet G.

A-65
4.2 (Continued)

WORKSHEET F COLLECTOR COMBINED PERFORMANCE CHARACTERISTICS, F' (to). FlUT R R L

PROJECT: 6fXk*J yJvKciian, C*/o.

(3.5.1) Collector Efficiency Data From Test

intercept, b = F_(to)

K n slope, m = F U

R L Reference Temperature Basis: 1. t

Collector area, A

c Collector volumetric flow rate

.os' v

700 H2 /soo ft */**•*

Correction to t, basis:

in

Case 1: (no correction) =

F U

R L

Case 2: Fr> (xa) =» b x

R n i j. “A

1 + c 2C

F U

R L m x

i . mA

1 + c 2C

C - Ac = /volumetric\ A

t \ (time \ /specific}

c p l flow rate / \ / \conversion/ \heat / ('”»£) £)(<*> $-')("£$) * mo h$%?mr

where: for liquids, density = ^8.33 lb/galj x (gravity

0

)

3 for air, density = 0.75 lb/ft , at 70° and 1 atm. specific heat * 0.24 Btu/lb*°F

Case 3: F^(xa)^ * b x

Vl ' ” *

i . mA

1 + c

\ **

t * (.US) Ctc»7

r . *TD

(3.5.2) Incident Angle Modifier, (ta)

(to).

C* . - . s-(

I 4 h ft'.T

(C*7© ~

9l\ for two cover plates

for one cover plate

A-66
4.2 (Continued)

WORKSHEET F (Continued)

fr

(3.5.3) Collector Loop Heat Exchanger Modifier, —

FR

for air systems and liquid systems without a collector/storage heat exchanger,

Capacitance Rate

C = (from above)

c C = (calc, as for C above)

s c Cmm. = (lesser of C of C ) c s

Collector Storage Heat Exchanger Effectiveness, e cs =

Y

=

e cs Cmin

Ac (FrUL )

Fr— = from figure A-ll or =

1 + y(x-l) l.o

(3.5.4) Fi (xct) = FR (xa) n

x

1

g Pil

_(TM) nJ~ i

n

i

fru

l

= fr

u

l

x

'f;

L

fr

(|.o) - -4C.

= . 5-1

A-67
4.2 (Continued)

WORKSHEET G CORRECTION FACTORS, ^ , K

£

, K

3

,

PE0JECT 4it a om Stand. JoacJus* 6»/o

Air Collector Flow Capacitance Rate Factor,

for liquid collectors = 1.0

for air collectors: C = (from worksheet F) = /CXQ fit** /h • ®

P

c A^ = (from worksheet A) = JO&

^ K

= 1^12 - 2 ?! *** ~ A

c 700 ‘ * h.fi’.T

(from Figure A-12) = loi

Storage Mass Capacitance Factor,

M = (vol. storage media) x (density) = Note: M includes hot water storage

volume where it is solar heated.

(406 4i>)(iOt£ )

-

( ro^/)(s.jf ~j*) -

4ot too (rocIt)

6*6 & (uK-f+r)

c = (from worksheet A) = . 2 Bit*/ (rocjc )f

= (46,CtOJt.2) 4 (6>CC* 0

706

= (2. 4

/ £~(t>//(? )

= (from Figure A-13) = /.OS~"

Hot Water Factor,

for liquid systems providing heating only or heating and

hot water, and for all ^ir systems = 1^2D

for DHW only systems: t = (from worksheet A) = °F

t = (from worksheet A or if variable see worksheet D) = °F m

t is taken from table A-4 section 5

o is taken from figure A-14 and tabulated on a monthly basis on worksheet C K^ = (tabulated or const.) = (. O

C , = lesser of C„ or C A min H A

UA bldg = (from worksheet D)

UA

C . min e

Li

(from Figure A-15)

A-68
4.3 SOLAR DOMESTIC HOT WATER SYSTEM - LIQUID WORKING FLUID

Our typical example of solar energy systems for a domestic hot water heating application

is a relatively simple device consisting of a collector, hot water storage or preheater

tank and associated pumps, piping and controls as depicted in Figure A-25 . The design

of a solar energy hot water heater differs from a building air-conditioning system because the demand is not a function of seasonal ambient temperature and the collector

operating temperature can be lower. Either liquid or air collecting systems are available for use with domestic hot water heating.

The City of Fort Worth was selected for the hot water calculation example because it

represents a climatic region with varying seasonal water main temperatures and it has

a relatively warm climate in contrast to the other examples. Utilizing the average

monthly water main temperature in Table A-8 and assuming a constant hot water demand of

70 gallons per day for the year at a design storage temperature of 140°F resulted in

average daily and monthly loads significantly higher in winter than in summer. The

large winter load resulted in selecting a collector tilt angle of latitude plus 15°

(0= 48°) to position the collector more normal to the sun in the winter.

A single glazed flat black type collector was chosen because of the relatively high

ambient temperature conditions and the resultant good thermal performance in the range

of 100 to 140°F. The use of corrosion inhibited water with the collector loop implies

the need for a double wall heat exchanger to transfer the heat to the stored domestic

hot water.

Collector Hot. Water

Loop Pump Loop Pump

Figure A-25 Liquid System: Domestic Hot Water Only
4.3 (Continued)

WORKSHEET A PROJECT DATA

PROJECT DfHO Example , Ft. kJor+L', Tx

Location Ft Icfor* M t Latitude

Building Heating and/orQfot Water Load^

Design Heat Loss Rate, qg

Winter Design Temperature (97 1/2%) , tw

Average Hot Water Consumption

(may vary on a monthly basis)

Average Cold Water Supply (main) Temp., t m

(may vary on a monthly basis)

Hot Water Supply Temp., t s Collector Subsystem Data

Collector Type : FUf

Selective or(non-s el ective^ no. cover plates / Collector Area, Ac Tilt Angle

Azimuth Angle

Collector Shading (av. % month of Dec.)

Collector Efficiency Data

(from manufacture) : FR

(xa) n

FR

UL

'

Reference Temp. Basis: cvP

Fluid : Composition : ft***

t. + t _ in out

"out

Specific Heat, Cp

Specific Gravity (if applicable)

Volumetric Flow Rate pet" . F. <lo/'feefor

Storage Subsystem Data

Volume

Storage Medium

Specific Heat, cP Specific Gravity/or Density

Circulation Loop Volumetric Flow Rate

Collector/Storage Heat Exchange Effectiveness, e Hot Water Preheat Storage Volume

Load Subsystem Data

Load Heat Exchanger Effectiveness,

Supply Loop Volumetric Flow Rate

Building Air Supply Volumetric Flow Rate

cs

= 32 SW

= Btu/h

= °F

= 70 gal /day

= O °F

= /tO °F

= S& ft

2

= 4

g

°

= 3- /to °

= O %

= .%(

= /. 35“ Btu/h* ft

2 °F

= 1.0

= 1.0

= /.*

Btu/lb * °F

lb/lb , , qcjj-fi 3 , gal /min or ft /mm

gal or ft

3

= Btu/lb •°F

= lb/lb or lb/ft

3

= /, V ^al/mi^or ft

3 /min

= HO gal

gal/min

3 ft /min

A- 70
4.3 (Continued)

1. Fraction of Total Heating Load Supplied by Solar Energy, F^nnua ^ The values and calculations developed in this section are tabulated on Worksheet B.

1.1 Monthly Fraction (f)

By locating the system parameters Di and D2 on figure A-6 , (f) can be determined on

a monthly basis. and D2 are taken from Worksheet C, L is from Worksheet D and S from Worksheet E. For February, the value for (f) was 0.76 and is tabulated in Worksheet E.

1.2 Annual Fraction (F^nnua^)

1.2.1 The solar energy supplied for the example month of February is,

EFeb(f Feb^ ^ LFeb )

= (0.65) (1.486 x 10 6

) = .966 x 10 6Btu

The total solar energy supplied for the entire year is calculated on Worksheet B

1.2.2 The total heating load for the entire year is calculated on Worksheet B

1.2.3 for the entire year is equal to,

F = ETotal = 11.661xl0

6 = ?5 Annual LTotal ^^gg^Q6

2 . System Performance Parameters, D^, D

2

The values and calculations developed in this section are calculated on Worksheet C.

The parameters and are obtained from equations 5 and 6.

For the month of February this is done as follows:

D

l = A F ’ (Ta) S c R

x K. = (D n 4 '“1 prod 7 L

q ^ 45 95 x 1 0^

= (40.88) i

=40.88 T.Vg' x 10^

=1 * 26

) f = ( 60 ) (.737) ( 1

) f

VL'

Pa F'UT (t c 1 - t ) Atime

c R L ref o

- V- "(212-t ) Atime

0 56 (1.320) (1.0) (1.0) L

x K;l x K

2 x K

3 = (D2 prod

x K„

(212-t ) Atime

o x Kn

(73.36)

(212-57 )672

1 • 49 xlO

6 1.10= 5.84

A-71
WORKSHEET

B

FRACTION

OF

TOTAL

HEATING

LOAD

SUPPLIED

BY

SOLAR

ENERGY,

F

An

nual

PROJECT

D&U)

Btarnfi/f*

4.3 (Continued)

*

M

Qj

>#

„ o

rH 0

rt i-i o 6 V orr» m a tu e

4-1 rH -- W 3

y o c < W « CQ

lo31

V**

0

<*• Sr

0*

h-£

o>

hot 0% »-

rJQ

•>- o

c M O

03 *H rH AJ o 4-< N to >A Co f4 m

0 0 6

LO 03 s* fL. N (V. ft*i <» 0V t*ft Oo vA

In

CO 6 0

0) 4-J 0 *45

'H*. W rJ (VS r4 O' m

H O CN

co a Q h- 0» s. >o O P P<

>4 03 CO H

03 K Oft $

6

V. >C s:

d.

CO a o

0) 4J W ID H h- o y 0* O Co u rv»

CN 05 B O «* tft vA O «n V»

>4 03 CO H \ < >4 S vl

% H «S ri •*4 >4

Cl,

• T3 v» O CO SO Q $

pH

Tot.

Htg.

L L

Btu/n *5

>*. S

Q,e

V*

r«

*4.

toK

•<

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•OC

v»

• ^ 1

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Q

6

o

Cl,

u

eo£

CN

U

ao

u

Inm

aO II u

in wm

A-72

Worksheet
WORKSHEET C

SYSTEM

PERFORMANCE

PARAMETERS

4.3 (Continued)

CT3 U-. Ex* o o O

(5

Li

03 4-J <D 4-> 03 4-» 03 Li

03 4-» 03

X 03 03 03 03 03 •C SI X -C x. c C/3 w W U) U) Ik 03 X X > H V* u

}( *H o o o o o s D£ ¥ a O O o $ II

r-.

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v. is Nj

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V o h- vft rN

N o S xl *< vl *Sb

COM • 03 o B • 2 -H M <r CN <r

O <r o ^d- o *d- o 'd- • 4J J= <r 'd- CN <r CN -d- <d CN <r CN <3- x> c O -H < H

v£> r-r r- 0

Li1 Ex* s. o (O a. > r\ o «N

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vA

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Uu Ex*

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ts

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Ex* sJ 1

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4-3

H 2

03 4-3 -PS 03 < PS

Ex* j=

cn

U o u < H 4—1 < O

*d- s 1

II 1 II < TO CM • c 03 rJ • T3 03 co H X) O rH 4-> o H 2 s—

H

CL 03

H cx

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03 -PS • rH Ex* . . u X • • 0) 03 cd U 03 H CO H < U

03 0) X E E 1 -5 £ o o ii 3 u u CN

Ex*

Q <3- m vO

A- 73
4.3

(Continued)

3 Total Building Heating and Domestic Hot Water Load, L

The total heating load is equal to the sum of the space heating load and the domestic hot

water heating load. Worksheet D is used for load calculations.

3.1 Space Heating Load - Not Applicable

3.2 Domestic Hot Water Heating Load

3.2.1 In this example, the hot water requirements are 70 gallons per day. Monthly re- quirements are then,

3.2.2 Water main temperature (tm) , varies and is tabulated on Worksheet D.

3.2.3 Domestic hot water supply temperature (t s ) in accordance with MPS requirement®, was assumed to be set at (t s = 140 C F)

.

3.2.4 Monthly domestic hot water heating load (Qw) is then,

Qw

= mc

p

(t s - tm)

where Cp is the specific heat of water [c p

= IBtu/ (lb • °F) ] . Qw is then calculated

on a monthly basis and tabulated in Worksheet D. In February for example,

x

Values obtained are tabulated in Worksheet D for the example problem. In February

for example,

(70 ) (28) = 1960 Sal

month

3.3 Total Heating Load (L) equals the hot water load (L)

.

A- 74
WORKSHEET

D

HEATING

AND/OR

DOMESTIC

HOT

WATER

LOAD,

L

PROJECT

DUUJ

/-/

LlarH

4.3 (Continued)

PS

X

p

4-J PQ

I

(D c rH

4-1 4J •H G o & CD G 4-J *H G

rH 0) c m CO H

P rH SN G • D P u G CN g p G G HD 4-» rH > CO o 4-J G

G •H rH P HD *H G M

U P u g 4-J HD O a) cr G p o O P. M <D n cr a) H HD e

O . 0) 0) 0) G 0) u ‘ll Pu flJ ,c •H 4-J G o 6 <d •> 4-J 4-» SCO (X CO G II G *-> £ ^ 4-> 4-J PD 1 a)

hd

cr

II

I ^

HD 4-J cr I <

il <

Pd

vc

«o

>r

II

v£5 Total

Heating

Load L Btu/Mo

.

V

f*

Monthly DHW

Load Qw

Btu/Mo.

S

H

0*b

S

>*- <

rtN

<

V)<

*

•>©

<

(<S ©

V. %

N

r\o<

O'* r*r» <

oNV

<

V

v>

DHW

Temp. Rise ts

~ t

m

°F >

0» VJ* to 0

Is- lo c

s. & t

CxM oT V

CK

Temp

.

Water

>1ain

Sup.

t-m°F t

Ifr” >

r-

<0 0

N h* x N o

0» N

e >*»

CO

Vol.

of

DHW Used/Mo

.

Gal.

/Mo. O

r-

(t

O

N& Q

r-

«*

r*

o

0«

0

r*V.

fj

0

I*

O

r*

N.tt

Q

f^. v.

06

0

0

>*

rc

o

N.

Of

0

0>.ns

O

r**

No.

of

Days/ Mo. N

rHCO

oo

CN

«HCO O

co

rHCO O

co

rH

CO

rHCO OcoiHco OcorH

CO

CM

Monthly Space Htg

Load Qs

Btu/Mo

.

%

rH

Monthly

Degree Days DD

°Fdays

X4-» cX

i

X

Cl) pH

Xu

P$

rH

*H

Q- <

>> a

CDG

P

*“>

rHP

*—)

603C

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>>

cfl o

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a)

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r < w [ E II oH CO O'

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« <u -a xi x

o co .> £ i

s

• O' x

o +

>—' cn o

co <r to x

A- 75
4.3

(Continued)

4 Solar Energy Available (Incident Solar Radiation), S

4.1 Monthly Averages of the Daily Radiation Incident on a Horizontal Surface (Ijj)> were

taken from Table A-4, section 5 and are tabulated in Worksheet E for the example

problem.

4.2 Monthly values for Kt were taken from Table A-4, section 5 and are also tabulated in

Worksheet E.

4.3 Knowing _the collector tilt (0 =*.48°). the latitude (d> =33° ), and monthly Kt values;

monthly R values were taken from Table A-6, section 5 and tabulated in Worksheet E.

For instance, in February, K = .54 Referring to Table A-6 (Kt _= . 5 ) and determining

the latitude minus tilt difference (<p - 0_= 33° -48°= -15°) the R value under the

February column opposite latitude 33° is R =*1.37.

Interpolating for Kt = .63 and <J> = 39° gives a value of R = 1.66.

4.4 Monthly Average Daily Radiation on a Tilted Surface (Ix ) is calculated using equation 12.

Ix = (IH) (R)

and tabulated in Worksheet E. For example, in February, — . ULU

I T

= ( 1198 ) (. 137 ) = 1641

p

-

y

.

-f-t

-2

4.5

Total Average Insolation per Month (S) is calculated using equation 13.

S = (IT) (N)

where N is the number of days in the month. S is then tabulated In Worksheet E . For

example, in February,

= 45.9 x 10 3 Btu Month -f

t

z

4.6 Assume no shading of the collector array in this example.

A-76
WORKSHEET

E

TOTAL

MONTHLY

SOLAR

RADIATION

AVAILABLE,

S

PROJECT

4.3 (Continued)

vO

Tot.

Monthly

Radiation

on

Tilt

Surf. S

Btu/

(Mo

• f

t^)

"V$

\

oN

>

9

o

H-

'p. $

v>

<0 Ef

o5

*\ VC

Hr

/V s

c6i V

toPH

cO X

n •*-> c

IH o

O Z Z

• e

O *H z

r-H CO00

CM

i—

1

co oco

rH

CO OCO

rHCO

r—

H

CO O

co

rHCO o

co

rHco

m

• . -—

.

60 CM CM > • U 4-1 <; to s >4-1 co in

pH K Ps

r-l 4J H (0 X >,h|h q

4J H Tl ' C -H H — O cfl 3 2 Q 3 4-1 o «

fc\

V- >

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pH

pH Cfl CO 1 -H O 4-1 CO V4 •H c V4 4J

4J O 4-1 CO 4.)

cfl N X 01 |6ct lit H W U

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, *

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fa-i

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cu r—

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X

03 H

e

o

u

pH

a

II CO

CO

cr

<ueo

3-i Pn

m

C

o

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0)wm

I <

v

r-H X

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e

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J-l pH

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<D

r-H X)

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6o

3-i Pn

55

I

II

-3

-

A-77

From

Table

A-6

section

5,

latitude

(0)

=

3j*-

JiZ>

*

,

with

collector

tilt

(0)

=

4Y

°

,

and

latitude

-

tilt
4.3 (Continued)

i » 5 Collector Combined Performance Characteristics FR (?a) , FRUq

The values and calculations developed in this section are tabulated in Worksheet F.

5.1 Collector Performance Characteristics, FR (ia) n , FRUq

The collectors are constructed with a single glass cover plate and an aluminum parallel

flow absorber coated with a non-selective flat black paint. Area of collector Ac = 56 ft 2

.

In this case the collector manufacturer has provided a thermal performance

efficiency curve as shown below for the collector, operating with a volumetric

flow rate of 1.8 gal/ft 2 of collector/hour and with the reference temperature

equal to the inlet fluid temperature. This corresponds to case 1 in the calculation method and the performance characteristics are obtained directly as follows

t i~t a . °F-hr-ft 2

I T

^ Btu >

Figure A-26

Fr

Ul = .81Btu/h-°F.ft 2 as determined from the slope of the efficiency curve

shown in Figure A-26

.

FR (xa) n = 1.35 as determined from the intercept of the efficiency curve with

the y axis.

5.2 Incident Angle Modifier, (TM) n

The incident angle modifier is calculated on Worksheet F. fR

5.3 Collector Loop Heat Exchanger Modifier, -

fR The collector loop heat exchanger modifier is calculated on Worksheet F.

6 Correction Factor, Kq, K2 , K3 , K4

Correction factors Kq, K2 , K3 , K4 are calculated on Worksheet G.

A- 78
4.3 (Continued)

WORKSHEET F COLLECTOR COMBINED PERFORMANCE CHARACTERISTICS, F' (xa). F'UT R R L

PROJECT :_ VHUJ jo/ri Pf. CJorfl Tx

(3.5.1) Collector Efficiency Data From Test

intercept, b = F (xa) R n m = fr

u

l

= . = /. 35-

siope ,

Reference Temperature Basis: 1. (2) 2

t, + t . in out

3. t'out

Collector area, A

c Collector volumetric flow rate

Correction to t, basis:

in

Case 1: (no correction) F (toi) R n

F UR L

Case 2: F (xa) = b x

R n 11 + c 2C

/.8 / /H *• h

F U

R L

= m x mA

1 + c 2C ^/>^*» /#» k

C - ic ./volumetric! A ± \ /time ' \ /specific}

c p l flow rate ) \ / (conversion/ \heat / = * 39 u tt

where: for liquids, density -(8.33 lb/gal) * (grISi CJ.&e r for air, density = 0.75 lb/ft , at 70° and 1 atm. specific heat = 0.24 Btu/lb*°F

Case 3: F (xa) = b x R n

F U

R L

(xa)

(3.5.2) Incident Angle Modifier,

yyyy

for two cover plates

37} for one cover plate

A-79
4.3 (Continued)

WORKSHEET F (Continued)

(3.5.3) Collector Loop Heat Exchanger

for air systems and liquid

f

r Modifier, —

systems without a collector/storage heat exchanger,

Fi

= 1

Capacitance Rate

C = (from above)

c C = (calc, as for C above)

s c C . = (lesser of C of C ) min c s

= *31.7 V

-(/•» “¥)(/ %'J-' mi

=

Collector Storage Heat Exchanger Effectiveness, G cs = O- If 199 c

e cs Cmin

ac (FrUl ) y

= —

c

= f

' / 3**1 Ct/ovUe u~(t.cov«+frl-lo~)

(S(.) (/-3S-)

131.7

. 69 O

F—R ! = from figure A-ll or =

x + y (xIiy

I1331 '/)

(3.5.4) (TM) FR

(Ta) n

(ra) 1

i

-n ?a

- )

X

(xa) nJ

X

‘ ^pa i

frul

= fr

u

l x

(.t/H.93) {.17J = 7 90

0 9?) (.11) “ I - 3/

77O

A-80
4.3 (Continued)

WORKSHEET G CORRECTION FACTORS, ^ , K

2

, K

3

,

project Ptftjj f~Y. ~7~J( Air Collector Flow Capacitance Rate Factor,

^'for* liquid collectors K1 = 1. for air collectors: C = (from worksheet F) =

c A = (from worksheet A) =

c C

c A

c (from Figure A-12)

Storage Mass Capacitance Factor,

M = (vol. storage media) x (density) = (jt& ) ( /. 3b) ( /• O) .r 3

Note: M includes hot water storage

volume where it is solar heated.

c = (from worksheet A) = /. O

P(Me ) P s = A

c

)Ct)

ST.

- /(.. 3C. K

2 = (from Figure A-13) = /• O

Hot Pater Factor,

for liquid systems providing heating only or heating and

hot water, and for all air systems K^ = 1.0

for DHW only systems: t = (from worksheet A) = /4o°y

t^ = (from worksheet A or if Variable see worksheet 3> *

° F

t is taken from table A-4 section 5 o is taken from figure A-14 and tabulated on a monthly basis on worksheet C = (tabulated or const.) =

Load Heat Exchange Factor,

for air systems and^DHW only systems, KA = TTSi^

e = (from worksheet A) =

Li Slot water supply loop

mC

p C . , = me = air loop p

C . = lesser of C„ or C, = min H A

UA bldg = (from worksheet D) =

UA

C . mm e

Li

= (from Figure A-15) - /, O

A-81
5 REFERENCE MATERIAL

'

.

'

,

.
5 . 1 NOMENCLATURE

A^ - Collector area (aperture or gross basis) (ft ) (AU) - Heat exchanger heat transfer factor [Btu/(h*°F)] nA

C^ = (TMcp

) c “ Fluid capacitance rate of the collector working fluid [Btu/(h-°F)]

C . = (me ) . - Min. fluid capacitance rate [Btu/(h*°F)] min p min

C

g = (m Cp) g = Fluid capacitance rate of the storage loop [Btu/(h - °F)]

0^ - Fluid specific heat [Btu/ (lb • °F)

]

D^, D

2 - System performance parameters (dimensionless)

E - Solar energy supplied for a particular month (Btu/Month)

FTotal

~ So -'- ar energy supplied for an entire year (Btu/Year)

f - Monthly fraction of total heating load supplied by solar energy

Annual Yearly fraction of the total heating load supplied by solar energy (Btu/Year)

fr

I

_sc

K.

- Collector heat removal factor

- Combined form of the collector heat exchanger effectiveness (e ) and the collector

heat removal factor (F ) R

2 - Monthly average of the daily radiation incident on a horizontal surface [Btu/ (Day ft )] - Monthly average of the daily extraterrestrial radiation on a horizontal surface

[Btu/ (Day • f t^)

]

2 - Monthly average of the daily radiation incident normal to a tilted surface [Btu/ (Day ft )]

2 - Solar constant, 429.2 Btu/ft

- Ratio of the monthly averages of the daily radiation on a horizontal surface to the

extraterrestrial radiation on a horizontal surface

- Air collector flow capacitance rate factor

- Storage mass capacitance factor

- Hot water factor

- Load heat exchanger factor

L Total heating and hot water load for a particular month (Btu/Month)

LTotal

~ Total heating and hot water load for an entire year (Btu/Year) m - Mass of domestic hot water used for a particular month (lb) m - Mass flow rate of the working fluid either air or liquid (lb/h)

M - Mass of thermal storage (lb)

N - Number of days in a particular month

NTU - Number of heat transfer units (dimensionless)

Q

g - Space heating load for a particular month (Btu/Month)

- Domestic hot water heating load for a particular month (Btu/Month)

q^

- Building design rate of sensible heat loss (Btu/h) R - Ratio of the monthly average-daily radiation on a tilted surface to that on a horizontal surface

*1

’

S - Monthly incident solar radiation on a tilted surface [Btu/ (month- ft"

1 ) ]

R

2 - Heat exchanger temperature ratios

A-83
5.1 NOMENCLATURE (Continued)

- Ambient air temperature (°F)

t^ - Collector inlet temperature (°F)

t - Temperature of water main supply (°F)

t - Storage temperature (°F)

t - Average day-time temperature (°F)

t Qut - Collector outlet temperature (°F)

t

^ - Reference temperature, 212 °F

t - Temperature of domestic hot water supply (°F)

t - 97 1/2% winter design temperature (°F) w

UA - Building heat loss factor [Btu/(h*°F)]

2 U - Collector heat loss factor [Btu/h*°F*ft )]

J-i

At^ - Design temperature difference for determining heating load (°F) At - Log-mean temperature difference

Atime - Total number of hours in a month (h)

e - Effectiveness of the collector-storage heat exchanger

cs

e - Heat exchanger effectiveness

Ha

e - Effectiveness of the load heat exchanger

J-j 0 - Collector tilt (°)

y

- Solar collector azimuth angle (For Due South = 180°)

p - Thermal efficiency (ratio of the thermal energy removed from the collector, to the

total incident solar radiation on the collector aperture area or collector gross area, see section 3.5.1)

4) - Latitude

(fa) - Average transmittance-absorptance product for design purposes

(to) - Transmittance-absorptance product at normal incidence

A-84
5.2 REFERENCES CITED

1. Klein, S. A., Beckman, W. A., and Duffie, J. A., "Design Procedure for Solar Heating

Systems," Solar Energy, Vol. 18, pp. 113-127, 1976.

2. Engebretson, C. D., "The Use of Solar Energy for Space Heating MIT Solar House IV,"

proceedings of the United Nations Conference on New Sources of Energy 5, 159, United

Nations, New York, N.Y., 1964.

3. Balcomb, J. D. and Hedstrom, J. C., "Simulation Analysis of Passive Solar Heated

Buildings Preliminary Results," LA-UR-76-89, Los Alamos Scientific Laboratory, Los

Alamos, New Mexico 87544, January 1976.

4. Balcomb, J. D., Hedstrom, J. C., and Rogers, B. T., "Design Considerations of Air

Cooled Collector /Rock-Bin Storage Solar Heating Systems," LA-UR-7 5-1334 , Los Alamos

Scientific Laboratory, Los Alamos, New Mexico 87544, August 1975.

5. Connelly, M. , Giellis, R., Jensen, C., and McMordie, R., "Solar Heating and Cooling

Computer Analysis - A Simplified Sizing Design Method for Non-Thermal Specialists,"

American Section, Solar Energy Society Conference, Winnipeg, Canada, August 1976.

6. de Winter, F., "Heat Exchanger Penalties in Double Loop Solar Water Heating Systems,"

Solar Energy, Vol. 17, pp. 335-338, 1976.

7. Kays, W. M., and London, A. L., "Compact Heat Exchanger," National Press, Palo Alto,

California, 1955.

8. ASHRAE Handbook of Fundamentals, American Society of Heating, Refrigeration, and Air

Conditioning Engineers, Inc., 345 East 47th Street, New York, N.Y. 10017, 1972.

9. ASHRAE Systems Handbook, Chapter 43, American Society of Heating, Refrigeration, and

Air Conditioning Engineers, Inc., 345 East 47th Street, New York, N.Y. 10017, 1976.

10. Liu, B. Y. H. , and Jordan, R. C., "Availability of Solar Energy for Flat Plate Solar

Heat Collectors," Low Temperature Engineering Application of Solar Energy , American

Society of Heating, Refrigeration, and Air Conditioning Engineers, Inc., 345 East

47th Street, New York, N.Y. 10017, 1967.

11. Bennett, I., "Monthly Maps of Mean Daily Insolation for the United States," Solar

Energy, Vol. 9, No. 31, pp. 145-158, 1965.

12. Hill, J. E., Streed, E. R. , Kelly, G. E. , Geist, J. C., and Kusuda, T., "Development

of Proposed Standards for Testing Solar Collectors and Thermal Storage Devices,"

Center for Building Technology, National Bureau of Standards, Washington, D.C. 20234,

February 1976.

13. Climate Atlas of the United States, U.S. Department of Commerce, NOAA, National

Climatic Center, Federal Building, Asheville, N.C. 28801.

14. Load Calculation for Residential Winter and Summer Air Conditioning, Manual J, National

Environmental Systems Contractors Association, 1501 Wilson Blvd., Arlington, Va. 22209.

15. Heat Loss Calculation Guide, No. H-21, The Hydronics Institute, 35 Russo Place, Berkeley

Heights, N. J. 07922.

16. Duffie, J. A. and Beckman, W. A., "Solar Energy Thermal Processes," Wiley, New York,

N. Y., 1974.

17. ASHRAE Applications of Solar Energy for Heating and Cooling of Buildings, American

Society of Heating, Ref rigeration and Air Conditioning Engineers, Inc., 345 East 47th

St._, New York, N. Y., 10017, 1977.

A-85
5.2 REFERENCES CITED (Continued)

18. Klein, S. A., Beckman, W. A., and Duffie, J. A., "A Design Procedure for Solar Air

Heating Systems," Proceedings of American Section ISES Meeting, Winnipeg, Canada,

Vol. 4, August, 1976.

19. "f-chart Computer Program," Solar Engineering Laboratory, University of Wisconsin,

Madison, Wisconsin.

A-86
5.3 TABLES AND GRAPHS
EFFICIENCY

100 r- Double Glazed, Flat Plate, Flat Black Paint

Antiref lective Double Glazed, Flat Plate, Black Chrome

Selective Surface

Single Glazed, Flat Plate, Black Chrome Selective Surface

Single Glazed, Evacuated Tube, Concentric Selective

Absorber

Linear Fresnel Lens, Tracking-concentrating, Black Chrome Selective Surface

Single Glazed, Flat Plate, Flat Black Paint

Single Glazed, Trickle Type

Figure A-27a Typical Thermal Efficiency Curves for Liquid

Collectors Based on Collector Aperture Area

Figure A-27b Typical Thermal Efficiency Curves for Liquid

Collectors Based on Collector Gross Frontal Area

A- 88
Figure A-28 Typical Thermal Efficiency Curves for Flat Plate

Collectors Using Air as the Working Liquid [12]

(Q indicates flow rate in standard cubic feet

per minute (scfm) per unit collector area)

A-89
Figure A-29 Mean Daily Insolation (Ipj) Btu/day-Ft for January and February [11]

A-90
1500

Figure A-29 (cont.) Mean Dally Insolation (1^) Btu/dayFt^ for March and April

A-91
MAY

1700

1800

800

2000

Figure A-29 (cont.) Mean Daily Insolation (ly) Btu/dayFt^ for May and June

A-92
A-93
750

Figute A-29 (cont.) Mean Daily Insolation (Iy) Btu/day-Ft^ for September and October

A-94
NOVEMBER

A-95
Material Thickness

{ inches;

Solar

^^ Transmittance \per cent)

Glass, water white crystal .156 0.91

Glass, untreated sheet .125 .86

Glass, untreated plate .250 .78

Polycarbonate 0.80 .84

Fiberglass .040 .90

Polyvinyl fluoride .004 .92

Polymethyl methacrylate .125 .89

FEP Teflon .001 .96

Polyimide .00025 .80

Polyethyelene Terephthalate .002 .84

Table A-i Solar Transmittance of various cover materials.

Material

* Abso?p?ance ('

)

( per cent;

Black Chrome 0.87 to 0.93

Black Nickel .87 to .92

Anodize .82 to .99

Copper Oxide .83 to .91

Black Paint, Inorganic .89 to .96

Black Paint, Acrylic .92 to .97

Black Paint, Silicone .86 to .94

Dependent upon thickness and vehicle-to- binder ratio

Table A-2 Solar Absorptance of several absorber coating

materials.

A-96
Stole Station

•7 1/21 VlBttl

. T««p. S' July Aug. Sept. Oct. Nov. Dec. Jon. Feb. Mar. Apr. May June

Yearly

Total

Ala. Birmingham A 22 0 0 6 93 363 555 592 462 363 108 9 0 2551

Huntsville A 17 0 0 12 127 426 663 694 557 434 138 19 0 3070 Mobile A 29 0 0 0 22 213 357 415 300 211 42 0 0 1560 Montgomery A 26 0 0 0 68 330 527 543 417 316 90 0 0 2291

Alaska Anchorage A -22 245 291 516 930 1284 1572 1631 1316 1293 879 592 315 10864 Fairbanks A -50 171 332 642 1203 1833 2254 2359 1901 1739 1068 555 222 14279 Juneau A - 4 301 338 483 725 921 1135 1237 1070 1073 810 601 381 9075 Nome A -28 481 496 693 1094 1455 1820 1879 1666 1770 1314 930 573 14171

Ariz. Flagstaff A

5 46 68 201 558 867 1073 1169 991 911 651 437 180 7152 Phoenix A

34 0 0 0 22 234 415 474 328 217 75 0 0 1765 Tucson A 32 0 0 0 25 231 406 471 344 242 75 6 0 1800 Winslow A 13 0 0 6 245 711 1008 1054 770 601 291 96 0 4782 Yuma A 40 0 0 0 0 108 264 307 190 90 15 0 0 974

Ark. Fort Smith A 19 0 0 12 127 450 704 781 596 456 144 22 0 3292

Little Rock A 23 0 0 9 127 465 716 756 577 434 126 9 0 3219 Texarkana A 26 0 0 0 78 345 561 626 468 350 105 0 0 2533

Calif. Bakersfield A

33 0 0 0 37 282 502 546 364 267, 105 19 0 2122 Bishop A 0 0 48 260 576 797 874 680 555 306 143 36 4275

Blue Canyon A 28 37 108 347 594 781 896 795 806 597 412 195 5596 Burbank A 38 0 0 6 43 177 301 366 277 239 138 81 18 1646 Eureka C 35 270 257 258 329 414 499 546 470 505 438 372 285 4643

Fresno A 31 0 0 0 84 354 577 605 426 335 162 62 6 2611 Long Beach A 38 0 0 9 47 171 316 397 311 264 171 93 24 1803 Los Angeles A 43 28 28 42 78 180 291 372 302 288 219 158 81 2061 Los Angeles C 44 0 0 6 31 132 229 310 230 202 123 68 18 1349 Mt. Shasta C 25 34 123 406 696 902 983 784 738 525 347 159 5722

Oakland A 37 53 50 45 127 309 481 527 400 353 255 180 90 2870 Red Bluff A 0 0 0 53 318 555 605 428 341 168 47 0 2515 Sacramento A 32 0 0 0 56 321 546 583 414 332 178 72 0 2502 Sacramento C 0 0 0 62 312 533 561 392 310 173 76 0 2419 Sandberg C 0 0 30 202 480 691 778 661 620 426 264 57 4209

San Diego A 44 9 0 21 43 135 236 298 235 214 135 90 42 1458 San Francisco A 37 81 78 60 143 306 462 508 395 363 279 214 126 3015 San Francisco C 42 192 174 102 118 231 388 443 336 319 279 239 180 3001 Santa Maria A 34 99 93 96 146 270 391 459 370 363 282 233 165 2967

Colo. Alamosa A

-13

65 99 279 639 1065 1420 1476 1162 1020 696 440 168 8529 Colorado Springs A 4

9 25 132 456 825 1032 1128 938 893 582 319 84 6423 Denver A 3 6 9 117 428 819 1035 1132 938 887 558 288 66 6283 Denver C 0 0 90 366 714 905 1004 851 800 492 254 48 5524 Grand Junction A 11 0 0 30 313 786 1113 1209 907 729 387 146 21 5641 Pueblo A - 1 0 0 54 326 750 986 1085 871 772 429 174 15 5462

Conn. Bridgeport A 8 0 0 66 307 615 986 1079 966 853 510 208 27 5617

Hartford A 5 0 12 117 394 714 1101 1190 1042 908 .519 205 33 6235 New Haven A 9 0 12 87 347 648 1011 1097 991 871 543 245 45 5897

Del. Wilmington A 15 0 0 51 270 588 927 980 874 735 387 112 6 4930

D.C. Washington A 19 .0 0 33 217 519 834 871 762 626 288 74 0 4224

Fla. Apalachicola C 0 0 0 16 153 319 347 260 180 33 0 0 1308 Daytona Beach A

36 0 0 0 0 75 211 248 190 140 15 0 0 879

Fort Myers A 42 0 0 0 0 24 109 146 101 62 0 0 0 442

Jacksonville A 32 0 0 0 12 144 310 332 246 174 21 0 0 1239

Key West A 58 0 0 0 0 0 28 40 31 9 0 0 0 108 Lakeland C 39 0 0 0 0 57 164 195 146 99 0 0 0 661 Miami A 47 0 0 0 0 0 65 74 56 19 0 0 0 214

•Data for United States cities from a publication of the United States Weather Bureau, Monthly Normals of Temperature. Precipitation and Heating Degree Days.

1962, are for the period 1931 to I960 inclusive These data also include information from the 1963 revisions to this publication, where available.

b Data for airport stations. A, and city stations, C. are both given where available.

c Data for Canadian cities were computed by the Climatology Division. Department of Transport from normal monthly mean temperatures, and the monthly values

of heating degree days data were obtained using the National Research Council computer and a method devised by H. C. S. Thom of the United States Weather Bureau. The heating degree days are based on the period from 1931 to 1960. ^Date from ASHRAE Handbook of Fundamentals, 1972

Table A-3 Average Monthly and Yearly Degree Days (Base 65 °F)

and 97 1/2% Winter Design Temperatures (a, b, c, d)

From: ASHRAE Systems Handbook 1976

A-97
State Station v mi

Winter

D..lp>

Tcsp. —

July Aug. Sept. Oct. Nov. Dec. Jan. Feb. Mar. Apr. May June

Yearly

Total

Fla. Miami Beach C 48 0 0 0 0 0 40 56 36 9 0 0 0 141 (Cont’d) Orlando A 37 0 0 0 0 72 198 220 165 105 6 0 0 766

Pensacola A 32 0 0 0 19 195 353 400 277 183 36 0 0 1463

Tallahassee A

29 0 0 0 28 198 360 375 286 202 36 0 0 1485 Tampa A 39 0 0 0 0 60 171 202 148 102 0 0 0 683 West Palm Beach A 44 0 0 0 0 6 65 87 64 31 0 0 0 253

Ga. Athens A

21

0 0 12 115 405 632 642 529 431 141 22 0 2929

Atlanta A 0 0 18 124 417 648 636 518 428 147 25 0 2961 Augusta A

23 0 0 0 78 333 552 549 445 350 90 0 0 2397 Columbus A 26 0 0 0 87 333 543 552 434 338 96 0 0 2383 Macon A 27 0 0 0 71 297 502 505 403 295 63 0 0 2136 Rome A 20 0 0 24 161 474 701 710 577 468 177 34 0 3326 Savannah A 27 0 0 0 47 246 437 437 353 254 45 0 0 1819 Thomasville C 0 0 0 25 198 366 394 305 208 33 0 0 1529

Hawaii Lihue A

62

0 0 0 0 0 0 0 0 0 0 0 0 0 Honolulu A 0 0 0 0 0 0 0 0 0 0 0 0 0

Hilo A 61 0 0 0 0 0 0 0 0 0 0 0 0 0

Idaho Boise A 10 0 0 132 415 792 1017 1113 854 722 438 245 81 5809

Lewiston A 12 0 0 123 403 756 933 1063 815 694 426 239 90 5542

Pocatello A - 2 0 0 172 493 900 1166 1324 1058 905 555 319 141 7033

III. Cairo C 0 0 36 164 513 791 856 680 539 195 47 0 3821 Chicago (O'Hare) A 0 12 117 381 807 1166 1265 1086 939 534 260 72 6639 Chicago (Midway) A

1 0 0 81 326 753 1113 1209 1044 890 480 211 48 6155 Chicago C 1 0 0 66 279 705 1051 1150 1000 868 489 226 48 5882 Moline A - 3 0 9 99 335 774 1181 1314 1100 918 450 189 39 6408

Peoria A 2 0 6 87 326 759 1113 1218 1025 849 426 183 33 6025 Rockford A - 3

6 9 114 400 837 1221 1333 1137 961 516 236 60 6830

Springfield A 4 0 0 72 291 696 1023 1135 935 769 354 136 18 5429

Ind. Evansville A 10 0 0 66 220 606 896 955 767 620 237 68 0 4435

Fort Wayne A 5 0 9 105 378 783 1135 1178 1028 890 471 189 39 6205

Indianapolis A 4 0 0 90 316 723 1051 1113 949 809 432 177 39 5699

South Bend A 3 0 6 111 372 777 1125 1221 1070 933 525 239 60 6439

Iowa Burlington A 0 0 0 93 322 768 1135 1259 1042 859 426 177 33 6114 Des Moines A - 3 0 6 96 363 828 1225 1370 1137 915 438 180 30 6588 Dubuque A - 7 12 31 156 450 906 1287 1420 1204 1026 546 260 78 7376

Sioux City A - 6 0 9 108 369 867 1240 1435 1198 989 483 214 39 6951 Waterloo A - 8

12 19 138 428 909 1296 1460 1221 1023 531 229 54 7320

Kans. Concordia A 0 0 • 57 276 705 1023 1163 935 781 372 149 18 5479 Dodge City A

7 0 0 33 251 666 939 1051 840 719 354 124 9 4986 Goodland A 4 0 6 81 381 810 1073 1166 955 884 507 236 42 6141 Topeka A 6 0 0 57 270 672 980 1122 893 722 330 124 12 5182 Wichita A 9 0 0 33 229 618 905 1023 804 645 270 87 6 4620

Ky. Covington A

8 0 0 75 291 669 983 1035 893 756 390 149 24 5265

Lexington A 10 0 0 54 239 609 902 946 818 685 325 105 0 4683

Louisville A 12 0 0 54 248 609 890 930 818 682 315 105 9 4660

La. Alexandria A

29

0 0 0 56 273 431 471 361 260 69 0 0 1921 Baton Rouge A

30 0 0 0 31 216 369 409 294 208 33 0 0 1560 Lake Charles A 33 0 0 0 19 210 341 381 274 195 39 0 0 1459 New Orleans A 35 0 0 0 19 192 322 363 258 192 39 0 0 1385 New Orleans C 0 0 0 12 165 291 344 241 177 24 0 0 1254

Shreveport A 26 0 0 0 47 297 477 552 426 304 81 0 0 2184

Me. Caribou A -14 78 115 336 682 1044 1535 1690 1470 1308 858 468 183 9767

Portland A 0 12 53 195 508 807 1215 1339 1182 1042- 675 372 111 7511

Md. Baltimore A 15 0 0 48 264 585 905 936 820 679 327 90 0 4654

Baltimore C 20 0 0 27 189 486 806 859 762 629 288 65 0 4111

Frederich A 11 0 0 66 307 624 955 995 876 741 384 127 12 5087

Mass. Boston A 10 0 9 60 316 603 983 1088 972 846 513 208 36 5634 Nantucket A 12 22 93 332 573 896 992 941 896 621 384 129 5891

Pittsfield A - 3

25 59 219 524 831 1231 1339 1196 1063 660 326 105 7578

Worcester A 06 34 147 450 774 1172 1271 1123 998 612 304 78 6969

Table A-3 (contd)
State Station

17 XjlX nuir

July Aug. Sept. Oct Nov. Dtc. Jan. F,b Mar. Apr. May June

Yearly

Total

Mich. Alpena A

- l

68 105 273 580 912 1268 1404 1299 1218 777 446 156 8506

Detroit (City) A 0 0 87 360 738 1088 1181 1058 936 522 220 42 6232

Detroit (Wayne) A 0 0 96 353 738 1088 1194 1061 933 534 239 57 6293

Detroit (Willow Run) A 0 0 90 357 750 1104 1190 1053 921 519 229 45 6258 Escanaba C - 3 59 87 243 539 924 1293 1445 1296 1203 777 456 159 8481

Flint A 3 16 40 159 465 843 1212 1330 1198 1066 639 319 90 7377

Grand Rapids A 6 9 28 135 434 804 1147 1259 1134 1011 579 279 75 6894

Lansing A 6 6 22 138 431 813 1163 1262 1142 1011 579 273 69 6909 Marquette C - 4 59 81 240 527 936 1268 1411 1268 1187 771 468 177 8393 Muskegon A 8 12 28 120 400 762 1088 1209 1100 995 594 310 78 6696

Sault Ste. Mane A - 8 96 105 279 580 951 1367 1525 1380 1277 810 477 201 9048

Minn. Duluth A

-15 71 109 330 632 1131 1581 1745 1518 1355 840 490 198 10000

Minneapolis A -10 22 31 189 505 1014 1454 1631 1380 1166 621 288 81 8382

Rochester A -13 25 34 186 474 1005 1438 1593 1366 1150 630 301 93 8295

Miss. Jackson A 24 0 0 0 65 315 502 546 414 310 87 0 0 2239

Meridian A 24 0 0 0 81 339 518 543 417 310 81 0 0 2289

Vicksburg C 26 0 0 0 53 279 462 512 384 282 69 0 0 2041

Mo. Columbia A 6 0 0 54 251 651 967 1076 874 716 324 121 12 5046 Kansas City A 8 0 0 39 220 612 905 1032 818 682 294 109 0 4711

St. Joseph A 3 0 6 60 285 708 1039 1172 949 769 348 133 15 5484

St. Louis A 8 0 0 60 251 627 936 1026 848 704 312 121 15 4900

St Louis C 11 0 0 36 202 576 884 977 801 651 270 87 0 4484

Spnngfield A 10 0 0 45 223 600 877 973 781 660 291 105 6 4900

Mont. Billings A

- 6

6 15 186 487 897 1135 1296 1100 970 570 285 102 7049 Glasgow A

-20

31 47 270 608 1104 1466 1711 1439 1187 648 335 150 8996 Great Falls A -16 28 53 258 543 921 1169 1349 1154 1063 642 384 186 7750 Havre A 28 53 306 595 1065 1367 1584 1364 1181 657 338 162 8700 Havre C -15 19 37 252 539 1014 1321 1528 1305 1116 612 304 135 8182

Helena A

-13

31 59 294 601 1002 1265 1438 1170 1042 651 381 195 8129

Kalispell A - 3 50 99 321 654 1020 1240 1401 1134 1029 639 397 207 8191 Miles City A -15 6 6 174 502 972 1296 1504 1252 1057 579 276 99 7723

Missoula A _ ** 34 74 303 651 1035 1287 1420 1120 970 621 391 219 8125

Neb. Grand Island A

- 2 0 6 108 381 834 1172 1314 1089 908 462 211 45 6530

Lincoln C

0 0 6 75 301 726 1066 1237 1016 834 402 171 30 5864

Norfolk A - 7 9 0 111 397 873 1234 1414 1179 983 498 233 48 6979 North Platte A - 2 0 6 123 440 885 1166 1271 1039 930 519 248 57 6684 Omaha A - 1 0 12 105 357 828 1175 1355 1126 939 465 208 42 6612

Scottsbluff A - 4 0 0 138 459 876 1128 1231 1008 921 552 285 75 6673

Valentine A 9 12 165 493 942 1237 1395 1176 1045 579 288 84 7425

Nev. Elko A

- 7

9 34 225 561 924 1197 1314 1036 911 621 409 192 7433

Ely A

- 2 28 43 234 592 939 1184 1308 1075 977 672 456 225 7733

Las Vegas A 26 0 0 0 78 387 617 688 487 335 111 6 0 2709 Reno A 7 43 87 204 490 801 1026 1073 823 729 510 357 189 6332 Winnemucca A 5 0 34 210 536 876 1091 1172 916 837 573 363 153 6761

N.H. Concord A

- 7 6 50 177 505 822 1240 1358 1184 1032 636 298 75 7383

Mt. Washington Obsv 493 536 720 1057 1341 1742 1820 1663 1652 1260 930 603 13817

NJ. Atlantic City A 18 0 0 39 251 549 880 936 848 741 420 133 15 4812 Newark A 15 0 0 30 248 573 921 983 876 729 381 118 0 4589

Trenton C 16 0 0 57 264 576 924 989 885 753 399 121 12 4980

N. M. Albuquerque A 17 0 0 12 229 642 868 930 703 595 288 81 0 4348

Clayton A 0 6 66 310 699 899 986 812 747 429 183 21 5158 Raton A 2 9 28 126 431 825 1048 1116 904 834 543 301 63 6228 Roswell A 19 0 0 18 202 573 806 840 641 481 201 31 0 3793

Silver City A 18 0 0 6 183 525 729 791 605 518 261 87 0 3705

N.Y. Albany A

0 0 19 138 440 777 1194 1311 1156 992 564 239 45 6875 Albany C 5 0 9 102 375 699 1104 1218 1072 908 498 186 30 6201 Binghamton A 22 65 201 471 810 1184 1277 1154 1045 645 313 99 7286 Binghamton C 2 0 28 141 406 732 1107 1190 1081 949 543 229 45 6451

Buffalo A 6 19 37 141 440 777 1156 1256 1145 1039 645 329 78 7062 New York (Cent. Park) C 15 0 0 30 233 540 902 986 885 760 408 118 9 4871 New York (La Guardia) A 16 0 0 27 223 528 887 973 879 750 414 124 6 4811

Table A-3 (contd)

A-99
State Station

•7 1/2X Winter

De.l*nd/ Tcnp. —

July Aug. Sept. Oct. Nov. Dec. Jan. Feb. Mar. Apr. May June

Yearly

Total

New York (Kennedy) A

21 0 0 36 248 564 933 1029 935 815 480 167 12 5219

Rochester A 5 9 31 126 415 747 1125 1234 1123 1014 597 279 48 6748

Schenectady C -

1

0 22 123 422 756 1159 1283 1131 970 543 211 30 6650

Syracuse A 2 6 28 132 415 744 1153 1271 1140 1004 570 248 45 6756

N. C. Asheville C

17

0 0 48 245 555 775 784 683 592 273 87 0 4042 Cape Hatteras 22

0 0 0 78 273 521 580 518 440 177 25 0 2612

Charlotte A 0 0 6 124 438 691 691 582 481 156 22 0 3191 Greensboro A 17 0 0 33 192 513 778 784 672 552 234 47 0 3805

Raleigh A 20 0 0 21 164 450 716 725 616 487 180 34 0 3393 Wilmington A 27 0 0 0 74 291 521 546 462 357 96 0 0 2347 Winston-Salem A 17 0 0 21 171 483 747 753 652 524 207 37 0 3595

N. D. Bismarck A

-19

34 28 222 577 1083 1463 1708 1442 1203 645 329 117 8851

Devils Lake C

-19 40 53 273 642 1191 1634 1872 1579 1345 753 381 138 9901 Fargo A -17 28 37 219 574 1107 1569 1789 1520 1262 690 332 99 9226

Williston A -17 31 43 261 601 1122 1513 1758 1473 1262 681 357 141 9243

Ohio Akron-Canton A 6 0 9 96 381 726 1070 1138 1016 871 489 202 39 6037

Cincinnati C 12 0 0 39 208 558 862 915 790 642 294 96 6 4410

Cleveland A 7 9 25 105 384 738 1088 1159 1047 918 552 260 66 6351 Columbus A 7 0 6 84 347 714 1039 1088 949 809 426 171 27 5660 Columbus C 0 0 57 285 651 977 1032 902 760 396 136 15 5211 Dayton A 6 0 6 78 310 696 1045 1097 955 809 429 167 30 5622

Mansfield A 3 9 22 114 397 768 1110 1169 1042 924 543 245 60 6403 Sandusky C 8 0 6 66 313 684 1032 1107 991 868 495 198 36 5796 Toledo A 5 0 16 117 406 792 1138 1200 1056 924 543 242 60 6494 Youngstown A 6 6 19 120 412 771 1104 1169 1047 921 540 248 60 6417

Okla. Oklahoma City A 15 0 0 15 164 498 766 868 664 527 189 34 0 3725

Tulsa A 16 0 0 18 158 522 787 893 683 539 213 47 0 3860

Ore. Astoria A

30

146 130 210 375 561 679 753 622 636 480 363 231 5186 Bums C 12 37 210 515 867 1113 1246 988 856 570 366 177 6957 Eugene A 26 34 34 129 366 585 719 803 627 589 426 279 135 4726 Meacham A 84 124 288 580 918 1091 1209 1005 983 726 527 339 7874 Medford A 23 0 0 78 372 678 871 918 697 642 432 242 78 5008

Pendleton A

10

0 0 111 350 711 884 1017 773 617 396 205 63 5127

Portland A

24 25 28 114 335 597 735 825 644 586 396 245 105 4635

Portland C 29 12 16 75 267 534 679 769 594 536 351 198 78 4109

Roseburg A 29 22 16 105 329 567 713 766 608 570 405 267 123 4491 Salem A 25 37 31 111 338 594 729 822 647 611 417 273 144 4754

Pa. Allentown A 5 0 0 90 353 693 1045 1116 1002 849 471 167 24 5810

Erie A 11 0 25 102 391 714 1063 1169 1081 973 585 288 60 6451 Harrisburg A 13 0 0 63 298 648 992 1045 907 766 396 124 12 5251

Philadelphia A 15 0 0 60 297 620 965 1016 889 747 392 118 40 5144

Philadelphia C 0 0 30 205 513 856 924 823 691 351 93 0 4486

Pittsburgh A

9 0 9 105 375 726 1063 1119 1002 874 480 195 39 5987

Pittsburgh C

11 0 0 60 291 615 930 983 885 763 390 124 12 5053 Reading C 9 0 0 54 257 597 939 1001 885 735 372 105 0 4945

Scranton A 6 0 19 132 434 762 1104 1156 1028 893 498 195 33 6254

Williamsport A 5 0 9 111 375 717 1073 1122 1002 856 468 177 24 5934

R. I. Block Island A 0 16 78 307 594 902 1020 955 877 612 344 99 5804

Providence A 10 0 16 96 372 660 1023 1110 988 868 534 236 51 5954

S. C. Charleston A

27 0 0 0 59 282 471 487 389 291 54 0 0 2033

Charleston C

30 0 0 0 34 210 425 443 367 273 42 • 0 0 1794 Columbia A 23 0 0 0 84 345 577 570 470 357 81 0 0 2484

Florence A 25 0 0 0 78 315 552 552 459 347 84 0 0 2387

Greenville-Spartenburg A 23 0 0 6 121 399 651 660 546 446 132 19 0 2980

S. D. Huron A

-12 9 12 165 508 1014 1432 1628 1355 1125 600 288 87 8223 Rapid City A - 6 22 12 165 481 897 1172 1333 1145 1051 615 326 126 7345

Sioux Falls A -10 19 25 168 462 972 1361 1544 1285 1082 573 270 78 7839

Tenn. Bristol A 16 0 0 51 236 573 828 828 700 598 261 68 0 4143 Chattanooga A 19 0 0 18 143 468 698 722 577 453 150 25 0 3254

Knoxville A 17 0 0 30 171 489 725 732 613 493 198 43 0 3494 Memphis A 21 0 0 18 130 447 698 729 585 456 147 22 0 3232

Table A-3 (contd)
Slat•

or

Pro*.

Station

•7 1/21 Vlntar

Dsalgn.. July Aug. Sept. Oct. Nor. Dec. Jan. Feb. Mar. Apr. May June

Yearly

Total

Memphis C 0 0 12 102 396 648 710 568 434 129 16 0 3015

Nashville A 16 0 0 30 158 495 732 778 644 512 189 40 0 3578 Oak Ridge C 0 0 39 192 531 772 778 669 552 228 56 0 3817

Tex. Abilene A

21

0 0 0 99 366 586 642 470 347 114 0 0 2624

Amarillo A

12 0 0 18 205 570 797 877 664 546 252 56 0 3985 Austin A 29 0 0 0 31 225 388 468 325 223 51 0 0 1711 Brownsville A 40 0 0 0 0 66 149 205 106 74 0 0 0 600 Corpus Christi A 36 0 0 0 0 120 220 291 174 109 0 0 0 914

Dallas A 24 0 0 0 62 321 524 601 440 319 90 6 0 2363

El Paso A 25 0 0 0 84 414 648 685 445 319 105 0 0 2700

Fort Worth A

24

0 0 0 65 324 536 614 448 319 99 0 0 2405 Galveston A 0 0 0 6 147 276 360 263 189 33 0 0 1274 Galveston C 0 0 0 0 138 270 350 258 189 30 0 0 1235 Houston A 32 0 0 0 6 183 307 384 288 192 36 0 0 1396 Houston C 33 0 0 0 0 165 288 363 258 174 30 0 0 1278 Laredo A 36 0 0 0 0 105 217 267 134 74 0 0 0 797 Lubbock A 15 0 0 18 174 513 744 800 613 484 201 31 0 3578

Midland A

23

0 0 0 87 381 592 651 468 322 90 0 0 2591

Port Arthur A

33 0 0 0 22 207 329 384 274 192 39 0 0 1447 San Angelo A 25 0 0 0 68 318 536 567 412 288 66 0 0 2255 San Antonio A 30 0 0 0 31 204 363 428 286 195 39 0 0 1546

Victoria A 32 0 0 0 6 150 270 344 230 152 21 0 0 1173 Waco A 26 0 0 0 43 270 456 536 389 270 66 0 0 2030

Wichita Falls A 19 0* 0 0 99 381 632 698 518 378 120 6 0 2832

Utah Milford A 0 0 99 443 867 1141 1252 988 822 519 279 87 6497

Salt Lake City A 9 0 0 81 419 849 1082 1172 910 763 459 233 84 6052 Wendover A 0 0 48 372 822 1091 1178 902 729 408 177 51 5778

Vt. Burlington A

- 7 28 65 207 539 891 1349 1513 1333 1187 714 353 90 8269

Va. Cape Henry C 0 0 0 112 360 645 694 633 536 246 53 0 3279 Lynchburg A 19 0 0 51 223 540 822 849 731 605 267 78 0 4166

Norfolk A 23 0 0 0 136 408 698 738 655 533 216 37 0 3421 Richmond A 18 0 0 36 214 495 784 815 703 546 219 53 0 3865 Roanoke A 18 0 0 51 229 549 825 834 722 614 261 65 0 4150

Wash. Olympia A

25 68 71 198 422 636 753 834 675 645 450 307 177 5236

Seattle-Tacoma A 24 56 62 162 391 633 750 828 678 657 474 295 159 5145

Seattle C 32 50 47 129 329 543 657 738 599 577 396 242 117 4424 Spokane A 4 9 25 168 493 879 1082 1231 980 834 531 288 135 6655 Walla Walla C 16 0 0 87 310 681 843 986 745 589 342 177 45 4805 Yakima A 10 0 12 144 450 828 1039 1163 868 713 435 220 69 5941 W. Va. Charleston A 14 0 0 63 254 591 865 880 770 648 300 96 9 4476

Elkins A 5 9 25 135 400 729 992 1008 896 791 444 198 48 5675 Huntington A 14 0 0 63 257 585 856 880 764 636 294 99 12 4446

Parkersburg C 12 0 0 60 264 606 905 942 826 691 339 115 6 4754

Wise. Green Bay A

- 7 28 50 174 484 924 1333 1494 1313 1141 654 335 99 8029 La Crosse A - 8 12 19 153 437 924 1339 1504 1277 1070 540 245 69 7589 Madison A - 5 25 40 174 474 930 1330 1473 1274 1113 618 310 102 7863 Milwaukee A - 2 43 47 174 471 876 1252 1376 1193 1054 642 372 135 7635

Wyo. Casper A

- 5

6 16 192 524 942 1169 1290 1084 1020 657 381 129 7410 Cheyenne A 28 37 219 543 909 1085 1212 1042 1026 702 428 150 7381 Lander A

-12 6 19 204 555 1020 1299 1417 1145 1017 654 381 153 7870

Sheridan A - 7 25 31 219 539 948 1200 1355 1154 1051 642 366 150 7680

AJta. Banff C 220 295 498 797 1185 1485 1624 1364 1237 855 589 402 10551 Calgary A -25 109 186 402 719 1110 1389 1575 1379 1268 798 477 291 9703 Edmonton A -26 74 180 411 738 1215 1603 1810 1520 1330 765 400 222 10268

Lethbridge A -24 56 112 318 61

1

1011 1277 1497 1291 1159 696 403 213 8644

B. C. Kamloops A

-10

22 40 189 546 894 1138 1314 1057 818 462 217 102 6799

Prince George* A

-31

236 251 444 747 1110 1420 1612 1319 1122 747 468 279 9755

Prince Rupert C 15 273 248 339 539 708 868 936 808 812 648 493 357 7029 Vancouver* A 19 81 87 219 456 657 787 862 723 676 501 310 156 5515

Victoria* A 136 140 225 462 663 775 840 718 691 504 341 204 5699

Victoria C 23 172 184 243 426 607 723 805 668 660 487 354 250 5579

Table A-3 (contd)

A-101
State or

Prov.

Station

•7 1/2Z Vint«r ?

,, tamp «v. —

July Aug. Sept. Oct. Nov. Dec. Jan. Feb. Mar. Apr. May June

Yearly

Total

Man. Brandon* A

-26 47 90 357 747 1290 1792 2034 1737 1476 837 431 198 11036

Churchill A

-38 360 375 681 1082 1620 2248 2558 2277 2130 1569 1153 675 16728 The Pas C -32 59 127 429 831 1440 1981 2232 1853 1624 969 508 228 12281 Winnipeg A -25 38 71 322 683 1251 1757 2008 1719 1465 813 405 147 10679

N. B. Fredericton* A

-10 78 68 234 592 915 1392 1541 1379 1172 753 406 141 8671 Moncton C

- 7 62 105 276 611 891 1342 1482 1336 1194 789 468 171 8727

St. John C - 7 109 102 246 527 807 1194 1370 1229 1097 756 490 249 8219

Nfld. Argentia A 260 167 294 564 750 1001 1159 1085 1091 879 707 483 8440 Comer Brook C

- 5 102 133 324 642 873 1194 1358 1283 1212 885 639 333 8978 Gander A - 1 121 152 330 670 909 1231 1370 1266 1243 939 657 366 9254 Goose* A -25 130 205 444 843 1227 1745 1947 1689 1494 1074 741 348 11887

St. John's* A 6 186 180 342 651 831 1113 1262 1170 1187 927 710 432 8991

N. W. T. Aklavik C 273 459 807 1414 2064 2530 2632 2336 2282 1674 1063 483 18017

Fort Norman C 164 341 666 1234 1959 2474 2592 2209 2058 1386 732 294 16109

Resolution Island C 843 831 900 1113 1311 1724 2021 1850 1817 1488 1181 942 16021

N. S. Halifax C 4 58 51 180 457 710 1074 1213 1122 1030 742 487 237 7361 Sydney A 5 62 71 219 518 765 1113 1262 1206 1150 840 567 276 8049 Yarmouth A 9 102 115 225 471 696 1029 1156 1065 1004 726 493 258 7340

Ont. Cochrane C 96 180 405 760 1233 1776 1978 1701 1528 963 570 222 11412

Fort William A

-23 90 133 366 694 1140 1597 1792 1557 1380 876 543 237 10405 Kapuskasing C

-28 74 171 405 756 1245 1807 2037 1735 1562 978 580 222 11572 Kitchener C 1 16 59 177 505 855 1234 1342 1226 1101 663 322 66 7566 London A 3 12 43 159 477 837 1206 1305 1198 1066 648 332 66 7349 North Bay C -17 37 90 267 608 990 1507 1680 1463 1277 780 400 120 9219 Ottawa C -13 25 81 222 567 936 1469 1624 1441 1231 708 341 90 8735 Toronto C i

7 18 151 439 760 1111 1233 1119 1013 616 298 62 6827

P.E.I. Charlottetown C - 3 40 53 198 518 804 1215 1380 1274 1169 813 496 204 8164 Summerside C - 3 47 84 216 546 840 1246 1438 1291 1206 841 518 216 8488

Que. Arvida C 102 136 327 682 1074 1659 1879 1619 1407 891 521 231 10528 Montreal* A -10 9 43 165 521 882 1392 1566 1381 1175 684 316 69 8203 Montreal C 16 28 165 496 864 1355 1510 1328 1138 657 288 54 7899 Quebec* A -13 56 84 273 636 996 1516 1665 1477 1296 819 428 126 9372 Quebec C 40 68 243 592 972 1473 1612 1418 1228 780 400 111 8937

Sasks Prince Albert A -35 81 136 414 797 1368 1872 2108 1763 1559 867 446 219 11630 Regina A -29 78 93 360 741 1284 1711 1965 1687 1473 804 409 201 10806

Saskatoon C -30 56 87 372 750 1302 1758 2006 1689 1463 798 403 186 10870

Y. T. Dawson C 164 326 645 1197 1875 2415 2561 2150 1838 1068 570 258 15067 Mayo Landing C 208 366 648 1135 1794 2325 2427 1992 1665 1020 580 294 14454

•The data for these normals were from the full ten-year period 1951-1960, adjusted to the standard normal period 1931-1960.

Table A-3 (contd)
Table A-4

Radiation and Other Data for 80 Locations in the United States

(IH Monthly average daily total radiation on a horizontal surface, Btu/day-ft^; Kt-the fraction of the extra terrestrial radiation transmitted through the atmosphere; t 0=average daytime ambient temperature. *F)

ALASKA

Annette Is.., Lat 55®02'N , El. 110 ft..,

Barrow

Lat. 71*20'N

El. 22 ft

Bethel Lat.60°47'N

El. 125 ft.

Fairbanks.

.

Lat.64*49'N

El. 436 ft.

Matanuska.

.

Lat.61°30'N.

El. 180 ft.

ALBERTA

Edmonton. . .

.

Lat.53°35'N

El. 2219 ft.

ARKANSAS

Little Rock. Lat . 34*44 'N El. 265 ft..

ARIZONA

Phoenix

Lat.33°26'N.,

El. 1112 ft.

Tucson

Lat. 32“07'N,

El. 2556 ft.,

CALIFORNIA

Davis

Lat. 38°33'N

El. 51 ft

Fresno

Lat. 36*46 'N El. 331 ft

Inyokern

Lat. 35* 39 'N El. 2440- ft

Los Angeles, (WBO) Lat . 34*03 'N El. 99 ft

Los Angeles, (WBAS)

Lat. 33*56 'N El. 99 ft

Riverside

Lat. 33*57 'N El. 1020 ft

Santa Marla. .

.

Lat. 34*54 'N.

.

El. 238 ft

COLORADO

Grand Junction

Lat. 39*07 'N.

.

El. 4849 ft...

Grand Lake. . .

.

Lat. 40*15 'N. El. 8389 ft...

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Xh 236.2 428.4 883.4 1357.2 1634.7 1638.7 1632.1 1269.4 962 454.6 220.3 152

Kt 0.427 0.415 0.492 0.507 0.484 0.441 0.454 0.427 0.449 0.347 0.304 0.361

c o 35.8 37.5 39.7 44.4 51.0 56.2 58.6 59.8 54.8 48.2 41.9 37.4

Ih 13.3 143.2 713.3 1491.5 1883 2055.3 1602.2 953.5 428.4 152.4 22.9 _ Kt - 0.776 0.773 0.726 0.553 0.533 0.448 0.377 0.315 0.35 - -

c o -13.2 -15.9 -12.7 2.1 20.5 35.4 41.6 40.0 31.7 18.6 2.6 -8.6

Ih 142.4 404 £ 1052 ;

4

1662.3 1711.8 1698.1 1401.8 938.7 755 430.6 164.9 83 Kt 0.536 0.557 0.704 0.675 0.519 0.458 0.398 0.336 0.406 0.432 0.399 0.459

c o 9.2 11.6 14.2 29.4 42.7 55.5 56.9 54.8 47.4 33.7 19.0 9.4

Ih 66 283.4 860.5 1481.2 1806.2 1970.8 1702.9 1247.6 699.6 323.6 104.1 20.3

Kt 0.639 0.556 0.674 0.647 0.546 0.529 0.485 0.463 0.419 0.416 0.47 0.458

bo -7.0 0.3 13.0 32.2 50.5 62.4 63.8 58.3 47.1 29.6 5.5 -6.6

Ih 119.2 345 _ 1327.6 1628.4 1727.6 1526.9 1169 737.3 373.8 142.8 56.4

Kt 0.513 0.503 - 0.545 0.494 0.466 0.434 0.419 0.401 0.390 0.372 0.36'

c o 13.9 21.0 27.4 38.6 50.3 57.6 60.1 58.1 50.2 37.7 22.9 13.9

in 331.7 652.4 1165.3 1541.7 1900.4 1914.4 1964.9 1528 1113.3 704.4 413.6 245

Kt 0.529 0.585 0.624 0.564 0.558 0.514 0.549 0.506 0.506 0.504 0.510 0.492

c o 10.4 14 26.3 42.9 55.4 61.3 66.6 63.2 54.2 44.1 26.7 14.0

Ih 704.4 974.2 1335.8 1669.4 1960.1 2091.5 2081.2 1938.7 1640.6 1282.6 913.6 701.1

Kt 0.424 0.458 0.496 0.513 0.545 0.559 0.566 0.574 0.561 0.552 0.484 0.463

to 44.6 48.5 56.0 65.8 73.1 70.7 85.1 84.6 78.3 67.9 54.7 46.7

IH 1126.6 1514.7 1967.1 2388.2 2709.6 2781.5 2450.5 2299.6 2131.3 1688.9 1290 1040.9

Kt 0.65 0.691 0.716 0.728 0.753 0.745 0.667 0.677 .722 0.708 0.657 0.652

c o 54.2 58.8 64.7 72.2 80.8 89.2 94.6 92.5 87.4 75.8 63.6 56.7

Ih 1171.9 1453.8 _ 2434.7 _ 2601.4 2292.2 2179.7 2122.5 1640.9 1322.1 1132.1

Kt 0.648 0.646 - 0.738 - 0 £98 0.625 0.640 0.710 0.672 0.650 0.679

co 53.7 57.3 62.3 69.7 78.0 87.0 90.1 87.4 84.0 73.9 62.5 56.1

Ih 599.2 945 1504 1959 2368.6 2619.2 2565.6 2287.8 1856.8 1235.5 795.6 550.5

Kt 0.416 0.490 0.591 0.617 0.662 0.697 0.697 0.687 0.664 0.598 0.477 0.421

c o 47.6 52.1 56.8 63.1 69.6 75.7 81 79.4 76.7 67.8 57 48.7

Ih 712.9 1116.6 1652.8 2049.4 2409.2 2641.7 2512.2 2300.7 1897.8 1415.5 906.6 616.6

Kt 0.462 0.551 0.632 0.638 0.672 0.703 0.682 0.686 0.665 0.635 0.512 0.44

to 47.3 53.9 59.1 65.6 73.5 80.7 87.5 84.9 78.6 68.7 57.3 48.9

Ih 1148.7 1554.2 2136.9 2594.8 2925 4 3108.8 2908.8 2759.4 2409.2 1819.2 3170.1 1094.4

Kt 0.716 0.745 0.803 0.8 0.815 0.830 0.790 0.820 0.834 0.795 0.743 0.742

to 47.3 53.9 59.1 65.6 73.5 80.7 87.5 84.9 78.6 68.7 57.3 48.9

Ih 911.8 1223.6 1640.9 1866.8 2061.2 2259 24284 2198.9 1891.5 1362.3 1053.1 877.8

Kt 0.538 0.568 0.602 0.571 0.573 0.605 0.66 0.648 0.643 0.578 0.548 0.566

57.9 59.2 61.8 64.3 67.6 70.7 75.8 76.1 74.2 69.6 65.4 60.2

Ih 930.6 1284.1 1729.5 1948 2196.7 2272.3 2413.6 2155.3 1898.1 1372.7 1082.3 901.1

Kt 0.547 0.596 0.635 0.595 0.610 0.608 0.657 0.635 0.641 0.574 0.551 0.566

to 56.2 56.9 59.2 61.4 64.2 66.7 69.6 70.2 69.1 66.1 62.6 58.7

Ih 999.6 1335 1750.5 1943.2 2282.3 2492.6 2443.5 2263.8 1955.3 1509.6 1169 979.7 Kt 0.589 0.617 0.643 0.594 0.635 0.667 0.665 0.668 0.665 0.639 0.606 0.626

c o 55.3 57.0 60.6 65.0 69.4 74.0 81.0 81.0 78.5 71.0 63.1 57.2

Ih 983.8 1296.3 1805.9 2067.9 2375.6 2599.6 2540.6 2293.3 1965.7 1566.4 1169 943.9

Kt 0.595 0.613 0.671 0.636 0.661 0.695 0.690 0.678 0.674 0.676 0.624 0.627

co 54.1 55.3 57.6 59.5 61.2 63.5 65.3 65.7 65.9 64.1 60.8 56.1

IH 848 1210.7 1622.9 2002.2 2300.3 2645.4 2517.7 2157.2 1957.5 1394.8 969.7 793.4

Kt 0.597 0.633 0.643 0.632 0.643 0.704 0.690 0.65 0.705 0.654 0.59 0.621

c o 26.9 35.0 44 .

6

55.8 66.3 75.7 82.5 79.6 71.4 58.3 42.0 31.4

Ih 735 1135.4 1579.3 1876.7 1974.9 2369.7 2103.3 1708.5 1715.8 1212.2 775.6 660.5

Kt 0.541 0.615 0.637 0.597 0.553 0.63 0.572 0 .

5

i.6 0.626 0.583 0.494 0.542

to 18.5 23.1 28.5 39.1 48.7 56.6 62.8 61.5 55.5 45.2 30.3 22.6

From: Applications of Solar Energy for Heating and Cooling of Buildings, ASHRAE [17]

A-103
Table A-4 (Continued)

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

DISTRICT OF COLUMBIA Washington (WBCO) Lat. 38°51'N IH 632.4 901.5 1255 1600.4 1846.8 2080.8 1929.9 1712.2 1446.1' 1083.4 763.5 594.1

Kt 0.445 0.470 0.496 0.504 0.516 0.553 0.524 0.516 0.520 0.506 0.464 0.460

El. 64 ft t o 38.4 39.6 48.1 57.5 67.7 76.2 79.9 77.9 72.2 60.9 50.2 40.2

FLORIDA Apalachicola IH 1107 1378.2 1654.2 2040.9 2268.6 2195.9 1978.6 1912.9 1703.3 1544.6 1243.2 982.3

Lat. 29‘45'N Kt 0.577 0.584 0.576 0.612 0.630 0.594 0.542 0.558 0.559 0.608 0.574 0.543

El. 35 ft to 57.3 59.0 62.9 69.5 76.4 81.8 83.1 83.1 80.6 73.2 63.7 58.55

Gainesville Ih 1036.9 1324.7 1635 1956.4 1934.7 1960.9 1895.6 1873.8 1615.1 1312.2 1169.7 919.5

Lat. 29*39'N Kt 0.535 0.56 0.568 0.587 0.538 0.531 0.519 0.547 0.529 0.515 0.537 0.508

El. 165 ft to 62.1 63.1 67.5 72.8 79.4 83.4 83.8 84.1 82 75.7 67.2 62.4

Miami Ih 1292.2 1554.6 1828.8 2020.6 2068.6 1991.5 1992.6 1890.8 1646.8 1436.5 1321 1183.4

Lat. 25”47'N Kt 0.604 0.616 0.612 0.600 0.578 0.545 0.552 0.549 0.525 0.534 0.559 0.588

El. 9 ft to 71.6 72.0 73.8 77.0 79.9 82.9 84.1 84.5 83.3 80.2 75.6 72.6

Tampa. Ih 1223.6 1461.2 1771.9 2016.2 2228 2146.5 1991.9 1845.4 1687.8 1493.3 1328.4 1119.5

Lat. 27*55'N Kt 0.605 0.600 0.606 0.602 0.620 0.583 0.548 0.537 0.546 0.572 0.590 0.589

El. 11 ft to 64.2 65.7 68.8 74.3 79.4 83.0 84.0 84.4 82.9 77.2 69.6 65.5

GEORGIA Atlanta Ih 848 1080.1 1426.9 1807 2618.1 2002.6 2002.9 1898.1 1519.2 1290.8 997.8 751.6

Lat. 33°39'N Kt 0.493 0.496 0.522 0.551 0.561 0.564 0.545 0.559 0.515 0.543 0.510 0.474

El. 976 ft to 47.2 49.6 55.9 65.0 73.2 80.9 82.4 81.6 77.4 66.5 54.8 47.7

Griffin Ih 889.6 1135.8 1450.9 1923.6 2163.1 2176 2064.9 1961.2 1605.9 1352.4 1073.8 781.5

Lat. 33'15'N Kt 0.513 0.517 0.528 0.586 0.601 0.583 0.562 0.578 0.543 0.565 0.545 0.487

El. 980 ft to 48.9 51.0 59.1 66.7 74.6 81.2 83.0 82.2 78.4 68 57.3 49.4

IDAHO Boise Ih 518.8 884.9 1280.4 1814.4 2189.3 2376.7 2500.3 2149.4 1717.7 1128.4 678.6 456.8

Lat. 43*34 'N Kt 0.446 0.533 0.548 0.594 0.619 0.631 0.684 0.660 0.656 0.588 0.494 0.442

El. 2844 ft to 29.5 36.5 45.0 53.5 62.1 69.3 79.6 77.2 66.7 56.3 42.3 33.1

ILLINOIS

Lemont Ih (590) 879 1255.7 1481.5 1866 2041.7 1990.8 1836.9 1469.4 1015.5 (639) (531) lat. 41°40'N Kt (0.464) 0.496 0.520 0.477 0.525 0.542 0.542 0.559 0.547 0.506 (0.433) (0.467)

El 595 ft to 28.9 30.3 39.5 49.7 59.2 70.8 75.6 74.3 67.2 57.6 43.0 30.6

INDIANA Indianapolis

Lat. 39‘44'N Ih 526.2 797.4 1184.1 1481.2 1828 2042 2039.5 1832.1 1513.3 1094.4 662.4 491.1

Kt 0.380 0.424 0.472 0.47 0.511 0.543 0.554 0.552 0.549 0.520 0.413 0.391

El. 793 ft t Q 31.3 33.9 43.0 54.1 64.9 74.8 79.6 77.4 70.6 59.3 44.2 33.4

KANSAS Dodge City Ih 953.1 1186.3 1565.7 1975.6 2126.5 2459.8 2400.7 2210.7 1841.7 1421 1065.3 873.8

Lat. 37*46'N Kt 0.639 0.598 0.606 0.618 0.594 0.655 0.652 0.663 0.654 0.650 0.625 0.652

El. 2592 ft to 33.8 38.7 46.5 57.7 66.7 77.2 83.8 82.4 73.7 61.7 46.5 36.8

KENTUCKY

Lexington. Ih

_ - - 1834.7 2171.2 - 2246.5 2064.9 1775.6 1315.8 - 681.5

Lat. 38'02'N Kt - - - 0.575 0.606 - 0.610 0.619 0.631 0.604 - 0.513

El. 979 ft to 36.5 38.8 47.4 57.8 67.5 76.2 79.8 78.2 72.8 61.2 47.6 38.5

LOUISIANA

Lake Charles Ih 899.2 1145.7 1487.4 1801.8 2080.4 2213.3 1968.6 1910.3 1678.2 1505.5 1122.1 875.6

Lat. 30‘13'N Kt 0.473 0.492 0.521 0.542 0.578 0.597 0.538 0.558 0.553 0.597 0.524 0.494

El. 12 ft to 55.3 58.7 63.5 70.9 77.4 83.4 84.8 85.0 81.5 73.8 62.6 56.9

MAINE

Caribou .... Ih 497 861.6 1360.1 1495.9 1779.7 1779.7 1898.1 1675.6 1254.6 793 415.5 398.9

Lat. 46*52 *N .... Kt 0.504 0.579 0.619 0.507 0.509 0.473 0.522 0.527 0.506 0.455 0.352 0.470

El. 628 ft •••• t Q 11.5 12.8 24.4 37.3 51.8 61.6 67.2 65.0 56.2 44.7 31.3 16.8

Portland .... |h 565.7 874.5 1329.5 1528.4 1923.2 2017.3 2095.6 1799.2 1428.8 1035 591.5 507.7

Lat. 43°39'N .... Kt 0.482 0.524 0.569 0.500 0.544 0.536 0.572 0.554 0.546 0.539 0.431 0.491

El. 63 ft .... to 23.7 24.5 34.4 44.8 55.4 65.1 71.1 69.7 61.9 51.8 40.3 28.0

MANITOBA

Winnipeg .... I„ 488.2 835.4 1354.2 1641.3 1904.4 1962 2123.6 1761.2 1190.4 767.5 444.6 345 > Lat. 49“54'N... . . . . Kt 0.601 0.636 0.661 0.574 0.550 0.524 0.587 0.567 0.504 0.482 0.436 0.503

El. 786 ft 3.2 7.1 21.3 40.9 55.9 65.3 71.9 69.4 58.6 45.6 25.2 10.1

MASSACHUSETTS

Blue Hill .... Ij, 555.3 797 1143.9 1438 1776.4 1943.9 1881.5 1622.1 1314 941 592.2 482.3

Lat. 42*13’N .... K t 0.445 0.458 0.477 0.464 0.501 0.516 0.513 0.495 0.492 0.472 0.406 0.436

El. 629 ft .... t D 28.3 28.3 36.9 46.9 58.5 67.2 72.3 70.6 64.2 54.1 43.3 31.5

Boston. .... 505.5 738 1067.1 1355 1769 1864 1860.5 1570.1 1267.5 896.7 535.8 442.8

Lat. 42*22 'N . . . . Kt 0.410 0.426 0.445 0.438 0.499 0.495 0.507 0.480 0.477 0.453 0.372 0.400

El. 29 ft .... t 0 31.4 31.4 39.9 49.5 60.4 69.8 74.5 73.8 66.8 57.4 46.6 34.9

A-104
Table A-4 (Continued)

Jan Feb Mar Apr MASSACHUSETTS (Contd.)

East Wareham in 504.4 762.4 1132.1 1392.6

Lat. 41°46'N.. 0.398 0.431 0.469 0.449

El. 18 ft to 32.2 31.6 39.0 48.3

MICHIGAN

East Lansing Ih 425.8 739.1 1086 1249.8

Lat. 42°44'N Kt 0.35 0.431 0.456 0.406

El. 856 ft to 26.0 26.4 35.7 48.4

Sault Ste. Marie Ih 488.6 843.9 1336.5 1559.4

Lat. 46°28'N Kt 0.490 0.560 0.606 0.526

El. 724 ft to 16.3 16.2 25.6 39.5 MINNESOTA

St. Cloud Ih 632.8 976.7 1383 1598.1

Lat. 45°35'N Kt 0.595 0.629 0.614 0.534

El. 1034 ft to 13.6 16.9 29.8 46.2 MISSOURI

Columbia Ih 651.3 941.3 1315.8 1631.3

Lat. 38°58I N K

t 0.458 0.492 0.520 0.514

El. 785 ft to 32.5 36.5 45.9 57.7

MONTANA

Glasgow Ih 572.7 965.7 1437.6 1741.3

Lat. 48°13'N K t 0.621 0.678 0.672 0.597

El. 2277 ft to 13.3 17.3 31.1 47.8

Great Falls Ih 524 869.4 1369.7 1621.4

Lat. 47°29'N Kt 0.552 0.596 0.631 0.551

El. 3664 ft c o 25.4 27.6 35.6 47.7

NEBRASKA

Lincoln Ih 712.5 955.7 1299.6 1587.8

Lat. 40°51'N K t 0.542 0.528 0.532 0.507

El. 1189 ft to 27.8 32.1 42.4 55.8

NEVADA

Ely ; Ih 871.6 1255 1749.8 2103.3

Lat. 39°17'N K

t 0.618 0.660 0.692 0.664

El. 6262 ft to 27.3 32.1 39.5 48.3

Las Vegas Ih 1035.8 1438 1926.5 2322.8

Lat. 36°05'N Kt 0.654 0.697 0.728 0.719

El. 2162 ft to 47.5 53.9 60.3 69.5

NEW JERSEY

Seabrook Ih 591.9 854.2 1195.6 1518.8

Lat. 39"30'N Kt 0.426 0.453 0.476 0.481

El. 100 ft c o 39.5 37.6 43.9 54.7

NEW MEXICO

Albuquerque Ih 1150.9 1453.9 1925.4 2343.5

Lat. 35°03'N Kt 0.704 0.691 0.719 0.722

El. 5314 ft to 37.3 43.3 50.1 59.6

NEW YORK

Ithaca Ih 434.3 '755 1074.9 1322.9

Lat. 42°27'N K

t 0.351 0.435 0.45 0.428

El. 950 ft to 27.2 26.5 36 48.4

New York Ih 539.5 790.8 1180.4 1426.2

Lat. 40°46'N Kt 0.406 0.435 0.480 0.455

El. 52 ft c o 35.0 34.9 43.1 52.3

Sayville Ih 602.9 936.2 1259.4 1560.5

Lat. 40°30'N Kt 0.453 0.511 0.510 0.498

El. 20 ft to 35 34.9 43.1 52.3

Schenectady Ih 488.2 753.5 1026.6 1272.3

Lat. 42°50’N Kt 0.406 0.441 0.433 0.413

El. 217 ft to 24.7 24.6 34.9 48.3

Upton Ih 583 872.7 1280.4 1609.9

Lat. 40°52'N K

t 0.444 0.483 0.522 0.514

El. 75 ft to 35.0 34.9 43.1 52.3

NORTH CAROLINA

Greensboro Ih 743.9 1031.

7

1323.2 1755.3

Lat. 36°05'N Kt 0.469 0.499 0.499 0.543

El. 891 ft to 42.0 44.2 51. 7 60.8

May Jun Jul Aug Sep Oct Nov Dec

1704.8 1958.3 1873.8 1607.4 1363.8 996.7 636.2 521 0.480 0.520 0.511 0.489 0.508 0.496 0.431 0.461

58.9 67.5 74.1 72.8 65.9 56 46 34.8

1732.8 1914 1884.5 1627.7 1303.3 891.5 473.1 379.7 0.489 0.508 0.514 0.498 0.493 0.456 0.333 0.349

59.8 70.3 74.5 72.4 65.0 53.5 40.0 29.0

1962.3 2064.2 2149.4 1767.9 1207 809.2 392.2 359.8 0.560 0.549 0.590 0.554 0.481 0.457 0.323 0.408

52.1 61.6 67.3 66.0 57.9 46.8 33.4 21.9

1859.4 2003.3 2087.8 1828.4 1369.4 890.4 545.4 463.1

0.530 0.533 0.573 0.570 0.539 0.490 0.435 0.504

58.8 68.5 74.4 71.9 62.5 50.2 32.1 18.3

1999.6 2129.1 2148.7 1953.1 1689.6 1202.6 839.5 590.4

0.559 0.566 0.585 0.588 0.606 0.562 0.510 0.457

66.7 75.9 81.1 79.4 71.9 61.4 46.1 35.8

2127.3 2261.6 2414.7 1984.5 1531 997 574.9 428.4 0.611 0.602 0.666 0.630 0.629 0.593 0.516 0.548

59.3 67.3 76 73.2 61.2 49.2 31.0 18.6

1970.8 2179.3 2383 1986.3 1536.5 984.9 575.3 420.7 0.565 0.580 0.656 0.627 0.626 0.574 0.503 0.518

57.5 64.3 73.8 71.3 60.6 51.4 38.0 29.1

1856.1 2040.6 2011.4 1902.6 1543.5 1215.8 773.4 643.2 0.522 0.542 0.547 0.577 0.568 0.596 0.508 0.545

65.8 76.0 82.6 80.2 71.5 59.9 43.2 31.8

2322.1 2649 2417 2307.7 1935 1473 1078.6 814.8

0.649 0.704 0.656 0.695 0.696 0.691 0.658 0.64

57.0 65.4 74.5 72.3 63.7 52.1 39.9 31.1

2629.5 2799.2 2524 2342 2062 1602.6 1190 964.2

0.732 ‘ 0.746 0.685 0.697 0.716 0.704 0.657 0.668

78.3' 88.2 95.0 92.9 85.4 71.7 57.8 50.2

1800.7 1964.6 1949.8 1715 1445.7 1071.9 721.8 522.5 0.504 0.522 0.530 0.517 0.524 0.508 0.449 0.416

64.9 74.1 79.8 77.7 69.7 61.2 48.5 39.3

2560.9 2757.5 2561.2 2387.8 2120.3 1639.8 1274.2 1051.6 0.713 0.737 0.695 0.708 0.728 0.711 0.684 0.704

69.4 79.1 82.8 80.6 73.6 62.1 47.8 39.4

1779.3 2025.8 2031.3 1736.9 1320.3 918.4 466.4 370.8 0.502 0.538 0.554 0.530 0.497 0.465 0.324 0.337

59.6 68.9 73.9 71.9 64.2 53.6 41.5 29.6

1738.4 1994.1 1938.7 1605.9 1349.4 977.8 598.1 476 0.488 0.53 0.528 0.486 0.500 0.475 0.397 0.403

63.3 72.2 76.9 75.3 69.5 59.3 48.3 37.7

1857.2 2123.2 2040.9 1734.7 1446.8 1087.4 697.8 533.9 0.522 0.564 0.555 0.525 0.530 0.527 0.450 0.447 63.3 72.2 76.9 75.3 69.5 59.3 48.3 37.7

1553.1 1687.8 1662.3 1494.8 1124.7 820.6 436.2 356.8 0.438 0.448 0.454 0.458 0.426 0.420 0.309 0.3?1

61.7 70.8 76.9 73.7 64.6 53.1 40.1 28.0

1891.5 2159 2044.6 1789.6 1472.7 1102.6 686.7 551.3

0.532 0.574 0.557 0.542 0.542 0.538 0.448 0.467

63.3 72.2 76.9 75.3 69.5 59.3 48.3 37.7

1988.5 2111.4 2033.9 1810.3 1517.3 1202.6 908.1 690.8

0.554 0.563 0.552 0.538 0.527 0.531 0.501 0.479

69.9 78.0 80.2 78.9 73.9 62.7 51.5 43.2

A-105
Table A-4 (Continued)

NORTH CAROLINA (Contd.) Hatteras

Lat. 35°13'N

El. 7 ft

NORTH DAKOTA

Bismarck

Lat. 46°47'N...

El. 1660 ft....

OHIO Cleveland

Lat. 41°24'N...

El. 805 ft

Columbus

Lat. 40°00’N...

El. 833 ft

OKLAHOMA

Oklahoma City..

Lat. 35°24'N...

El. 1304 ft

Stillwater

Lat. 36°09'N...

El. 910 ft

ONTARIO

Ottawa

Lat. 45*20^...

El. 339 ft

Toronto

Lat. 43°41'N...

El. 379 ft

OREGON Astoria

Lat. 46*12'N...

El. 8 ft

Medford

Lat. 42°23'N. .

.

El. 1329 ft

PENNSYLVANIA

State College..

Lat. 40‘48'N...

El. 1175 ft

RHODE ISLAND New Port

Lat. 41°29'N. .

.

El. 60 ft

SOUTH CAROLINA

Charleston

Lat. 32°54'N...

El. 46 ft

SOUTH DAKOTA

Rapid City

Lat. 44°09'N...

El. 3218 ft

TEXAS

Brownsville. . .

.

Lat. 25*55'N...

El. 20 ft

El Paso

Lat. 31*48 'N. .

.

El. 3916 ft

Fort Worth

Lat. 32°50'N...

El. 544 ft

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

IH 891.9 1184.1 1590.4 2128 2376.4 2438 2334.3 2085.6 1758.3 1337.6 1053.5 798.1

Kt 0.546 0.563 0.593 0.655 0.661 0.652 0.634 0.619 0.605 0.58 0.566 0.535

to 49.9 49.5 54.7 61.5 69.9 77.2 80.0 79.8 76.7 67.9 59.1 51.3

IH 587.4 934.3 1328.4 1668.2 2056.1 2173.8 2305.5 1929.1 1441.3 1018.1 600.4 464.2

Kt 0.594 0.628 0.605 0.565 0.588 0.579 0.634 0.606 0.581 0.584 0.510 0.547

c o 12.4 15.9 29.7 46.6 58.6 67.9 76.1 73.5 61.6 49.6 31.4 18.4

Ih 466.8 681.9 1207 1443.9 1928.4 2102.6 2094.4 1840.6 1410.3 997 526.6 427.3

Kt 0.361 0.383 0.497 0.464 0.543 0.559 0.571 0.559 0.524 0.491 0.351 0.371

tO 30.8 30.9 39.4 50.2 62.4 72.7 77.0 75.1 68.5 57.4 44.0 32.8

Ih 486.3 746.5 1112.5 1480.8 1839.1 (2111) 2041.3 1572.7 1189.3 919.5 479 430.2

Kt 0.356 0.401 0.447 0.470 0.515 (0.561) 0.555 0.475 0.433 0.441 0.302 0.351

‘o 32.1 33.7 42.7 53.5 64.4 74.2 78 75.9 70.1 58 44.5 34.0

Ik 938 1192.6 1534.3 1849.4 2005.1 2355 2273.8 2211 1819.2 1409.6 1085.6 897.4

K

t 0.580 0.571 0.576 0.570 0.558 0.629 0.618 0.565 0.628 0.614 0.588 0.608 40.1 45.0 53.2 63.6 71.2 80.6 85.5 85.4 77.4 66.5 52.2 43.1

Ih 763.8 1081.5 1463.8 1702.6 1879.3 2235.8 2224.3 2039.1 1724.3 1314 991.5 783

Kt 0.484 0.527 0.555 0.528 0.523 0.596 0.604 0.607 0.599 0.581 0.548 0.544

to 41.2 45.6 53.8 64.2 71.6 81.1 85.9 85.9 77.5 67.6 52.6 43.9

Ih 539.1 852.4 1250.5 1506.6 1857.2 2084.5 2045.4 1752.4 1326.6 826.9 458.7 408.5

Kt 0.499 0.540 0.554 0.502 0.529 0.554 0.560 0.546 0.521 0.450 0.359 0.436

to 14.6 15.6 27.7 43.3 57.5 67.5 71.9 69.8 61.5 48.9 35 19.6

Ih 451.3 674.5 1088.9 1388.2 1785.2 1941.7 1968.6 1622.5 1284.1 835 458.3 352.8

Kt 0.388 0.406 0.467 0.455 0.506 0.516 0.539 0.500 0.493 0.438 0.336 0.346

c o 26.5 26.0 34.2 46.3 58 68.4 73.8 71.8 64.3 52.6 40.9 30.2

Ih 338.4 607 1008.5 1401.5 1838.7 1753.5 2007.7 1721 1322.5 780.4 413.6 295.2

Kt 0.330 0.397 0.454 0.471 0.524 0.466 0.551 0.538 0.526 0.435 0.336 0.332

c o 41.3 44.7 46.9 51.3 55.0 59.3 62.6 63.6 62.2 55.7 48.5 43.9

Ih 435.4 804.4 1259.8 1807.4 2216..2 2440.5 2607.4 2261.6 1672.3 1043.5 558.7 346.5

Kt 0.353 0.464 0.527 0.584 0.625 0.648 0.710 0.689 0.628 0.526 0.384 0.313

to 39.4 45.4 50.8 56.3 63.1 69.4 76.9 76.4 69.6 58.7 47.1 40.5

Ih 501.8 749.1 1106.6 1399.2 1754.6 2027.6 1968.2 1690 1336.1 1017 580.1 4443.! Kt 0.381 0.413 0.451 0.448 0.493 0.539 0.536 0.512 0.492 0.496 0.379 0.376

to 31.3 31.4 39.8 51.3 63.4 71.8 75.8 73.4 66.1 55.6 43.2 32.6

Ih 565.7 856.4 1231.7 1484.8 1849 2019.2 1942.8 1687.1 1411.4 1035.4 656.1 527.7

Kt 0.438 0.482 0.507 0.477 0.520 0.536 0.529 0.513 0.524 0.512 0.44 0.460

c o 29.5 32.0 39.6 48.2 58.6 67.0 73.2 72.3 66.7 56.2 46.5 34.4

Ih 946.1 1152.8 1352.4 1918.8 2063.4 2113.3 1649.4 1933.6 1557.2 1332.1 1073.8 952

Kt 0.541 0.521 0.491 0.584 0.574 0.567 0.454 0.569 0.525 0.554 0.539 0.586

to 53.6 55.2 60.6 67.8 74.8 80.9 82.9 82.3 79.1 69.8 59.8 54.0

Ih 687.8 1032.5 1503.7 1807 2028 2193.7 2235.8 2019.9 1628 1179.3 763.1 590.4

Kt 0.601 0.627 0.649 0.594 0.574 0.583 0.612 0.622 0.628 0.624 0.566 0.588

t 0 24.7 27.4 34.7 48.2 58.3 67.3 76.3 75.0 64.7 52.9 38.7 29.2

Ih 1105.9 1262.7 1505.9 1714 2092.2 2288.5 2345 2124 1774.9 1536.5 1104.8 982.3

Kt 0.517 0.500 0.505 0.509 0.584 0.627 0.650 0.617 0.566 0.570 0.468 0.488

tQ 63.3 66.7 70.7 76.2 81.4 85.1 86.5 86.9 84.1 78.9 70.7 65.2

Ih 1247.6 1612.9 2048.7 2447.2 2673 2731 2391.1 2350.5 2077.5 1704.8 1324.7 1051.

f

Kt 0.686 0.714 0.730 0.741 0.743 0.733 0.652 0.669 0.693 0.695 0.647 0.626

to 47.1 53.1 58.7 67.3 75.7 84.2 84.9 83.4 78.5 69.0 56.0 48.5

Ih 936.2 1198.5 1597.8 1829.1 2105.1 2437.6 2293.3 2216.6 1880.8 1476 1147.6 913.6

Kt 0.530 0.541 0.577 0.556 0.585 0 . 654 0.624 0.653 0.634 0.612 0.576 0.563

c o 48.1 52.3 59.8 68.8 75.9 84.0 87.7 88.6 81.3 71.5 58.8 50.8

A- 10 6
Table A- 4 (Continued)

Jan Feb Mar Apr

TEXAS (Contd.) Midland IH 1066.4 1345.7 1784.8 2036.1

Lat. 31°56'N Kt 0.587 0.596 0.638 0.617

El. 2854 ft 47.9 52.8 60.0 68.8

San Antonio IH 1045 1299.2 1560.1 1664.6

Lat. 29°32 'N Kt 0.541 0.550 0.542 0.500

El. 794 ft 53.7 58.4 65.0 72.2

TENNESSEE

Nashville In 589.7 907 1246.8 1662.3

Lat. 36°07'N Kt 0.373 0.440 0.472 0.514

El. 605 ft 42.6 45.1 52.9 63.0

Oak Ridge In 604 895.9 1241.7 1689.6

Lat. 36°orN Kt 0.382 0.435 0.471 0.524

El. 905 ft 41.9 44.2 51.7 61.4

UTAH

Salt Lake City

Lat. 40°46'N

In 622.1 986 1301.1 1813.3 Kt 0.468 0.909 0.529 0.579

El. 4227 ft 29.4 36.2 44.4 53.9

WASHINGTON

Seattle III 282.6 520.6 992.2 1507

Lat. 47°27'N Kt 0.296 0.355 0.456 0.510

El. 386 ft 42.1 45.0 48.9 54.1

Seattle Ih 252 471.6 917.3 1375.6

Lat. 47°36'N Kt 0.266 0.324 0.423 0.468

El. 14 ft 38.9 42.9 46.9 51.9

Spokane Ih 446.1 837.6' 1200 1864.6

Lat. 47°40'N K t 0.478 0.579 0.556 0.602

El. 1968 ft 26.5 31.7 40.5 49.2

WISCONSIN

Madison Ih 564.6 812.2 1232.1 1455.3

Lat. 43°08'N Kt 0.4 0 0.478 0.522 0.474

El. 866 ft 21.8 24.6 35.3 49.0

WYOMING

Lander In 786.3 1146.1 1638 1988.5

Lat. 42°48'N Kt 0.65 0.672 0.691 0.647

El. 5370 ft .. 20.2 26.3 34.7 45.5

*Original values incorrect. Values estimated from

May Jun Jul Aug Sep Oct Nov Dec

2301.1 2317.7 2301.8 2193 1921.8 1470.8 1244.3 1023.2

0.639 0.622 0.628 0.643 0.642 0.600 0.609 0.611

77.2 83.9 85.7 85.0 78.9 70.3 56.6 49.1

2024.7 2250* 2364.2 2185.2 1844.6 1487.4 1104.4 954.6

0.563 0.62 0.647 0.637 0.603 0.584 0.507 0.528

79.2 85.0 87.4 87.8 82.6 74.7 63.3 56.5

1997 2149. 4 2079.7 1862.7 1600.7 1223.6 823.2 614.4 0.556 0.573 0.565 0.554 0.556 0.540 0.454 0.426

71.4 80.1 83.2 81.9 76.6 65.4 52.3 44.3

1942.8 2066.4 1972.3 1795.6 1559.8 1194.8 796.3 610 0.541 0.551 0.536 0.534 0.542 0.527 0.438 0.422

69.8 77.8 80.2 78.8 74.5 62.7 50.4 42.5

- - - - 1689.3 1250.2 552.8

- - - - 0.621 0.610 0.467 63.1 71.7 81.3 79.0 68.7 57.0 42.5 34.0

1881.5 1909.9 2110.7 1688.5 1211.8 702.2 386.3 239.5 0.538 0.508 0.581 0.533 0.492 0.407 0.336 0.292

59.8 64.4 68.4 67.9 63.3 56.3 48.4 44.4

1664.9 1724 1805.1 1617 1129.1 638 325.5 218.1 0.477 0.459 0.498 0.511 0.459 0.372 0.284 0.269

58.1 62.8 67.2 66.7 61.6 54.0 45.7 41.5

2104.4 2226.5 2479.7 2076 1511 844.6 486.3 279 0.603 0.593 0.684 0.656 0.616 0.494 0.428 0.345

57.9 64.6 73.4 71.7 62.7 51.5 37.4 30.5

1745.4 2031.7 2046.5 1740.2 1443.9 993 555.7 495.9

0.493 0.540 0.559 0.534 0.549 0.510 0.396 0.467

61.0 70.9 76.8 74.4 65.6 53.7 37.8 25.4

2114 2492.2 2438.4 2120.6 1712.9 1301.8 837.3 694.8 0.597 0.662 0.665 0.649 0.647 0.666 0.589 0.643

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A-110

Table

A-6

(continued)

Ratio

of

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on

a

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A-lll

Table

A-6

(continued)

Ratio

of

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on

a

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to

that

on

a

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A-112

Table

A-6

(contlaued)

Ratio

of

Monthly

Average

-

Dally

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on

a

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to

that

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f>j r\j

+ 00 r-

'O oo rsi «— r- rg

IA O

fA 00

fA 00

h- ia

rg fO

r- Csj

O O o o o

O tA O rming] 0 0-0

oP

1 ^

p oo o o

O IA

O' o

00 P

o O

O' O O'

P ao o O P

o o o o o

-» 4

O' O'

IA IA

O' o

M O' O «“ r- fM

<3 ®Q MN

o o o o o

IA P

fA 4

00 P

00 00 P P P

OO CO ao

00 O' ao ao

O M ia g g

oo ao oo ao as

«

a. r- fA O O

•A ao r- O O tO r- O T- P 4 4

t- (M to

<0 P **

O O

O O'

4 -o

P O *• IA tA * At IO ^ «

P O

f fA

IA O At tA

O O' tA 4 0 0

tA O IA

Kl 4 4

O' tA

*- P

o o

IA IA

• • P tA

O IA

IA IA

00 O

O' o

O O r~ > o o

IA tA

ao ao

aj 4

o o

AJ tA ao O O O

*- o

4 4

AJ tA

P Aj

tA IA

IA O

P fA

POO iMiAg

tA O'

fA P

IA

o pg ia »• 4 O 00 r- O

ao ao P O' tA

tA o IA

IA <4 >4

P P

O O' o o

a ia

W*l IA

O tA «A Pa0 P tA a ton

r- P AJ 4® « r s

g tA p o ia

P O P r* IA

tA IA O O' p tA O

P tA

f -4 O O

II r- rr Pp

f 4 *

g tnp

O >4 O O' O O T~ P f\| 4

O tA O P

P IA O CO P IA

O *-

O- tA

IA O

oo ao P cO O

oo ao O'

O IA P P

tA P

P P

IA 4 CA ia O

A* N P a* A

P -O

O- O'

p p •“ p p

oo ao ao ao o> P N N tA fA

r- p

O' O'

O' -4 O «-

P p

P P

o *-

ao CO

-4 -O O

O' O' O'

O ao ao P P IA

O O' tA tA

O' IA 4 o

tA O

P fA

P O' f» IA « 0>

4 O' o o

f O' IA <3

gs ia oo E f IA

«“ p p

IA O IA A 44

P p

P >4

O IA

lA IA

O IS* IA fA IS- IA O

fA i/1 oo p f* o r

g

• • • • • • r» f• eg f\ fA IA

ao \rt p g) ic tA CO K ia ao n ao N

r-• f- f r\ P fA

in p r O0 O fs. IA

ao a f- P 4 rr- t- r“ rg

rg o O' O' o fA O ia <3 O P O' a f

4> r* r— a

d

4-1

iS »- p tA O P lA fA

to ^ IA ia O P

rH

COu

•H

tl ^ s P P tA CO IA

ai rg rg fA IA 4 p* IA

f- lA 0 4 0 lA

rsi rg P tA 4 IA

IA O' IA r N fA O

I, p p tA 4 4 «A O

P -4 *- O P O ^ tA -4 IA IA O ^ ao

'

*4” fA 4 0 0 P O O P ao O f rg ia

T- r~ n

gs o> OOP p Ot

O' o P 4 P 3 IA

• • • • • • • r- r- t- rg

o gs 3 tA ao & O' P 4 P O 4 1- tA

• • • • • • ® »• r* t— <M IM A 4

tA O hA O IA C3 IA P fA 4A 4 4 wA IA

a)o

n) tMM

3

CO

G

O

NM

O

PS

CO

A-113

Table

A-6

(continued)

Ratio

of

Monthly

Average

-

Daily

Radiation

on

a

Tilted

Surface

to

that

on
5.4 WORKSHEETS FOR THE CALCULATION PROCEDURE

.

A-114
WORKSHEET A PROJECT DATA

PROJECT

Location Latitude

Building Heating and/or Hot Water Load

Design Heat Loss Rate, qg

Winter Design Temperature (97 1/2%) , tw

Average Hot Water Consumption

(may vary on a monthly basis)

Average Cold Water Supply (main) Temp . , tm

(may vary on a monthly basis)

Hot Water Supply Temp., t s Collector Subsystem Data

Collector Type : Selective or non-selective , no. cover plates

Collector Area, Ac Tilt Angle

Azimuth Angle

Collector Shading (av. % month of Dec.)

Collector Efficiency Data

(from manufacture) : FR(xa) n

FR

UL Reference Temp. Basis:

Fluid : Composition :

t in 1

t. + t in out

"out

Specific Heat, cp Specific Gravity (if applicable)

Volumetric Flow Rate

Storage Subsystem Data

Volume

Storage Medium

Specific Heat, c Specific Gravity/or Density

Circulation Loop Volumetric Flow Rate

Collector/Storage Heat Exchange Effectiveness, e Hot Water Preheat Storage Volume

Load Subsystem Data

Load Heat Exchanger Effectiveness, el

Supply Loop Volumetric Flow Rate

Building Air Supply Volumetric Flow Rate

cs

Btu/h

°Fgal /day

°F

°F

ft

2

%

Btu/h • ft

2 * °F

Btu/lb • °F

lb /lb

3 gal/min or ft /min

gal or ft

3

Btu/lb *°F

lb/lb or lb/ft 3

gal/min or ft /min

gal

gal/min

f

t

3 /min

A-115
WORKSHEET

B

FRACTION

OF

TOTAL

HEATING

LOAD

SUPPLIED

BY

SOLAR

ENERGY,

FAnnual

PROJECT

m Actual Solar en/mo E Btu/mo.

Solar

Fraction/ mo. f

CO

System

Parameters d2

CN

System

Parameters D

1

iH

Tot.

Mo.

Htg.

Load L Btu/mo.

Month Jan. Feb.

March April

May

June July

Aug.

Sept. Oct

.

Nov. Dec.

« a o

AJ AJ AJ

<u <1) aj

01 Q) <u X X X

cn CO CO x x X

u M u

o O O s s S

B B B

o o o

u > u

M-l Ml M-l

rH CNJ m

II W

m

A-116

f

chart
WORKSHEET

C

SYSTEM

PERFORMANCE

PARAMETERS

D

t

, D

?

PROJECT

pH o CJ o CO u 4-1 u u 4-1 4J

CO 0) <U Q) <u <u T3 0) 0) 0) 01 01 4= X X X

C CO CO CO CD CO

<D M M W M

> U u M M

•H o o o O O O !2 3 3

II II n WWW x cn st

vO CN Q

m

co

fcrf

Tot.

Hrs

in

Mo. A

time hr. 744 672 744 720 744 720 744 744 720 744 720

0

4J

1 PH

CN O rH

CN

<r

Mo.

Av.

Day

Time

Temp, to °F

co r—

1

o

S/L

CN Total

Heating Load L Btu/Mo

.

rH

Tot.

Monthly

Radiation

on

Tilt

Surf.

S

Btu/

(Mo

-f

t^)

Month Jan. Feb.March April

May

June July

Aug.

Sept. Oct. Nov. a

w

C/3 X «a- W

CS| w

w

X

CN w

w

X

O /-"s 1

I 8 o aj /—

N

i

1 H 0 X AJ •H D

rH <13 4J a •erf 03 < • erf 'w' Ph 4= (fa CO /•“s

II cj w 0 a

H U < w l —— -i o

<r 3 i M II i II < *o 4h

1 • c 0) X • in T3 <u cO u TD w a O rH •u 0

\ rQ 'w' t-i 4J U 1 8 CL CO rH CL

<u <D 1 H H 1 X

0) 01 V-/ rH < X CN X X Q m a

CO CO -w x 03 •erf w w w • rH w

M u •• a XI • • 0 o y

(1) 0) cO o a) 3 3 < cn H < H

<U 0) s 0 a 0

0 0 II o o II 3

w H -H u u CN

pH Ph o u* Ph Q

. , . # , # rH CN CO m vD

A-117
WORKSHEET

D

HEATING

AND/OR

DOMESTIC

HOT

WATER

LOAD,

L

PROJECT

u fa fa <D fa CO 4= <D • g 1—

1

fa p m fa •H cd o So P cd g £ fa •H CD fa rH CD g m CO fa fa P 1—

1

0) • a) P

a cd CM <u £ G cd nd fa rH > M Cd o fa cd

Cd •rl rH 3 Td •H cd fa fa

CJ G 4-1 a fa •Td o CD cr cd g a o Q*

fa 0) II cr> u fa 0) fa 'Td 8 o 0) CO a) G 0) fa ll &• pj rC •H fa

cd o 6 <c * fa fa sa> fa CO cd II cd *-) fa fa 3 1 <u Td U CO < o rH • • P

<3 O

G cd 1 | a) bO 8

<d n

CD P fa •H 1—

1

> g o o <D CO O rfa O

•rH cd rj <D fa cd a o § fa H

T3 I fa cr <]

X)

cr

<tj

Total

Heating

Load L Btu/Mo

.

m Monthly DHW

Load Qw

Btu/Mo

.

DHW

Temp. Rise ts

- t

m

°F

Temp

.

Water

ylain

Sup. t

m°F

co

Vol.

of

DHW

Used

/Mo

.

Gal

.

/Mo

.

No

.

of

Days/ Mo. N

31 00

CM 31 30 31 30 31 31 30 31 30 31

Csl

Monthly Space

Htg

Load Qs

Btu/Mo

.

rH

Monthly

Degree Days DD

°Fdays

Month Jan

.

Feb.

March April

May

June July

Aug.

Sept

.

Oct

.

Nov. Dec

.

II

cd Q

CD

<D

fa00 rs

<d • Q O

• 'w' 8

»n X co GO cd •H Hd

faa • a; o

CO VG

co aJ ^ i 3 td < »H T3

cd ^ CD > • • rH rH —

S

<D cd 8

cd fa 00 fa H cd *H 1 fa fa o a. CO o fa

CO fa 'w'

cd (X rH a X

fa cd < II CD rH a /-N fa X

*H o • fa cd 8 CO

(rt Q CO 0 fa cd • •H <D O II > 00

rHo

CDfa m O >> X

oo

* <d • CO O O

0

<U fa <3

CO Ed

CO <r W CM 2XSC f*4 3^:

8 II o

fa co fa O'

CO

II So

cd fa T3

fa o

•• c

cd T3

faO.C?

rH§ + ^ CO o

>

11

II

co -a- m io

A-118
WORKSHEET

E

TOTAL

MONTHLY

SOLAR

RADIATION

AVAILABLE,

S

PROJECT

vO

Tot.

Monthly

Radiation

on

Tilt

Surf. S

Btu/

(Mo

- f

t^)

No.

of

Days

in

Month N 31 28 31 30 31 30 31 31 30 31 30 31

Monthly

Avg.

Daily

Rad.

Dn

Tilt

Surf.

IT

Btu/

(Day

*f

t^)

Ratio

Horizontal

to

Tilt R

co Ratio

Horizontal

to

Extra- terrestrial Kt

CN

Extraterrestrial

Insolation T

°

9

Btu/(Day*ft

z

.

rH

Horizontal Insolation

Btu/

(Day

• f

t

z)

Month Jan. Feb.

March April

May

June July

Aug.

Sept

.

Oct

.

Nov. Dec.

So

I* fa

o 4-1

II -O

fi

B J= O 4J

I- T*

fa J

A-119

Table

A-4

section

5,

or

eq.

11.
WORKSHEET F COLLECTOR COMBINED PERFORMANCE CHARACTERISTICS, F'R

(to), FlUT R L

PROJECT:

(3.5.1) Collector Efficiency Data From Test

intercept, b = F (xa)

R. n slope, m = F U =

L

C in + t out Reference Temperature Basis: 1. t. , 2. -

, 3. t in 2 out

Collector area, A =

c Collector volumetric flow rate =

Correction to t. basis:

in

Case 1: (no correction) F (xa) = R n

F U

R L

Case 2: F (xa) = b x

R. n

1 + c 2C

fru

l

= m x

I , mA

1 + c 2C

C - me A t

\ /time \ c p l flow rate / \

J ) yconversion/ yheat /

where: for liquids, density =^8.33 lb/gal^ x specific ' gravity )

3 for air, density = 0.75 lb/ft , at 70° and 1 atm. specific heat = 0.24 Btu/lb*°F

Case 3: F (xa) = b x R n

fru

l

= m x

(3.5.2) Incident Angle Modifier, .91, for two cover plates

.93, for one cover plate

A-120
WORKSHEET F (Continued)

(3.5.3) Collector Loop Heat Exchanger Modifier, —FR

for air systems and liquid systems without a collector/storage heat exchanger,

Capacitance Rate

C = (from above) =

c

C

g = (calc, as for C

^ above) =

C . = (lesser of C of C ) = min c s

Collector Storage Heat Exchanger Effectiveness, e cs =

C c x = =

£ cs Cmin

= AC (FRUL ) C c

f—R 1 = from figure A-ll or = f

=

(3.5.4) (ra) = FR

(ra) n

x

fru

l

fru

l x

1

g

_(Ta)nT _ Fr

_
WORKSHEET G CORRECTION FACTORS, K , K

3

, K

4

PROJECT

Air Collector Flow Capacitance Rate Factor,

for liquid collectors = 1.0

for air collectors: C = (from worksheet F)

c A = (from worksheet A)

c

C

c _ A

c

= (from Figure A-12)

Storage Mass Capacitance Factor,

M = (vol. storage media) x (density) = Note: M includes hot water storage

volume where it is solar heated.

c = (from worksheet A) =

P

(Me ) P_s = A

c

= (from Figure A-13)

Hot Water Factor,

for liquid systems providing heating only or heating and

hot water, and for all air systems = 1.0

for DHW only systems: t = (from worksheet A) = °F

t = (from worksheet A or if variable see worksheet D) = °F m

t is taken from table A-4 section 5 o is taken from figure A-14 and tabulated on a monthly basis on worksheet C

* (tabulated or const.

Load Heat Exchange Factor,

for air systems and DHW only systems, = 1.0

e = (from worksheet A) a

L» Slot water supply loop

mC

p

C . , = me = air loop p C . = lesser of C„ or C, = min H A

UA bldg = (from worksheet D) =

TTA = K

4 * (from Figure A-15)

min

A-122
APPENDIX B

MATERIALS TABLES

Material

Poly

(vinyl

Poly

(ethylene

Polycarbonate

Fiberglass

Reinforced

Poly

(methyl

Fluorinated

Clear

Lime

Sheet

Water

fluoride)

terephthalate)

Plastics

methacrylate)

ethyleneGlass

(Float)

Lime

White

propylene

Glass

Glass

Property %

Solar

CO

Q) CO a a) c c

co a* X u X X b x

COC

M

ctJO

X 4-4 H ^

IB ’S

O

X

O

X

O CO 0) 000 a

<r c o 6 C H 0)

CO

X 0) o OHO O CO O 0 o c H e

co0 0

co

O 0 0 a COB C O 0

c0

Hu I ooo

CN o

V-/ •H

CO 0 CL 00 X CO

60

C

X

C

X

X 1 6 X co 0 X Q 3 X X i—

60 E cO 0 X c v

•HX

a CO 0 X 0 B Pi x CO 3 a 0 0 X < X o H EH CO I 0 O C X H

CO

O

cl

x

x

X

X

W 4-4 pH 0 o H o . co cj e 3X \ O 4) X o

CO

X vO

CO CO I h aa

4-1

XI

rH 0 CO w > CO O 0 u X C X CO ^

goa

•hx *h 0 o x

^2

X

x

CO

X

X 0 4-i X 0 C

PS

X

X pa

CO 0 CO c X X o c 1 •H 0 c X CO o

CO 0 X U Pi X

•H cl

u

X c 0

CL P< o CO

cl 0 X < CL X

CO

X CO

60 cl CO C o d

•H z CL X r> X

X

CO CO pa co 0 Pi X 0 X X > c 0 X o co X

CO cj c

r-H CO 0 o p4 CO CO CO o 0 0 X X X C a 60 CL

•H 0 c X o X X o 0 0 o CL

CO o CO co X w CL

Pi CO

CO cOX z i—1 X r> CO o X CO *H CO co X X o 0 0 X X X X 0 u

eg COX 0 X • X c X a X 0 X

4-4

C 1 CO o O M X 0 CJ

CO

X S cs X CL >5 0 0 X 60

*H

X

XX > x Pi 0 0 0 X c • CL C

pci

X CO pa

r^- CL < - cr o>

X

to

XX

T (0 r> * X •• 05 X r CO 0

60

XXXX CO c 0 CN o

•H •*

X | X

X

X VO co

O

u o

cOX

X CN 0 X 0 1 X X <r X X co X C CO o X X CO O CJ X

CO

X

X 60 0 X 0 CO 3 X X O X x <S cO CO o CO X 60 X 0 ** o c X u PS o CO X o o 1 X N 0 CO X CO CO r 60 X o X X 60 CO O X c u C .-X x 0 X co O X X

Xo

4-J cOxoX

cO X

CO co 0 x

•r—) <£ C0 CO o o H X

B-l

Plastics

Encyclopedia,

1975-1976,

McGraw-Hill

Publishing

Comoany.
Appendix Table B-2 : Characteristics of Absorptive Coatings

Property

Materia^^

Absorptance*

a Emittancee a

ef Breakdown

Temperature

°F (°C)

Comments

Black Chrome .87-. 93 .i ^9

Alkyd Enamel .9 .9 1 Durability Limited at High

Temperatures

Black Acrylic

Paint

.92-. 97 .84-. 90 VL

Black Inorganic

Paint

.89-. 96 .86-. 93 VL

Black Silicone

Paint

CO O' 1 kO 4^ .83-. 89 ^1 Silicone Binder

PbS/Silicone

Paint

.94 .4 2.5 662 (350) Has a High Emittance for Thicknesses >10pm

Flat Black

Paint

.95-. 98 .89-. 97 VL

Ceramic Enamel .9 .5 1.8 Stable at High Temperatures

Black Zinc .9 .1 9

Copper Oxide

over Aluminum

.93 .11 8.5 392 (200)

Black Copper

over Copper

.85-. 90 .08-. 12 7-11 842 (450) Patinates with Moisture

Black Chrome

over Nickel

.92-. 94 .07-. 12 8-13 842 (450) Stable at High Temperatures

Black Nickel

over Nickel

.93 .06 15 842 (450) May be Influenced by Moisture

at Elevated Temperatures

Ni-Zn-S over

Nickel

.96 .97 14 536 (280)

Black Iron

over Steel

.90 .10 9

*Dependent on thickness and vehicle to binder ratio.

G. E. McDonald, "Survey of Coatings for Solar Collectors", NASA TMX-71730, paper presented at Workshop on Solar Collectors for Heating and Cooling of Buildings, November 21-23, 1974, New York City.

G. E. McDonald, "Variation of Solar-Selective Properties of Black Chrome with Plating Time", NASA

TMX-71731, May 1975.

S. W. Moore, J. D. Balcomb, J. C. Hedstrom, "Design and Testing of a Structurally Integrated Steel

Solar Collector Unit Based on Expanded Flat Metal Plates", LA-UR-74-1093 , paper presented at U. S. Section-ISES Meeting, Ft. Collins, Colorado, August 19-23, 1974.

D. P. Grimmer, S. W. Moore, "Practical Aspects of Solar Heating: A Review of Materials Use in Solar Heating Applications", paper presented at SAMPE Meeting, October 14-16, 1975, Hilton Inn.

R. B. Toenjes, "Integrated Solar Energy Collector Final Summary Report", LA-6143-MS, Los Alamos

Scientific Laboratory, Los Alamos, New Mexico, November 1975.

G. L. Merrill, "Solar Heating Proof-of-Concept Experiment for a Public School Building", Honeywell

Inc., Minneapolis, Minnesota National Science Foundation Contract No. C-870.

D. L. Kirkpatrick, "Solar Collector Design and Performance Experience", for the Grover Cleveland

School, Boston, Massachusetts, paper presented at Workshop on Solar Collectors for Heating and Cooling of Buildings, November 21-23. 1974, New York City.

B-2
Appendix Table B-3: Properties of Typical Absorber Substrate Materials*

Material Aluminum Copper Mild Carbon

Steel

Stainless

Steel

Property

Elastic Modulus,

Tension

psi x 10^

10 19 29 28

Density

lbs/cu.in.

0.098 0.323 0.283 0.280

Expansion Coefficient

(68-212°F)

in/ in/°F x 10 6

13.1 9.83 8.4 5.5

Thermal Conductivity

(77-212°F)

Btu/hr*ft2. °F*ft

128 218 27 12

Specific Heat

(212 °F)

Btu/lb • °F

0.22 0.09 0.11 0.11

Typical valves: standard specifications or manufacturer's literature should be

consulted for specific types or alloys.
Appendix Table B-4: Standards for Piping, Valves and Ducts

Description ANSI ASTM Federal Specifications

Ferrous pipe & fittings

Steel pipe, black and hot dipped zinc- coated (galvanized) welded and seamless

for ordinary use B125. 2-1972 A120-73 WW-P-406D-1973

WW-P-406D-1-1974

Steel pipe welded and seamless B125. 1-1972 A53-73 —

Nipples, Pipe, threaded — — WW-N~351b-1967

WW-N-351b [lj-1970

Pipe fittings: (bushings, locknuts and

plugs) iron, steel and aluminum (threaded) 125-150 lbs. ... WW-P-471B-1970

Malleable-iron threaded fittings, 150 and 300 lbs. B16. 3-1971 — WW-P-521F-1968

Unions, pipe, steel or malleable iron; threaded connection, 150 lbs. and 250

lbs. WW-U-531D

Standard Specification for Seamless

and Welded Ferritic Stainless Steel Tubing for General Service B125.14 A268-73

Standard Specification for Seamless

and Welded Austenitic Stainless Steel Tubing for General Service B125.15 A269-73

Nonferrous metallic pipe and fittings

. Copper pipe, seamless H26. 1-1973 B42-75 WW-P-377d-1962

Copper pipe, threadless H26. 2-1973 B302-74a —

Copper tube, seamless H23. 3-1973 B74-74b —

Copper tube, seamless, for refrigeration and general use H23. 5-1974 B280-75 WW-T-775a-1962

Copper water tube seamless H23. 1-1973 B88-75 WW-T-799D-1971

General requirements for wrought seamless copper and copper alloy tube H23. 4-1973 B251-75 —

Seamless brass tube H36. 1-1973 B136-74 WW-T-791A-1971

Seamless red brass pipe H27. 1-1973 B43-75 WW-P-35 la-196

3

Bronze flanges and flanged fittings,

150 and 300 lbs. B16. 24-1971 — —

Cast-bronze fittings for flared copper tubes B16. 26-1967 — —

Cast-bronze solder joint drainage

fittings-DMV

B16. 23-1969

B16. 23a-1973 — —

Cast bronze solder joint pressure

fittings B16. 18-1972 — —

Cast bronze threaded fittings,

125 and 250 lbs. B16 15-1971

ww-.p 460b-1967 WW-P-460b-l-1972

Copper tube fittings, solder ends — — W-T-725a-1973

Unions, brass or bronze, threaded pipe

connections and solder-joint tube connections WW-U-516B

Unions, pipe, bronze or naval brass, threaded pipe connection 250 lbs. WW-U-516a-1967

B-4

Other

ASME SA33

CS5-65

ASME SB42

ASME SB75

ASME SB251

ASME SB135

ASME SB43
Appendix Table B-4: continued

Description ANSI ASTM Federal Other Specifications

Welded Copper Tube — B-447 — —

Welded Copper Nickel Pipe and Tube — B-467 — —

Welded Copper and Copper Alloy Tube — B-543 — —

Welded Copper Alloy Water Tube — B-586 — —

Welded Brass Tube — B-587 — —

Welded Copper Alloy Pipe — B-608 — —

Copper-silicon alloy seamless pipe

and tube H26. 3-1973 B315-75 — —

Wrought copper and bronze solder-joint

pressure fitting B16. 22-1973 — — —

Wrought copper and wrought copper alloy

solder-joint drainage fittings B16. 29-1973 — — —

Aluminum-alloy seamless pipe and seamless extruded tube H38.7 B241 — —

Aluminum-alloy drawn seamless tubes H38.7 B310-74a — —

Aluminum-alloy drawn tubes for general purpose application H38. 17-1974 B483-73 — ___

Aluminum-alloy extruded round coiled tubes

for general purpose application H38. 18-1974 B491-73 — —

Wrought aluminum and aluminum alloy welding

fittings H38. 19-1974 B361-73 — —

Pipe hangers and supports — — WW-H-17 ID-19 70 —

Pipe hangers and supports, materials,

design and manufacture — ___ — MSS SP-58-1975

Pipe hangers and supports, selection

and application — — — MSS SP-69-1966

Polybutylene (PB) plastic hot-water

distribution systems (180°F Max.) — D3309-74 — —

Plastic hot-water distribution systems: chlorinated poly (vinyl chloride) (CPVC) for water service (180°F Max.) D2846-73 NSF 14-1965

Cold water service, clamps, hose, low pressure — — WW-C-440B(2) —

Standard methods of testing rubber hose J2.5 D380-75 — —

Standard method of test for sealability

of gasket materials Z193. 1-1970 F37-68 — —

Standard method of test for fluid resistance of gasket materials ___ F146-72

B-5
Appendix Table B-4 : continued

Description ANSI ASTM Federal Other Specifications

Valves

Standard for solenoid valves for use with volatile refrigerants and water ARI 760, 1975

Valves, pressure, reducing and regulating

for installation on domestic water

supply lines IAPM0 PS15-71 y

Water pressure reducing valves for domestic water supply systems ASSE 1003, 1970

Valves, automatic relief (For water/

steam). ANSI 21.22-1971

Valves, cast iron gate, 125 & 250 lb; threaded and flanged WW-V-58a-1966

Combination check and relief valves IAPMO TSC-8-66 1/

Valves, ball WW-V-35a-1965

Valves, bronze, angle, check and

globe, 125 and 150 lb, threaded

and flanged or soldered WW-V-51d-1967

Valves, water heater drain ASSE 1005

Globe type loglighter valves,

angle or straight pattern IAPMO PS 10-66 -

Valves, electrically operated UL 429, 1955

Valves (125 pound bronze gate) MSS SP 37, 1969

Valves (150 pound corrosion resistant,

cast, flanged) MSS SP 42

Valves (butterfly) MSS SP 67, 1966 -

Low velocity duct construction standards — SMACNA

High velocity duct construction standards SMACNA

Fibrous glass duct construction standards SMACNA

Pressure sensitive tape standards

for fibrous glass duct SMACNA

Duct liner application standard SMACNA

Fire damper guide SMACNA

1/ International Association of Plumbing and Mechanical. Officials, 5032 Alhambra Avenue, Los Angeles, California 90032

2/ Manufacturers Standardization Society of the Valve and Fitting Industry, 1815 North Fort Meyer Drive

Arlington, Virginia 22209

B-6
1 / Appendix Table B-5 : Temperature and Pressure Ratings for Ball Valves—

Size

(inches)

Temperature,

°F Materials (Pressure in psi)

Bronze Iron Carbon Steel Alloy Steel

1/2 -20 to 100 ' 200 and 400 1000 1000

150 400 850 850

200 150 and 400 700 700

TO 250 15.2 / and 400 500 500

300 300 300 300

325 200 200 200

3/4 353 125 125 125

375 90 90 90

400 60 60 60

1 -20 to 100 400 720 720

150 400 710 710

200 400 700 700

TO 250 400 500 500

300 300 300 300

2 325 200 200 200

353 125 125 125

375 90 90 90

400 60 60 60

2-1/2 -20 to 100 220 275 275

150 205 255 255

TO 200 190 240 240

12 250 180 225 225

1/ These ratings for ball valves, presented in Federal Specification WW-V-35a-1975 , are intended for guidance and are not intended to be restrictive. Valves should not be used

for pressures and temperatures exceeding the manufacturer's rating.

2J 15 pounds saturated steam temperature.

B-7
Appendix Table B-6: Thermal Storage Unit Containers-^

Container Recommended-3/ Recommended

Usage

Above Below

Transfer

Media PressureConditions

Container

Standard

Protective

Coating

Coating

Standard

Material Ground Ground Air Liquid High Low 2/ Compliance Ext . Int

.

Compliance

Aluminum X X X X X X ANSI B96.1

1973

- -

Concrete X X X X X X IAPMO PS

I

(1966) X X Ext. MPS

609-7.3

Int. TTP-95A(3)

27 May 66

Earth X X X Vapor Barrier

Materials as per ASTM E154.68

Vapor Barrier

Covering of Solids Required

MPS 507.2.2

Plastics X X X X X MIL-T-52777 4/ 21 Feb 1974

- -

Steel X X X X X X AWWA D-100

(1967) X X Ext. MPS

609-7.4 1/

Ext. & Int. AWWA DIO

2

(1964)

Wood X X X X NFO 8 (1965) - -

1/ Thermal Storage Unit - any container, space, or device which has the capacity to store transfer media

(liquid or solid) containing thermal energy for later use.

2/ Low pressure systems are those subjected to atmospheric pressure only, i.e. vented.

3/ When applicable, ASME Boiler and Pressure Vessel Code, Section VIII may be used.

4J Refers to fiber reinforced polyester containers

5/ In lieu of interior galvanized, glass-lined or stone-lined tanks.
Appendix Table B-7 : Examples of Typical Heat Transfer Liquids

1 /

Water

50% Ethylene 50% Propylene Silicone Paraffinic

Glycol/Water Glycol/Water Fluid Aromatics Oil

Freezing Point,

°F (°C)

32 (0) -33 (-36) -28 (- 33 ) -58 (-50) -100 to -25

(-73 to -32) —

Boiling Point,

°F (°C) (at atm. pressure)

212 (100) 230 (110) — None 300-400

(149-204)

700 (371)

Fluid Stability Requires pH

or inhibitor

monitoring

Requires pH

or inhibitor

monitoring

Requires pH

or inhibitor

monitoring

Good Good Good

2/ Flash Point,

°F (°C) None None 600 (315) 600 (315) 145-300

(63-149)

455 (235)

Specific Heat

(73°F)

[ Btu/ (lb • °F)

]

1.0 0.80 0.85 0.34-0.48 0.36-0.42 0.46

Viscosity

(cstk at 77°F) 0.9 21 5 50-50000 1-100 —

Toxicity Depends on inhibitor

used

Depends on inhibitor

used

Depends on inhibitor

used

Low Moderate —

1/ These data are extracted from manufacturers literature to illustrate the properties of a few types of liquid that have been used as transfer fluids.

y it is important to identify the conditions ot tests for measuring flash point. Since the manufacturers

literature does not always specify the test, these values may not be directly comparable.

B-9
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B-10
APPENDIX C

ILLUSTRATED DEFINITIONS

AN ILLUSTRATED SOLAR APPENDIX

Table of Contents

I. SOLAR HEATING AND HOT WATER SYSTEMS: A FUNCTIONAL DESCRIPTION

R. SOLAR HEATING AND HOT WATER SYSTEMS: OPERATIONAL DESCRIPTION

A. SOLAR HEATING SYSTEM C- 3 B. DOMESIC HOT WATER SYSTEM C- 5

in. BASICS OF SOLAR UTILIZATION

A. CLIMATE C- 6

B. SOLAR RADIATION C- 6 C. THE SOLAR WINDOW C- 8 D. SOLAR COLLECTION AND CONVERSION C-10

E. COLLECTOR ORIENTATION AND TILT C-ll

F. SHADING OF COLLECTOR C-12

IV. SOLAR HEATING AND HOT WATER SYSTEMS: ACTIVE SYSTEMS

A. HEATING AND DOMESTIC HOT WATER DIAGRAMS C-13

B. COLLECTOR-STORAGE DIAGRAMS C-14

C. STORAGE-DISTRIBUTION DIAGRAMS C-15

D. DOMESTIC HOT WATER PREHEATING C-17

E. AUXILIARY ENERGY DIAGRAMS C-18

V. SOLAR HEATING AND HOT WATER SYSTEMS: PASSIVE SYSTEMS

A. SPACE AND BUILDING-SURFACE HEATING C-19

B. LIQUID ROOF MASS C-19

C. COMBINED COLLECTOR-STORAGE-DISTRIBUTION WALL C-19

D. THERMOSYPHONING SYSTEM: DOMESTIC HOT WATER PREHEATING C-19

VI. SOLAR HEATING AND HOT WATER SYSTEMS: COMPONENT DESCRIPTION

A. FLAT-PLATE COLLECTORS: AN EXPLODED VIEW C-20

B. FLAT-PLATE COLLECTORS C-21

C. HIGH TEMPERATURE COLLECTORS C-22

D. COLLECTOR MOUNTING C-23

E. MULTIPLE COLLECTORS C-24

F. HEAT EXCHANGERS C-25
'

.
Solar Heating and Hot Water Systems:

Functional Description

The basic function of a solar heating and domestic hot water system is the collection and conversion

of solar radiation into usable energy. This is accomplished — in general terms — in the following manner. Solar radiation is absorbed by a collector, placed in storage as required, with or without the use of a transport medium, and distributed to point of use. The performance of each operation is maintained by automatic or manual controls. An auxiliary energy system is usually available for operation, both to supplement the output provided by the solar system and to provide for the total energy demand should the solar system become inoperable.

The conversion of solar radiation to thermal energy and the use of this energy to meet all or part of a dwelling's heating and domestic hot water requirements has been the primary application of solar energy in buildings.

The parts of a solar system — collector, storage, distribution, transport, controls and auxiliary

energy — may vary widely in design, operation, and performance. They may, in fact, be one and the same element (a south-facing masonry wall can be seen as a collector, although a relatively

inefficient one, which stores and then radiates or "distributes" heat directly to the building interior).

They may also be arranged in numerous combinations dependent on function, component

compatibility, climatic conditions, required performance, site characteristics, and architectural

requirements.

Of the numerous concepts presently being developed for the collection of solar radiation, the

relatively simple flat-plate collector has the widest application. It consists first of an absorber

plate, usually made of metal coated black to increase absorption of the sun's energy. The plate is then insulated on its underside and covered with a transparent cover plate to trap heat within the

collector and reduce convective losses from the absorber. The captured heat is removed from the

absorber by means of a working fluid, generally air or water. The fluid is heated as it passes through

or near the absorber plate and then transported to points of use, or to storage, depending on energy

demand.

The storage of thermal energy is the second item of importance since there will be an energy

demand during the evening, or on sunless days when solar collection cannot occur. Heat is stored

when the energy delivered by the sun and captured by the collector exceeds the demand at the point

of use. The storage element may be as simple as a masonry floor that stores and then re-radiates

captured heat, or as relatively complex as a latent heat storage. In some cases, it is necessary to transfer heat from the collector to storage by means of a heat exchanger (primarily in systems with

a liquid working fluid). In other cases, transfer is made by direct contact of the working fluid with

the storage medium (i.e., heated air passing through a rock pile).

The distribution component receives energy from the collector or storage, and dispenses it at points

of use. Within a building, heat is usually distributed in the form of warm air or warm water.

The controls of a solar system perform the sensing, evaluation and response functions required to operate the system in the desired mode. For example, if the collector temperature is sufficiently

higher than storage temperature, the controls can cause the working fluid in storage to circulate in the collector and accumulate solar heat.

An auxiliary energy system provides the supply of energy when stored energy is depleted due to severe weather or clouds. The auxiliary system, using conventional fuels such as oil, gas, electricity, or wood provides the required heat until solar energy is available again.

The organization of components into solar heating and domestic hot water systems has led to two

general characterizations of solar systems: active and passive. The terms active and passive solar

systems have not yet developed universally accepted meanings. However, each classification possesses characteristics that are distinctively different from each other. These differences

significantly influence solar dwelling and system design.

C-1
An active solar system can be characterized as one in which an energy resource — in addition to

solar — is used for the transfer of thermal energy. This additional energy, generated on or off the

site, is required for pumps, blowers, or other heat transfer medium moving devices for system

operation. Generally, the collection, storage, and distribution of thermal energy is achieved by

moving a transfer medium throughout the system with the assistance of pumping power.

A passive solar system , on the other hand, can be characterized as one where solar energy alone is used for the transfer of thermal energy. Energy other than solar is not required for pumps, blowers,

or other heat transfer medium moving devices for system operation. The major component in a passive solar system generally utilizes some form of thermal capacitance, where heat is collected,

stored, and distributed to the building without additional pumping power. Collection, storage, and

distribution is achieved by natural heat transfer phenomena employing convection, radiation,

conduction, in conjunction with the use of thermal capacitance as a heat flow control mechanism.

C-2
Solar Heating and Hot Water Systems:

Operational Description

A. Solar Heating System

Solar systems may be designed to operate in a number of different ways depending on function,

required performance, climatic conditions, component and system design, and architectural re- quirements. Usually, however, solar systems are designed to operate in four modes. In a very basic manner, the four modes of solar system operation for both active and passive systems are described

and illustrated below.

1. HEATING HOUSE FROM COLLECTOR Solar radiation captured by the collectors and converted to thermal energy can be used to directly heat the house.

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2. HEATING STORAGE FROM COLLECTOR If the house does not require heat, the captured

(collected) thermal energy can be placed ffTstorage for later use. C-3
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3. HEATING HOUSE FROM STORAGE Heat from storage can be removed to heat the house when the sun is not shining — at night or on consecutive sunless days.

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4. HEATING HOUSE FROM AUXILIARY If heat from the collector and storage is not sufficient to

totally heat the house, an auxiliary system supplies all or part of the house's heating requirement.

C-4

system
B. Domestic Hot Water System

The solar system may also be designed to preheat water from the incoming water supply prior to passage through a conventional water heater. The domestic hot water preheat system can be

combined with the solar heating system or designed as a separate system. Both situations are

illustrated below.

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1. DOMESTIC HOT WATER PREHEATING - SEPARATE SYSTEM Domestic hot water preheating

may be the only solar system included in some designs. A passive thermosyphoning arrangement is shown above.

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as it passes through heat storage enroute to the conventional water heater.
Basics of Solar Utilization

A.Climate

Solar radiation, wind, temperature, humidity and many other factors shape the climate of the United

States. Basic to using solar energy for space heating and domestic hot water heating is understanding the relationship of solar radiation, climate and dwelling design.

The amount and type of solar radiation varies

between and within climatic regions: from hotdry climates where clear skies enable a large

percentage of direct radiation to reach the

ground, to temperate and humid climates where

up to 40 percent of the total radiation received

may be diffuse sky radiation, reflected from

clouds and atmospheric dust, to cool climates

where snow reflection from the low winter sun may result in a greater amount of incident

radiation than in warmer but cloudier climates.

As a result of these differences in the amount

and type of radiation reaching a building site, as well as in climate, season and application —

heating or domestic hot water — the need for and the design of solar system components will vary in each locale.

B. Solar Radiation

The sun provides almost all of the earth's energy in the form of radiation. Solar energy, also known

as solar radiation reaches the earth's surface in two ways : by direct (parallel) rays, and by diffuse

(nonparallel) sky radiation. The solar radiation reaching a building includes not only direct and

diffuse but also radiation reflected from adjacent ground and building surfaces. It is these three sources of solar radiation that may be used for space and domestic hot water heating.

1.THE SOLAR CONSTANT A nearly constant amount of solar energy strikes the outer atmosphere = 429.2 BTU per square foot per

hour. This quantity is known as the solar constant. A large amount of this energy,

however, is lost in the earth's atmosphere,and

cannot be regained regardless of collector

design.

2. ABSORPTION AND REFLECTION On the

average, almost half of the solar radiation

reaching the earth's outer atmosphere is lost by

absorption in the atmosphere and by reflection

from clouds, as it passes through the atmosphere to the earth's surface. The radiation lost actually varies between 60% in Seattle, Washington to only 30% in Albuquerque, New

Mexico.

06
3JEARTH'S ATMOSPHERE As already stated,

the radiation reaching the earth's surface is diminished by the condition of the earth's atmosphere: its vapor, dust and smoke content. At lower sun angles, the length of travel

through the atmosphere is greatly increased, so the relative amount of radiation received is further diminished.

4 . DIFFUSE RADIATION Clouds and particles in the atmosphere not only absorb solar energy, but scatter it in all directions. As a result, a part of the solar radiation reaching the earth's surface is diffused, and received from all parts

of the sky. Diffuse radiation, as opposed to direct radiation, is more predominant on hazy

days- than clear ones. At most, however, diffuse

radiation can only be about one quarter of the

solar constant, or about 100 BTU/hr./sq. ft.

5. DIRECT RADIATION ON A HORIZONTAL

SURFACE Although the amount of radiation

remains constant, less radiation strikes a given

horizontal area as the sun gets lower in the sky.

6.DIRECT SOLAR RADIATION ON A TILTED

SURFACE The same principle applies to a

tilted surface such as a collector. By tilting the

collector so that it is nearly perpendicular to the sun's ray, more energy strikes its surface,

undiminished by a cosine factor.

07 •
C. Solar Window

collector of a house. The path of the sun can be

painted (projected) onto the dome, as can be

the outline of surrounding houses and trees. The morning and afternoon limits of useful solar

collection (roughly 9 A.M. and 3 P.M.) and the

sun's path between those hours throughout the

year scribes a "solar window" on the dome.

Almost all of the useful sun that reaches the

collector must come through this window ex- cept for the added effect of diffuse radiation.

If any of the surrounding houses, trees, etc., intrude into this "solar window," the intrusion

will cast a shadow on the collector. The

isometric drawing above illustrates the "solar window" for a latitude 40° N. The solar window

will change for different latitudes.

C-8
SIDE VIEW OF SKY DOME WITH "SOLAR

WINDOW17 A side view of the sky dome from

the east illustrates the relative position and

angle of the sun throughout the year that

defines the boundaries of the "solar window."

ANGLE OF INCIDENCE, a term often used in solar collector design, is the angle measured from the

normal of the collector surface to the line indicating the sun's altitude at a particular time. The

diagram specifically identifies the angle of incidence for June 21.

PLAN VIEW OF SKY DOME WITH "SOLAR

WINDOW77 Viewed from above the sky dome,

the seasonal path of the sun can be plotted thus

defining the boundaries of the "solar window."

This is easily accomplished by the use of a standard sun path diagram for the proper

latitude. Sun path diagrams are widely

reproduced and used for determining the

azimuth and altitude of the sun at any time

during the year, and give the points which can be

plotted to determine the solar window.

PANORAMA OF THE SKY DOME As with the spherical earth, the spherical sky dome with its “solar window" can be mapped using a Mercator projection, in which all latitude and longitude lines are straight lines. Such a map is very useful for comparing the site surroundings with the "solar window" outline, since both can be easily plotted on the map. Any elements surrounding the site that intrude into the "solar window" will cast shadows on the collector.

C-9
D. Solar Collection and Conversion

Basic to the utilization of solar energy for space and domestic hot water heating is the process by

which solar radiation is converted to thermal energy. This conversion process is the basic link between the energy supply -- the sun — and the energy load -- the dwelling. The process is best

understood by briefly explaining solar radiation and then discussing the characteristics of collection.

ULTRAVIOLET

If INFRARED

VISIBLE

RADIATION

THERMAL

RADIATION

icr 8 icr 6 icr 4 10-2 10 102 i 0

4 106 10 8 WAVELENGTH /jJ*

RE-RADIATION

LOST TO SKY

ABSORBING SURFACE

INSULATION

1, SOLAR ENERGY CONVERSION Solar radiation is electromagnetic radiation generated by

the sun, which reaches the earth's surface with

a wavelength distribution of .3 to 2.4 micrometers. Radiation is perceived as visible light

between ultraviolet and infrared, specifically

between .36 and .76 micrometers. For most

solar applications, solar radiation in the visible and near-infrared range is the most important.

The drawings to the left show the principle of solar energy collection and conversion. When

incoming solar radiation impinges on the sur- face of a body, it is partially absorbed, partially

reflected, and, if the body is transparent,

partially transmitted. The relative magnitude

of each varies with the surface characteristics,

body geometry, material composition, and

wavelength.

For solar applications, energy must be first absorbed, then converted into thermal energy

and, finally removed by a heat transfer mechanism in order to be useful. Absorbed radiation

heats up the absorbing body, which then re- emits energy in the form of thermal radiation in the infrared (longwave) part of the spectrum. If the absorbing surface is exposed to the atmosphere, part of the absorbed energy will be lost by convection or radiation.

o THE GREENHOUSE EFFECT Most glass and some plastics are transparent in the solar

wavelength region and hence are used as windows. At the same time, this glazing has low

transmission in the infrared (longwave) region.

By placing glass or plastic over the absorber in a collector, energy is trapped in two ways:

first, the infrared radiation emitted by the

absorbing surface is stopped by the glazing,

with a portion re-radiated back toward the

absorber, and thereby trapped. Second, the

glazing also traps a layer of still air next to the

absorber and reduces the convective heat loss. This behavior of glazing is called the "greenhouse effect" and is used in most solar collectors. C-10
E. Collector Orientation and Tilt Solar collectors must be oriented and tilted within prescribed limits to receive the optimum level of

solar radiation for system operation and performance.

1.COLLECTOR TILT FOR HEATING The optimum collector tilt for heating is usually equal

to the site latitude plus 10 to 15 degrees.

Variations of 10 degrees on either side of this optinrun are acceptable.

CUOLINfT The optimum collector tilt for heating and cooling is usually equal to site latitude plus 5 degrees. Variations of 10 degrees on either side of the optinrun are acceptable.

WATEft The optimum collector tilt for domestic water heating alone is usually equal to the

site latitude. Again, variations of 10 degrees on

either side of the optinrun are acceptable.

5. SNOWFALL CONSIDERATION The snowfall

appropriateness of these optinrun collector tilts. of the collector, should be avoided.

4 MODIFICATION OF OPTIMUM COLLECTOR

TILT A greater gain in solar radiation collection sometimes may be achieved by tilting

the collector away from the optinrun in order to capture radiation reflected from adjacent

ground or building surfaces. The corresponding

reduction of radiation directly striking the

collector, due to non-optinun tilt, should be

recognized when considering this option,

characteristics of an area may influence the

Snow buildup on the collector, or drifting in front

WEST £AST

COLLECTOR ORIENTATION A collector orientation of 2 6 degrees to either side of true South is acceptable. However, local climate

and collector type may influence the choice

between East or West deviations.

C-11
F. Shading of Collector

Another issue related to both collector orientation and tilt is shading. Solar collectors should be

located on the building or site so that unwanted shading of the collectors by adjacent structures,

landscaping or building elements does not occur. In addition, considerations for avoiding shading of the collector by other collectors should also be made. Collector shading by elements surrounding the

site may be addressed by considering the "solar window" concept.

SELF-SHADING OF COLLECTOR Avoiding all shelf-shading for a bank of parallel collectors

during useful collection hours (9 AM and 3 PM) results in designing for the lowest angle of incidence

with large spaces between collectors. It may be desirable therefore to allow some self-shading at the end of solar collection hours, in order to increase collector size or to design a closer spacing of

collectors, thus increasing solar collection area. By making the collector's back slope reflective, one

could increase the amount of solar radiation striking the adjacent collector, thus negating some of

the shading loss.

2.SHADING OF COLLECTOR BY BUILDING

ELEMENTS Chimneys, parapets, fire walls,

dormers, and other building elements can cast shadows on adjacent roof-mounted solar collectors, as well as on vertical wall collectors. The

drawing to the right shows a house with a 45°

south-facing collector at latitude 40° North.

By mid-afternoon portions of the collector are shaded by the chimney, dormer, and the offset

between the collector on the garage. Careful

attention to the placement of building elements

and to floor plan arrangement is required to assure that unwanted collector shading does not

occur.

C-12
Solar Heating and Hot Water Systems:

Active Systems

Active solar systems are characterized by collectors, thermal storage units and transfer media, in an assembly which requires additional mechanical energy to convert and transfer the solar energy into

thermal energy. The following discussion of active solar systems serves as an introduction to a range of active concepts which have been constructed.

A. Heating and Domestic Hot Water Diagrams

In common use today is the combined solar heating and domestic hot water system. The system

operates as follows: solar radiation is absorbed by a collector or series of collectors, and removed to storage in the form of thermal energy by a heat transfer medium. The heat is later removed from

storage and distributed to the living spaces, again by a heat transfer medium, which may or may not be the same medium as that flowing through the collector. Circulation throughout the system is aided by pumps, blowers, or other medium moving devices. An auxiliary heating system should be

available both to supplement the output supplied by the solar system and to provide for the total energy demand should the solar system become inoperative. Manual or automatic controls monitor

both the solar and auxiliary system operation. In a solar heating and hot water combined system, the

domestic water supply is preheated in the heat storage, and then passed through the conventional

water heater before distribution.

1. SOLAR HEATING SYSTEM; PROCESS

DIAGRAM A space heating system alone can be

developed by simply removing the domestic hot

water preheating unit from the heat storage.

The operation of the solar heating system is then the same as described above.

2.SOLAR DOMESTIC HOT WATER SYSTEM:

PROCESS DIAGRAM 1 The combined system

diagram can be modified into a domestic hot

water system alone by eliminating the heating

distribution and the auxiliary heating unit, and

also reducing the size of the storage tank. Only

the domestic water supply would then pass through the heat storage, preheating the hot

water supply, enroute to a conventional water

heater.

3. SOLAR DOMESTIC HOT WATER SYSTEM:

PROCESS DIAGRAM 2 Another method of

preheating the domestic hot water involves

passing the potable water supply itself through

the collectors. The heated water is stored in the water storage tank until a demand is initiated. An auxiliary heat source is usually

present to boost the water temperature when

preheat has been inadequate. The preheated

water is either pumped from storage, or flows

by supply pressure to the house.

J

C-13
B. Col lector - Storage

The removal of heat from the collector and its placement in heat storage involves the circulation of

a heat transfer medium in a transport loop. Several collector-storage conditions are shown below.

1 OPEN CIRCUIT LIQUID COLLECTOR In this system, storage water itself, treated as necessary to prevent corrosion, is drawn from the

bottom of storage , pumped through the collec- tor and then returned to the top of storage.

The circulating water, which runs through, on

top of or under the absorber plate, is distributed

to the absorber by a manifold at the top of the

collector, or pumped up from below the collector through tubes attached to or integral with

the absorber plate. When the system is not

running, air is allowed to enter into the collec- tor and piping, and the water drains into

storage. In open circuit collectors, storage is at atmospheric pressure, a condition that should be

considered in the design of the distribution

system.

? CLOSED CIRCUIT LIQUID COLLECTOR In

" this system, a heat transfer liquid — such as treated water, anti-freeze solution or another

liquid — is pumped through the collector and

then through a heat exchanger in storage and

back to the collector, in a closed loop. In this system of separate transfer and storage mediums, the storage may be pressurized. The loop

may remain filled "with fluid, and therefore

must be protected from freezing, or may be

drained and replaced with pressurized inert gas.

3. AIR COLLECTOR Although many arrangements of air collector-rock storage and warmair distribution systems are possible, the one diagrammed is typical of the most popular

system in use. Air from the cold end of the

rock storage bin is pumped through the collector, gaining heat, and returned to the hot end of

storage.

Warm air distribution systems are usually used

with air collectors to enable direct heating

from the collector. In this case, the dampers

must be adjusted to supply heat directly to the

house, returning air to the collector, thereby

bypassing storage. (See diagram page C3.)

C-14
C. Storage -Distribution Diagrams

Heat is removed from storage and circulated to the house by the distribution component. There are numerous ways this storage-distribution function can be performed, and in numerous combinations

with the preceding collector-storage circuits. Six typical storage-distribution methods are diagrammed.

1. WARM AIR DISTRIBUTION - HOT vV-ATER COIL IN DUCT A warm-air distribution sys- tem can be used with liquid heat storage, by

pumping the heated storage medium through a

suitably sized heat exchange coil in the main

supply duct of the distribution system.

2. HYDRONIC DISTRIBUTION In a hydronic sys- tem, with a pressurized storage, liquid from

storage is pumped directly through standard

baseboard convector units. Because of the

relatively low temperatures that usually occur

in solar systems during winter conditions, the

size of baseboard units, and possibly the piping

may change from ordinary hydronic systems.

3 INDIVIDUAL FAN-COIL UNIT DISTRIBUTION

' When storage is not pressurized, in a fan coil distribution system (as well as a hydronic

system), a secondary, heat transfer fluid is often circulated in a closed loop to prevent air binding. This fluid is pumped through storage to

individual fan-coil units located throughout the

dwelling for heat distribution. The design and

sizing considerations are similar to those for

ordinary hydronic distribution.

C-15
4.

RADIANT HEAT DISTRIBUTION In a radiant

heating system, with a non-pressurized storage, a secondary heat transfer fluid is circulated in a

closed loop from heat storage to coils or panels

located in the floor, walls and or ceiling of the

living space. Besides the liquid temperature,

the size and spacing of the coils is critical for effective radiant heat distribution.

5.

WARM AIR DISTRIBUTION FROM ROCK

STORAGE For an air-collector system employing rock storage, it is advantageous to employ the natural high level of temperature

stratification in storage and distribute air to the living space from the hottest section of

storage. As diagrammed, this will require

reversing the flow of air through storage relative to the collection cycle. The most common

method for doing this is diagrammed. Using the same fan that supplies the collector along with

two automatic dampers, the direction of air flow is reversed from storage, forcing air in a house loop to return, thereby bypassing the

collector ducts.

6

.

HEAT PUMP ASSISTED DISTRIBUTION Either

air or liquid collector-storage systems can be

used as the source of thermal energy for a heat

pump distribution system. As diagrammed,

liquid from storage is circulated through a heat

exchanger in the heat pump unit, and heat is transferred to the heat pump's working fluid. By means of its compression cycle, the heat

pump further elevates the working fluid temperature and it functions as the auxiliary heat

source. This high temperature fluid then

transfers heat through another exchanger to either an air or hydronic distribution system.

The heat pump may also be used in parallel with

thermal energy storage to remove heat from

the outside air when storage is depleted.

C-16
D. Domestic Hot Water Preheating

Domestic hot water can be preheated either by circulating the potable water supply itself through

the collector, or by passing the supply line through storage enroute to a conventional water heater.

Three storage related preheat systems are shown below.

1. PREHEAT COIL IN STORAGE Water is passed through a suitably sized coil placed in storage enroute to the conventional water

heater. Unless the preheat coil has a protective

double-wall construction, this method can only

be used for solar systems employing non-toxic

storage media.

2. PREHEAT TANK IN STORAGE In this system, the domestic hot water preheat tank is located within the heat storage. The water

supply passes through storage to the preheat

tank where it is heated and stored, and later piped to a conventional water heater as needed.

A protective double-wall construction again

will be necessary unless a non-toxic storage

medium is used.

3 PREHEAT OUTSIDE OF STORAGE In this

' preheat method, the heat transfer liquid in storage is pumped through a separate heat

exchanger to be used for domestic hot water

preheating. This separate heat exchanger could

be the conventional water heater itself. However, if the liquid from storage is toxic, the

required separation of liquids is achieved by the

use of a double-wall exchanger, as diagrammed,

in which the water supply simply passes through

enroute to the conventional water heater. COLD WATER SUPPLY

I I

I J

AUXILIARY

WATER HEATER

C-17
E. Auxiliary Energy Diagrams

The provision of auxiliary energy to the dwelling is needed when the solar heating system becomes

inoperative or cannot meet the dwelling's total energy demand. The auxiliary heating component

may operate independently or in conjunction with the solar storage and distribution systems. The

control of solar and auxiliary system operation becomes an important consideration for the

effectiveness of both. Four possible combinations are shown below.

1.

AUXILIARY HEAT COILS IN AIR

DISTRIBUTION SUPPLY DUCT Two heat ex- change coils — one from solar storage and one from the auxiliary unit — are located in the

primary distribution supply duct. Depending on

the temperature in storage, the auxiliary energy

system may provide a full or partial temperature boost to the supply of air. The need for auxiliary energy is determined typically by a two contact room thermostat.

2.

AUXILIARY WITH SEPARATE DISTRIBUTION

The auxiliary energy system may be a totally

separate component not integrated with solar

storage or distribution. This may involve a

totally separate distribution network, such as

individual electric baseboard units placed in the

dwelling in locations and numbers as required.

The two separate heating systems, however, are

linked by temperature controls. 3.

AUXILIARY HEATING WITH COMBINED

DISTRIBUTION In this system, the auxiliary

energy source is located between the storage

and distribution components. In this way, an

integrated control component monitors whether

heat from storage or heat from the auxiliary source is in use. Pumps and valves located at the connection points between the systems

regulate the auxiliary energy supply use, and

prevents the auxiliary from heating storage.

A AUXILIARY HEATING WITH AIR COLLEC-

' flON-falSTRtBUTION In this system, the

auxiliary heat unit is located within the distri- bution air ducts downstream from the system's

fan or blower. In this way, the auxiliary

subsystem provides an energy boost to the

heated air coming either: 1) from storage, or 2) directly from the collector. The auxiliary unit

may be a coil in the duct, containing boilerheated water, or an electric resistance element,

or it may be a furnace. The auxiliary and solar

system operation is maintained and monitored

by an integrated control component.

C-18
Solar Heating and Hot Water Systems:

Passive Systems

Passive solar systems are characterized by the use of the sun's energy alone for the transfer of

thermal energy throughout the system. Four passive systems are discussed below — three space

heating and one domestic hot water preheating system. There are innumerable other concepts, but

the following will serve as an introduction to passive solar systems.

SPACE AND BUILDING-SURFACE HEATING

This concept relies on a large transparent

surface for the southern exposure, to increase

heat gain directly into the building — thus

heating the space. To avoid daytime overheating, an adequate area and thickness of a thermal mass, such as heavy masonry, should be

used on the floors or walls to absorb heat during

the day and release it to the space after the sun

has set. Insulation devices should also be available to regulate daytime solar exposure and to minimize nighttime heat loss.

COMBINED COLLECTOR-STORAGE-DISTRIBUTION WALL This passive concept relies on

the solar exposure of a south facing thermal mass (containerized water, masonry or concrete) located behind a transparent surface and

a separating air space. The thermal mass acts

as the collector, storage, and distribution components. Solar radiation collected and stored in the thermal mass is distributed to the space by:

1) radiation, 2) convection, and 3) conduction.

When collection ceases due to lack of solar

radiation, it is advantageous to prevent heat

loss through the transparent surface to the

outside, by an insulating device. In this example air valves or dampers allow air to circulate across the hot face of the storage mass for convective heat transfer.

MOVABLE INSULATION j. -

j

^ ^ ^

WATERBAGS

RADIATION

L - ' LIQUID ROOF MASS This

”1

concept

Qis similar

to the previous passive system except that the

thermal mass — water — is now located in containers above the living space. In some cli- mates, both heating and cooling can be provided

by this system. Like the previous concept,

proper control must be maintained over the

heat exchange process. This can be accomplished by the use of movable insulating panels

to expose or cover the containers, or by filling

and draining them according to heating or cooling demand.

HOT WATTR PREHEATING This passive concept utilizes the natural upward movement of

heated fluids for the collection and storage of

domestic hot water. The cold water supply is pressure fed to the bottom of a storage tank

located above a solar collector. Exposure of

the collector to solar radiation allows the cold

water to circulate by convection — through the

collector -- from bottom to top — and, once

heated back into storage. The heated water is stored in the tank until a demand is initiated; then water is drawn off the top and fed directly

to the dwelling or to a conventional water

heater.

C-19
Solar Heating and Hot Water Systems:

Component Description

A solar heating and domestic hot water system is composed of numerous individual parts and pieces

including: collectors; storage; a distribution network with ducts and/or pipes, pumps and/or blowers,

valves and/or dampers; fixed or movable insulation; a system of manual or automatic controls; and

possibly heat exchangers, expansion tanks and filters. These parts are assembled in a variety of

combinations depending on function, component compatibility, climatic conditions, required

performance, site characteristics and architectural requirements, to form a solar heating and/or

domestic hot water system. Some components that are unique to the collector system or that are used in an unconventional manner are briefly illustrated and discussed in the next few pages. A. Flat- Plate Collectors: An Exploded View

The flat-plate collector is a common solar

collection device used for space heating and

domestic water heating. The collector may be

designed to use either gas (generally air) or

liquid (usually treated water) as the heat transfer medium. Regardless of the medium used,

most flat-plate collectors consist of the same

general components, as illustrated below.

1. BATTEN Battens serve to hold down the cover plate(s) and provide a weather tight seal between

the enclosure and the cover. ? COVER PLATE The cover plate usually consists of one or more layers of glass or plastic film or combinations thereof. The cover plate is separated from the absorber plate to reduce reradiation

and to create an air space, which traps heat by reducing convective losses. This space between the cover and absorber can be evacuated to further reduce convective losses. 3. HEAT TRANSFER FLUID PASSAGE Tubes or fins are attached above, below or integral with an

absorber plate for the purpose of transferring thermal energy from the absorber plate to a heat

transfer medium. The largest variation in flat-plate collector design occurs with this component and

its combination with the absorber plate. Tube on plate, integral tube and sheet, open channel flow,

corrugated sheets, deformed sheets, extruded sheets and finned tubes are some of the techniques

used for liquid collectors. Air collectors employ such configurations as gauze or screens, overlapping plates, corrugated sheets, and finned plates and tubes. 4. ABSORBER PLATE Since the absorber plate must have a good thermal bond with the fluid passages, an absorber plate integral with the heat transfer media passages is common. The absorber

plate is usually metallic, and normally treated with a surface coating which improves absorptivity.

Black or dark paints or selective coatings are used for this purpose. The design of this passage and

plate combination is of significance in a solar system's effectiveness.

5. INSULATION Insulation is employed to reduce heat loss through the back of the collector. The

insulation must be suitable for the high temperature that may occur under no-flow or dry-plate

conditions, or even normal collection operation. Thermal decomposition and outgassing of the

insulation must be considered

6. ENCLOSU RE The enclosure is a container for all the above components. The assembly is usually

weatherproof. Preventing dust, wind and water, from coming in contact with the cover plate and

insulation, is essential to maintaining collector performance.

C-20
B. Flat- Plate Collectors

A flat-plate collector generally consists of an absorbing plate, often metallic; which may be flat, corrugated or grooved; coated black to increase absorption of solar radiation; insulated on its backside to minimize heat loss from the plate; and covered with a transparent cover plate to trap

heat within the collector and reduce cooling of the absorber plate. The captured solar heat is then

removed from the absorber by means of a working fluid, generally air or treated water, which is heated as it passes through or over the absorbing plate. Although there are innumerable variants,

three types of flat-plate collectors will be discussed here as an introductory classification.

1, FLUID TUBE AND PLATE COLLECTOR Most

flat-plate collectors in use today employ water,

oil or an antifreeze solution as the heat transfer

medium. The liquid is pumped through fluid passage ways attached to or integral with the

absorber plate. There it is solar heated before

being circulated through storage in either a closed or open circuit. Freeze protection and

prevention of corrosion and leaks require special consideration.

2. TRICKLING WATER COLLECTOR This type

of collector uses corrugated metal panels for the exposed circulation of the heat transfer

medium. The transfer medium "trickles" down

the channels from a manifold or spray distribution at the top to a trough to the bottom of the

collector. The heated water then flows by

gravity to the storage tank. Because of the

heat transfer fluid's exposure to the atmosphere

in this collector, it is always used with the open

circuit collector-storage system. Therefore,

when collection is not occurring, the transfer

medium drains back into storage. Efficient

operation of this collector is limited to low

temperatures because of evaporation effects.

3

.

FLAT-PLATE AIR COLLECTOR Air collectors circulate air or other gases through or over

the absorber plate, returning heated air through

the ducts to storage or the living space. Compared with liquid collectors, leakage, maintenance, and freeze protection problems are minimal. However, air collectors do require relatively large ducts for their heat transfer medium and often require more mechanical transfer

energy per unit of solar energy delivered.

C-21
C.High Temperature Collectors

For heating and cooling systems requiring higher operating temperatures, evacuated tube or concentrating collectors are available. Depending upon the optical and thermal insulation design,

the performance of these systems is influenced by the ratio of the diffuse to total available solar radiation.

EVACUATED TUBE COLLECTOR These col- lectors employ a vacuum tube to contain the

absorber. The vacuum serves to reduce convective heat losses allowing higher working temperatures and efficiencies. The absorber consists of metal or glass tubes or fins which

transfers captured thermal energy to the heat

transfer medium (which may be a liquid or

gas). The basic modes of heat transfer within

the collector are analogous to those illustrated for flat-plate collection. No insulation is required for the tubular collector itself; however, the manifold and connecting piping re- quire insulation similar to flat-plate units. Both

direct and diffuse radiation can be collected.

CONCENTRATING COLLECTORS Concentrating collectors (also known as foeuss ing

collectors) employ curved and multiple point

target reflectors to focus radiation on a small area The area where solar radiation is absorbed can be a point -- the focal point — or a line -

- the focal axis. A concentrating collector consists of three

basic components: the reflector and/or lens,

the absorber, and the housing which maintains

alignment and contains insulation for the absorber and connecting piping. Often a mechanism is required to allow the collector/reflector

or the absorber to follow or track the sun's movement across the sky. Maintenance of the

reflective surface, particularly in dusty or air polluted areas, and of the tracking mechanism

are important considerations for collector performance.

Concentrating collectors are usually best

suited for areas with clear skies where most

solar radiation is direct. The high temperatures

generated may make concentrating collectors

particularly viable with solar cooling systems.

As with flat-plate collectors, numerous variations of concentrating collectors have been

developed including linear and circular concentrators, lens focussing collectors, collectors

with directional and non-directional focussing

and tube concentrators. A number of concentrating configurations are shown to the left.

C-22
D.Collector Mounting

Flat-plate collectors are generally mounted on the ground or on a building in a fixed position at prescribed angles of solar exposure— angles which vary according to the geographic location,

collector type, and the use of the absorbed heat. Flat-plate collectors may be mounted in four

general ways as illustrated below.

1. RACK MOUNTING Collectors can be mounted at the prescribed angle on a structural frame

located on the ground or attached to the

building. The structural connection between

the collector and the frame and the frame and

the building or site must be adequate to resist any impact loads such as wind.

2.STAND-OFF MOUNTING Elements that separate the collector from the finished roof

surface are known as stand-offs. They allow air and rain water to pass under the collector

thus minimizing problems of mildew and leakage. The stand-offs must also have adequate

structural properties. Stand-offs are often used

to support collectors at an angle other than that

of the roof to optimize collector tilt.

3JIRECT MOUNTING Collectors can be

mounted directly on the roof surface. Generally, the collectors are placed on a water-proof

membrane on top of the roof sheathing. The

finished roof surface, together with the necessary collector structural attachments and

flashing, are then built up around the collector. A weatherproof seal between the collector and

the roof must be maintained, or leakage, mildew, and rotting may occur.

COLLECTORS

STRUCTURAL

MEMBER

4. INTEGRAL MOUNTING Unlike the previous

three component collectors which can be applied or mounted separately, integral mounting

places the collector within the roof construction itself. Thus, the collector is attached to and supported by the structural framing members. In addition, the top of the collector serves as the finished roof surface. Weather

tightness is again crucial to avoid problems of

water damage and mildew. This method of

mounting is frequently used for site built collectors.

C-23
E. Multiple Collectors

In active systems, a building's solar collector area is generally composed of individual collector

units or panels arranged to operate as a single system. The arrangement and relationship of one

collector unit to another, sometimes known as collector ganging, is extremely important for effective solar collection and efficient system operation. Three basic multiple collector arrays are shown below.

BALANCE VALVE HEALER

OR DAMPER OR MANIFOLD

1. PARALLEL FLOW - DIRECT RETURN A

direct return distribution circuit circulates the

transfer medium from the bottom of the col- lector to a return header or manifold at the top.

This arrangement may cause severe operating

problems by allowing wide temperature variations from collector to collector due to flow

imbalance. Although the pressure drops across each collector are essentially the same and at the same flow rate, high pressure drops occurring along the supply/return header or manifold

will cause flow imbalance. This problem can be

reduced by sizing each header for minimum

pressure drop, although this may be prohibitive

because of economic and space limitations.

Even manual balancing valves may be difficult to adjust, so automatic devices or orifices

might be required for efficient system per- formance. Provisions must also be made to measure the pressure drop in order to adjust the

flow rate to prevent collectors closer to the

circulating pump from exceeding design flow

rates and those farther away from receiving

less.

2. PARALLEL FLOW - REVERSE RETURN Reverse return piping systems are considered

preferable to direct return for their ease of

balancing. Because the total length of supply

piping and return piping serving each collector

is the same and the pressure drop across each

collector is equal, the pressure drop across each

manifold are also theoretically equal. The major advantage of reverse return piping is that

balancing is seldom required since flow through

each collector is the same. Provisions for flow

balancing may still be required in some reverse

return piping systems depending on overall size

of the collector array and type of collector. 3.SERIES FLOW Series flow is often used in large planar arrays, to reduce the amount of

piping required, by allowing several collector

assemblies to be served by the same supply

return headers or manifolds. Series flow can

also be employed to increase the output temperature of the collector system or to allow the

placement of collectors on non-recta ngular

surfaces. Either direct or reverse return

distribution circuits can be employed, but unless

each collector branch has the same number of

collectors, the reverse return system has no advantage over direct return — each would re- quire flow balancing.
F.Heat Exchangers

A heat exchanger is a device for transferring thermal energy from one fluid to another. In some

solar systems, a heat exchanger may be required between the transfer medium circulated through

the collector and the storage medium or between the storage and the distribution medium. Three

types of heat exchangers that are most commonly used for these purposes are illustrated below.

1. SHELL AND TUBE This type of heat exchanger is used to transfer heat from a circulating

transfer medium to another medium used in storage or in distribution. Shell and tube heat

exchangers consist of an outer casing or shell surrounding a bundle of tubes. The water to be

heated is normally circulated in the tubes and

the hot liquid is circulated in the shell. Tubes

are usually metal such as steel, copper or

stainless steel. A single shell and tube heat

exchanger cannot be used for heat transfer

from a toxic liquid to potable water because

double separation is not provided and the toxic

liquid may enter the potable water supply, in the case of tube failure.

2. SHELL AND DOUBLE TUBE This type of heat

exchanger is similar to the previous one except

that a secondary chamber is located within the

shell to surround the potable water tube. The

heated toxic liquid then circulates inside the

shell but around this second tube. An intermediary non-toxic heat transfer liquid is then

located between the two tube circuits. As the

toxic heat transfer medium circulates through

(I the shell, the intermediary liquid is heated,

which in turn heats the potable water supply

circulating through the innermost tube. This

heat exchanger can be equipped with a sight

glass to detect leaks by a change in color - toxic liquid often contains a dye - or by a change in the liquid level in the intermediary

chamber, which would indicate a failure in either the outer shell or intermediary tube

lining.

TRANSFER FLUID

VISUAL

INDICATOR TOXIC

HEAT TRANSFER

MEDIUM

INNERMOST

POTABLE WATER

TUBE

i

j 3. DOUBLE WALL Another method of providing

a double separation between the transfer medium and the potable water supply consists of tubing or a plate coil wrapped around and

bonded to a tank. The potable water is heated

as it circulates through the coil or through the

tank. When this method is used, the tubing coil must be adequately insulated to reduce heat

losses.

C-25
-

.
APPENDIX D

DEFINITIONS

General: Abbreviations, terms, phrases, and words and their derivatives used in these

Intermediate Standards for solar application shall have the meanings given in this

Appendix. The terms defined herein apply only for The Department of Housing and Urban

Development (HUD) purposes and may differ in some respects from definitions prepared for

building codes or other purposes. Wherever possible, the meaning in common use in the

residential construction field is used.

Active Solar System : An assembly of collectors, thermal storage device (s), and transfer

liquid which converts solar energy into thermal energy, and in which energy in addition

to solar is used to accomplish the transfer of thermal energy.

Air Gap : An air gap in a potable water distribution system is the unobstructed vertical

distance through the free atmosphere between the lowest opening from any pipe or faucet

supplying water to a tank, plumbing fixture, or other device and the flood level rim of

the receptacle. (NSPC)*

Auxiliary Energy Subsystem : Equipment utilizing energy other than solar both to supplement

the output provided by the solar energy system as required by the design conditions, and

to provide full energy backup requirements during periods when the solar H, or DHW systems

are inoperable.

Backflow : The unintentional reversal of flow in a potable water distribution system

which may result in the transport of foreign materials or substances into the other

branches of the distribution system. (NBS)

Backflow Preventer : A device or means to prevent backflow.

Back Pressure : Pressure created by any means in the water distribution system on the

premises, which by being in excess of the pressure in the water supply main could cause backflow. (NBS)

Back Slphonage : The backflow of possibly contaminated water into the potable water

supply system as a result of the pressure in the potable water system becoming unintentionally less than the atmospheric pressure in the plumbing fixtures, pools, tanks, or vats

that may be connected to the potable water distribution piping. (NBS)

Chemical Compatibility : The ability of materials and components in contact with each other

to resist mutual chemical degradation, such as that caused by electrolytic action or plasticizer migration.

Collector, Combined : The collector and storage are constructed and operated such that

they functionally perform as one unit and the thermal performance of the individual

components cannot be meaningfully measured.

Collector, Component : Collector that is not structurally integrated with the storage

or building. The collector performance can be thermally characterized as an individual

component with a moving heat transfer fluid.

Collector Efficiency (instantaneous) : The ratio of the amount of energy removed by the

heat transfer fluid per unit of aperture over a time period of 5 minutes or less to the

total incident solar radiation on the collector for the same time period under steady

state conditions (test method details described in ASHRAE 93)

.

Collector, Integral (Passive) : The collector is constructed and operated as part of the

building structure and heating system. The thermal performance is considered a part

of the building heating load and solar energy provides a significant fraction of the

building heat requirements.

* Abbreviations in parentheses indicate the sources of the definitions used here.

(See Appendices E and F)

D-l
Collector Subsystem : The assembly used for absorbing solar radiation, converting it into

useful thermal energy, and transferring the thermal energy to a heat transfer fluid.

Components : An individually distinguishable product that forms part of a more complex

product (i.e., subsystem or system).

Contaminants (hazardous) : Materials (solids or liquids or gasses) which when added

unintentionally (or intentionally) to the potable water supply cause it to be unfit for

human or animal consumption. (ASSE 1013)

Control Subsystem : The assembly of devices and their electrical, pneumatic or hydraulic

auxiliaries used to regulate the processes of collecting, transporting, storing, and

utilizing energy in response to the thermal, safety, and health requirements of the building occupants.

Creep : A time-dependent deformation resulting from sustained loads which can be influenced

by local environmental factors such as, thermal atmosphere and/or cycling, and solar

radiation.

Cross Connection : Any physical connection or arrangement between two otherwise separate

piping systems, one of which contains potable water and the other either water of unknown

or questionable safety or steam, gas, chemicals, or other substances whereby there may be

a flow from one system to the other, the direction of flow depending on the pressure

differential between the two systems.

Design Life : The period of time during which an H, and DHW system is expected to perform

its intended function without requiring major maintenance or replacement.

DHW : Domestic hot water system.

DWV : Drain, Waste, Vent.

Emittance : The ratio of the radiant energy emitted by a body to the energy emitted

by a black body at the same temperature.

Energy Transport Subsystem : That portion of the H, and DHW systems which contains heat

transfer fluids and transports energy throughout the system.

Failure (structural) : Failure of a structure or any structural element is defined as one

of the following:

(a) Sudden, locally-increased curvature, major spalling, or structural collapse.

(b) The inability of the structure to resist a further increase in load.

(c) Structural deflections under design loads that cause significant performance degradation of the component or subsystem.

Flow Condition : The condition obtained when the heat transfer fluid is flowing through

the collector array under normal operating conditions.

H; Heating system.

Heat Capacity : The amount of heat necessary to raise the temperature of a given mass

one degree.

Heat Transfer Medium : A medium, liquid, or air or solid, which is used to transport thermal

energy

.

Laminated Glass : Consists of two or more sheets of glass held together by an intervening

layer or layers of plastic material.

D-2
MAP: Manual of acceptable Practices. A HUD Document providing information and guidance

to assist in the use of the MPS

.

Maximum "Flow" Temperature : The maximum temperature that will be obtained in a component

when the heat transfer fluid is not flowing through the system.

Maximum Service Temperature : The maximum temperature to which a component will be exposed

in actual service, either with or without the flow of heat transfer fluid.

Minimum Service Temperature : The minimum temperature to which a component will be exposed

in actual service, either with or without the flow of heat transfer fluid.

MPS 4900.1 : FHA "Minimum Property Standards For One and Two Family Dwellings."

MPS 4910.1 : FHA "Minimum Property Standards For Multifamily Housing."

"No-Flow" Condition : That condition obtained when the heat transfer fluid is not flowing

through the collector array due to shut-down or malfunction and the collector is exposed

to the amount of solar radiation that it would receive under normal operating conditions.

Non-Potable Water : Water containing impurities in amounts sufficient to cause disease or harmful physiological effects and not conforming in its bacteriological and chemical quality

to the requirements of the Public Health Service Drinking Water Standards or the regulations

of the public health authority having jurisdiction.

Outgassing : The emission of gases by materials and components usually during exposure to elevated temperature or reduced pressure.

Passive Solar System : An assembly of natural and architectural components including collectors, thermal storage device (s) and tranfer fluid which converts solar energy into

thermal energy in a controlled manner and in which no fans or pumps are used to accomplish

the transfer of thermal energy. The prime elements in a passive solar system are usually

some form of thermal capacitance and solar energy control.

Pitting : The process by which localized material loss is caused in materials or components

by erosion or chemical decomposition.

Physical Compatibility : The ability of materials and components in contact with each other

to resist degradation by physical actions such as differential thermal expansion.

Plasticizer migration : The process by which plasticizers used in plastics migrate within

the specimen and either concentrate in a narrow boundary area or migrate to another material

in connection with the specimen.

Potable Water : Water free from impurities present in amounts sufficient to cause disease

or harmful physiological effects and conforming in its bacteriological and chemical quality

to the requirements of the Public Health Service Drinking Water Standards or the regulations

of the public health authority having jurisdiction.

Pphm : Parts per hundred million.

Premature Failure : Failure that occurs before the design lifetime.

Safety Glass : Glazing materials predominately inorganic in character which meet the appropriate requirements of the ANSI Standard and includes laminated glass, tempered glass and

wired glass.

Safety Glazing Materials : Glazing materials so constructed, treated or combined with other

materials as to minimize the likelihood of cutting and piercing injuries resulting from

human contact with these glazing materials.

Significant (Deterioration Loss, etc.): Deterioration that either results in a decrease

in performance greater than that allowed for in the design or in the creation of a hazard.

Solar Absorptance : The ratio of the amount of solar radiation absorbed by a surface to the

amount of radiation incident on it (for terrestrial applications usually calculated for

Air Mass 2 characteristics)

.

D-3
Solar Building : A building which utilizes solar energy by means of an active or passive

solar system.

Solar Degradation : The process by which exposure to sunlight deteriorates the properties

of materials and components.

Solar Energy ; The photon energy originating from the sun's radiation in the wavelength

region from 0.3 to 2.7 micrometers.

Solar Heating System : The complete assembly of subsystems and components necessary to convert solar energy into thermal energy for heating purposes in combination with aux- iliary energy when required.

Solar Time : The hours of the day as reckoned by the apparent position of the sun. Solar noon is that instant on any day at which time the sun reaches its maximum altitude for

that day. Solar time is very rarely the same as local standard time in any locality.

Storage Subsystem : The assembly used for storing thermal energy so that it can be used

when required.

Subsystem : A major, separable, functional assembly of a system such as complete collector,

or storage, assembly, etc.

System : The complete assembly necessary to supply heat and/or domestic hot water to the

dwelling.

Thermal Energy : Heat possessed by a material resulting from the motion of molecules

which can do work.

TLV, Threshold Limit Values : Threshold limit values refer to airborne concentrations of

substances ’ and represent conditions under which it is believed that nearly all workers

may be repeatedly exposed day after day without adverse effect. Threshold limit values

refer to time-weighted concentrations for a 7 or 8-hour workday and 40-hour workweek.

Toxic Fluids : Gases or liquids which are poisonous, irritating and/or suffocating, as classified in the Hazardous Substances Act, Code of Federal Regulations, Title 16,

Part 1500.

Transmittance : The ratio of the radiant flux transmitted through and emerging from a body to the total flux incident on it.

UV : Ultra-violet radiation, that part of the terrestrial solar spectrum between 0.3 and

0.4 micrometers.

Water Hammer : The term used to identify the hammering noises and severe shocks that may

occur in pressurized water supply systems when flow is halted abruptly by the rapid

closure of a valve or faucet (NBS)

.

Water Hammer Arrester : A manufactured device, other than an air chamber, containing a permanently sealed cushion of gas or air designed to provide protection against excessive

shock pressure without maintenance.

97 1/2% Winter Design Temperature : The outdoor air temperature will be lower than the

stated values for not more than 65 hours per year (2 1/2% of the 2,160 hours in December,

January and February)

.

D-4
APPENDIX E

REFERENCED STANDARDS

AASHTO H20-44 Standard Specification for Highway Bridges

ANSI A13.1 (1956) Scheme for the Identification of Piping Systems

ANSI A58.1 (1972) Building Code Requirements for Minimum Design Loads

in Buildings and Other Structures

ANSI A112.1.1 (1971) Performance Requirements, Methods of Test for

(ASSE 1001-1970) Pipe-Applied Atmospheric-Type Anti-Siphon Vacuum Breakers

ANSI A112.1.2 Air Gaps in Plumbing Systems (Reaffirmation and redesignation of

A40. 4-1942)

ANSI B9.1 (1971) Safety Code for Mechanical Refrigeration

ANSI B15.1 (1972) Safety Standard for Mechanical Power Transmission Apparatus

ANSI B16.18 (1972) Cast Bronze Solder Joint Pressure Fittings

ANSI B31.1, Section I (1973) Power Piping

ANSI B96.1 (1973) Specification for Welded Aluminum-Alloy Field-Erected

Storage Tanks

ANSI B124.1 (1971) Safety Standard for Air Filter Units (UL 900-April 1971)

ANSI B137.1 (1971) Steel Underground Tanks for Flammable and Combustible

Liquids (UL 58-July 1971)

ANSI B191.1 (1976) Standard for Heat Pumps (UL 559)

ANSI S2.8 (1972) Guide for Describing the Characteristics of Resilient Mountings

ANSI Z95.1 (1974) Oil Burning Equipment (NFPA 31-1972)

ANSI Z97.1 (1975) Performance Specifications and Methods of Test for

Safety Glazing Material Used in Buildings

ARI Standard 240 (1975) Standard for Unitary Heat Pump Equipment

ARI Standard 260 (1967) Standard for Application, Installation, and

Servicing of Unitary Systems

ARI Standard 410 Forced Circulation Air-Cooling and Air-Heating Coils

ARI Standard 760 (1975) Standard for Solenoid Valves for Use with

Volatile Refrigerants and Water

ASHRAE 37-69 Method of Testing for Unitary Air Conditioning and Heat

Pump Equipment

ASHRAE 55-74 (1974) Thermal Environmental Conditions for Human Occupancy

ASHRAE 90-75 (1975) Energy Conservation in New Building Design

ASHRAE 93-77 (1977) Methods of Testing Solar Collectors Based on Thermal Performance

ASHRAE 94-77 (1977) Method of Testing Thermal Storage Devices Based on Thermal

Performance

E-l
ASHRAE Handbook of Fundamentals

ASME SA-53, Section VIII Boiler and Pressure Vessel Code

ASSE 1011 Performance Requirements for Hose Connection Vacuum Breakers

ASSE 1012 Performance Requirements for Backflow Preventers with Intermediate

Atomospheric Vent

ASSE 1013 Performance Requirements for Reduced Pressure Principle Back

Pressure Backflow Preventers

ASSE 1015 Performance Requirements for Double Check Valve Type Back Pressure

Backflow Preventers

ASSE 1020 Performance Requirements for Vacuum Breakers, Anti-Siphon, Pressure

Type

ASTM A53-75 Specification for Welded and Seamless Steel Pipe

ASTM C739-73, Section 10.4 (1973) Flame Resistance Permanency

ASTM D471-75 Test for Rubber Property - Effect of Liquids

ASTM D660-44 (1970) Evaluating Degree of Resistance to Checking of

Exterior Paints

ASTM D661-44 (1975) Evaluating Degree of Resistance to Cracking of Exterior

Paints

ASTM D714-56 (1974) Evaluating Degree of Blistering of Paints

ASTM D750-68 (1974) Recommended Practice for Operating Light-and-Weather

Exposure Apparatus (Carbon-Arc Type) for Artificial Weather Testing of

Rubber Compounds

ASTM D772-47 (1975) Evaluating Degree of Flaking (Scaling) of Exterior Paint

ASTM D822-60 (1973) Recommended Practice for Operating Light-and-Water-Exposure

Apparatus (Carbon-Arc Type) for Testing Paint, Varnish, Lacquer, and

Related Products

ASTM D1081-60 (1974) Test for Evaluating Pressure Sealing Properties of

Rubber and Rubber-Like Materials

ASTM D1149-64 (1970) Test for Accelerated Ozone Cracking of Vulcanized Rubber

ASTM D1308-57 (1973) Test for Effect of Household Chemical on Clear and

Pigmented Organic Finishes

ASTM D1384-70 Corrosion Test for Engine Antifreeze in Glassware

ASTM D2247-68 (1973) Testing Coated Metal Specimens at 100 Percent Relative

Humidity

ASTM D2570-73 Simulated Service Corrosion Testing of Engine Antifreeze

ASTM D2776-72 Tests for Corrosivity of Water in the Absence of Heat Transfer

(Electrical Methods)

ASTM E72-74a Conducting Strength Tests of Panels for Building Construction

ASTM E84-70 (1970) Surface Burning Characteristics of Building Materials

E-2
ASTM E108-75 (1975) Methods of Fire Tests of Roof Coverings (NFPA 256-1970)

ASTM E154-68 Testing Materials for Use as Vapor Barriers Under Concrete

Slabs and as Ground Cover in Crawl Spaces

ASTM E424-71 Test for Solar Energy Transmittance and Reflectance (Terrestrial)

of Sheet Materials

ASTM F146-72 Test for Fluid Resistance of Gasket Materials

ASTM Gl-72 Recommended Practice for Preparing, Cleaning, and Evaluating

Corrosion Test Specimens

ASTM G16-71 Recommended Practice for Applying Statistics to Analysis of

Corrosion Data

ASTM G46-76 Recommended Practice for Examination and Evaluation of

Pitting Corrosion

AWWA C203-73 Standard for Coal-Tar Protective Coatings and Linings for

Steel Water Pipelines

AWWA C506-69 Backflow Prevention Devices-Reduced Pressure Principle and

Double Check Valve Types

AWWA D100 (1967) Steel Tanks - Standpipes, Reservoirs and Elevated Tanks

for Water Storage

AWWA D102 Painting and Repainting Steel Tanks, Standpipes, Reservoirs, and

Elevated Tanks for Water Storage

BMC, Section M302 (1975) Specific Requirements for the Materials, Design,

and Fabrication of Ductwork

CPSC 16 CFR, Part 1201 (1976) Architectural Glazing (Code of Federal

Regulation)

Federal Hazardous Substances Act, Code of Federal Regulations, Title 16, Part 1500

FCCCHR, Chapter 10 Manual of Cross-Connection Control (Foundation for Cross

Connection Control Research)

FS-DD-G-451C (1972) Glass, Plate, Sheet, Figured (Float, Flat, for Glazing,

Corrugated, Mirrors and Other Uses)

FS-TT-C-00598C(1) Caulking Compound, Oil and Resin Base Type (For Building

Construction) (18 March 1971)

FS-TT-S-001543A Sealing Compound: Silicone Rubber Base (For Caulking,

Sealing, and Glazing in Buildings and Other Structures) (9 June 1971)

FS-TT-S-001657 Sealing Compound: Single Component, Butyl Rubber Based,

Solvent Release Type (for Buildings and Other Types of Construction)

(8 October 1970)

FS-TT-S-00227E(3) Sealing Compound Elastomeric Type, Multi-compound (For

Caulking, Sealing and Glazing in Buildings and Other Structures)

(9 October 1970)

FS-TT-S-00230C(2) Sealing Compound: Elastomeric Type, Single Component

(For Caulking, Sealing and Glazing in Buildings and Other Structures)

(9 October 1970)

E-3
FS-TT-P-95A(3) Paint, Rubber: For Swimming Pools and Other Concrete and

Masonry Surfaces, 27 May 1966

FS-WW-U-516B Unions, Brass or Bronze, Threaded Pipe Connections and SolderJoint Tube Connections

FS-WW-U-531D Unions, Pipe, Steel or Malleable Iron; Threaded Connection,

150 lbs. and 250 lbs.

FS-WW-V-35B (1973) Valve, Ball

IAPMO PS 31-74 Specification for Backflow Prevention Devices

IAPMO PSI Prefabricated Concrete Septic Tanks (1966)

NACE TM-01-69 (1972) Laboratory Corrosion Testing of Metals for the Process

Industries

NACE TM-02-70 Method of Conducting Controlled Velocity Laboratory Corrosion

Tests

NACE TM-01-71 Autoclave Corrosion Testing of Metals in High Temperature Water

NACE TM-02-74 Dynamic Corrosion Testing of Metals in High Temperature

National Primary Drinking Water Regulation - Federal Register, 24 December 1975

NFPA 26 (1958) Supervision of Valves

NFPA 30 (1973) Flammable and Combustible Liquids Code

NFPA 31 (1974) Standard for the Installation of Oil Burning Equipment

NFPA 54 (1974) National Fuel Gas Code

NFPA 70 (1976) Section 240.24, National Electrical Code

NFPA 72A (1974) Local Protective Signaling Systems

NFPA 89M (1971) Clearances for Heat Producing Appliances

NFPA 90B (1973) Standard for the Installation of Warm Air Heating and Air

Conditioning Systems

NFPA 211 (1972) Standard for Chimneys, Fireplaces, and Vents

NFPA 321 (1973) Basic Classification of Flammable and Combustible Liquids

NFO 8 National Forest Products Association, The Wood Tank

NRCA - A Manual of Roofing Practice 1970 (71)

NSPC, Section 2.13 Ratproofing

MIL-T-52777 21 February 1974 Military Specifications for Tanks:

Storage, Underground, Glass Fiber Reinforced Plastic

MSS SP-73 Silver Brazing Joints for Cast and Wrought Solder Joint Fittings

SAE J447e(1964) Prevention of Corrosion of Metals

E-4
SAE J20e(1974) Coolant System Hoses

Threshold Limit Values for Chemical Substances and Physical Agents in the Workroom Environment with Intended Changes, 1975 - American Conference of Governmental Industrial Hygienists

UL 58 (1973) Standard for Steel Underground Tanks for Flammable and Combustible

Liquids (ANSI B137. 1-1971)

UL 174 (1972) Standard for Household Electric Storage-Tank Water Heaters (ANSI

C33. 87-1972)

UL 181-74, Section 10 Factory-Made Air Duct Materials and Air Duct Connectors

UL 296 (1974) Standard for Oil Burners

UL 573 (1972) Standard for Electric Space-Heating Equipment (ANSI C33. 12-1972)

UL 726 (1973) Standard for Oil-Fired Boiler Assemblies

UL 727 (1973) Standard for Oil-Fired Central Furnaces (ANSI Z96. 1-1973)

UL 730 (1974) Standard for Oil-Fired Wall Furnaces

UL 732 (1974) Standard for Oil-Fired Water Heaters

UL 900 (1971) Safety Standard for Air Filter Units (ANSI B124. 1-1971)

UL 1042 (1973) Standard for Electric Baseboard Heating Equipment (ANSI C33.95-

1973)

Water Quality Criteria 1972, National Academy of Science and National Academy

of Engineering

E-5

APPENDIX F

ABBREVIATIONS

(Code Groups, Associations, and Gov't Agencies)

AASHO

AGA

AMCA

ANSI

ARI ASHRAE

ASME

ASSE

ASTM

AWWA

BMC

BOCA

CISPI

CPSC

CSFCCCHR

FSHUD

HVI

IAPMO

IBR

ICBO

IEC

ISO

MCA

MSS

NACE

NAS/NRC

NBS

NEMA

NESCA

NFO

NFPA

NRCA

NSF

NSPC

PL

SAE

SBI

SMACNA

SPMA

TEMA

UBC

UPC

UMC

UL

American Association of State Highway and Transportation Officials

American Gas Association

Air Moving and Conditioning Association, Inc. American National Standards Institute

Air-Conditioning and Refrigeration Institute

American Society of Heating, Refrigerating, and Air Conditioning

Engineers

American Society of Mechanical Engineers

American Society of Sanitary Engineering

American Society for Testing and Materials

American Water Works Association, Inc. Basic Mechanical Code (Division of BOCA)

Building Officials and Code Administrators International, .Inc. Cast Iron Soil Pipe Institute

Consumer Product Safety Commission

Commercial Standard

Foundation for Cross-Connection Control and Hydraulic Research

Federal Specifications

Department of Housing and Urban Development

Home Ventilating Institute

International Association of Plumbing and Mechanical Officials

Institute of Boiler' and Radiator Manufacturers (Now Hydronic Inst.)

International Conference of Building Officials

International Electrotechnical Commission

International Standards Organization

Mechanical Contractor's Association

Manufacturer's Standardization Society of the Valve and

Fitting Industry

National Association of Corrosion Engineers

National Academy of Science/National Research Council

National Bureau of Standards

National Electrical Manufacturer's Association

National Environmental Systems Contractors Association

National Forest Products Association

National Fire Protection Association

National Roofing Contractor's Association

National Sanitation Foundation Testing Laboratory, Inc. National Standard Plumbing Code

Public Law

Society for Automotive Engineers

Steel Boiler Institute (Now Hydronic Institute)

Sheet Metal and Air Conditioning Contractors National

Association, Inc. Sump Pump Manufacturer's Association

Tubular Exchanger Manufacturer's Association, Inc. Uniform Building Code

Uniform Plumbing Code

Unfiorm Mechanical Code

Underwriter's Laboratories, Inc.

4 BS - 1 14A (REV. 7-73)

U.S. DEPT. OF COMM.

BIBLIOGRAPHIC DATA

SHEET

1. PUBLICATION OR REPORT NO.

NBSIF. 77-1226

2. Gov’t Accession

No.

3. Recipient’s Accession No.

4. TITLE AND SUBTITLE

Intermediate Minimum Property Standards for Solar

Heating and Domestic Hot Water Systems

5. Publication Date March 1977

6. Performing Organization Code

465.00

7. AUTHOR(S)

Solar Energy Program Team, Center for Building Technology

8 . Performing Organ. Report No.

9. PERFORMING ORGANIZATION NAME AND ADDRESS

NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE

WASHINGTON, D.C. 20234

10. Project/Task/Work Unit No. 4656500

11. Contract/Grant No. IAA-H-3S-76

12. Sponsoring Organization Name and Complete Address (Street, City, State, ZIP)

Division of Energy, Building Technology & Standards

Office of Policy Development and Research

Department of Housing and Urban Development

Washington, D.C. 20410

13. Type of Report & Period Covered

Final

14. Sponsoring Agency Code

15. SUPPLEMENTARY NOTES

This publication NBSIR 77-1226 superseeds NBSIR 76-1059 published in April 1976

16. ABSTRACT (A 200-word or less factual summary of most significant information. If document includes a significant

bibliography or literature survey, mention it here.)

This report presents standards for the use of solar heating and domestic hot

water systems in residential applications. The standards have been developed

for application in numerous housing programs of the Department of Housing and

Urban Development and are a companion document to be used in conjunction with

the HUD "Minimum Property Standards for One and Two Family Dwellings," 4900,

and "Minimum Property Standards for Multifamily Housing," 4910. To the greatest

extent possible, these standards are based on current state-of-the-art practice

and on nationally recognized standards including the MPS and the HUD "Interim

Performance Criteria for Solar Heating and Combined Heating/Cooling Systems and

Dwellings .

17. KEY WORDS (six to twelve entries; alphabetical order, capitalize only the first letter of the first key word unless a proper name; separated by semicolons)

Solar buildings; solar collectors; solar domestic hot water systems; solar —

heating; standards; thermal storage.

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