NBSIR 76-1059

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, lAT

National Bureau of Standards

Washington. D. C. 20234

April 1976

Interim 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 76-1059

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, lAT

National Bureau of Standards

Washington, D. C. 20234

April 1976

Interim 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

U.S. DEPARTMENT OF COMMERCE, Elliot L. Richard«on. S^cMtary

James A. Baker. III. Under Seentary t^u^i^

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

NATIONAL BUREAU OF STANDARDS, Emest Ambtor. Acting Director

ACKNOWLEDGEMENTS

The preparation of this interim 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

Dave Waksman

John Holton

Kenneth DeCorte

Thermal Engineering Section

Elmer Streed

James Hill

John Jenkins

Dennis Jones

Materials and Composite Section

Larry Masters

Leopold Skoda

Elizabeth Clark

Paul Brown

Building Services Section

Robert Beausoliel

Grover Sherlin

Structures Section

William Greene

Architectural Research Section

Richard Crenshaw

Building Safety Section

Theresa Raper

Office of Building Standards and Codes Services

Robert Eisenhard

Bertram Vogel

Program for Fire Control - Construction (Center for Fire Research)

Edward Budnick

Typing, Editing and Preparation by

Mary Lou Miller

Linda Sacchet

Linda Armitage

Vicki Reider

Linda Covel].
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

Mervln Dlzenfeld

Consultant Review Panel

William Beckman

John Bowen

John Duffle

Mel Green

Michael Holtz

Alwln Newton, P.E.

Andrew Parker

Richard Rittelmann

Daniel Talbott

Gordon Tulley

Ed Wachter

Edgar Welsman

Professor, University of Wisconsin

Chairman, Standards Committee, Solar Energy Industries

Association (AMETEK Corporation)

Professor, University of Wisconsin

International Conference of Building Officials

AIA Research Corporation

American Society of Heating, Refrigerating and

Air Conditioning Engineers

AIA Research Corporation

AIA, Burt, HJll & Associates

National Association of Home Builders

AIA Research Corporation

International Conference of Building Officials

Falcon Construction Co., Inc.

11
PREFACE

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

Property Standards for Multifaraily Housing" 4910 have been set out 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 suppl ement 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 require^^ents and standards applicable to ',oth 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 'Dne and Two Family

Dwellings" 4900.1 and the "Minimum Property Standard 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 comparision, 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 appendicies 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 existant

MPS section

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

dwellings and multifamily housing

BOLD FACF TYPF - to present standards and commentaries applicable to mult i /family

HOUSING only

Italics - to present aommentaries appliaable to one and two family dwellings and

rmlti family 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 = 0.0254 meter (exactly)

1 ft = 0.3048 meter (exactly)

A^e^

2 -4 2 1 in„ = 6.45 X 10 meter

1 ft = 0.09290 meter

Volume- _e; T 1 in = 1.639 X 10 ^ meter • 1 gal (U.S. liquid) = 3.785 x 10~ meter

Mass ' 1 ounce-mass (avoirdupois) = 2.834 x 10 kilogram

1 pound-mass (avoirdupois) = 0.4536 kilogram

Pressure or Stress (Force/Area)

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

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

Energy

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

1 Btu (International Table) = ].055 x 10 joule

Power

^ 1 watt = 1 X 10 erg/second

1 btu/hr = 0.2929 watt

Temperature

to(, = 5/9 (top, - 32)

'

Heat

1 Btu-in/h-ft^- F = 1.442 x 10"^ W/m-K (thermal conductivity)

1 Btu/lbm - °F = 4.184 X 10^ J/kg-K (heat capacity)

1 langley = 4.184 x lO'* J/m^ = 1 cal/cm^ = 3.69 Btu/ft^

iv
GENERAL TABLE OF CONTENTS

Chapter 1 General Use 1-1

Chapter 2 (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-1

Appendix B Materials Tables B-1

Appendix C Illustrated Definitions C-1

Appendix D Definitions D-1

Appendix E Referenced Standards E-1

Appendix F Abbreviations F-1

V

CHAPTER 1

General Use

S-100 APPLICATION

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 combination thereof.

Commentary : MPS 4900.1, and MPS 4910.1 are available from HUD Regional Offices.

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 whic'-. do not comply with the MPS and

this document, whose acceptance cannot be determined by other

provisions of this standard.

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.

CommentoTij

One basis for design, fabrication, aonstruation and aaaeptanoe 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", Jan. 1975, issued by HUD.

S-101 VARIATIONS TO STANDARDS

S-101-1 NEW MATERIALS AND TECHNOLOGIES

1-1

CHAPTER 3

SITE DESIGN

S-300 GENERAL

The provisions of this chapter are applicable to solar energy systems

including heating (H) , and domestic hot water (DH^O systems. This chapter is a supplement to the Minimum Property Standards (MPS) Chapter 3.

S-301 PROPOSED SITE

S-301-1 Site Surroundings

S-301-1.1 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 components may include elements which ore 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.

S-303 LAND USE

S-303-1 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 he 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-61S-2.1.2,

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 circulation systems.

Commentary : Proper location of solar equipment to circulation may reduce

tampering and vandalism.

3-1
f. Existing and proposed surrounding buildings and facilities.

Cormientary : The location and orientation of the solar collector should

consider physical and chemical air home waste from nearby faoilitieo such as incinerators and factories which might have an impact on the efficiency of

the solar collector. (See S-51S-1 .4)

S-303-2 SITE HAZARDS

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

system do not create unnecessary safety hazards to users.

Cormentary : 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.

S-304 LOTS, YARDS AND BUILDING SETBACK DISTANCE

S- 304-1 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.

S-304-2 USABLE OUTDOOR AREA

Components of the solar system shall not impinge on the requirements of

Section 304-3 of MPS.

Commentary : Reasonable outdoor open space must he maintained for liveahility,

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

property

S-304-3 SNOW AND ICE

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

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

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

Cormentary : 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 he considered.

S-309 SERVICES

S-309-1 MAINTENANCE

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

adjusting, servicing, examination, replacement or repair without tresspassing

on adjoining property.

Commentary : Components should not be located unnecessarily under buildings or roads or in other places which ore difficult to reach. Storage tanks in

particular are large and may need periodic replacement or inspection.

3-2
Solar collectors on roofs over ? stories mjst have access provided

for cleaning and maintenance.

CoriMENTARY : ThE USE OF PORTABLE LADDERS IS NOT CONSIDERED TO BE

ADEOUATE UNDER THESE C I RCUf^STANCES .

S-311 DRAINAGE

S-311-5 DRAINAGE SWALES AND GUTTERS

Gutters shall be provided on solar collectors when the soil is of such a nature that excessive erosion or expansion will occur.

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.

Commentca'ij : When downspoute are used as part of a solar system, it is acceptable for it to empty into a storage tank provided consideration has heen given

the quality of the water and its effect on the solar system. (See 515-2. S)

S-312 PLANTING DESIGN f S-312-3 NEW PLANT MATERIAL

S-312-3.9 Plant material should be selected and located to prevent the unwanted reduction

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

plants

3-3

CHAPTER 4

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 does not interfere with the intended use of these spaces.

S-401-1. 1 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° [I]

Ceiling above 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

he necessary such as shutters , draperies or louvered. screens.

S-401-1.2 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-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.

[1] Grandjean, Etienne. 1973. Ergonomics of the Home, New York: Halsted Press

[2] Flynn, John E. and Segil, Arthur W. 1970. Architectural Interior Systems . New York: Van Nostrand Reinhold Co.

4-1
S-402-10 SOLAR ENERGY EQUIPMENT

Solar energy equipment shall be accessible for maintenance without disassembling any major structural or mechanical element. There shall be

sufficient space or clearance around solar equipment based upon solar equipment sizes and potential maintenance equipment sizes to permit examination,

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

Cormcntarij : Aooessihility for repair' and maintenance should refleat the

expected life of the equipment and the frequency of routine maintenance

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

should he- 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 prevent unwanted moisture build up in the building.

S-405 FIRE PROTECTION

S-405-1 GENERAL

S-405-1.1 The incorporation of the solar subsystems shall not reduce the fire resistance

ratings required by Section 405 of >fPS,

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

THE roof construction MAY REDUCE THE FIRE RESISTANCE RATING OF THE

ROOF BELOW ACCEPTABLE LEVELS.

S-405-4 FIRE RESISTANCE REQUIRE>rENTS .

Penetrations through fire-rated assemblies shall not reduce the fire resistance

below the levels specified in Section 405 of MPS.

S-405-6 EXITS

Components of the solar subsystem shall be located in such a way that a fire in

these components cannot block the primary means of occupant egress.

. Commentary : The location of solar equipment on a roof could reduce

thf usability of that roof for access or egress.

S-405-7 FIRESTOPPING .

. .. -

Any solar collectors Installed as an integral part of the roof assembly shall

be firestopped on all sides. Firestopping material shall be wood blocking of

minimum 2 in. nominal thickness or of noncombustlble materials providing

equivalent protection.

4-2
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-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 5-20

S-515-4 Mechanical Supporting Devices 5-21

S-515-5 Valves 5-22

S-515-6 Pumps and Compressors 5-23

S-515-7 Thermal Storage Units 5-24

S-515-8 Heat Transfer Fluids 5-25

S-515-9 Heat Exchangers 5-27

S-515-10 Gaskets and Sealants 5-28

S-515-11 Insulation/Thermal and Moisture Protection 5-29

S-515-12 Catch Basins 5-30

S-515-13 Organic Coupling Hoses 5-31

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

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 or 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.

5-2
DIVISION 1

S-501 GENERAL REQUIREMENTS

S-501-1 GEIJERAL

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) acceptable durability

and economy of maintenance and market acceptance.

S-501-2 LABELING

Mandatory labeling requirements, where applicable, are contained herein for

specific materials and products. Additional labeling in accordance with the

Federal Hazardous Substances Labeling Act (1960) shall be provided.

Cormentary : The "Federal Hazardous Substance Labeling Act, " Public Law 86-613,

July 12, 1960, normally exempts parts of heating, cooling and refrigeration

systems. The newness and lack of familiarity with solar equipment and materials

warrants increased, readily accessible consumer information as provided by this

Act.

S-501-3 SAFETY

S-501-3.1 Protection of potable water and circulated air

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

shall be employed that will support the growth of micro-organisms or introduce

toxic substances, impurities, bacteria or 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 m.ildew 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.

5-3
DIVISION 8

S-508 DOORS, WINDOWS, GLAZING PANELS

S-508-7 HARDWARE

S-508-7.3 Screening

Louvered solar control insect screening for windows and doors shall have 16 mesh or equivalent in one direction.

Cormentary : There are 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
S-515

S-515-1

S-515-1.1

S-515-1.

S-515-1.

S-515-1.

S-515-1.

S-515-1.

DIVISION 15

>rECHANICAL - SOLAR POIJERED EQUIPMENT

GENERAL PROVISIONS

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

the nationally recognized codes for fire safety under all operating and nonoperating conditions. The provisions of Section S-405 of this document and

MPS Section 405, FIRE PROTECTION, shall apply.

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 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 temperatures and pressures that can be developed

in the system under both flow and no-flow conditions.

Materials Compatibility

All materials which are joined 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

of joined materials.

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 expelled

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 that are intended to be buried in soils shall not be degraded under

in-use conditions to an extent that will significantly impair their function

during their intended design life.

5-5
S- 515-1.8 Corrosion by Leachable Substances

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

the system shall not cause corrosive deterioration of any other materials to an extent that will significantly Impair their function during their Intended

design life.

S-515-2 COLLECTORS

S-515-2.1 General

Collectors shall perform their function for their Intended design life.

Commentary : Collector panels aan be used as the roofing membrane. They can also be 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 becomes a factor of concern and must be considered in the

design.

When collectors are mounted over a roofing membrane, consideration should be

given to the growth of fungus, mola and mildew between the roofing membrane

and the collector. 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. This

is discussed further in Section S^615-2. 1 . 4. 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

Collectors shall be labeled in accordance with 515-1.2 of the MPS. In addition,

collector labels shall list total weight, cover plate materials, the types of

heat transfer fluids that can or cannot be used, maximum allowable operating

and no-flow temperatures, maximum allowable operating and no-flow pressures,

maximum flow rates and collector efficiency as measured according to S-615-2.2.1.

S-515-2. 1.2 Thermal Stability

Collectors shall not have more than a 10% reduction in the intercept or a

v,hange in slope of more than 10% that results in decreased performance as measured according to the method in S-615-2.2.1, after being exposed to solar

radiation having an average dally solar flux of 1500 Btu/ff^ at the tilt angle

under "no-flow" conditions for 30 days. At least one four hour period during

the 30 day exposure shall have a minimum solar flux of 300 Btu/ft^/hr. Sufficient data points shall be taken before and after the 30 day exposure to verify

the slope and intercept of the efficiency curve. The 30 day "no-flow" exposure must be performed on a complete collector without the transfer medium.

The angle of collector exposure should be + 10° of that used in service. For

tracking collectors, the exposure angles shall be the same as those used in

service

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

of time, potential problems with collector materials. The test will be re- ferred to for numerous materials in subsequent requirements. The ZO days do

not necessarily have to be consecutive

5-6
S-515-2.1.3 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 dlstrubing 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.

Cormentaj'y : Suggested pvaatiaes 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-515-2.1.4 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 ajce likely to be replaced, repaired or maintained within the

design life of the collector, it is important to provide easy access to those

m,aterials.

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.

Commentary : Table S-51S-2. 2 lists a number of materials that have been used

for cover plates and properties of the materinl!^

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 Labeling and product Description

In addition to the labeling requirements of Section 508-8.4 of the MPS,

product description shall include technical data regarding chemical composition,

physical, mechanical and thermal properties such as fire resistance, flammability and flamespread, weather resistance, electrical properties, products of

combustion, coefficient of expansion, transmittance , impact resistance,

scratch resistance and recommended or disallowed cleaning methods.

S-515-2.2.4 .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.

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S-515-2.2.5 Types of Applications

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

both integral with dwelling construction and freestanding components.

a . Outermost glazing near walking surface

Glazing materials exposed at ground level or at the level of a walking surface must meet the intent of the requirements for safety

glazing as specified in A?TSI Z97. 1-1972 and >rPS Section 508-8.1.

Commentary : Consumer Product Safety Commission's 16 CFR, Part 1201 was published in the Federal Register on February 11,1976. 180 days

after issuance of a final standard in the Fed.eral Register

the

standard will be mandatory for the safety of arohitectural glass.

(See Cormentary wrid-er b) below.

)

b . Vertically oriented outermost glazing materials in fixed panels

which are installed above a rail or sill at least 3' - 6"

above the walk^^^ay or finished floor line must meet the intent of the

requirements for glazing in MPS Section 508-8.3.

Commentary .- An additional consideration is that film-type glazing

materials for the outermost cover plate, if unsupported, may be

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 t^ie 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.

c. 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.

Cormentary : This commonly refers to glazing on which children may

climb or against which a passerby may fall.

d. 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. (Annealed glass or films

may be acceptable.)

S-515-2.2.6 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

significantly impair its function.

S-515-2.2.7 UV Stability

Documentation shall be provided that the decrease in transmittance , as measured by ASTM E-424-71, will not significantly impair the function of

the cover plate (s) during its intended design life.

S-515-2.2.8 Dirt Retention

The cover plate (s) shall not collect or retain dirt to an extent that

would significantly reduce its ability to transmit sunlight.

Cormenzary : The possible collection and retention of dirt by the cover

plate arvd the effect of reatined dirt on collector performance may be

significant. The retention of dirt may depend on the tilt angle of

the collector. Rainfall and snow melt are generally sufficient

5-9
to keep the coHeotor cover plates clean. If periodic scrubbing is

necessary for cleaning, the cover plates should be resistant to damage

by abrasion resulting from the scrubbing. If the collector is ventilated.^

provisions should be made for exclusion of dust by appropriate filters.

S-515-2.2.9 Outgassing of Volatiles

After exposure as described in S-515-2.1.2, there shall be no visible

signs of outgassing products on the cover plate surface (s) that will

significantly reduce the transmittance

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

reduce the transm.issivity of the cover plate (s).

S-515-2.2.10 Condensation

Condensation formed on the underside of the cover plate (s) shall not

significantly reduce its transmittance during its design life.

Commentary : If flat plate collectors are not hermetically sealed, the

likelihood of condensate forming on the underside of the cover plate (s)

is quite high. Dessicants in breather tubes or breather plugs can be used

to maintain a dry environment. TVie dessicants should be located in such a way that they are not in contact with the collector plate.

One additional potential problem with collectors which are not hermetically

sealed is that, in industrial atmospheres, the introduction of dilutants

in condensate solution may cause permanent etching of the underside of

the cover plate(s) over a period of time. Such etching can permanently

reduce the transmittance. When this possible condition exists, design

considerations must be given to avoid the problem.

S-515-2 . 2 . 11 Flamespread

Installation of glazing or other related components of the solar system

as part of the roof assembly shall not reduce the fire retardant characteristics of the roof covering below the accepted level against a fire

originating outside the building in accordance with ASTM E 108-58, Methods

of Fire Tests of Roof Coverings (NFPA No. 256-1970).

S-515-2. 2. 12 Glass

Where tempered glass is used, it shall meet the requirements of ANSI - Z97. 1-1972 and MPS, Section 508, as specified in S-515-2. 2. 5 of this

document. Other glass cover plates shall meet the requirements for glass

as specified in Federal Specification DD-G-A51C (June 15, 1972).

, , Commentary : Table S-515-2. 2 contains solar transmittance data and

recommended maximum continuous operating temperature for a number of

types of glass.

S-515-2. 2. 13 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 . 11. Table S-515-2. 2 lists

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

5-10
shall not be used for cover plates if the maximum temperature to which

they will be exposed in service under operating and non-operating conditions exceeds the maximum operating temperatures listed in Table S-515-2.2.

Absorber Plate

Thermal Stability

Any deformation that occurs in the test described in S-515-2.1.2 shall

not adversely affect the flow rate of the transfer medium.

Eros ion /Corrosion

The absorber plate or flow conduits shall not be adversely affected

by erosive wear, such as by the flow of a liquid transfer medium to an extent that will significantly impair its function during its intended

design life. In lieu of other documentation, compliance with this requirement shall be demonstrated by testing with appropriate revisions of one

of the following methods:

NACE TM-02-7^

NACE TM-02-70

NACE TM-01-69

ASTM D257C-73

Corrmentary : Appropriate revisions of the above tests should include

conditions which closely simulate in-service operation. The variables

which have an important impact on the rate or 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 corudition of the pipe

Compatibility With Transfer Medium

a. The absorber plate or flow conduits shall not be pitted or otherwise

corroded by the heat transfer medium to an extent that will significantly impair its function during its design life. In lieu of

other documentation, modifications of tests listed in Table S-515-2.3.1

shall be used to demonstrate compliance with this requirement.

Corrmentary : SAE Report J447a(1964) , Prevention of Corrosion of Metals,

provides guidance in preventing corrosion.

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

heat transfer fluids in open systems shall be used in accordance with

the acceptable conditions listed in Table S-515-2.3.2, where applicable.

Unacceptable conditions listed in this table shall not be used.

Documentation shall be provided to demonstrate that materials applications not explicitly covered in Table S-515-2.3.2 meet the intent

of S-515-1.3 and S-515-2.3.3

Metallic absorber plates or flow conduits in direct contact with heat

transfer fluids in closed systems shall be used in accordance with

the acceptable conditions listed in Table S-515-2.3.3 where applicable.

Unacceptable conditions listed in this table shall not be used.

Documentation shall be provided to demonstrate that materials applications not explicitly covered in Table S-515-2.3.3 meet the intent of

S-515-1.3 and S-515-2.3. 3 5-11
Table S-515-2.3.1: Corrosion Test Methods

Number Title Comment

NACE TM-01-71 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 an solar system

NACE TM-02-70

NACE TM-01-69 (1972)

ASTM D138-70

ASTM D2570-73

ASTM D2776-72

Conducting Controlled Velocity

Laboratory Corrosion Tests

Laboratory Corrosion Testing

of Metals for the Process

Industries

Corrosion Test for Engine Antifreeze in Glassware

Simulated Corrosion Testing

of Engine Coolants

Corrosivity of Water in the

Absence of Heat Transfer

Modify to reflect conditions

present in solar system

Describes factors to consider

in corrosion testing

Modify to reflect conditions

present in solar system.

Modify to reflect conditions

present in solar system

Commentary : Open systems are those in which air, in addition to that

already in the transfer fluid initially^ can he absorbed into the

fluid by contact with the atmosphere. Closed systems are those in

which air, in addition to that in the fluid initially cannot be

absorbed by the fluid.

In a closed system, there is no exposure of the fluid to the atmosphere except above the expansion tank, 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.

Corrosion is a very complex phenom.enon in which many parameters are of importance. In the case of the corrosion of metals likely to be used in the fluid 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 metals

- the temperature

the flow rate because of the possibility of erosion-corrosion

- system design factors, particularly the presence of galvanic

cells or differential aeration cells.

Galvanic cells result with contact between dissimilar metals while

differential aeration cells are areas where a metal is in contact

with the fluid which has a variable dissolved oxygen content.

Water composition is important for corrosion. It 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

(O2, 002)3 chloride content, sulfate content, solids content (organic

matter), and conductivity. Because of this variation in water similar

variations in the type and severity of corrosion may be expected.

Therefore, rather thxin specifying an acceptable corrosion rate based

on the weight loss of a test coupon alone there is value in specifying

5-12
a maximum rate of penetration. A spec, of this type would, however,

require interaction with design specifications because of minimim

wall thickness to maintain adequate strength during the design life

is necessary . Although the instnmentation by rihich corrosion

penetration (pitting) may be measured (x-ray, eddy current devices,

etc. ) exists, recommended practices with regard to the frequency of

measurement and the points at which these measurements should be

carried out require development.

Weight loss corrosion measurements are also important. While the

losses in wall thicknesses may not be significant the build-up of

corrosion products could be. This could result either in flow

restriction or in pitting corrosion. Depending on the O2 content

of the transfer medium pitting corrosion as a result of differential

aeration at the pipe-deposit interface could occur. This type of

attack may also result because of scale formation. Because calcium

carbonate exhibits retrograde solubility , precipitation of this

compound will occur in saturated room temperature water as it is

warmed. In addition each time make up water is added or the system

flushed and refilled additioyial scale will be built up. Softening

of water will help to alleviate this problem, and may be recommended.

Chlorides

Chlorides should be kept to a minimum since their presence in water

accelerates pitting corrosion. Aside from its presence in water

there are several potential sources of chloride in a solar unit:

1. Residual chloride from pickling treatment of metallic components.

This may also be a source of sulfate. This is a rather unlikely

source of these ions but care should be taken that the components

of the system are thoroughly cleaned before assembly

2. Chloride from the decomtposition of nonmetallic components in the

system.

3. Chloride from flux used in soldering or brazing components during

installation.

Galvaniziyig

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 much lower than that of

iron, so a relatively thin coating will last for quite a long time.

However, there are data indicating that at elevated temperatures of

above 158 °F (70°C), this effect is reversed and the iron corrodes

rather than the zinc. [1]

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

the temperature range between 111 and Idi^F (55 and 90'^C).

Accordingly the use of galvanized steel in this temperature range

is not recommended.

Copper in a Recirculating System

In "once through" systems copper pipe is usually only connected

upstream from iron pipe. Residential plumbing is an example of this.

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

Reinhold Publishing N.Y. 1966.

5-13
This praatice is carried out because small mounts of copper tend, to go into solution. When these copper ions contact more active

metals such as Fe or Al they are reduced to copper metal which

subsequently deposits on the metal surface, l^en 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 for Al in the presence

of Fe.

pl

The pH of the transfer medium will }iave an important impact on corrosion rates. However, the optimum pH to achieve minirmm corrosion

will change with temperature. [2] Because varying temperatures

occur within a solar heating system and the temperature at a given

point will change with tim.e, care must be taken to optimize the pH.

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 open systems, 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 closed system, from which the dissolved

oxygen cannot escape, corrosion may continue at an accelerated rate.

Stress corrosion

This could be a problem in the collector panels where high strength

alloys (esp Al) are clad to higher purity Al. Residual stresses in

roll bonded and blown collectors could be sufficient for stress

corrosion to occur. However, stress corrosion is unlikely unless

chloride is present.

O2 content of water

Generally corrosion will decrease with a decreasing amount of O2 in

water. In a closed system, O2 will be depleted and in theory

corrosioyi will cease. However, the probability of designing and

constructing a system in which there is no leakjage of oxygen is

uncertain. If this were possible the only other sources of oxygen

would be that frari decomposition of organic components and from

chemicals added to elevate the boiling point of water. Corrosion

inhibitor's would not be necessary in a completely closed containment

system composed of steel or copper ; if the proper pH is maintained.

In the absence of oxygen, measurable corrosion of copper and steel

does not occur.

The corrosion of aluminum, however, may continue even in the absence

of oxygen. Because aluminum is more electropositive than Cu, Fe or

Zn, an alternative cathodia process may occur. This is the reduction

of water to molecular hydrogen. This reaction may be suppressed if

the pH is maintained in the range between about 5 and 7. The presence

of chlorides and more noble metals should be avoided regardless of

the oxygen content and the pH of the fluid since these factors

accelerate pitting corrosion. Stainless steel is unacceptable for

use in contact with fluids, such as water/glycol mixtures, in closed

[2] P.. M. Diamant: The Prevention of Corrosion, Business Books Ltd.

London 1971.

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5-17
systems because hXitiir/glycol mixture;: pyccluflr the. use of oxidizing

inhibitors . Jn solutions with low oxygen oonte-nt, stainless steel

is susceptible to crevice corrosion because insufficient oxygen is

available to replenish the protective oxide layer once crevice

corrosion starts.

UV Stability

Absorber plates shall not degrade to an extent that will significantly

impair their function during theJr design life wlien exposed to UV radial ion

Absorptive Coatings

General

Absorptive coatings are generally of two types, either selective or nonselective. A nonselective coating has an absorptance to emmitance

ratio near unity whereas in a selective coating, the ratio is higher.

Appendix B-1 lists some characteristics of potential absorptive coatings.

Commentary : An effecient coating has a high absorptance (a) over the

solar spectrum (.3 to 2.0 \m) with low emittance (e) to reduce thermal

radiative heat losses.

For coatings applied by an electroplating processy as are many selective

coatings, the substrate finish, plating geometry, bath composition,

and current density may influence the properties necessary for optimum

solar applications.

Thermal Stability

After exposure 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 D660-44 (1970),

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

UV 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 for 500 hours according to ASTM D 822-60 (1973)

Corrmentary : 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 configuration as used in an actual collector.

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).

5-18
Commentary : Moisture is not expected to come in co?itact with absorptive

coating in collectors which have a dessicant

S-515-2.4.5 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 D 1308-57 (1973)

S-515-2.5 Collector Enclosure

S-5 15-2. 5.1 Thermal Stability

After exposure as described in S-515-2.1.2, there shall be no cracking

or warping of the collector enclosure materials that will significantly

impair their function.

S-515-2.5. 2 UV Stability

Documentation shall be provided that materials used in the collector

enclosure do not degrade significantly over their intended lifetimes

when exposed to solar radiation.

S-515-2.5 3 Materials

Collector enclosure materials shall be in accordance with applicable

sections of Division 5 and 6 of the MPS.

S-515-2.5 4 Coating

Protective coatings, where used, shall be in accordance with Section

509-7 of the MPS.

S-515-2.6 Reflective Surfaces

S-515-2.6.1 General

These provisions are applicable where reflective or antireflective

surfaces are an inherent part of the collector design.

S-515-2.6. 2 Thermal Stability

After exposure as in S-515-2.1.2, there shall be no cracking, crazing,

delamination or change in reflectance of the reflective surfaces that

will significantly impair their function.

S-515-2.6. 3 UV Stability

Documentation shall be provided that the reflectance properties of the

surfaces will not decrease by more than 10% below the design reflectance

when exposed to solar radiation for the intended life of the surface.

S-515-2.6. 4 Damage by Impact

The reflective surfaces shall not be adversely affected by impact, such

as by hail, to an extent that would significantly impair their function

during their design life.

5-19
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

exchanger or storage facility to the collector subsystem.

Applicable Standards for Liquid Systems

Compliance with MPS

Materials used in the transport system shall be in accordance with

Sections 515-3.1, 515-3.2, 515-5.1, 515-5.2 and 515-6.4 of the MPS where

applicable

Other Standards

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

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

are given in Appendix Table B-2.

Cormentary : Most of the standards for piping shown in Appendix Table B-2 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. The standards

and specifications for each component of the piping system shall also

be given on plans and specifications.

Thermal Stability

Components comprising the transport system shall not be damaged by

normal thermal expansion and contraction of piping materials uiider

in-use conditions. Proper pipe hangers and supports and fittings shall

be used to allow normal movement of piping. See Appendix Table B-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 deterioration.

b. Materials comprising the piping or transport system shall have

sufficient chemical and physical compatibility with the heat

transfer medium to prevent corrosive wear and deterioration.

(For metals, see S-515-3 . 1. 7 .

)

Erosion/Corrosion

Materials comprising the transport system shall be in conformance with

S-515-2.3.2.

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.

5-20
Commentary : Dieleatria aouptings used to isolate dissimilar metals

whiah are buried in soil may be ineffective because of contact of the

metals with ground water.

S-515-3.1.7 Metals

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

heat transfer fluids shall be used in accordance with the acceptable

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

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-515-1.3 and S-515-3.1.5.

S-515-3.2 Applicable Standards for Air Systems

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

recommendations of the ASHRAE Guide on applicable manuals of NESCA and

ARI. Installation shall comply with NFPA Standards 31 and 54 and either

NFPA 90A or 90B, as applicable.

S-515-3.2.1 Size

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

S-515-3.2. 2 Humidifiers of the central type shall be in compliance with ARI Standard

610, "Standard for Central Humidifiers (197A)."

S-515-3.2. 2 Self Contained Humidifiers shall be in compliance with ARI Standard 620,

"Standard for Self-Contained Humidifiers."

S-515-3.2.4 Air Filters shall conform to the requirements of UL 900 (ANSI B124. 1-1971)

S-515-3.2. 5 Heating supply and return air ducts in unconditioned spaces shall be

insulated with materials or have thermal characteristics as specified in

Section 515-3.1 of MPS.

S-515-4 MECHANICAL SUPPORTING DEVICES

S-515-4.1 General

Mechanical supporting devices shall be sufficiently durable to perform

their intended functions for their design lives.

S-515-4. 2 Roof Mounted Collectors

When collector panels are added to an existing roof, the attachment

hardware shall be fabricated of materials that will not be seriously

affected by weathering for the expected design life of the roof membrane.

S-515-4. 3 Remote Mounted Collectors

The materials used to support collector panels remotely located from

the dwelling unit shall not be adversely affected by external environmental factors including solar radiation, temperature extremes or cycles

of moisture.

5-21
Wood

a. ^•Jhen mounting racks are constructed of wood, the applicable

provisions of Division 6, Chapter 5 of MPS shall apply.

b. When mounting racks are constructed of wood and may be subjected

to termite damage, Division 2 of Chapter 5 of MPS shall apply.

Concrete /Masonry

When concrete is used as any portion of mounting construction, the

applicable provisions of Division 3, Chapter 5 of MPS shall apply.

When masonry is used as any portion of mounting construction the

applicable provisions of Division 4, Chapter 5 of MPS shall apply.

Metals

When metals are used as any portion of mounting rack construction the

applicable provisions of Division 5, Chapter 5 of MPS shall apply.

Coatings

Coatings on wood, concrete/masonry or metals, if used, shall comply to Section 509-7 of MPS

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

mater%al, metal surface plates should be used to avoid damapina the

insulation.

VALVES

Applicable Standards

Valves shall conform to one or more of the following standards as appropriate. Valves manufactured to other standards not listed but

fulfilling the requirements of a particular solar heating system design

may be acceptable.

Standard for Solenoid Valves for use with volatile Refrigerants and

Water (1975) — ARI Standard 760.

Valves, Pressure, Reducing and Regulating for Installation on Domestic

Water Supply Lines ~ lAPMO PS15-71 [4]

Water Pressure Reducing Valves for Domestic Water Supply Systems —

ASSE No. 1003, 1970,

Valves, Automatic Relief — ANSI 21.22 - 1971. (For Water /Steam)

Valves, Cast Iron Gate, 125 & 250 lb; Threaded and Flanged —

WW-V-58a-1966

[4] International Association of Plumbing and Mechanical Officials,

5032 Alhambra Ave., Los Angeles, California 90032

5-22
Combination Check and Relief Valves — lAPMO TSC-8-66

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 Typp loglighter valves, angle or straight pattern — lAPMO PSlO-66

Valves, Electrically Operated (1955) — UL 429.

Valves (125 pound Bronze Gate) (1969) — MSS SP 37 [5]

Valves (150 pound Corrosion Resistant, Cast, Flanged) — MSS SP 42

Valves (Butterfly) 1966 — MSS SP67

Commentary : Standards for valves usually present pressure-temperature

ratings. Appendix Table B-3 presents these ratings as an example for

ball valvesi Federal Specification WW-V-3Sa-l975. The valve standards

do not consider valve sealing materials. The sealing material may not

be compatible with the heat transfer fluid. The designer should consult

the valve manufacturer for advice concerning appropriate valves and seals.

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.

S-515-6 Pmrps AOT) COMPRESSDRS

S-515-6.1 General

Pumps and compressors shall be in accordance with Section S-615-5

S-515-6. 2 Applicable Standards

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

with the requirements of the Hydraulic Institute.

b. Sump pumps shall be tested, rated and labeled in conformance with

the current SPMA Domestic Sump Pump Standards.

c. Heat pumps shall be in compliance with ASHRAE Standard 37-69, "Method

of Testing for Unitary Air Conditioning and Heat Pump Equipment",

and /or the ARI Standard 240, Standard for Unitary Heat Pump Equipment (1975).

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

and shall be tested, rated and labeled accordingly.

[5] Manufacturers Standardization Society of the Valve & Fitting Industry,

1815 North Fort Meyer Drive, Arlington, VA 22209

5-23
Comnentari] : A Hydraulic Institute Standard defines the productj material,

process or procedure with, reference to one or more of the following:

nomenclature, composition, construction, dimensions, tolerances, safety,

operating characteristics, performance, quality, rating, testing

and service for which designed [6]

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 sufficient durability to fulfill

the heating storage requirements of the system for the intended design

life of the storage unit.

Cormentary : Storage units which are inaccessible for replacement,

as defined in 615-1.5 of the MPS, should be designed to perform their

function for the lifetime of the building. Routine maintenance

and minor repairs is acceptable during the expected life of the

unit.

Applicable Standards

Applicable standards for thermal storage units are presented

in Appendix Table B-4.

Contamination

Thermal storage tank materials, Including any interior protective

coatings and the heat storage medium used, shall not Impart toxicity,

undeBirable tastes, or odors to either air or water intended for human

consumption.

Materials Compatibility

a. Materials comprising the thermal storage system shall have sufficient

chemical compatibility with the heat transfer medium to prevent

corrosive wear and deterioration.

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

contact with heat transfer fluids shall be in accordance with

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

where applicable. 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-515-1.3 and S-515-7.4 a.

[6] 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-515-8 HEAT TRANSFER FLUIDS

The heat trnasfer fluid Is generally a gas or liqu^d which transports

generated heat from the collector subsystem to the thermal storage

subsystem.

S-515-8.1 General

S-515-8.1.1 Labeling

The information described in the Federal Hazardous Substances Labeling

Act (1960) is required for heat transfer fluids. In addition, heat

transfer media must be classified and containers duly labeled with ref- erence to NFPA 30, the Flammable and Combustible Liquids Code.

Flashpoint and classification as to flammability and combustibility

shall be given as indicated in the General Provisions of NFPA 30.

Labeling shall also include the following items:

° service temperature range

° viscosity over service temperature range

° freezing point

° boiling point

° specific heat

* vapor pressure over service temperature range

° materials with which it is compatible

" instructions for inspection, treatment and disposal of the fluid

S-515-8.1. 2 Function - GenlT'al

The heat transfer fluid shall perform its intended functions without

deleterious effects to those parts of the solar energy system with which

it comes into contact. Appendix Table B-5 presents a partial listing of

properties of several types of heat transfer fluids.

S-515-8.2 Toxic and Flammable Fluids

S-515-8.2.1 General

Heat transfer fluids which require special handling (e.g., toxic,

flammable, corrosive, explosive, etc.) shall not be used unless the

systems in which they are used are designed to avoid exposure to un- necessary or unreasonable hazards, see Sec. S-615-10.1

S-515-8.2. 2 Flashpoint

The flashpoint of the heat transfer medium shall not be less than AOO^F

(204°C) as determined by NFPA 321, 1971, Standard on Basic Classification

of Flammable and Combustible Liquid except as provided in Section S-615-14.2.2

Commentary : The maximum temperature to which the heat transfer medium

will he exposed is that achieved by the fluid in the collector during

no-flaw conditions.

S-515-8.2. 3 Atmospheric Concentration of Toxic Materials

The concentration of the vapor of the heat transfer medium in the interior

atmospheric environment shall not exceed 1/lOth the threshold limit value

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

5-25
Comnentary : The TLV is primarily concerned with industrial exposures

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

the 1/lOth value of the TLV is recommended. TLV's are under continuous

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

Conference of Government Industrial Hygienists

S- 515-8.2.4 Fluid Disposal - Biodegradability and Aquatic Quality

a. A list of the chemical components of the heat transfer medium must be

provided in mg/liter. This list must include any substances which

comprise more than 0.10% of the medium.

b. The organic constituents of these substances must have a five-day

Biochemical Oxygen Demand (BOD), using sewage seed, of at least

70% of the theoretical oxygen demand. This test shall be in con- formance with the Standard Methods for the Examination of Water and

Waste Water, American Public Health Association (1971).

c. The concentration of chemical constituents must be compared with the

96 Hour LC-50* bioassay value for protection of aquatic life. This

comparison is to be made in accordance with the Water Quality Criteria

1972 .

Using the gallon/day capacity of the local sewage treatment plant,

approximate the concentration at the treatment plant. If the dilution

of the chemical constituents is 1/lOth the LC-50 value or greater at the sewage treatment plant, the heat transfer medium must be diluted

before emptying into a public sewer.

Commentary : Means for the disposal of heat transfer fluids are discussed

in Section S-62S-9 of this document. Consideration should also 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 Commimity Sewage Systems . A preliminary draft of the

Environmental Protection Agency 's Quality Criteria for Water, October 10,

1975, is currently under review. After its publication in the Federal

Register, EPA's criteria will supercede those currently cited.

S-515-8.3 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,

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.

S-515-8.4 Chemical Compatib il ity

Heat transfer fluids designed to be used in contact with component

materials shall be sufficiently chemically compatible with those materials

to prevent deterioration that would impair their function during their

design lives. Inhibitors, added to the transfer fluid to prevent corrosion,

shall be compatible with all components in the system with which they come

in contact.

' Commentary : This problem is further discussed in Section S-525-2.3 of this

document. Appendix Table B-6 presents a list of inhibitors which have been

reported in the literature for use with various metals.

*LC = Lethal Concentration. See definitions in Appendix D.

5-26
S-515-8.5 Thermal Stability

The heat transfer fluid shall not degrade at the maximum temperature

to which it wil 1 reach in-service to an extent that would significantly

impair its function during its design life.

Commentary : Tiiis maximum temperature will generally be reached under

"no-flaw" conditions. Appendix Table b-5 includes data for a number of

typical transfer fluids. Some fluids may decompose somewhat at elevated

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

acids. Buffers are usually included with such fluids to control the pH.

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

periodically

S-515-9 HEAT EXCHANGERS

S-515-9.1 Coir.pllance with Standards

Heat exchangers shall be in compliance with the appropriate standards

given in S-515-9. 2 and S-515-9. 3. 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 Tubular Heat Exchangers

Tubular heat exchangers shall be in compliance with the appropriate

requirements of TEMA.

S-515-9. 3 Heating Coils

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

requirements of ARI Standard 410.

5-27
GASKETS AND SEALANTS

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-7 is

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

Materials Performance

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.

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-7.

h. 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 temperature. ASTM F82-67(1973) Standard Recommended Practice

for Fast Quality Check on Immersion For Nonmetallic Gasket Materials,

shall be used as a guide in performing these tests.

UV 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 : Gaskets of ethylene propylene diene monomer (EPDM) rubber

or silicone rubber may be appropriate for these applications.

5-28
S-515-11 INSULATION/THERMAL AND MOISTURE PROTECTION

S-515-11.1 General

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 conti;ol or 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 Section 507-3 of the MPS.

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

all other insulation material 150.

The ASTM E84-70 flame spread test method shall be the basis for evaluating

the surface burning characteristics of the residential insulation

material. 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 are difficult to evaluate in ASTM E84-70. The requirement of flame spread classification

of 25 maximum for these foams will provide as much a safety assurance as

is possible with current test methods. Such a classification (or any

other numerical 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.

S-515-11. 2 Collector Insulation

S-515-11. 2.1 General

Collector insulation shall be sufficiently stable at the maximum temperature to which it will be exposed in-service. Suggested upper temperature

limits for several insulating materials are listed in Appendix Table B-8.

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 willnot be exposed to extreme

temperatures. Fiberglass insulation with binders can be pre-heated to expel volatiles prior to use in collectors . If such pretreatment is used,

the upper temperature limit becomes somewhat higher.

5-29
Some plastic foam insulations are available with various encapsulated

gases. Those using freon can cause severe outgassing problems while

those insulations blown with CO^ could be acceptable.

Thermal Stability

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

or other dimensional changes in the collector insulation that will

significantly affect the collector performance. In addition, the

insulation shall not, during operating or non-operating periods, give

off volatile materials that could affect the performance of components

of the solar energized system or the safety of the dwelling occupants.

Pipe or Duct Insulation

Pipe or duct Insulation shall be sufficiently stable at the maximum

temperature to which it will be exposed in-service. Suggested upper

temperature limits for several insulating materials are listed in

Appendix Table B-8.

Storage Subsystem Insulation

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

the insulation shall be protected in accordance with S-515-11.5 and

S-515-11.6 of this document.

Waterproofing and Dampprooflng

Materials used for waterproofing shall be in accordance with Section

507-1 of the MPS.

Vapor Protection

Materials used for vapor barriers shall be in acccordance with Section

507-2 of the MPS.

CATCH BASINS

General

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

intended functions.

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.

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.

5-30
S-515-13 ORGANIC COUPLING HOSES

S-515-13. 1 General

Organic coupling hoses shall be of proven effectiveness and durability

under the expected operating and exposure conditions.

S_515_13,2 Materials Performance

S-515-13. 2.1 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

coraplet ion 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 olampSy 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. 2. 2 UV 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. 2. 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 F82-67 (1973)

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

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

may be applicable for demonstrating compliance with S-S15-13. 2. 2. It

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

S-515-13. 2, 4 Compatibility with Piping Materials

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

with the piping.

5-31
S-515-13.2.5 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''C according to ASTM 01149-64(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-i4

S-600-6 Safety and Health Requirements 6-<4

S-601 GENERAL STRUCTURAL REQUIREMENTS 6-6

S-601-1 General 6-6

S-601-2 Design Dead Loads 6-6

S-601-3 Design Live Loads 6-6

S-601-4 Wind Loads 6-6

S-601-5 Snow Loads 6-7

S-601-6 Seismic Loads 6-8

S-601-7 Hail Loads 6-9

S-601-8 Maintenance Loads 6-15

S-601-9 Thermal Distortion 6-15

S-601-10 Collector Cover Plates 6-15

S-601-11 Connections of Collector Frames and/or Other

Support Structures 6-15

S-601-12 Storage Tanks 6-16

S-601-13 Dynamic Loads 6-16

S-604 MASONRY 6-17

S-604-1 General 6-17

S-607 THERMAL AND MOISTURE PROTECTION 6-18

S-607-3 Building Insulation for Passive Solar Systems 6-18

S-615 MECHANICAL = 6-19

S-615-1 Thermal Design ;

•. 6-19

S-615-2 Collectors 6-23

6-1
S-615-3 Mechanical Supporting Devices 6-27

S-615-4 Valves 6-27

S-615-5 Pumps and Compressors 6-27

S-615-6 Mechanical Vibration Isolation 6-27

S-615-7 Thermal Storage 6-28

S-615-8 Heat Transfer Fluids 6-30

S-615-9 Waste Disposal 6-30

S-615-10 Plumbing 6-31

S-615-11 Auxiliary Energy System 6-35

S-615-12 Heat Exchangers 6-3A

S-615-13 Air Distribution 6-36

S-615-14 Controls and Instrumentation 6-37

S-615-15 Chimneys and Vents 6-38

S-615-16 Mechanical Ventilation 6-38

6-2
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, equipment and

hazardous substances shall be labeled or given clear indication of their

input and output, operating temperatures, pressures, flow and filled weight

as appropriate.

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

Section S-101 of this document.

S-600-3 INSTALLATION OPERATION AND MAINTENANCE MANUAL

A manual shall be provided for the installation, operation and maintenance of

the H and/or DHW systems.

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 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

These instructions shall include descriptions of both interconnection and

connections with the dwelling and site.

S-600-3. 2 Maintenance 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,

6-3
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.

S-600-3.3 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.

S-600-4 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.

Cormentgpy

This oriterion is intended to prealude long periods of system down-time

due to the need for the repair or replacement of parts.

S-600-5 MAINTAINABILITY OF SYSTEMS AND SUBSYSTEMS

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 ^ larger collector installations it may be desirable to make provisions

for supplying electrical power and water for maintenance purposes.

S-600-6 SAFETY AND HEALTH REQUIREMENTS

S-600-6 . 1 General

Materials or construction used in the Installation of solar systems shall

be in accordance with the fire protection provisions of Section 405-7

of MPS.

S-600-6. 2 Penetrations Through Fire Rated Assemblies

Penetrations through fire-^ated assemblies as a result of the solar

subsystems shall not reduce the fire resistance below the levels specified

in Section 405 of MPS.

S-600-6. 3 Protection From Heated Components

The surface temperature of any accessible surfaces, exposed pipes and/or

ducts must be less than 150°F. Evidence shall be provided that no hazard

exists from such exposure.

6-4
S-600-6.4 System Component Clearances

Any system components Installed within a confined area or as an integral

part of a structural assembly of the building which can be expected to operate under elevated temperatures shall be installed in accordance with

NFPA No. 89M-71, Clearances for Heat Producing Appliances.

S-600-6.5 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-615.14.2.

S-600-6.6 Personal Safety

Where access for service or 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.

S_600-6.7 Growth of Fungi, Mold or Mildew

Components 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.

S-600-6.8 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 or 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.

S-600-6.9 Protection of Potable Water Supply

The design and installation of the complete system and its individual

components shall be completed in such a manner as to provide complete protection of the potable water supply. Such installations shall be in

accordance with Chapter 10 of the National Standard Plumbing Code and

other applicable codes (see Sec. S-615-10)

6-5
DIVISION 1

S-601 GENERAL STRUCTURAL REQUIRE>fENTS

S-601-1 GENERAL

This section contains those supplemental requirements to Chapter 6 of MPS

needed to cover solar systems which utilize conventional structural

materials (materials covered by the current >1PS 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

fluid in the collector, fluid in storage tank, and fluid in other subsystems

and components shall be included.

S-601-3 DESIGN LIVE LOADS

S-601-3.1 Roof Mounted Solar Systems

Design live roof loads prescribed in Table 6-1.2 of MPS 4900.1 shall not be

required for flat plate collector panels that are mounted on roofs that do

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

service and maintenance personnel. For flat plate collectors which form

an integral part of the roof, the design live roof loads listed in Table

6-1.2 shall be required.

Cormentarij

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 reparied from time to time; therefore^ it must support the

workman making the repairs, regardless of the wind and snow loading re- quirements. 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-601-4 WIND LOADS

S -601-4.1 Flat Plate Collectors Mounted on Roofs and Walls

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

roofa and walls in Section 601-6 of the MPS or as modified In paragraphs S-601-4. 1.1, .2, .3, and .4 below.

S-601. 4. 1.1 Flat plate collectors that are mounted with their cover plates

and back surfaces fln«h with t^e surface of the roof shall be

subjected to the wind loads that would have been imposed on those areas of the roof covered by the collectors.

S 601-4.1.2 Flat plate collectors mounted at an angle or parallel to the

6-6
surface of the roof on open racks can have an 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

loads to which the collectors shall be subjected, 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.

S-601-4.1.3 In calculating design wind loads for flat plate collectors

mounted on roofs, the internal pressure coefficients, Cpi, listed

in Table 11, ANSI A58.1 shall be neglected. (See Commentary)

S-601-4.1.4 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 re- quired for exterior walls.

S-601-4.2 Concentrating Solar Collectors

Wind loading on concentrating solar collectors shall be deteruiind using

the results of accepted eugineeriiig procedures or physical simulation,

which may Include wind tunnel testing.

S-601-4.3 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.

S-601-4.4 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 non- enclosed structures as given in section 6.6, ANSI A58.1, taking into

account local terrain characteristics.

S-601-4.5 Exposed Storage Tanks

Wind loads on exposed storage tanks shall be determined in accordance

with ANSI A58.1.

Commentary

Paragraph. 4.1.3 It is assumed that no uplift pressure is exerted on

the underside of a aolleotor except as indicated in paragraph 4.1.2

above. However^ in calculating the overall roof loading, internal

pressure in the dwelling must be considered in the usual manner.

S-601-5 SNOW LOADS

S-601-5.1 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

6-7
Section 601.-5 of MPS or as modified in paragraphs S-601-5.1.1, .2, and .3 below

S-601-5.1.1 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 be designed to 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 must

be considered in the design of the roof.

S-601-5.1.2 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.

S-601-5.1.3 Consideration shall be given to the potential local accumlation

of snow under flat plate collectors.

S-601-5.2 Roof Loading

S-601-5.2.1 A single or multiple saw-tooth array of collectors may cause

severe drifting between rack 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.

S-601-5.2. 2 Snow loods on concentrating solar collectors shall be determined

by accepted engineering procedures.

S-601-6 SEISMIC LOADS

5-601-6.1 General

Seismic design requirements for the mechanical and electrical com- ponents 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, p sr.'l.ar 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.

S-601-6. 2 Design Provisions

S-601-6. 2.1 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.

The design of all connections between the mechanical or electrical

components and the structural frame shall allow for anticipated

movements of the structure. The details of the connections shall be

made a part of the design documents.

6-8
S-601-6.2.2 Seismic Forces. Mechanical and electrical components of solar

energy systems and their connections shall be designed to resist the

seismic forces stipulated hereafter in accordance with Section 2314

of the Uniform Building Code, as adopted and revised in October 1975,

which provides the following equation. [1]

F = ZC SW

P P P Where

F = Force on the part or component and in the direction under con-

^ sideration

Z = Numerical coefficient related to the seismiclty of the region as shown in Figures S-601.1, a,b,c, and d. The values of Z for the

respective zones are listed below:

Zone 0 Z = 0 (no damage)

Zone 1 Z = 3/16

Zone 2 Z = 3/8

Zone 3 Z = 3/4

Zone 4 Z = 1

S = Numerical coefficient for site structure resonance. When the

characteristic site resonance is not established in accordance with

Section 2314 of UBC the value of S shall be taken as 1.5.

C = Numerical coefficient specified in Table S-601.2

PW = The weight of the part or component, including the weight of

^ contents in accordance with Section S-601.2

S-601-7 HAIL LOADS

The cover plates of solar collectors shall be designed to resist, without

failure, the vertical 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 » mean annual number of days with hail taken from Figure

S-601.2 [2].

Terminal velocities for various hail sizes are given in Table S-601.3. [3],

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 [4] or analytical procedures acceptable to HUD.

[1] The design provisions in this paragraph have been extracted from the business meeting reports of the International Conference of Building Officials

(UBC) . These provisions contain the approved code changes which will appear

in the 1976 UBC.

[2] Baldwin, J. L. , Climates of the United States , U.S. Dept. of Commerce,

Washington, D.C. (1973).

[3] Mathey, R. C. , Hail Resistance Tests of Aluminum Skin Honeycomb Panels for

the Relocatable Lewis Building, Phase II , NBS Report 10 193, National

Bureau of Standards, Washington, D. C. (1970).

[4] Greenfield, H. , Hail Resistance of Roofing Products , Building Science

Series 23, National Bureau of Standards, Washington, D.C. (August 1969).

6-9
Figure S-601.1a Seismic zone map of Continental United States

(Zone 4 is shown in figures S-601.1b and S-601.1c)

Figure S-601.1b Seismic zone map of Alaska.

6-10
Figure S-601.1c Seismic map of zone 4 in Continental

United States.

HAWA I

t

Figure S-601.1d Seismic zone map of the

Hawaiian Islands.

6^11
TABLE S-601.2

Part of System Direction of

Force

Value of C -

P 2 /

Storage tanks, pressure vessels

boilers, furnaces, absorption

air conditioners, other equipment

using combustible or high temperature energy sources , electrical

motors and motor control devices

,

storage tanks, heat exchangers,

pressure vessels

any

direction

0.12 when resting on ground

0.20 when connected to, or housed, elsewhere

in the building.

Flat plate and concentrating

solar collectors

any

direction

0 . 20

Tranfer liquid pipes larger

than 2 l/2 in. in diameter

any horizontal

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 atjy building where the IL/D patio is 5:1 or

greater the cp value shall be increased by 50k

Where H^, = height in ft. of the part of the system above the base level of

^ the building

D = The DIh€NSION of the structure in feet IN A DIRECTION PARALLEL TO

THE APPLIED FORCE

6-12
6-13
TABLE S-601.3

Values of weight and terminal velocity in free fall computed for smooth ice spheres.

Diameter Weight Terminal

in gm lb Velocity

ft/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

6-14
Commentary

The aorrelation of hail size with mean annual number of days with hail was determined using data relating the probability of ocaurrenae of hail

particle size to the number of days with hail (tabulated in Ref. [1]) , and

limited statistical information relating the local area covered by a hailstorm, and the regional area for which statistical data is compiled.

The hail size indicated has a 5% probability of being exceeded 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 imrplementing the requirements of this section.

S-601-8 MAINTENANCE LOADS

All components of the solar energy systems which must support maintenance

personnel shall be designed to 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.

S-601-9 TKEKJIAL DISTORTION

(1) Thennal distortion of the mechanical or structural components of the

solar system during operation and periods of stagnation shall not cause deterioration of the system's performance.

(2) Thermal distortion of the solar system shall not cause distress to the system or the supporting dwelling structure.

S-601-10 COLLECTOR COVER PLATES

(1) Deflection or local distress of cover plates resulting from the maximum

design loading shall not impair the functioning of the unit. 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.

[1] Storm Data , U.S. Dept. of Commerce, National Oceanic and Atmosphere

Administration, Environmental Data Service (monthly periodical)

6-15
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 practices

for the materials used. These standards shall be approved by HUD.

S-601-12. 2 Testing

Each liquid storage tank shall be tested by the manufacturer or the

installation contractor to prove that leakage does not occur. The test

pressure shall be 1.5 times the maximum design pressure for pressures less

than 15 psi; however, these pressures shall not be less than 5 psi. For

tanks designed for pressures greater than 15 psi, the proof test pressures

shall be approved by HUD.

Storage tanks designed to contain 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 the design, fabrication and test requirements, for storage

tanks stipulated in the preceeding paragraphs of this section, the

following loading requirements shall be included in the design of storage

tanks

S-601-12. 3.1 Above Ground

Unsheltered storage tanks shall be designed to resist loads resulting from,

snow, wind, hail, and siesmic loading. Sheltered (completely enclosed)

tanks need only be designed to resist seismic loading.

S-601-12. 3.1 Underground

Underground tanks shall be designed to 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, the wheel loads specified in AASHO H20-44 shall be used with no

impact. For areas subject to other vehicular or human traffic, the pertinant

loads stipulated in the MPS, section 601-4.3 shall be used.

Cormentary

The oHterion speaifies the level of vehicular traffic for which buried

aomponents 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.

S-601-13 DYNAMIC LOADS

Dynamic Loads resulting from sun tracking solar collectors or other moving

equipment shall be taken in to account in the design of the dwelling frame.

6-16
DIVISION 4

S-604

S-604-1

S-604-1.1

MASONRY

GENERAL

Termination Height of Masonry Chimneys

Termination height of masonry chimneys shall be in accordance with NFPA 211.

Commentary

The pvesenae of solar equipment may -introduce building components that are elevated above the roof surface more than is usually required, thus producing

wind distrubanoe at a higher level. The standard of NFPA 211 provides for

proper clearance and separation.

6-17
DIVISION 7

S-607 THERMAL AND MOISTURE PROTECTION

S-607-3 BUILDING INSULATION FOR PASSIVE SOLAR SYSTEMS

S-607-3.1 Insulation Values

Insulation values may vary where they can be shown to improve the overall

energy balance of the building.

CoTmentavii

Section 607-2 of MPS was originally written to conserve energy or minimize the U-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 shuttered window which has single glazing. Wnen the shutters are open

'the window collects energy and its U-value can be 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 607-2.

S-607-3. 2 Areas of Application

Materials used for thermal insulation may be applied in residential housing

to the following areas: walls, roofs, ceilings, floors, pipes, ducts,

vessels and equipment exposed to the external environment

Exposed plastic foam (untreated or f ire-retardant treated) and non-fireretardant treated cellulosic loose-fill insulation shall not be permitted

in habitable areas. These materials should be protected by a layer of

gypsum board of 1/2 inch thickness or greater, or an equivalent fire barrier.

Installed insulation and vapor barrier shall not make contact with recessed

light fixtures, motors, fans, blowers, heaters, flues, and chimneys.

Thermal insulation should 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.

Cormentary

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 praticular fire problem due to its

susaeptibilty to smouldering and its inaccessibility for firefighting

6-18
DIVISION 15

S-615 MECHANICAL

S-615-1 THEKMAL DESIGN

S-615-1.

General

The solar system shall be capable of collecting and converting solar energy

into thermal energy. Solar thermal energy shall be used, in combination

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.

Cormentavy

Solar systems for residential applications generally are capable of storing

and providing thermal energy to meet at least one design winter 24 hour

heating load.

The solar energy system thermal energy contribution shall be backed up 100 per cent with a thermal energy subsystem utilizing a conventional

energy source or a back-up system 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 system to meet comfort and hot water

standards.

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

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 temperatures

and night-time set-back.

a. The solar energy system size shall be based upon monthly average heat

loads detemined 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

S-615-1. 2 Back-up

S-615-1. 3 System Capacity - Space Heating

S-615-1. 3.1 Auxiliary Energy Subsystem

Commentary

S-615-1. 3. 2 Solar Energy System

6^9-
in sizing solar energy subsystem shall be performed for the full

heating season using a method at least as sophisticated as described

in Appendix A.

Cormentax'y

Since the methods of aalaulating heat losses and heat gain specified in

615-3.1 and 615-4.2 of the MPS may not be detailed enough to pvediot the

performanae of the heating and cooling systems fov 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

,i of detailed analysis are presented in ASHRAE Standard 90-75 Energy

,.. , . Conservation in Nei) 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 con- ditions 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

SO to 70% for an active system is generally optimum when cost benefits

have been considered. Passive systems may contribute from 5 to 100%

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 system shall meet the

minimum requirements for storage, draw and recovery shown in Tables 615-2

or 615-3 of MPS.

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

system performance with the load.

b. A minimum daily usage of 50 gal. of hot water from domestic use and 75 gal. when automatic cycle washers are included shall be used for

design purposes.

6-20
Cormentaru

The desicrn shall al7-0hi fov the higher requivement wheve the potentiat

increase in use exists.

c. An average hot water temperature of 140°F and an average source water

temperature of 50°F shall be used for design purposes, if local

temperatures are unkno^m.

Commentary

Tap temperatures as lew as 120''F may be local option however lower storage

temperatures are usually combined with larger storage to provide equivalent

thermal capacity. Local source water temperature can vary from. 45 to 75°

with climate region and season.

d. The solar energy contribution shall be determined as a percentage of

the dwelling average annual DHW energy requirements. Analytical

simulations 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 - Integral 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 hall and storage areas can be designed for fluctuation

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 6-15-3.16 of MPS when the space

is in use.

[1] Grandjean, Ftienne, 1973 Ergonometrics of the Home , New York,

Halstead Press. 6-21
Cormentary

The operation of a passive system is usually dependent upon natural oonveotive

or radiative heat transfer processes which are in turn dependent upon temperature gradients . Therefore the temperature differences of at least 4"? to

6''F are required in a completely passive system.

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 SHI Onoifi

The shutdown of the heating or domestic hot water system in one unit of a

multi-family duelling shaix not interfere with the function of these systems

in any other unit.

CoftlENTARY

This is to permit the shutdw^in 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.

6-22
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, provision shall

be incorporated in the manifolds and/or collectors to maintain the design

flow rate through each collector.

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. 1, No. 81266 (Associated Air Balance Council 2146

Sunset Blvd., Los Angeles, California 90026). "Fhe 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 IS 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-615.4 which shows, for a particular

example, the effect on annual performance of variations of tilt angles for a collector facing south.

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-61S.5.

A fixed collector tilt ar^le equal to the latitude or latitude +IS 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. The orientation of concentrator type collectors is a function of the collector acceptance an^le design and may require tracking

within specific limits.

S-615-2.1. 3 Shadowing

Shadowing of collectors shall be considered during the design so that

shadowing by trees or other obstructions do not exceed design limits.

Commentary

On east and west exposures during the entire year, and on south exposures

during the winter, and solar altitude may be low enough to cause direct

shading and a resultant loss in collection capability.

6-23
Figure S-615.A An example of the effect of Collector Tilt for

a particular System/Climate Combination.*

-90 -60 -JO O iO feO SO West seulh Eoit

Figure S-615.5 An example of the effect of Collector Orientation

(45° Tilt) for a particular Collector/Climate

Combination .

*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.

6-24
S-615-2.1.4 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 eves), thereby forming

an ice dam which can cause water to back up under roofing or into the

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 bottoyn 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.

S-615-2.1.5 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.

S-615-2.1.6 Protection Against Maximum Temperature and Pressure

Collectors shall not be damaged or adversely affected by maximum temperature

and pressure that could occur during periods when heat transfer fluid is not

flowing.

Commentary

Temperatures in excess of SOO'^F would probably occur within flat plate

collectors that are not cooled by heat transfer fluid. Such conditions

could occur during normal shut down, loss of fluid flow resulting from

pump or fan failure, system blockade, or loss of electric power.

The designer should either assure that the materials used in the collector

can withstand the maximxm temperatures and pressures or provide temperature

and pressure relief from thermal cyling or shock.

S-615-2.2 Collector Thermal Performance

S-615-2.2.1 General

This section is intended to cover subsystem, component and integral collectors

which can be flat plate, concentrating, reflector aided, fixed or tracking

types

6-25
Flat Plate Collectors

This type collector can be characterized as a subsystem or 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.

Commentar'y

The oolleotoT performanae Gharaateristics can be measured using the National

Bureau of Standards proposed test method (NBSIR 74-635) for rating solar

Golleators 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 shoim 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.

b. Combined Collectors and Storage Devices

This type of combined component system can be characterized as a 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.

c. Integral Collector, Storage and Building (Passive)

An integral collector system can be characterized as one in which the

collector and storage components are an integral part of the building in

a passive solar system. Auxiliary energy may be used for control purposes

but heating is generally achieved by natural heat transfer phenomena.

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 collectors.

The thermal performance of an integral collector system can be obtained

from a detailed simulation analysis of the climate, building thermal

properties and occupancy thermal influence.

6-26
Commentary

A more detailed simulation of solar heating, building thermal aapaoitanae and

thermal energy control must he included in the traditional building load

determination programs for the design and evaluation of an integral solar

system. Experimental evaluation of the system performance includes measure- ment of the climatic conditions, auxiliary energy use and comfort level for

sufficient periods to account for building thermal capacitance effects

(minirmm of 7 days) and, preferably, monthly or seasonal averages are obtained.

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 or similar valves shall be used for flow

control

S-615-5 PUMPS & COMPRESSORS

S-615-5.1 Applicable Standards

a. Pumps shall be installed in accordance with the requirements of the

Hydraulic Institute.*

b. Pump motors shall conform to appropriate NEMA Standards such as NEMA

Standard M Gl-18.615.

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 con- nections 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.

^ Hydraulic Institute Standards for Centrifugal, Rotary and Reciprocating Pumps, Thirte.

Edition, 1975. The Hydraulic Institute, 1230 Keith Building, Cleveland, Ohio 44115.

6-27
S-615-7 THERMAL STORAGE

S-615-7.1 Thermal Storage Requirements

S-615-7. 1.1 General Provisions

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 shovm in Appendix C.

Cormentary : The interaction between storage temperature and colleator

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 electrical "peak shaving" power or which use solar

assisted heat pumps may influence storage temperature or operation.

S-615-7. 1.2 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 a component

(active) system. The thermal energy storage capacity for space heating

shall be not less than 1000 Btu per square foot of collector area for an integral (passive) system.

Commentary : The relationship between the load fraction supplied by solar

energy to the storage capacity for liquid and air applications is presented

in Avvendix A. 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 cajpaoity is desired.

S-615-7. 1.3 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. 1.4 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.

S-615-7. 1.5 Thermal Energy Loss

The thermal energy loss from storage containers shall not exceed 10 percent

of the maximum operating thermal energy capacity over a 24 hour winter

design day.

6-28
Ccrmentarij : Calculations of the thermal loss from tanks, piping, and valves

aan be performed using average fluid and ambient temperatures and thermal

insulation conductivity values with procedures described in the ASHRAE Handbook of Fundamentals. In addition to energy loss, consideration of the heat

contribution to occupied spaces can result in more insulation.

S-615-7.1.6 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 shall

have provisions for utilizing a pump or siphon or other means to allow

emptying.

S-615-7.1.7 Vacuum Relief

The solar system, including collectors, pipes, tanks, and heat exchangers

shall be designed with vacuum relief valves or otherwise protected against

possible collapse.

Commentary : System components may be subjected to collapse if heating

system leakage were to occur or if the system were drained without venting.

S-615-7.1.8 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.

I

6-29
S-615-8 HEAT TRANSFER FLUIDS

S-615-8.1 Toxic and/or Flammable Media

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 Flammable Fluids

If nonpotable heat transfer fluids are used, means shall be provided for the

detection of leaks and the warning of occupants when leaks occur.

Conmentavy : These substances shall be treated in a manner similar to air

conditioning condensates, refrigerants (Chapter 14, ASHRAE Handbook of

Fundamentals) , and gases (NFPA 54) when providing for tell-tale indicators

For instance, antifreeze agents, such as ethylene glycol, should 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 con- tainers which are labeled in accordance with the Hazardous Substances Labeling

Act and are protected from easy opening by children, e.g., childproof lids.

Safe storage locations should be provided.

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. 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 hazardous media

Adequately sized and protected recepticles shall be provided when liquids

requiring special handling are used in order to collect and store the overflow from pressure relief valves, liquids drained from the system when it

is being serviced, potential leakage, and accidental drainage. Provisions

of MPS Section 615-A.4 shall be applied.

Commentary : When a toxic heat transfer medium is used (see Section S-515-

8.2.4), a catch basin must be provided. It must be sufficiently large to accept dilution as required by MPS Section 515-9 before disposal. 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).

6-30
S-615-10 PLUMBING

S-615-10. 1 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.

S-615-10. 1.1 Separation of Circulation Loops

Subsystems requiring the circulation of nonpotable heat transfer fluids

shall be separated from the domestic (potable) water system so that

contamination of the domestic water will not occur.

S-615-10. 1.2 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 Administrative Authority. Such

identification may not be required in all cases.

S-615-10. 1.3 Backflow Prevention

Backflow of nonpotable heat transfer fluids into the potable water system

shall be prevented in a manner approved by the Administrative Authority.

Cormentcanj : The use of air gaps and/ov mechanical backflow preventers are

two possible solutions to this problem. The following are some recognized

standards that may be acceptable to the administrative authority: Complete

titles are given in Appendix F.

Air gaps - A1^SI-A112. 1.2

Backflow preventers - FCCCHR Chapter 10

lAPMO 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-A112.1.1

S-615-10. 2 Pipe Sizing

Pipe sizing shall be in accordance with recognized methods.

Commentary : Piping system design guidance is given in Model Plumbing CodeSj

the Hydraulic Institute ' s Pipe Friction Manual - 1967, and in handbooks such

as "Handbook of Hydraulics" by King and Brater. [2]

]] Scheme for the Identification of Piping Systems, ANSI A13.1 - 1956.

2] Handbook of Hydraulics for the Solution of Hydrostatic and Fluid-Flow Problems,

by Horcace Williams King and Ernest F. Brater (McGraw-Hill Book Company)

5th ed. 1962.

6-31
S-615-10.

System Drainage

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. 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-615-7.1.6, Tank Drainage.

Commentary : One means of preventing oorrosion during system drainage would

be by introducing an inert gas suoh as nitrogen.

S-615-10. 4 Protection from Scalding

All domestic hot water systems shall be equipped with means of limiting

•

• . . temperature as required in MPS section 615-6.

S-615-10. 5 Provision of Valves and Fittings

S-615.10.5.1 Shutoffs

All domestic water heaters and water heating systems shall be valved to provide shutoff from the cold water supply systems.

S-615-10. 5.2 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

S-615-10. 5.3 Air Bleeds

When liquid heat transfer fluids are used in solar heating systems, the

systems shall be provided with suitable means for air removal from high

points in the piping system.

S-615-10. 5.4 System Flushing

To facilitate solar heating system maintenance and repair, systems employing

liquids shall be capable of being conveniently filled and drained. Suitable

connections shall be provided for flushing (cleaning) the system. All

piping shall be pitched to drain completely.

6-32
S-615-10.6 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-615-10.7 Leak Testing

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 [!]•

Cormentarij : A hydrostatic test pressure of 1-1/2 times design pressvo'e is

considered a standard test pressure. {2]. For most applications, clear water

is used. The temperature of the water should he 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

-615-10.8 Discharge of Liquids

Relief valves shall be piped to discharge to locations acceptable to the

administrative authority having jurisdiction.

10-615-10.9 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.

S-615-10.10 Underground Piping

Undergound 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-615-10.11 Treatment of Water

When make-up water is of such a quality that excessive corrosion is known

to exist, a suitable water treatment system as recommended by the Water

Conditioning Foundation shall be provided.

[1] The BOCA Basic Plumbing Code, Southern Standard Plumbing Code, and the Uniform

Plumbing Code.

[2] Piping Handbook, Remo C. King and Sabin Crocker, McGraw-Hill Book Company, 5th Edition.

6-33
S-615-10.12 Excess Collected Energy

Provisions for the dumping of thermal energy may be required when the energy

demand is less than the collected useful energy.

Commentary : For systems in which it is not praatiaal to shut the oolleation

system down, excess thermal energy can be disposed of by dumping to the

external environment.

S-615-11 AUXILIARY ENERGY SYSTEMS

S-615-11.1 Applicable Standards

a. Domestic water heaters shall comply with the following appropriate

standards

Oil UL-732

Gas AGA Listed

Electric UL-174

b. Heating systems shall comply with the following appropriate standards;

Oil UL-727 & 730

Gas AGA Listed

Electric UL-573, NFPA-70

Boiler (Steam & Water)

Oil MCA, SBI, IBR, UL-726 & 296

Gas MCA, SBI, AGA, IBR

Electric SBI, UL-174

Radiation

Baseboard IBR Rated

Finned Tube IBR Rated

Electric UL-1042, NESCA

Fuel Tanks UL-58

c. Heat pumps shall be installed in compliance with the requirements of

ANSI B9.1 - 1971, "Safety Code for Mechanical Refrigeration" (ASHRAE)

and ARI Standard 260, "Standard for Application, Installation, and

Servicing of Unitary Systems" (1967)

6-34
S-615-12 HEAT EXCHANGERS

S-615-12.1 Sizing

a. A heat exchanger when used in conjunction with the solar collector and

storage shall be sized such that the effectiveness in transferring heat

from the collector to storage is not less than 0.70. The heat exchanger

effectiveness is expressed by:

E = (m c ) (t - t)/(lTl c ) . (t- - t)

c p s 1 ' p mm 0

where

(m c ) . = the minimum capacitance rate of (m c ) collector

p mm p

(m c ) = flow circuit

P s

t = storage temperature (°F)

tQ = collector outlet temperature (°F)

ti = collector inlet temperature (°F) = effectiveness of the collector - storage heat exchangers

in = flow rate of the working fluid (Ibm/min)

Cp = fluid capacitance (Btu/lbm - °F)

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 5. This

dimensionless parameter and relationship is expressed by:

1< ^p^min < 3 UA

where

e = Effectiveness of load heat exchanger

UA = Building heat loss factor (Btu/Day °F)

Commentary : Diagrams of the typiaal location and performance of heat exchangers

are presented in Appendix A and C. Calculation methods for heat exchanger

performance are described in the ASHRAE Handbook of Fundamentals.

S-615-12. 2 Handling of Nonpotable Fluids

When nonpotable fluid is used in a solar energy system to transfer heat to domestic (potable) hot water, the design of the heat exchanger shall prevent

diffusion or mixing of the toxic fluid into the potable water should a leak

occur in the heat exchanger. The system should be designed so that a leak is

readily apparent.

6-35
S-615-13 AIR DISTRIBUTION

S-615-13. I Applicable Standards

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

recommendations of the ASHRAE GUIDE, manuals of NESCA and ARI. Installation

shall comply with NFPA standards 90B, 31 and 54.

Cormentary : Duat work should be designed for the shortest practical run and

elbows should he kept to a minimum. Constrictions should be avoided.

S-615-13. 2 Dust and Dirt Prevention

Duct and fan systems shall be protected against accumulation of deposits of

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 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 he removable or hinged to permit access to the fan and motor for cleaning, servicing, replacement, or

repair.

6- 36
S-615-14 CONTROLS AND INSTRUMENTATION

S-615-14. 1 Fall-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 requirements of Section 515-6.4 of MPS and

be demonstrated to be adequately safe and protected for the intended application.

S-615-14. 2.1 Automatic Pressure and Temperature Relief Valves for Nonflammable or Noncombustible Fluids

Adequately sized pressure and/or temperature relief valves, such as in MPS

Section 615-6.2, shall be provided in those parts of the energy transport

subsystem containing pressurized fluids.

Relief valves shall drain to locations acceptable to the local administrative

code authority.

Commentary : Precautions must he taken to assure that heat transfer solutions

do not discharge on asphalt base roofing materials or other type of roofing

or other locations which may he hazardous, cause structural damagey huilding

finish discoloration, or damage to shruhs and lawns.

S-615-14. 2. 2 Automatic Pressure and Temperature Relief Valves for Flammable or Combustible

Fluids

The fluid transfer system shall include a pressure relief valve. The valve

and its discharge system shall not permit fluid dischrage directly into the

occupancy. It is recommended that a holding tank be included in the system

for collection of discharge. The pressure relief valve shall be designed

based on maximum temperature criteria for abnormal operating conditions such

as no-flow. (AP must be limited to comply with temperature criteria.)

The fluid transfer system shall include a temperature relief valve. It shall

prevent further increase in temperature and provide discharge in the same manner as the pressure relief valve.

Maximum fluid temperature at which temperature relief valve shall operate:

a) 100°F below flashpoint of f luid» flash point to be determined in

accordance with NFPA 321, 1971, Standard on Basic Classification

of Flammable and Combustible Liquids.

b) 400°F

Local alarm shall be required to indicate a failure of the fluid transfer

system (e.g., leakage, pump failure) or activation of relief valves. Alarms

shall be installed in accordance with NFPA 26, Supervision of Valves, and

NFPA 72A.

S-615-14. 3 Identification and Location of Controls

Main shutoff valves and switches shall be considered comparable to electrical

service panels and be conspicuously marked and placed in an easily accessible

location in accordance with Section 240.24 of NFPA 70, and MPS, Section 616.

6-37
S-615-14.4 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

615-14.5 Efficient Operation

A differential thermostat shall be utilized to control operation of the collector

heat transfer fluid pump.

Commentary : The collector operation is limited to conditions when the heat

transfer fluid temperature in the collector is greater than in storage or for load requirements , a start-up AT" of 10"F and shutdown LT of 2°F are aormonly used.

S-615-15 CHIMNEYS AND VENTS

S-615-15.1 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 components

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.

S-615-16 MECHANICAL VENTILATION

S-615-16.1 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.

6-38
APPENDIX A

Calculation Procedures for Determining

the Thermal Performance of Solar Space

Heating and Domestic Hot Water Systems

TABLE OF CONTENTS

Page

INTRODUCTION A-1

SOLAR HEATING SYSTQIS A-3

Liquid Working Fluid A-3

Air Working Fluid A-5

SOLAR HEATING SYSTEM PERFORMANCE A-6

SYSTEM PERFORMANCE A-10

Total Heating Load A-10

Incident Solar Radiation A-13

Component Parameters A-15

Dimenslonaless Parameters A-17

Monthly Fraction of Total Heating Load

Supplied by Solar Energy A-17

Annual Fraction of Tol:al Heating Load

Supplied by Solar Energy A-19

A-1
Appendix A

INTRODUCTION

The performance of any solar heating system is directly related to the amount of solar

radiation available, the outside air temperature, the heated space thermal characteristics,

and the solar heating system characteristics. One type of a simplified solar heating

system and energy flow diagram is shown in the figure below.

Fluid Pump

Figure A-1

The goal in a solar heating system is to convert the absorbed solar radiation on the

collector into useful energy for keeping the heated space at a comfortable temperature with

reduced usage of conventional energy. The challenge is to do it In a way that is economically

competitive with conventional forms of heating.

Starting on the left side of the figure, solar energy falls on the solar collector.

Some energy is lost from the collector due to reflection from the collector and heat transfer to the ambient. 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 to the 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 is transferred as needed to meet the heating

load. If the TSD cannot meet the heating load , auxiliary energy from a conventional source

is necessary. Heat exchangers and pumping systems must be properly sized to meet energy

flow requirements.

Prediction of performance of solar heating systems is difficult due to the unpredictable

nature of weather and the mathematically complex relationships between the system components.

The procedure for estimating performance of a solar heating system used in this document

was developed by Klein, Beckman, and Duffie of the University of Wisconsin. Their approach

was to use a detailed hour by hour computer simulation for several typical solar heating

systems covering a wide range of system parameters and at several locations in order to develop a generalized performance chart (f-chart) to predict long-term system performance.
Although differences were found between the simulated and estimated performance using

the generalized chart for specific monthly periods, the correlation was found to be quite

satisfactory in most cases for predicting year-long performance, as shown in Fig. A-3. It should be emphasized, however, that the generalized performance chart 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 error in the fraction

of load to be met by solar predicted for four different cities was 0.014, an error judged to be substantially lower than the errors inherent in the simulation model and the recorded data.

The 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, the difference between actual performance and estimated performance over two complete heating seasons was about eight percent.

There are some limitations on the use of this procedure. The procedure was developed

for a liquid system as shown in Figure A-2 Figure A-2 is typical of most active solar heating

systems using a liquid as the heat transfer fluid. The procedure has been applied to air

systems with fairly good results; however, a study of the applicability of the procedure for

air systems has not been released. The procedure does not apply to passive systems or active systems that are not generally configured like Figure A-2. These other systems must

be analyzed in some other manner. The procedure cannot be used for systems in latitudes

farther north than sixty degrees.

The procedure is intended for use by architects and engineers to evaluate long-term

performance of most solar heating systems using a simple desk calculator or slide rule.

Solar Heating Systems

Liquid Working Fluid

A typical solar heating system that utilizes liquid as an energy transport medium is

shown in the figure below.

Figure A-2

As can be seen, the liquid system uses an insulated liquid thermal storage tank and heat

exchanger in appropriate fluid loops to transfer energy.

A-3
I.000

I I I I I I I I I

I

I I I I I I I I I

I I I I I I I I I I

I

I I I I I I I I I

I

I I ' ' -»'vv^'

.800 _

•GOO _

.400

.200 _

-.000

^

X X -I

X '^x

X)^

X * ^ X ^

X

x^x^

x^ X

XX

Standard Dev. - 0.0366 ~

Avg. Yr. Std, Dev. - 0.018 _

^^iln ^ 2 UA

- ^

"i Y\ ' ' ' ' ' ' 1 1 ' ' ' ' ' I ' ' I ' ' 1 1 1 ' 1 1 ' 1 1 ' ' I ' I ' ' ' I ' ' ' 1 1 1 ' 1

0.000 .200 .400 .600

f — SIMULATED

-BOO I. 000

Figure A-3 Comparison of system performance between f- chart and detailed simulation

A-4
Liquid systems are very flexible in that all components are independently connected

to the storage tank.

Liquid systems must be protected against corrosion, freezing, and over pressurizing;

but have the advantage over air systems of significantly more compact piping and storage.

Overall performance of a liquid system is comparable to that of an air system.

Air Working Fluid

A typical solar heating system that utilizes air as the energy transporting medium is

shown in the figure below.

Figure A-4

As can be seen, in addition to the air-cooled collector, an air system is generally characterized by the absence of heat exchangers and the use of a pebble bed thermal storage device.

By use of the thermostatically controlled dampers, four basic modes of operation are possible using a single fan; direct space heating from the collector, space heating from the

pebble bed storage unit, charging of the pebble bed storage unit from the collector, and

space heating using the auxiliary energy source.

Air systems in general do not have corrosion, freezing, or over-heating problems. Aircooled collectors generally run at lower efficiencies than liquid colled collectors, but the

absence of heat exchangers and the characteristics of pebble bed storage units make up for this

difference in performance. Air systems generally require more power to operate than do

liquid systems, but power requirements in a properly designed system are small when compared

to the solar energy gained.

A-5
SOLAR HEATING SYSTEM PERFORMANCE

General

a) The following procedure allows the estimation of long-term solar heating system

performance applicable for combined space heating and domestic hot water systems.

The method is also applicable to air heating systems. 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.

b) The evaluation of system heating performance is applicable for systems schematically

identical to Figure 1 or similar simplified models. 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. The auxiliary energy source is

connected such that it does not heat the thermal storage unit directly. The rate

of use of auxiliary energy is such that it provides just enough energy to supplement the solar heating system in meeting the 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 it was found that an energy per degree

day model was adequate. But in general, any procedure that accurately 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, but in general 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) 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 evacuated tubular collectors cannot be incorporated

into the solar heating system evaluation as it is presently written in this Appendix.

8) The system evaluation procedure as outlined in this Appendix can only accurately

predict system performance for systems using south facing collector arrays. Cases

of different collector orientations must be analyzed using a different procedure.

c) The fluid mass flow rate through the collectors may vary considerably for different

systems. The collector efficiency curve used as part of this evaluation procedure

shall have been generated for the collector flow rate used in the system under

consideration.

d) To eliminate reductions in system performance resulting from an undersized load heat

exchanger, the ratio of the capacitance rate in the heat exchanger to the heating load

(as given in equation [1]) should be greater than or equal to 1. Additionally, for

most considerations the ratio should be less than five. Cases involving a factor

outside this range may be evaluated by using a correction factor (K, ) for correcting

the fraction of the total heating supplied by solar. The method for utilizing the

correction factor will be described later in the procedure. The ratio of capacitance

rate in the heat exchanger to the heating load is given by:

A-6
1 _< L (liiCp)mln < 5 UA

(1)

effectiveness of the load heat exchanger

actual heat transfer

maximum possible heat transfer

minimum fluid capacitance rate / Btu \ Vh°F/

flowing across the load heat exchanger.

building load heat loss factor

Design Heat Loss Rate / StuN Design Temperature Difference \h°F/

The water to air or air to water load heat exchanger effectiveness (e^^) is easily

calculated from methods given in the ASHRAE Handbook of Fundamentals or from data

supplied by the manufacturer of the heat exchanger.

e) In the evaluation procedure, an example problem has been included for a system using

a liquid as the transfer fluid. Notes are included within the example whenever a different calculation step would be required in evaluating a system using air.

f) The system evaluation procedure consists basically of six steps:

1) Calculate the monthly total heating load (L)

2) Calculate the monthly incident solar radiation on the collector array (S)

3) Determine the component parameters; i.e., collector area, effectiveness of heat

exchangers, storage capacity, etc.

4) Knowing 1, 2, and 3 calculate two dimensionless parameters (D^, D2) for each month.

5) Using D and D„ for each month, calculate the monthly fraction of the heating load

supplied by solar energy, (f)

6) With the monthly loads and monthly functions supplied by solar, calculate (F ) the annual fraction of the heating load supplied by solar energy.

"

where

(mc )min

P

UA =

A-7
Nomenclature

2 A - Collector aperture area (ft ) (mCp) min - Min fluid capacitance [Btu/(h°F)]

c - Fluid capacitance [Btu/(lb°F)]

PD^, ^2 ~ Dimensionless parameters

At^ - Temperature difference for building design temperature conditions (°F) At - Total number of hours in a particular month (h) - Effectiveness of the collector-storage heat exchanger

e - Effectiveness of the load heat exchanger

1-1 © - Collector tilt (°)

E - Solar energy supplied for a particular month (Btu/Month)

^Total

~ Solar energy supplied for an entire year (Btu/Year)

f - Monthly fraction of total heating load supplied by solar energy

^annual

~ ^^^^^^ fraction of the total heating load supplied by solar energy

F - Collector heat removal factor

R

F^' - Combined form of the collector heat exchanger effectiveness (e ) and the collector

heat removal factor (F ) R Y- Solar collector azimuth angle (For Due South = 180°)

I - Monthly average of the daily radiation incident on a horizontal surface

[Btu/(Dayft2)]

_ 2

Irj, ~ Monthly average of the daily radiation incident on a tilted surface [Btu/(Dayft )] - Ratio of the monthly averages of the daily radiation on a horizontal surface to the

extraterrestrial radiation on a horizontal surface

- Correction factor to correct f for various storage capacities other than 15 Btu/(°F*ft2)

K„ - Correction factor to correct for (mc )min/UA other than 2

Z L p L - Total heating and hot water load for a particular month (Btu/Month)

'"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 - Flow rate of the working fluid either air or liquid (Ib/hr)

M - Mass of thermal storage (lb) N - Number of days in a particular month

0 - Latitude

- Space heating load for a particular month (Btu/Month)

- Domestic hot water heating load for a particular month (Btu/Month)

- 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

S - Monthly incident solar radiation on a tilted surface [Btu /(month- ft^)

]

t - Monthly average ambient air temperature (°F)

Si t^ - Temperature of domestic hot water supply (°F)

t^ - Temperature of water main supply (°F)

t^^^ - Reference temperature, 212°F

Atime - total number of hours in each month

A-8
Nomenclature (cont'd)

Ta - Average transmissivity-absorptivity product for design purposes

(xa)^ - Transmissivity-absorptivity product at normal incidence

- Collector heat loss factor [Btu/ (h- °F- f t^)

]

UA - Building heat loss factor [Btu/(h-°F)

References Cited

1. Klein, S. A., Beckman, W. A., and J. A. Duffie, "Design Procedure for Solar Heating

Systems," presented at the 1975 International Solar Energy Congress, UCLA,

Los Angeles, California, July 1975.

2. B. Y. H. Liu, R. C. Jordan, "Availability of Solar Energy for Flat-Plate Solar Heat

Collectors," Low Temperature Engineering Application of Solar Energy , ASHRAE,

New York, 1967.

A-9
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A-20
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A-21
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A-26
Table A-4

Radiation and Other Data for 80 Locations In the United States

.2 Monthly average dally total radiation on a horizontal surface, Btu/day-ft ; Kj = the fraction of the extraterrestrial radiation transmitted through

Albuquerque, N. M

Lat. 35°03'N

El. 5314 ft

Annette Is . , Alaska

Lat. 55''02'N n. 110 ft

Apalachlcola, Florida . . . Lat. 29°45'N

El. 35 ft

Astoria, Oregon

Lat. 46°12'N

El. 8 ft

Atlanta, Georgia

Lat. 33°39'N

El. 976 ft

Barrow, Alaska

Lat. 71°20'N

El. 22 ft

Bethel, Alaska

Lat. 60°47'N , El. 125 ft ,

Bismarck, North Dakota . Lat. 46°47'N

El. 1660 ft

Blue Hill, Mass

Lat. 42°13'N

El. 629 ft

Boise, Idaho

Lat. 43°34'N

El. 2844 ft

Boston, Mass.

Lat. 42°22'N

El. 29 ft

Brownsville, Texas . . . . Lat. 25''55'N

El. 20 ft

Caril»u, Maine

Lat. 46°52'N

El. 628 ft

Charleston, S.C

Lat. 32°54'N

El. 46 ft

Cleveland, Ohio .......

Lat. 41°24'N , El. 805 ft

Columbia, Mo

Lat. 38°58'N

El. 785 ft

Columbus, Ohio , Lat. 40''00'N , El. 833 ft ,

Davis, Calif Lat. 38''33'N

El. 51ft

Dodge City, Kan

Lat, 37°46'N

El. 2592 ft

East Lansing, Michigan

Lat. 42°44'N

El. 856 ft

East Wareham, Mass . . Lat. 41° 4674

El. 18 ft

2h

Jh

-5

a

aIn

aIhh

Ih

in

haIhbahaIh

hahaIh

Jan

1150.9 0.704

37.3

236.2

0.427

35.8

1107 0.577

57.3

338.4

0.330

41.3

848 0.493

47.2

13.3

-13.2

142.4 0.536

9.2

587.4 0.594

12.4

555.3 0.445

28.3

518.8 0.446

29.5

Feb

1453.9 0.691

43.3

428.4

0.415

37.5

1378.2 0.584

59.0

946.

0.541

53.6

466.8 0.361

30.8

651.3

0.458

32.5

486.3 0.356

32.1

599.2 0.416

47.6

953.

0.639

33.8

425.8 0.35

26.0

504.4

0.398

32.2

Mar

1925.4 0.719

50.

883.4

0.492

39.7

1654.2 0.576

62.9

607 1008.5 0.397 0.454

44.7 46.9

1080.

0.496

49.6

143.2 0.776

-15.9

1426.9 0.522

55.9

713.3 0.773

-12.7

404.8 1052.4 0.557 0.704

11.6 14.2

934.3

0.628

15.9

797 0.458

28.3

884.9 0.533

36.5

505.5 738 0.410 0.426

31.4 31.4

1105.9 1262.7 0.517 0.500

63.3 66.7

497 861.6 0.504 0.579

11.5 12.8

1152.8

0.521

55.2

681.9 0.383

30.9

941.3

0. 492 36.5

746.5 0.401

33.7

739.

0.431

26.4

1328.4

0.605 29.7

1143.9 0.477

36.9

1280.4 0.548

45.0

1067.

0.445

39.9

1505.9 0.505

70.7

1360.

0.619

24.4

1352.4 0.491

60.6

1207 0.497

39.4

1315.8 0.520

45.9

1112.5 0.447

42.7

945 1504 0.490 0.591

52.1 56.8

1186.3 1565.7 0.598 0.606

38.7 46.5

1086 0.456

35.7

762.4 1132.1 0.431 0.469

31.6 39.0

Apr

2343.5

0. 722 59.6

1357.2 0.507

44.4

2040.9 0.612

69.5

1401.5 0.471

51.3

1807 0.551

65.0

1491.5 0.726

2.1

1662.3 0.675

29.4

1668.2 0.565

46.6

1438 0.464

46.9

1814.4 0.594

53.5

1355 0.438

49.5

1714

0. 509 76.2

1495.9 0.507

37.3

1918.8 0.584

67.8

1443.9 0.464

50.2

1631.3 0.514

57.7

1480.8 0.470

53.5

1959 0.617

63.

1975.6 0.618

57. 7

1249.8 0.406

48.4

1392.6 0.449

48.3

May Jun

2560.2757.

0.713 0.737

69.4 79.1

1634.

1638.

0.484 0. 441 51.0 56.2

2268.

2195.9 0.630 0.594

76.4 81.8

1838.

1753.

0.524 0.466

55.0 59.3

2618. 12 2002.

0.561 0.564

73.2 80.9

1883 2055 .

0.553 0.533

20.5 35.4

1711.1698.

0. 519 0. 458

42. 7 55.5

2056.2173.8 0.588 0. 579 58.6 67. 9

1776.4 1943.9 0.501 0. 516

58. 5 67. 2

2189.3 2376.7

0. 619 0. 631

62. 1 69.3

1769 1C64 0.499 0.495 60.4 69.8

2092.2288.

0.584 0.627

81.4 85. 1

1779.1779.

0.509 0.473

51.8 61.6

2063.2113.

0.574 0. 567

74.8 80.9

1928.

2102.

0. 543 0. 559

62. 4 72. 7

1999.6 2129.

0. 559 0. 566

66. 7 75.9

1839.

(2111)

0. 515 (0.561)

64. 4 74.2

2368.6 2619.

0.662 0.697

69.6 75. 7

2126.5 2459.8 0.594 0.655

66. 7 77.2

1732.8 1914 0.489 0.508

59.8 70.3

1704.8 1958.3 0.480 0.520

58.9 67.5

Jul

2561.2 0.695

,82.8

1632.

0. 454

58.6

1978.6 0.542

83.

2007.7 0.551

62.6

2002.9

0.545 82.4

1602.2 0.448

41.6

1401.8 0.398

56.9

2305.5 0.634

76.

1881.5 0.513

72.3

2500.3 0.684

79.6

Aug

2387.8

0. 708 80.6

1269.

0.427

59.8

1912.9 0.558

83.

1721 0.538

63.6

1898.

0.559

81.6

953. 5 0.377

40.0

938. 7 0.336

54.8

1929.

0.606

73.5

1622.1

0. 495 70.6

2149.4

0.660

77. 2

1860.5 0.507

74.5

2345 0.650

86.5

1898.1 0.522 67.2

1649.4 0.454

82.9

2094.4

0.571

77.0

2148.7 0.585

81.

2041.3

0.555

78

2565.6 0.697

81

2400.7 0.652

83.8

1884.5 0.514

74.5

1873.8 0.511

74.1

Sep

2120.3 0.728

73.6

962 0.449

54.8

1703.3 0.559

80.6

1322.5 0.526

62.2

1519.2 0.515

77.4

428.4

0.315

31.7

755 0.406

47.4

1441.3 0.581

61.6

1314 0.492

64.2

1717.7 0.656

66.7

1570.

0.480

73.8

2124 0.617

86.9

1675.6 0.527

65.0

1933.6 0.569

82.3

1840.6 0.559

75.

1953.1 0.588

79.4

1572.7 0.475

75.9

2287.8 0.687

79.4

2210.7 0.663

82.4

1627.7 0.498

72.4

1607.4 0.489

72.8

Oct

1639.8 0.711

62.

454.6 0.347

48.2

1544.6 0.608

73.2

780.4 0.435

55.7

1290.8 0.543

66.5

152.4 0.35

18.6

430.6

0.432

33.7

1267.5 0.477

66.8

1774.9 0.566

84.

1254.6 0.506

56.2

1557.2 0.525

79.1

1410.3 0.524

68.5

1689.6 0.606

71.9

1189.3 0.433

70.

1856.8 0.664

76.7

1841.7 0.654

73.7

1303.3 0.493

65.0

1363.8 0.508

65.9

Nov

1274.2 0.684

47.8

220.3 0.304

41.9

1243.2 0.574

63.7

Dec

1051.6 0.704

39.4

152 0.361

37. 4

982.3

0.543

58. 55

413.6 295.2

0.336 0.332

48.5 43.9

997.8

0.510

54.8

22.9

2.6

164.9 0.399

19.0

1018.1 600.4

0.584 0.510

49.6 31.4

941 0.472

54.

1128.4 0.588

56.3

592.2 0.406

43.3

678.6

0. 494

42.3

896. 7 0.453

57.4

1536.5 0.570

78.9

793 0.455

44.7

997 0.491

57.4

919.5

0.441

58

479 0.302

44.5

1421 0.650 61.7

891.5 0.456

53.5

996.7 0.496

56

751.6

0. 474 47.7

-8.6

830.459

9.4

464.2 0.547

18.4

482. 3 0.436

31. 5

456.8

0.442

33.

535,8 442.8 0.372 0.400

46.6 34.9

1104.8 982.3

0.468 0.488

70.7 65.2

415.5 398.9 0.352 0.470

31.3 16.8

1332.1 1073.8 952 0.554 0.539 0.586

69.8 59.8 54.0

526.6 427.3 0.351 0.371 44.0 32.8

1202.6 839.5 590.4

0.562 0.510 0.457

61.4 46.1 35.8

430.2

0.351

34,0

1288.5 795.6 550.5

0.598 0.477 0.421

67.8 57 48.7

1065.3 873.8

0.625 0.652

46.5 36.8

473.1 379.7

0.333 0.349

40.0 29.0

636.2 521 0.431 0.461

46 34.8

Ar-27
Jan Feb Mar Apr

Edmonton, AlberU lu 331.7 652.4 1165.3 1541.7

Lat. 53°35'N K 0.529 0.585 0.624 0.564

El. 2219 ft T 10.4 14 26.3 42.9

Q

El Paso, Texas Ih 1247.6 1612.9 2048.7 2447.2

Lat, 31°48'N ft 0.686 0.714 0.730 0.741

El. 3916 « f 47.1 53.1 58.7 67.3 a

Ely, Nevada 'l^ 871.6 1255 1749.8 2103.3

Lat. 39°17'N fC 0.618 0.660 0.692 0.664

El. 6262 ft t 27.3 32.1 39.5 48.3

a

Fairbanks, Alaska Ih 66 283.4 860.5 1481.2

Lat. 64'49'N R 0.639 0.556 0.674 0.647

El. 436 ft t -7.0 0.3 13.0 32.2 a

Fort Worth, Texas Ih 936.2 1198.5 1597.8 1829.1

Lat. 32'>50'N . . . K 0.530 0.541 0.577 0.556

El. 544 ft t 48. 1 52.3 59.8 68.8 a

Fresno, Calif Ih 712.9 1116.6 1652.8 2049.4

Lat. 36°46'N Tt 0.462 0.551 0.632 0.638

El. 331 ft t 47.3 53.9 59.1 65.6

a

Gainesville, Fla Ih 1036.9 1324.7 1635 1956.4

Lat. 29°39'N 'R^ 0.535 0.56 0.568 0.587

El. 165 ft t 62. 1 63. 1 67.5 72.8 a

Glasgow, Mont Ifl 572.7 965.7 1437.6 1741.3

Lat. 48°13'N R. 0.621 0.678 0.672 0.597

El. 2277 ft t' 13.3 17.3 31.1 47.8 a Grand JuncUon, Colo Ip 848 1210.7 1622.9 2002.2

Lat. 39°07'N •. KL 0.597 0.633 0.643 0.632

El. 4849 ft t^ 26.9 35.0 44.6 55.8 a

Grand Lake, Colo ^^ 735 1135.4 1579.3 1876.7

Lat. 40°15'N K 0.541 0.615 0.637 0.597

El. 8389 ft t 18.5 23.1 28.5 39.1 a

Great Falls, Mont l^ 524 869.4 1369.7 1621.4

Lat. 47°29'N jC 0.552 0.596 0.631 0.551

El. 3664 ft t 25.4 27.6 35.6 47.7 a

Greensboro, N.C Ih 743.9 1031.7 1323.2 1755.3

Lat. 36°05'N K. 0.469 0.499 0.499 0.543

El. 891 ft t 42.0 44,2 51.7 60.8 Q

Griffin, Georgia Ih 889.6 1135.8 1450.9 1923.6

Lat. 33°15'N K 0.513 0.517 0.528 0.^86

El. 980 ft y 48.9 51.0 59.1 66.7

Hatteras, N.C l^ 891.9 1184.1 1590.4 2128

Lat. 35°13'N K 0.546 0.563 0.593 0.655

El. 7 ft y 49.9 49.5 54.7 61.5

Indianapolis, Ind Ijj 526.2 797.4 1184.1 1481.2

Lat. 39°44'N K 0.380 0.424 0.472 0.47

El- 793 ft V 31.3 33.9 43.0 54.1

Inyokern, Calif 'l^ 1148.7 1554.2 2136.9 2594.8

Lat. 35''39'N K. 0.716 0.745 0.803 0.8

El. 2440 ft . . . y 47.3 53.9 59.1 65.6

Ithaca, N.Y 434,3 755 1074,9 1322,9

Lat, 42°27'N vL 0,351 0,435 0.45 0 428

El. 950 ft V 27.2 26.5 36 48.4 Lake Charles, La 1^ 899.2 1145.7 1487.4 1801.8

Lat. 30'13'N K 0.473 0.492 0.521 0.542

El. 12 ft V 55.3 58.7 63.5 70.9 Lander, Wyo Ih 786.3 1146.1 1638 1988,5

Lat, 42°48'N IC 0.65 0.672 0.691 0.647

El. 5370 ft y 20.2 26.3 34.7 45.5 Las Vepas, Nev Ih 1035.8 1438 1926.5 2322.8

Lat. 36°05'N TL 0.654 0.697 0.728 0.719

El. 2162ft y 47.5 53.9 60.3 69.5 Lemont, Ullnols 1^ (590) 879 1255.7 1481.5

Lat. 41°40'N R (0.484) 0.496 0.520 0.477

El. 595 ft y 28.9 30.3 39.5 49.7

Lexington, Ky I„ . . - 1334.

Lat. 38''02'N K - - - 0.575

El- 979 ft V 36.5 38.8 47.4 57.8

May Jun Jul Aug Sep Oct Nov Dec

1900.4 1914.4 1964.9 1528 1113.3 704.4 413.6 245 0,558 0,514 0,549 0,506 0,506 0.504 0.510 0.492

55.4 61.3 66.6 63.2 54.2 44.1 26.7 14.0

2673 2731 2391.1 2350,5 2077,5 1704,8 1324,7 1051.6 0.743 0.733 0.652 0.669 0.693 0.695 0.647 0,626

75,7 84.2 84,9 83,4 78.5 69.0 56.0 48.5

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

1806.2 1970.8 1702,9 1247,6 699.6 323.6 104.1 20.3 0.546 0.529 0.485 0.463 0.419 0.416 0.47 0.458

50.5 62.4 63.8 58.3 47.1 29.6 5.5 -6.6

2105.1 2437.6 2293.3 2216.6 1880.8 1476 1147.6 913,6 0.585 0.654 0.624 0.653 0.634 0.612 0.576 0,563

75,9 84.0 87.7 88.6 81.3 71.5 58.8 50.8

2409.2 2641.7 2512.2 2300.7 1897.8 1415.5 906.6 616.6

0.672 0.703 0.682 0.686 0.665 0.635 0.512 0.44

73.5 80.7 87.5 84.9 78.6 68.7 57.3 48.9

1934.7 1960.9 1895.6 1873.8 1615,1 1312,2 1169,7 919,5

0.538 , 0.531 0.519 0.547 0.529 0.515 0.537 0.508

79.4 83.4 83.8 84.1 82 75.7 67.2 62.4

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

2300.3 2645.4 2517.7 2157.2 1957.5 1394.8 969.7 793.4

0.643 0.704 0.690 0.65 0.705 0.654 0.59 0.621

66.3 75.7 82.5 79.6 71.4 58.3 42.0 31.4

1974.9 2369,7 2103,3 1708.5 1715.8 1212.2 775.6 660.5

0.553 0.63 0.572 0.516 0.626 0.583 0.494 0.542

48.7 56.6 62.8 61.5 55.5 45.2 30.3 22.6

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

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

2163.1 2176 2064.9 1961.2 1605.9 1352.4 1073.8 781.5 0.601 0.583 0.562 0.578 0.543 0.565 0.545 0.487

74.6 81.2 83.0 82.2 78.4 68 57.3 49.4

2376.4 2438 2334.3 2085.6 1758.3 1337,6 1053,5 798,1 0,661 0,652 0,634 0,619 0,605 0,58 0,566 0.535

69,9 77,2 80,0 79,8 76,7 67.9 59.1 51.3

1828 2042 2039.5 1832.1 1513.3 1094.4 662.4 491.1 0.511 0.543 0.554 0.552 0.549 0.520 0.413 0.391

64.9 74.8 79.6 77.4 70.6 59.3 44.2 33.4

2925.4 3108.8 2908.8 2759.4 2409.2 1819.2 3170.1 1094.4 0.815 0.830 0.790 0.820 0.834 0.795 0.743 0.742

73.5 80.7 87.5 84.9 78.6 68.7 57.3 48.9

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

2080.4 2213.3 1968.6 1910.3 1678.2 1505.5 1122.1 875.6 0.578 0.597 0.538 0.558 0.553 0.597 0.524 0.494

77.4 83.4 84.8 85.0 81.5 73.8 62.6 56.9

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

56.0 65.4 74.6 72.5 61.4 48.3 33.4 23.8

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

1866 2041.7 1990.8 1836.9 1469.4 1015.5 (639) (531) 0.525 0.542 0.542 0.559 0.547 0.506 (0.433) (0.467) 59.2 70.8 75.6 74.3 67.2 57.6 43.0 30.6

2171.2 - 2246.5 2064.9 1775.6 1315.8 - 681.5 0.606 - 0.610 0.619 0.631 0.604 - 0.513

67.5 76.2 79.8 78.2 72.8 61.2 47.6 38.5

A-28
Lincoln, Neb

Lat. 40°51'N Q. 1189 ft

Little Rock, Ark

Lat. 34°44'N

El. 265 ft

Los Angeles, Calif. (WBAS).

Lat. 33°56'N

El. 99 ft

Los Angeles, Calif. (WBO). . Lat. 34°03'N

El. 99 ft

Madison, Wis

Lat. 43°08'N

El. 866 ft

Matanuska, Alaska

Lat. 61°30'N

El. 180 ft

Medford, Oregon H

Lat. 42°23'N

El. 1329 ft

Miami, Florida

Lat. 25°47'N

El. 9 ft

Midland, Texas

Lat. 31°56'N

El. 2854 ft

Nashville, Tenn

Lat. 36°07'N

El. 605 ft New Port, R.I

Lat. 41°29'N

Ei. 60 ft New York, N. Y

Lat. 40°46'N

El. 52 ft Oak Ridge, Tenn

Lat. 36°01'N

El. 905 ft

Oklahoma City, Oklahoma . . Lat. 35°24'N

El. 1304 ft

Ottawa, Ontario

Lat. 45°20'N

El. 339 ft

Phoenix, Ariz

Lat. 33°26'N

El. 1112 ft

Portland, Maine

Lat. 43°39'N Q. 63 ft

Rapid City, S.D

Lat. 44°09'N

El. 3218 ft

Riverside, Calif Lat. 33°57'N

El. 1020 ft

St. Cloud, Minn

Lat. 45''35'N

El. 1034 ft

Salt Lake City, Utah

Lat. 40°46'N

El. 4227 ft

San Antonio, Tex

Lat. 29°32'N

El. 794 ft

Q

ha

Ih

QIn

QIh

aIh

iHft

-5

iHft

iH

Jan

712.5 0.542

27.8

704.4 0.424

44.6

930.6

0.547

56.2

911.8

0.538

57.9

564.6

0.49

21.8

119.2 0.513

13.9

435.4

0.353

39.4

1292.2 0.604

71.6

1066.4 0.587

47.9

589. 7 0.373

42.6

565.7 0.438

29.5

539.5 790.8 0.406 0.435

35.0 34.9

Feb Mar

955. 7 1299.

0.528 0.532

32.

42.4

974. 2 1335.

0.458 0.496

48.5 56.0

1284.

1729.

0.596 0.635

56.9 59.2

1223.6 1640.9 0.568 0.602

59. 2 61.8

812. 2 1232.

0.478 0.522

24.6 35.3

345 0.503 - 21.0 27.4

804. 4 1259.

0.464 0.527

45.4 50.8

1554. 6 1828.

0.616 0.612

72.0 73.8

1345.1784.8 0.596 0.638

52.8 60.0

907 1246.

0. 440 0. 472

45. 1 52.9

856.4 1231.7 0.482 0.507

32.0 39.6

604 0.382

41.9

895.9

0.435

44.2

938 1192.6 0.580 0.571

40.1 45.0

539.

0.499

14.6

852, 4 0.540

15.6

1126.6 1514.7 0.65 0.691

54.2 58.8

565.7

0.482 23.7

874. 5 0.524

24.5

687.8 1032.5 0.601 0.627

24.7 27.4

999.6

0.589

55.3

1335 0.617

57.0

632.8 976.7

0.595 0.629

13.6 16.9

622.1 986 0.468 0.909

29.4 36.2

1045 1299.2 0.541 0.550

53.7 58.4

1180.4 0.480

43.

1241.7 0.471 51.7

1534.3 0.576

53.2

1250.5 0.554

27.7

1967.

0.716

64.7

1329.5 0.569

34.4

1503.7 0.649

34.7

1750.5 0.643

60.6

1383 0.614

29.8

1301.1 0.529

44.4

1560.1 0.542

65.0

Apr

1587.8 0.507

55.8

1669.4 0.513

65.8

1948 0.595 61.4

1866.8 0.571

64.3

1455.3 0.474

49.0

1327.6 0.545

38.6

1807.4 0.584

56.3

2020.6 0.600

77.0

2036.

0.617

68.8

1662.3 0.514

63.0

1484.8 0.477

48. 2

1426.2 0.455

52.3

1689.6 0.524

61.4

1849.4 0.570

63.6

1506.6 0.502

43.3

2388.2 0.728

72.2

1528.4 0.500

44.8

1807

0. 594 48.2

1943.2 0.594

65. 0

1598,

0.534

46.2

1813.3 0.579

53.9

1664.6 0.500

72.2

May

1856.

0.522

65.8

1960. 0.545

73.

2196.7 0.610

64.2

2061.2 0.573

67.6

1745.4 0.493

61.0

1628.4 0.494

50.3

2216.2 0.625

63.

2068.6 0.578

79.9

2301.

0.639

77.2

1997 0.556

71.4

1849 0.520

58.6

1738.4 0.488

63.3

1942.8 0.541

69.8

2005.

0.558

71.2

1857.2 0.529

57.5

2709.6

0. 753 80,8

1923.2 0.544

55.4

2028

0. 574

58.3

2282.3 0.635

69.4

1859.4 0.530

58.8

Jun

2040.6 0.542

76.0

2091.5

0.559

76,7

2272,3 0,608

66.7

2259 0.605

70.7

2031.7 0.540

70.9

1727.6 0.466

57.6

2440.5 0.648

69.4

1991.5 0.545

82.9

2317.7 0.622

83.9

2149.4

0.573

80.

2019.2 0.536

67.0

1994.1 0.53

72.2

2066.

0.551

77.8

2355 0.629

80.6

2084.5 0.554

67.5

2781.5

0.745

89.2

2017.3 0.536

65.

2193.7

0.583

67.3

2492.6 0.667

74.0

2003.3 0.533

68.5

Jul

2011.4

0.547

82.6

2081.2 0.566

85.

2413.6 0.657

69.6

2428.4

0.66

75.8

2046.5 0.559

76.8

1526.9 0.434

60.

2607.4 0.710

76.9

1992.6 0.552

84.1

2301.8

0.628 85.7

2079.7

0. 565 83.2

1942.8 0.529

73.2

1938.7 0.528

76.9

1972.3 0.536

80.2

2273.8 0.618

85.5

2045.4

0.560

71.9

2450.5 0.667

94.6

2095.6 0.572

71.1

2235.8 0.612

76.3

2443.5 0.665 81.0

2087.8 0.573

74.4

Aug

1902.6 0.577

80.2

1938.7 0.574

84.6

2155.3 0.635

70 .-2

2198.9 0.648

76. 1

1740.2 0.534

74.4

1169 0.419

58.

2261.6

0.689

76.4

1890.8 0.549

84.5

2193 0.643

85,0

1862.7 0.554

81.9

1687.

0.513

72.3

1605.9 0.486

75.3

1795.6 0.534

78,8

2211 0.565

85.4

1752.4 0.546

69.8

2299.6 0.677

92.5

1799.2 0.554

69.7

2019.9 0.622

75.0

2263.8 0.668

81,0

1828.4 0.570

71.9

63.

2024.7 0.563

79.2

71.7

814.8

0.220

85.0

81.3

2364.2 0.647

87.4

79.0

2185.2 0.637

87.8

Sep

1543.5 0.568

71.5

1640.6 0.561

78.3

1898, 1 0.641

69.

1891,5 0.643

74.2

1443.9 0.549 65.6

737.3 0.401

50.2

1672.3 0.628

69.6

1646.8 0.525

83.3

1921.8 0.642

78,9

1600.7 0.556

76.6

1411.4 0.524

66,7

1349.4 0.500

69.5

1559.8 0.542

74. 5

1819.2 0.628 77.4

1326.6 0.521 61.5

2131.3

0.722 87.4

1428.8 0.546

61.9

1628 0.628

64.7

1955.3 0.665

78.5

1369.4 0.539

62.5

1689.3 0.621

68.7

1844.6 0.603

82.6

Oct

1215.8 0.596

59.9

Nov

773.4 0.508

43.2

Dec

643.2

0.545

31.8

1282.6 913.6 701.1 0.552 0.484 0.463

67.9 54.7 46,7

1372.7 1082.3 0.574 0.551

66.1 62.6

901. 1 0.566

58, 7

1362.3

0. 578 69.6

993 0.510

53.7

373.8 0.390

37.7

1043.5 0.526

58.7

1436.5 0.534

80.2

1470.8 0.600

70.3

1223,6

0. 540 65,4

1035.4 0.512

56.2

977.8

0.475

59.3

1194.8 0.527

62.7

1409.6 0.614

66.5

826.9 0.450

48.9

1688.9 0.708

75.8

1035 0.539

51.8

1053.1 877.8 0.548 0.566 65.4 60.2

555.7 0.396

37.8

495.9 0.467

25.4

142.8 56.4 0.372 0.364

22.9 13.9

558. 7 0.384

47.1

346.5

0.313

40.5

1321 1183,4

0.559 0.588

75.6 72.6

1244.3 0.609

56.6

1023.2 0.611

49.

823.2 614,4

0.454 0.426

52.3 44,3

656.

0.44

46.5

527.7 0.460

34,4

598. 1 476 0.397 0.403

48.3 37.7

796.3 0.438

50.4

610 0.422

42.5

1085.6 897.4

0.588 0.608

52.2 43.1

458.7

0.359

35

1290 0.657

63.6

591.5 0.431

40.3

408,5 0.436

19.6

1040.9 0.652

56,7

507.7

0.491

28.0

1179.3 763.1 590.4 0.624 0.566 0.588

52,9 38.7 29.2

1509.6 1169 979.7

0.639 0.606 0.626

71.0 63.1 57.2

890.4 0.490

50.2

545.4 463.1

0.435 0.504

32.1 18.3

1250.2 0.610

57.0 42.

552.8 0.467

34.0

1487.4 1104.4 954.6

0.584 0.507 0.528

74.7 63.3 56.5

A^29.
Jan Feb Mar Apr

SanU Maria, Call!

Lat. 34''54'N

El. 238 ft

Sault Ste. Marie, Michigan

Lat. 46°28'N a. 724 it

Sayville, N.Y

Lat. 40°3O'N

El. 20 ft

Schenectady, N.Y

Lat. 42''50'N

El. 217 ft

Seattle, Wash

Lat. 47°27'N

El. 386 ft

Seattle, Wash

Lat. 4T'36'N •. . . . El. 14 ft

Seabrook, N.J

Lat. 39° 30 'N

El. 100 ft

Spokane, Wash

Lat. 47°40'N

El. 1968 ft

State College, Pa

Lat. 40°48'N

El. 1175 ft

Stillwater, Okla

Lat. 36''09'N

El. 910 ft

Tampa, Fla

Lat. 27°55'N

El. 11 ft

Toronto, Ontario

Lat. 43°41'N

El. 379 ft

Tucson, Ai'izona

Lat. 32°07'N

El. 2556 ft

Upton, N.Y

Lat. 40°52'N

El. 75 ft

Washington, D. C. (WBOO).

Lat. 38°5rN , El. 64 ft ,

Winnipeg, Man

Lat. 49°54'N

El. 786 ft

iH

In

-5

a

in

a

983.

1296.

0. 595 0.613

54.1 55. 3

488.

843.

0. 490 0. 560

16.3 16.2

602.9 936. 2

0. 453 0. 511

35 34.9

488. 2 753. 5

0. 406 0. 441 24.7 24.6

282. 6 520.

0. 296 0. 355

42.

45.0

252 471.6

0. 266 0. 324

38.9 42.9

591.9 854. 2

0. 426 0. 453 39.5 37.6

446.837.

0. 478 0. 579 26.5 31.7

501.749. 1 0. 381 0. 413 31.3 31.4

763. 8 1081.

0. 484 0. 527

41.2 45.6

1223.

1461.

0. 605 0. 600 64.2 65.7

451. 3 674. 5 0. 388 0. 406 26.5 26.0

1171.9 1453.

0. 648 0. 646 53.7 57.3

583 872 7

0. 444 0. 483 35.0 34.

632.4 901.5

0.445 0.470

38.4 39.6

488.2 835.4

0.601 0.636

3.2 7.

1805.9 0.671

57.6

1336.5 0.606

25.6

1259.4 0.510

43.

1026.6

0. 433 34.9

992.2

0.456

48.9

917.3 0.423

46.9

1195.6 0.476

43.9

1200 0.556

40.5

1106.6 0.451

39.8

1463.8 0.555

53.8

1771.9 0.606

68.8

1088.9

0. 467

34.2

62.3

2067.9 0.636

59.5

1559.4 0.526

39.5

1560.5 0.498

52.3

1272.3 0.413

48.3

1507 0.510

54. 1

1375.6 0.468

51.9

1518.8 0.481

54.7

1864.6 0.602

49.2

1399.2 0.448

51.3

1702.6 0.528

64. 2

2016.2 0.602

74.3

1388.2 0.455

46. 3

2434.

0. 738 69.7

1280.4 1609.9 0.522 0.514

43.1 52.3

1255 0.496

48.

1600.4 0.504

57.5

May

2375.6 0.661

61.2

1962.3 0.560

52. 1

1857.2 0.522

63. 3

1553.

0.438

61.7

1881.5 0.538

59.8

1664.9 0.477

58.

1800.7 0.504

64.9

2104.4

0.603

57.9

1754.6 0.493

63.4

1879.3 0.523

71.6

2228 0.620

79.4

1785.2 0.506

58

78.0

1891.5 0.532

63.3

1846.8 0.516 67.7

Jun

2599.6 0.695

63.5

2064.2

0. 549 61.6

2123.2 0.564

72.2

1687.8 0.448

70.8

1909.9 0.508

64.4

1724 0.459

62.8

1964.6 0.522

74.1

2226.5 0.593

64.6

2027.6 0.539

71.8

2235.8

0.596

81. 1

2146.5 0.583

83.0

1941.7 0.516

68. 4

2601.4 0.698

87.0

2159

0. 574

72.2

Jul

2540.6 0.690

65.3

2149.4

0.590

67.3

2040.9

0.555

76.9

1662.3

0. 454 76.9

2110.7

0.581

68.4

1805.

0.498

67.2

1949.8 0.530

79.8

2479.7

0.684

73.4

1968.2

0. 536 75.8

2224.3 0.604

85.9

1991.9 0.548

84.0

1968.6

0. 539 73.8

2292.2

0. 625

90. 1

2044.6 0.557

76.9

Aug Sep

2080.8 1929.9 0.553 0.524

76.2 79.9

1354.2 1641.3 1904.4 0.661 0.574 0.550

21.3 40.9 55.9

1962 0.524

65.3

2123.6 0.587

71.9

2293.3 0.678

65.7

1767.9 0.554

66.0

1734.7 0.525

75.3

1494.8

0. 458 73.7

1688.5

0. 533 67.9

1617 0.511

66. 7

1715 0.517

77.7

2076 0.656

71.7

1690 0.512

73.4

2039.

0.607

85.9

1845.4 0.537

84.4

1622.

0. 500

71.8

2179.7

0.640

87.4

1789.6

0. 542 75.3

1712.2 0.516

77.9

1761.2 0.567

69.4

1965.7 0.674

65.9

1207

0. 481 57.9

1446.8 0.530

69.5

1124.7 0.426

64.6

1211.8 0.492

63.3

1129.

0.459

61.6

1445.7 0.524

69.7

1511 0.616 62.7

1336.1 0.492

66. 1

1724.3 0.599

77.5

1687.8 0.546

82.9

1284.

0. 493

64. 3

2122.5

0. 710 84.0

1472.7 0.542

69.5

1446.1 0.520

72.2

1190.4 0.504

58.6

Oct

1566.4 0.676

64.

809.2 0.457

46.8

1087.4 0.527

59.3

820. 6 0.420

53. 1

702.2

0. 407 56.3

638 0.372

54.0

1071.9 0.508

61.2

844.6 0.494

51.5

1017 0.496

55.6

1314 0.581

67.6

1493.3 0.572

77.2

835 0.438

52.6

1640.9 0.672

73.9

1102.6 0.538

59.3

1083.4 0.506

60.9

767.5

0. 482 45.6

Nov

1169 0.624

60.8

Dec

943.9

0.627

56. 1

392.2 359.8 0.323 0.408

33.4 21.9

697.8 533.9 0.450 0.447

48.3 37.7

436.2 356.8 0.309 0.331

40.1 28.0

386.3 0.336

48.4

721.8

0. 449 48.5

486.3 0.428

37.4

991.5

0.548

52.6

1328.4 0.590

69.6

458. 3

0. 336 40.9

1322.

0. 650 62.5

239.5

0. 292 44.4

325.5 218.1 0.284 0.2G9

45.7 41.5

522.5 0.416

39.3

279 0.345

30.5

580.1 443.9 0.379 0.376

43.2 32.6

783 0.544

43.9

1119.5 0.589

65.5

352. 8

0. 346 30.2

1132.

0.679

56. 1

686.7 551.3 0.448 0.467

48.3 37.7

763.5 594.1

0. 464 0. 460

50.2 40.2

444.6 0.436

25.2

345 0.503

10.1

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A-38
APPENDIX B

MATERIALS TABLES

Appendix Table IS-1: Characteristics of Absorptive Coatings

Property

Materials

Absorptance*

a Emittancee

a

e" Brea kd own Temperature

°F (°C)

Comments

Black Chrome .87- .93 . 1

Alkyd Enamel .9 .9 1 Durability Limited at High

Temperatures

Black Acrylic

Paint

.92- .97 .84- .90

Black Inorganic

Paint

.89- .96 .86- .93

Black Silicone

Paint

.86- .94 .83- .89 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) Pastinates 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-1
Appendix Table B-2: Standards for Piping and Duct Materials

Description ANSI ASTM Federal Specifications

Other

Ferrous pipe & fittings

Steel pipe, black and hot dipped zinc- coated (galvanized) welded and seamless

for ordinary use

Steel pipe welded and seamless

Standard Specification for seamless

and welded carbon, ferritic, and austenitic alloy steel heat exchanger

tubes with integral fins

Nipples, Pipe, threaded

Pipe fittings: (bushings, locknuts and

plugs) iron, steel and aluminum (threaded) 125-150 lbs.

Malleable-iron threaded fittings, 150 and 300 lbs.

Unions, pipe, steel or malleable iron; threaded connection, 150 lbs. and 250

lbs.

Nonferrous metallic pipe and fittings

Copper pipe, seamless

Copper pipe, threadless

Copper tube, seamless

Copper tube, seamless, for refrigeration and general use

Copper water tube seamless

General requirements for wrought seamless

copper and copper alloy tube

Seamless brass tube

Seamless red brass pipe

Copper and copper alloy seamless condenser tubes and ferrule stock

Copper-alloy condenser tube plates

U-bend seamless copper and copper

alloy heat exchanger and condenser tubes

Copper and copper alloy seamless condenser

and heat exchanger tubes with integral fins

Bronze flanges and flanged fittings,

150 and 300 lbs.

Cast-bronze fittings for flared copper tubes

Cast-bronze solder joint drainage

fittings-DMV

Cast bronze solder joint pressure

fittings

B125. 2-1972

B125. 1-1972

B36-55-1966

B16. 3-1971

H26. 1-1973

H26. 2-1973

H23. 3-1973

H23.5-197A

H23. 1-1973

H23. 4-1973

H36. 1-1973

H27. 1-1973

H23. 14-1973

H23. 7-1974

B16. 24-1971

B16. 26-1967

B16. 23-1969 B16.23a-1973

B16. 18-1972

A120-73

A53-73

A498-68

WW-P-406D-197 3 WW-P-406D-1-1974

B42-75

B302-74a

B74-74b

B280-75

B88-75

B251-75

B136-74

B43-75

Blll-75

B171-75

B395-74b

B359-75

ASME SA53

WW-N-351b-1967 CS5-65 WW-N-351b[l]-1970

WW-P-471B-1970

WW-P-521F-1968

WW-U-531D

WW-P-377d-1962 ASME SB42

ASME SB75

WW-T-775a-1962

WW-T-799D-1971

ASME SB251

WW-T-791A-1971 ASME SB135

WW-P-351a-1963 ASME SB43

ASME SBlll

ASME SB171

--- ASME SB395

ASME SB359

B-2
Appendix Table B~2 : continued

Description ANSI ASTM Federal Specifications

Other

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

Unions, brass or bronze, threaded pipe

connections and solder-joint tube connections

WW-T-725a-1973

WW-U-516B

Unions, pipe, bronze or naval brass, threaded pipe connection 250 lbs. WW-U-516a-1967

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

Aluminum-alloy drawn seamless tubes H38.7

B241

B310-74a

Aluminum-alloy drawn seamless tubes for condensers and heat exchangers

Aluminum-alloy drawn tubes for general purpose application

Aluminum-alloy extruded round coiled tubes

for general purpose application

Aluminum-alloy seamless round condenser

and heat exchanger tubes with integral fins

Wrought aluminum and aluminum alloy welding

fittings

Pipe hangers and supports

Pipe hangers and supports, materials,

design and manufacture

H38. 6-1974

H38. 17-1974

H38. 18-1974

H38-1974

H38. 19-1974

B234-73

B483-73

B491-73

B404-73

B361-73

WW-H-171D-1970

MSS SP-58-1975

Pipe hangers and supports, selection

and application

Polybutylene (PB) plastic hot-water distribution systems (180°F Max.)

Plastic hot-water distribution systems:

chlorinated poly (vinyl chloride) (CPVC)

for water service (180°F Max.)

D3309-74

D2846-73

MSS SP-69-1966

NSF 14-1965

Cold water service, clamps, hose, low pressure

Standard methods of testing rubber hose

Insulation sleeving, thermal, pipe covering

(cellular glass)

Insulation sleeving, thermal (pipe and

tube covering)

Standard method of test for scalability

of gasket materials

Standard method of test for fluid resistance of gasket materials

J2.5

Z193. 1-1970

D380-75

F37-68

F146-72

WW-C-440B(2)

HH-1-175113A

HH-1-1751/GEN

B-3
Appendix Table B-2: continued

Description ANSI ASTM Federal Specifications

Other

Low velocity duct construction standard

High velocity duct construction standards

Fibrous glass duct construction standards

Pressure sensitive tape standards for fibrous glass duct

Duct liner application standard

Fire damper guide

SMACNA

SMACNA

SMACNA

SMACNA

SMACNA

SMACNA

B-4
Appendix Table B-3: Temperature and Pressure Ratings for Ball Valves—

Size Temperature

,

1 Id L. ^ 1- .1- CL J- l3 (Pressure in psi)

( inches

)

°F 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 250 152 /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 manuf acturer

s rating.

2/ 15 pounds saturated steam temperature.

B-5
Appendix Table B-4 : Thermal Storage Unit Containers—

Recommended— Recommended

Container

Usage

Above Below

Transfer

Media Pressure

Conditions

Container

Standard

Protective

Coating

Coating

Standard

Material Ground Ground Air Liquid High Low—' Compliance Ext. Int. Compliance

Aluminum X X X X X X ANSI B96.1

1973

Concrete X X X X X X IPM PS

(1966) X X Ext. MPS 609.7.4 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

Fiber Rein.

Polyester

X X X X X MIL-T-52777

21 Feb 1974

Steel X X X X X X AWWA D-lOO

(1967) X X Ext. MPS

609. 7. 3^/

Ext. & Int. AWWA D102

(1964)

Wood X X X NFO 8 (1965)

ll 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.

2/ When applicable, ASME Boiler and Pressure Vessel Code, Section VIII may be used.

hj In lieu of interior galvanized, glass-lined or stone-lined tanks.

B-6
Appendix Table B-5 : Typical Heat Transfer Fluids

Water

85% Ethylene

Glycol/Water

50% Propylene

Glycol/Water

Silicone

Fluid

Alkylated

Phenol

Paraf f inic

Oil

Freezing Point,

°F CO

Boiling Point,

"F (°C) (at atm. pressure)

Fluid Stability

Flash Point,

°F (°C)

32 (0)

212 (100)

-33 (-36)

265 (130)

-28 (-33)

Requires pH Requires pH

or inhibitor or inhibitor

monitoring monitoring

None None

Requires pH

or inhibitor

monitoring

600 (315)

-58 (-50)

None

Good

-100 (-73)

358 (181)

Good to 575°F

600 (315) 145 (63)

700 (371)

Good

455 (235)

Specific Heat

(BTU/lb/°F)

1.0 0.65 0.85 0.34-0.48 0.42 0.46

Viscosity

(cstk at 77°F)

0.9 21 5-50000

Toxicity None Low Low Low Moderate

B-7
Appendix Table B-6: Typical Corrosion Inhibitors

Cliemical Names Effective With References

Calcium Hydroxide

Chromates

Molecularly Dehydrated Phosphates

and Chromates

Molecularly Dehydrated Phosphates

and Ferro Cyanides

Molecularly Dehydrated Phosphates

and Organic

Molecularly Dehydrated Phosphates

and Silicates

Hexameta, Phosphates, Na & Ca

Sodium Benzoate

Sodium Hexametaphosphate

Sodium Hydroxide

Sodium Nitrate

Sodium Septa

Sodium Silicate

Sodium Sulfite

Tetraphosphoglucosate

Fe, Zn, Cu, Brass

Fe, Zn, Cu, Brass

Fe, Zn, Cu, Brass

Fe, Zn, Cu

Fe, Zn, Cu, Brass

Fe, Zn, Cu, Brass

Fe, Zn, Cu, Al, Brass

Fe

Fe, Zn, Cu, Pb, Brass

Fe, Zn, Cu, Brass

Fe, Zn, Cu, Al, Brass

Fe, Zn, Cu, Al, Brass

Fe, Zn, Cu, Brass

All Metals

Fe, Zn, Cu, Al, Brass

Corrosion Causes & Prevention,

2nd Edition, 361-366

Ind. & Engr. Chem. Vol. 41,

No. 11, 2376-2382 (1949): Oil & Gas J., Vol. 47, No. 37, 83-87

(1949) Jan. 13.

Oil & Gas J., Vol. 49, No. 43, 52-62 (1951) March 1: Ind. & Engr. Chem., Vol. 44, No. 8, 1770-1774 (1952); Corrosion,

Vol. 6, No. 10, 331-340 (1947)

Oct.

Oil & Gas J., Vol. 49, No. 43, 52-62 (1951) March 1.

Oil & Gas J., Vol. 49, No. 43, 52-62 (1951) March 1; Ind. & Engr. Chem., Vol. 30, No. 12 1356-1361

Corrosion, Vol. 8, No. 12, 402-406 (1952) Dec.

Ind. & Engr. Chem., Vol. 37,

No. 8, 724-735 (1945) Aug.

Journal Soc. Chem. Indus. (Br.),

Vol. 66, 137; Chem. 6, Ind. (Br.), Vol. 53, 1194 (1951)

Corrosion, Vol. 8, No. 11, 381-390 (1952) Nov; Ind. & Engr. Chem., Vol. 32, No. 12, 1572-1579 (1938) Dec.

Ind. & Engr. Chem., Vol. 37, No. 8, 724-735 (1945) Aug.

Journal Electrochemical Soc,

Vol. 93, 63 (1948); Ind. & Engr. Chem., Vol. 35, 358

(1943)

Ind. & Engr. Chem., Vol. 37,

No. 8, 724-735 (1948) Aug.

Ind. & Engr. them.. Vol. 30, No. 3, 348-351 (1938) March;

Ind. & Engr. Chem., Vol. 44,

No. 8, 1765-1769 (1952) Aug.

Petro. Processing, Vol. 7, No. 5, 620-622 (1952) May; J. Amer. Water Works Assoc., 39 (1121)

(1947).

Ind. & Engr. Chem., Vol. 37, No. 8, 724-735 (1945) Aug.

B-8
.1

,1 I

III

i": MM

llMli I I

Mm

mmm

mm

:1|

ml

mir

lililil

if 5

.5.2 i mIs

£5 5

il..

II

If

if

Is

^1

^1

III

hih 3 §

Mi

II

II

II

il

II 1 

I ^27 f 5 I PS

I. I

1^ I II!

II i II s 'ill

Is ii mi h litII "

IS

ii

if !fl5

II IJM J mi I i: i«l 1 5I fill

!^ ii

if P fill 1 H ii

ii PI:

II

!^ i! il

Ji J: Mil

B-9
Appendix Table B-8: Upper Temperature Limits for Insulation Materials *

Insulation Materials Density

(Ib/ft^)

Upper Temperature Limits

°F (°C)

Fiberglass with Organic Binder 0.6 350 (177)

1.0 350 (177)

1.5 350 (177)

3.0 350 (177)

Fiberglass with Low Binder 1.5 850 (454)

Ceramic Fiber Blanket , 3.0 2300 (1260)

Mineral Fiber Blanket 10.0 ^ 1200 (649)

Calcium Silicate 13.0 1200 (649)

Urea-Formaldehyde Foam 0.7 210 (99)

Ureathane Foam 1-U 250-400 (121-204)

*Table from "Integrated Solar Energy Collector Final Summary Report", Robert B. Teonjes,

LA-6143-MS, Los Alamos Scientific Laboratory, Los Alamos, New Mexico, November 1975.

B-10
APPENDIX C

ILLUSTRATED DEFINITIONS

Table of Contents Page Number

SOLAR HEATING AND DOMESTIC HOT WATER SYSTEMS: C - 1 A FUNCTIONAL DESCRIPTION

SOLAR HEATING AND DOMESTIC HOT WATER SYSTEMS: C - 3 AN OPERATIONAL DESCRIPTION

BASICS OF SOLAR ENERGY UTILIZATION C - 6

SOLAR HEATING AND DOMESTIC HOT WATER SYSTEMS: C - 13

ACTIVE SYSTEMS

SOLAR HEATING AND DOMESTIC HOT WATER SYSTEMS: C - 19 PASSIVE SYSTEMS

SOLAR HEATING AND DOMESTIC HOT WATER SYSTEMS:

COMPONENT DESCRIPTION

C - 20

Solar Heating and Domestic Hot

Water Systems: A 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 ineffi- cient 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 per- formance, 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 found

the widest application. It consists of an absorbing

plate, usually made of metal painted black to increase absorption of the sun's heat. This plate is insulated on its underside and covered with a

transparent cover sheet to trap heat within the

collector and reduce convection 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 absorbing plate. The heated

working fluid is then transported to points of use

or to storage depending on energy demand.

Storage of thermal energy is necessary because

there will be an energy demand during the evening

or on sunless days when collection is not occurring. 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 relatively

complex such as latent heat storage. In some

cases, heat from the collector is transferred 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 consumption. Comfort heat usually is distri- buted in the form of warm air or warm water

within a building.

The controls of a solar system perform the

sensing, evaluation and response functions re- quired to operate the system in the desired

mode. For example, when heat is needed for hot

water or space heat, the controls cause the hot

working fluid to be delivered to whatever system

is being used, perform its function and distribute

the energy to the point of use. An auxiliary energy system provides a supply of

energy during periods of extremely severe weather or extended cloudy weather. The

auxiliary system, using conventional fuels such as

oil, gas or electricity, 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.

An active solar system can be characterized as one in which energy—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

C - 1
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, and evaporation in conjunction with the use of thermal capacitance as a heat

flow control mechanism.

C - 2
Solar Heating and Domestic

Hot Water Systems: An

Operational Description

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 require- ments. Usually, however, solar systems are

PASSIVE SOLAR SYSTEM

HEATING HOUSE FROlVl COLLECTOR Solar

radiation captured by the collectors and converted

to thermal energy can be used to directly heat the

house.

HEATING STORAGE FROM COLLECTOR If the

house does not require heat, the captured (collected) thermal energy can be placed in storage

for later use.

designed to operate in four basic modes. In a very

simplistic manner, the four modes of solar system

operation for both active and passive systems are

described and illustrated below.

ACTIVE SOLAR SYSTEM

C
C - 4

I
The solar system rr,Hy >i]su \jq designed to preheat water from the incumiiig water supply prior to passage through a conventional water heater. The

domestic hot water preheat system can be comPASSIVE SOLAR SYSTEM

DOMESnC HOT WATER PREHEATING - COMBINED SYSTEM Domestic hot water is preheated as it passes through heat storage enroute to the conventional water heater.

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.

bined with the solar heating system or designed as a separate system. Both situations are illustrated

below.

ACTIVE SOLAR SYSTEM

C - 5
Solar Heating and Domestic Hot

Water SVstems: Basics of Solar

Energy Utilization

CLIMATE Sun, wind, temperature, humidity and

many other factors shape the climate of the

United States. Basic to using solar energy for heating and domestic hot water is understanding

the relationship of sun, climate and dwelling

design.

COOL

The amount and type of solar radiation varies

between and within climatic regions: from hot-dry

climates where clear sl<ies 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.

SOLAR RADIATION The sun provides the earth

with almost all of its energy in the form of

radiation. Solar energy, also i<nown 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.

THE SOLAR CONSTANT A nearly constant amount of solar energy strikes the outer atmosphere—427 Btu per square foot per hour. This

quantity is known as the solar constant. A large

amount of this energy is lost in the atmosphere

before it can be collected. No collector design can increase the amount of solar energy striking

it, by focussing or other mesms.

ABSORPTION AND REFLECTION Nearly half

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.

C - 6
AIR MASS More solar radiation is lost by

absorption at low sun angles than at high angles

because the length of travel through the

atmosphere is greatly increased. The relative

amount of atmosphere through which solar radiation passes is called the "air mass."

DIFFUSE-RADIATION Clouds and particles in the atmosphere not only reflect and absorb solar energy, but scatter it in all directions. Because of

this, solar energy is received from all parts of the

sky—more so on hazy days than on clear days. This

type of radiation is called diffuse , as opposed to direct radiation. At most, diffuse radiation can

only be about one-fourth of the solar constant or about 100 Btu/hr./sq. ft.

DIRECT SOLAR RADIATION ON A

HORIZONTAL SURFACE Less solar radiation

strikes a given horizontal area as the sun gets

lower in the sky. The amount changes by the

cosine of the angle, measured from the vertical.

DIRECT SOLAR RADIATION ON A TILTED

SURFACE The same principle applies to a

tilted surface, such as a solar collector. By tilting

the collector so that it is nearly perpendicular to the sun, more energy strikes its surface.
5

THE SOLAR WINDOW Imagine the sky as a transparent dome with its center at the solar collector or 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. All of

the useful sun that reaches the collector must come through this window. 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 wiU change for different latitudes.

C - 8
SIDE VIEW OF SKY DOME WITH "SOLAR

WINDOW" A side view of tlie 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."

\fc-6uM AT

June ^

PLAN VIEW OF SKY DOME WITH "SOLAR

WINDOW" 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 lati- tude. Sun path diagrams are widely reproduced

and used for determining the azimuth and alti- tude of the sun at any time during the year; but can also be used to define the "solar window" and

siirrounding intrusions.

60h AT

-foH AT

peon

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
COLLECTION ORIENTATION AND TILT Solar

collectors must be oriented and tilted within

prescribed limits to receive the necessary level of

solar radiation for optimum system operation and

performance.

COLLECTOR TILT FOR HEATING The optimal

collector tilt for heating is usually equal to the

site latitude plus 10 degrees either side of the

optimal are acceptable.

COLLECTOR TILT FOR HEATING AND

COOLING The optimal collector tilt for heating

and cooling usually is site latitude plus five

degrees. Variations 10 degrees either side of the

optimal are acceptable.

COLLECTOR TILT FOR DOMESTIC HOT WATER

The optimal collector tilt for domestic water

heating is usually the site latitude. Variations 10 degrees either side of the optimeil are acceptable.

COLLECTOR ORIENTATION A collector

orientation of 20 degrees either side of true south

is acceptable. However, an orientation west of true south is considered best in most situations.

MODIFICATION OF OPTIMAL COLLECTOR TILT

A gain in solar radiation may be achieved by

tilting the collector away from the optimal to capture radiation reflected from adjacent ground

or building surfaces. The corresponding reduction

of radiation directly striking the collector due to non-optimal tilt should also be recognized when

considering this option.

SNOWFALL CONSIDERATION The snowfall

characteristics of an area may influence the

appropriateness of an optimal collector tilt. Snow

build-up on the collector or drifting infront of the

collector should be avoided.

C - 10
SHADING OF COLLECTOR BY BUILDING

ELEMENTS 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 buildings, landscaping, building elements,

or other collectors does not occur. Collector

shading by elements surrounding the site has been

addressed by considering the "solar window" concept. Several considerations for avoiding un- wanted shading of the collector by building

elements or collector arrangements are presented

below.

SELF-SHADING OF COLLECTOR Avoiding all self-shading for a bank of parallel collectors

during useful collection hours (9 A.M. and 3 P.M.)

can result in large spaces between collectors, as shown above. It may be desirable to allow some

self-shading in order to optimize collection during

peak heating load, which may not occur at the

lowest sun angle (December 21). This may allow a

closer spacing of collectors, as shown below, thus

increasing solar collection area. Also, by making

the collector's back slope reflective can increase

the amount of solar radiation striking the adjacent

collector.

SHADING OF COLLECTOR BY BUILDING

ELEMENTS Chimneys, parapets, fire walls,

dormers, and other building elements can cast shadows on adjacent roof-mounted solar collectors. The drawing to the right shows a house with

a 45^^ south-facing collector at latitude 40°N.

By mid-afternoon portions of the collector are shaded by the chimney, dormer, and the offset

between the collector on the house and the

collector on the garage. A 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 - 11
THE GREENHOUSE EFFECT Basic to the

utilization of solar energy for space and domestic

hot water heating is understanding the process by

which solar radiation is converted to thermal

energy. This conversion process is the basic link between the energy source—the sun—and the

energy load—the dwelling. The process is best

understood by briefly explaining solar radiation

and then discussing the characteristics of a greenhouse.

SOLAR RADIATION 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 surface 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 absorbed,

converted into useful thermal energy and removed

by a heat transfer mechanism to be useful. Absorbed radiation heats up the absorbing body,

which re-emits energy in the form of thermal

radiation in the infrared 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.

THE GREENHOUSE EFFECT Many glasses and some plastics are transparent in the solar wavelength region and hence are used as windows. At

the same time, these materials usually have low

transmission values in the infrared region. By

placing glass or plastic over the absorbing surface,

energy is trapped in two ways. First, infrared

radiation re-emitted by the absorbing surface is absorbed by the glazing, with a portion re-emitted

again back toward the absorber and thereby

trapped. Second, the glazing 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 - 12
Solar Heating and Domestic

Hot Water Systems:

Active Systems

Active solar systems are characterized by the use of energy—in addition to solar—for the transfer of

thermal energy throughout the system. A variety

of active concepts that have been constructed or

proposed. The following discussion of active solar systems serves as an introduction to a range of

active concepts.

-transport

water supply

[71

I ' i pre-heat

I !

-I auxiliary!

SOLAR HEATING AND DOMESTIC HOT WATER

SYSTEMS: PROCESS DIAGRAM The most

common solar system in use today is a combined

solar heating and domestic hot water system. The

system operates as follows. Solar radiation is absorbed by a collector and removed by a heat

transfer (transport) medium to storage. Heat is removed from storage and distributed to the living

spaces by a heat transfer medium (may or may not be same medium flowing through the collector).

Circulation throughout the system is by pumps,

SOLAR HEATING SYSTEM: PROCESS DIAGRAM

A solar heating only system can be developed by

simply removing domestic hot water preheating

from the combined system diagram. The operation

of the solgir heating system is the same as described above.

living

space

fixture

J

blowers, or other heat transfer medium moving

devices. An auxiliary energy system is available

both to supplement the output supplied by the

solar system and to provide for the total energy

demand should the solar system become inoperable. Manual or automatic controls maintain and

monitor the system operation. Domestic hot

water is preheated by passing the water supply

through heat storage prior to passage through a conventional water heater.

SOLAR DOMESTIC HOT WATER SYSTEM:

PROCESS DIAGRAM The combined system

diagram can be modified into a domestic hot

water only system by eliminating the heating

distribution and auxiliary component. The domestic water supply would pass through heat storage enroute to the conventional water heater thus

preheating the hot water supply.

SOLAR DOMESTIC HOT WATER SYSTEM:

PROCESS DIAGRAM Another method of preheating domestic hot water is by passing the

potable water supply through the collectors. The

heated water is placed in storage until a demand

is initiated. The preheated water is then pumped

from storage or flows by supply pressure to a conventional water heater.

C - 13
COLLECTOR - STORAGE DIAGRAMS The

removal of heat from the collector and its placement in storage involves a heat transfer medium

circulating in a transport loop. Several collectorstorage conditions are shown below.

OPEN CIRCUIT LIQUID COLLECTOR Storage

water, treated as necessary to pervent corrosion, is drawn from the bottom of storage and, pumped

through the collector and then returned to the top

of storage. The circulating water, that can run

through, on top or under the absorber plate, is distributed to the absorber by a manifold at the top

of the collector; or it can be pumped up from below

through tut>es attached to or integral with the

absorber plate. When the system is not running, air or an inert gas is allowed to enter into the

collector and piping, and the water drains into

storage. Storage is at atmospheric pressure, a condition that should be considered in the design of

the distribution system.

CLOSED CIRCUIT LIQIIID COLLECTOR A heat

transfer liquid— treated water, anti-freeze solution

or other liquid—is pumped through the collector

and then through a heat exchange in storage and

back to the collector, in a closed loop. The loop is always filled with fluid, and therefore must be

protected from freezing.

AIR COLLECTOR Although many arrangements

of air collector-rock storage— warm-air distribution systems are possible, the one diagrammed is typical of the most popular systems in use. Air

from the cold end of the rock storage bin is pumped

through the collector and returned to the hot end

of storage. The process is modified when air is circulating through the collectors and the house

requires heat. In this case, the dampers must be

adjusted to supply heat directly to the house.

C - 14
STORAGE - DISTRIBUTION DIAGRAMS Heat is removed from storage and circulated to the house

by the distribution component. There are WARM-AIR DISTRIBUTION - HOT WATER COIL

IN DUCT A warm-air disturibution system can

be used with liquid storage by pumping the storage

medium through a suitably sized heat exchange

coil in the main supply duct of the distribution

system.

numerous ways this can be performed,

methods are diagrammed below.

HYDRONIC DISTRIBUTION Liquid from storage

is pumped directly through standard baseboard

convector units, despite the relatively low

temperatures that usually occur in solar systems

during winter conditions. The size of baseboard

units, and possibly the circuiting may change

from ordinary hydronic systems.

INDIVIDUAL FAN—COIL UNIT DISTRIBUTION

Liquid from storage is pumped to individual fancoil units located throughout the dwelling from

distribution. The design and sizing considerations are similar to those for hydronic distribution.

e

f

'

C - 15
RADIANT COIL DISTRIBUTION Liquid from

storage is circulated through coils located in the

floor, walls and/or ceiling of the living space. Besides the water temperature the size and

spacing of the coils is critical for effective

radiant heat distribution.

ITiijiillTiTiTifiriiir,

f

m

WARM-AIR DISTRIBUTION FROM ROCK

STORAGE For an air collector system employing rock storage, it is advantageous to 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. This can be done in several ways, the most common is diagrammed,

using the same fan that supplies the collector

along with two automatic dampers to control the

direction of air flow.

WARM-AIR DISTRIBUTION - HEAT PUMP

Either air or liquid 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. Where heat is transferred to the heat

pump working fluid the compression cycle of the

heat pump elevates the working fluid temperature

and this high temperature heat is transferred to

air through a heat exchanger to heat the space.

C - 16
DOMESTIC HOT WATER PREHEATING

PREHEAT COIL IN STORAGE A suitably sized

coil passed through storage enroute to the

conventional water heater. Unless the preheat

coil has double-wall construction, this method

can only be used for solar systems employing

non-toxic storage media.

Domestic hot water can be preheated either by

circulating the potable water supply through the

collectors or by passing the supply line through

storage. Three storage related preheat systems

are shown below.

1

PREHEAT TANK IN STORAGE The domestic

hot water storage tank is located within the

space heating storage tank. The water supply

passes through storage to the preheat tank where

it is heated, stored, and piped to a conventional or tankless water heater prior to distribution. Double wall constructicai again wiU be

necessary unless a non toxic storage media is used. TAH<

PREHEAT COIL OR TANK OUTSIDE OF

STORAGE Liquid from storage is pumped to a

heat exdianger-coil or tank—for domestic hot water preheating. If liquid from storage is toxic, the required separation is achieved by two

separate heat exchange coils within a preheat

tank or, as diagrammed, by the use of a double • wall exchanger.

r—1 V

C - 17
STORAGE - DISTRIBUTION - AUXILIARY

ENERGY DIAGRAMS The provision of auxiliary

energy to the dwelling, should the solar heating

system not meet the dwelling's total energy demand or become inoperable, can be accomplished in numerous ways in combination with storage ano

distribution. The auxiliary energy component may

AUXILIARY HEAT COILS IN AIR DISTRIBUTION

SUPPLY DUCT Two heat exchange 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 boost to the supply air. The need for auxiliary energy is determined by the control

component that maintains and monitors both the

solar system and auxiliary system.

1 ^

1

AUXILIARY HEATING STORAGE TRANSPORT

LOOP TO DISTRIBUTION The auxiliary energy

system is located between the storage and distribution component to permit a full or partial operation. The auxiliary system uses the same

distribution network as the solar system. Valves at

the connection between systems regulates auxiliary

energy supply and prevents auxiliary from heating

storage. Solar and auxiliary system operation is maintained and monitored by an integrated control

component.

operate independent of or in conjunction with the

solar system. The control of solar and auxiliary

system operation becomes an important consideration for the effective utilization of both. Four

possible combinations are shown below.

c

1^

AUXILIARY WITH SEPARATE DISTRIBUTION

The auxiliary energy system may be a totally

seperate component not integrated with solar storage or distribution. This may involve a totally

separate distribution network or, as diagrammed,

individual electric baseboard units placed in the

dwelling in locations and numbers as required. The

two separate heating systems, however, are linked

by the control competent that regulates the

systems operation.

AUXILIARY WITH AIR COLLECTOR The

auxiliary is located between the storage and the

distribution compoient. The auxilisiry stystem

may be operated in two modes: 1) in conjunction

with house heating, from the collector and 2) in conjunction with house heating from storage. In the first mode, the house is being heated directly

from the collector. The auxiliary may provide an

energy boost as the air from the collector

circulates through the in-line auxiliary

compenent. In the second mode, the house is being heated from stroage. Again, as the air circulates from storage through the auxiliary an

energy boost may be supplied. The auxiliary and

solar system operation is maintained and monitored by an integrated control component.

C - 18
Solar Heating and Domestic Hot

Water Systems: Passive

Systems

Passive solar systems are characterized by the use

of solar 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.

SOUTH-FACING TRANSPARENT BUILDING

SURFACES This concept relies on the southern

exposure of large transparent building surfaces to increase heat gain directly into the building—thus

heating the space. To avoid overheating and space

collecting energy, an adequate quantity and coverage of thermal mass such as masonry surfaces on

the floor or waUs should be used to absorb heat

during the day and radiate it to the space after

passage of the sun. Insulating devices should be

available to minimize nighttime heat loss and to regulate daytime solar exposure.

THERMOSYPHONING DOMESTIC HOT WATER

PREHEATING This passive concept utilizes the

natural rise of heated fluids for the collection and

storage of domestic hot water. Domestic cold water supply is fed to the bottom of the storage

tank that is located above the solar collector. Exposure of the collector to solar radiation causes

the cold water to circulate by convectionthrough the collector—from bottom to top—and

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 by gravity to the

dwelling or a conventional water heater.

SOLAR POND This concept is similar to the

previous passive system except that the thermal mass—water—is now located in a roof pond above

the living space. In some climates, both heating

and cooling can be provided by the 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 pond, by

filling and draining the pond according to the

heating or cooling demand or by covering the pond

with a transparent roof structure.

COMBINED WALL COLLECTOR-STORAGEDISTRIBUTION This passive concept relies on

the exposure of a south-facing thermal mass

(containerized water, masonry or concrete),

located behind a transparent surface and

separated from the surface by an air space, to

solar radiation. The thermal mass acts as the

collector, storage and distribution component.

Solar radiation collected and stored in the thermal mass is distributed to the space by convection,

conduction, and radiation. When collection ceases, it is advantageous to prevent heat loss through the transparent surface by an insulating

device.

C - 19
Solar Heating and Domestic Hot

Water Systems: Component

Descriptions

A solar heating and domestic hot water system is composed of numerous individual parts and pieces

including collectors, storage, a distribution net- work, ducts and/or pipes pumps and/or blowers,

valves and/or dampers, fixed or movable insulation, a system of manual or automatic controls,

gaskets, hoses and with some systems one or more

heat exchangers, an expansion tank, and filters. These parts are assembled in a variety of combinations depending on function, component

compatibility, climatic conditions, required per- formance, site characteristic and architectural

requirements to form a solar heating and/or

domestic hot water system. Those components

that are unique to a solar system or that are used

in an unconventional manner are briefly

illustrated and discussed below.

FLAT-PLATE COLLECTOR: AN EXPLODED

VIEW The flat-plate collector is the most

common solar collection device for space heating

and domestic water heating in use today. 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.

^/ \\yLZ. _6 enclosure

1. BATTEN Battens serve to hold down the cover plate(s) and provide a weather tight seal

between the enclosure and the cover.

2. COVER PLATE The cover usually consists of one or more layers of glass or plastic film or sheet or combinations thereof. The cover

plate is separated from the absorber plate to create an air space which traps heat by

reducing re-radiation and convective losses. The space between the cover and absorber can

be evacuated to further reduce convective

losses.

3. HEAT TRANSFER MEDIUM PASSAGE Tubes

or fins are attached to the absorber plate to

facilitate transfer of thermal energy from the

absorber plate to the heat transfer medium.

The largest variation in flat-plate collector

design occurs with this component. 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. The heat transfer

passage must be affixed to the absorber plate so that a good thermal bond is assured.

4. ABSORBER PLATE The absorber plate is usually metallic and may contain integral heat

transfer media passages. The surface is normally treated with a surface coating which

improves absorptivity. Black or dark paints or selective coatings are used for this purpose.

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

normal operation, no flow and dry plate condiplate tions. Thermal decomposition and outgassing

of the insulating may significantly affect

collector performance.

6. ENCLOSURE 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
CLOSED FLAT-PLATE LIQUID COLLECTOR

Most flat-plate collectors in use today employ

water, oil or an antifreeze solution as the heat

transfer medium. The liquid circulates through

passage ways attached to or integral with the

absorber plate where it is heated before being

pumped to storage or to the load. Freeze

protection and prevention of corrosion and leaks

require special consideration in transfer media,

material and control selection.

OPEN FLAT-PLATE LIQUID COLLECTOR This

type of collector uses corrugated metal panels or

integral passage panels covered with a transparent cover plate for the circulation of the heat

transfer medium. In the first instance, the

transfer medium circulates—"trickles"—down the

corrugated channels from a manifold at the top to a trough or gutter at the bottom of the collector. The heated water then flows by gravity to the

storage tank. In the second case, the transfer

medium is pumped from a manifold at the bottom

through the collector where it is returned by

gravity to storage. When collection is not occurring the transfer medium drains back into

storage.

FLAT-PLATE AIR COLLECTOR Air coUectors

circulate air or other gases through or near the

absorber plate to ducts that return the heated air to storage or the living space. Compared with

liquid collectors, leakage, maintenance, and

freeze protection problems are minimal. However, air coUectors do require relatively large

ducts for the heat transfer medium and more

energy for medium transport.

C
EVACUATED TUBE COLLECTOR These collectors employ a vacuum tube containing an

absorber. The vacuum serves to reduce convective heat losses allowing higher working temperatures and efficiencies. The absorber consists of

metal or glass tubes or tubes with fins where the

captured thermal energy is transferred 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 require insulation similar to flat-plate units. Both direct and diffuse radiation can be collected.

CONCENTRATING COLLECTORS Concentrating collectors (also known as focussing

collectors) employ curved and multiple point

target reflectors or lenses to increase radiation on a smaU 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 lense, the

absorber, and the housing which maintains alignment and contains insulation for the absorber and

connecting piping. Often a mechanism is employed to allow the coUector/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 best suited for areas with clear skies where most solar radiation

is direct. Their inability to function on cloudy or overcast days is a disadvantage when compared

to flat-plate collectors. However, the high

temperatures generated may make concentrating

collectors particularly viable with solar cooling

systems.

As with flat-plate collectors, numerous configurations and arrangements of concentrating

collectors have been developed including linear

and circular concentrators, lens focussing

collectors, collectors with directional and nondirectional focussing and tube concentrators. A

number of concentrating configurations are shown to the left.

C - 22
FLAT-PLATE COLLECTOR MOUNTING Flatplate collectors are generally mounted on the

ground or on a building in a fixed position at prescribed angles of solar exposure—which vary

RACK MOUNTING CoUectors can be mounted

at the prescribed angle on a structural frame

located on the site 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 loads such as wind that may impact on it.

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 circulate under the collector thus minimizing

problems of mildew and leakage. The stand-offs

must have adequate structural properties to assure

the maintenance of a fixed collector mounting.

Stand-offs are often used to support collectors at an angle other than that of the roof to optimize

collector tilt.

DIRECT 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 built up

around the collector. A weatherproof seed between the collector and the roof must be

achieved or leakage, mildew, and rotting may

occur.

INTEGRAL MOUNTING Integral mounting

places the collector within spaces between structural roof members. The collector is attached to and supported by the structural framing members.

The top of the collector is located almost flush with 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 on-site built collectors.

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.

C - 23
COLLECTOR GANGING A building's solar

collector is generally composed of individual col- lection units or panels arranged to operate as a

single system. The arrangement and relationship of one collector unit to another is extremely important for effective solar collection and efficient

system operation. Three basic multiple collector

arrangements are shown below.

balance valve header or manifold

or damper

—- header or manifold ^ —balance \^ve

or damper

T I

X

header or manifold

COLLECTOR GANGING: PARALLEL FLOW - DIRECT RETURN A direct return distribution

circuit circulates the transfer medium from the top

of the collector to a return header or manifold at the bottom. 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 will be essentially the same for the same flow rate, high pressure drops occurring along

the supply/return header or manifold wiU cause

flow imbalance, especially if no flow balance

device is used. This problem can be reduced by

sizing the header for minimum pressure drop,

although this may be prohibitive because of eco- nomic and space limitations. Even manual balancing valves may be difficult to adjust and automatic

devices or orifices may be required for efficient

system performance. 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. COLLECTOR GANGING: 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 tmd the pressure drop

across each collector is equal, the pressure drops

are theoretically equal. The major advantage of reverse return piping is that balancing is seldom

required since flow through each collector is theoretically 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.

COLLECTOR GANGING: 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 and 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-rectangular sur- faces. 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 require flow t)alancing for this situation.

C - 24
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

SHELL AND TUBE This type of heat exchanger is used to transfer heat from a trsinsfer medium

containing antifreeze to water used for storage.

SheU 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 and the shell is often steel for solar applications. A single shell and tube heat exchanger cannot be used for heat transfer from the toxic

liquid to potable water because double separation is not provided and the toxic liquid may enter the

potable water supply.

SHELL AND DOUBLE TUBE This type of heat

exchanger is similar to the previous one except

that a secondary tube is located in the shell. The

heated liquid circulates between the shell and the

second tube. An intermediary non-toxic heat

transfer liquid is located between the two tube

circuits. As the heated liquid circulates through

the tube, the intermediary is heated which in turn heats the potable water supply. The heat ex- changer can be equipped with a sight glass to detect leaks—toxic liquid often contains a dye—or

to increase the liquid level in the intermediary

chamber.

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. When this method is used the

tubing or coil must be adequately insulated to reduce heat losses.

storage medium or between storage and the'* distri- bution component. Three types of heat exchangers

that are most commonly used for these purposes

are illustrated below.

outer shell

heat transfer medium

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 media 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 un- obstructed vertical distance through the free atmosphere between the

lowest opening from any pipe or faucet supplying water to a tank,

pliambing fixture or other device and the flood level rim of the

receptacle. (NSPC) *

Auxiliary energy subsystem ; Equipment utilizing conventional energy

sources 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)

Backf low 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-Siphonage : 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)

Biochemical Oxygen Demand : The quantity of oxygen used in the biochemical

oxidation of organic matter in a specified time, at a specified temperature, and under specified conditions.

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.

* Abbreviations in parentheses indicate the sources of the definitions

used here. (See Appendices E and F)

D-1
Collectors, 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.

Collectors, component : Collector that is not structurally integrated

with the storage or building. The collector performance can be thermally

characterized as an individual component with an active heat transfer

fluid.

Collectors, integrated : 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.

Components ; The smallest identifiable elements of a solar heating subsystem, such as valves, piping, controls, and containers, etc.

Contaminants : Materials (solids or liquids or gases) which when added

unintentionally (or intentionally) to the potable water supply and cause

it to be unfit for human or animal consumption. (ASSE 1013)

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

Energy transport subsystem : A portion of the H, and DHW systems which

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

thermal 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.

D-2
Forced-Circulation Air Coil : A coil for use in an air stream whose

circulation is caused by a difference in pressure produced by a fan or blower.

Forced-Circulation Air Heating Coil : A heat exchanger, with or without

extended surfaces, through which either hot water or steam is circulated

for the purposes of sensible heating of a forced-circulation air stream.

H: Heating system.

Heat Transfer Medium : A medium, either fluid or air, 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.

Lethal Concentration (LC) : Any concentration of a substance in air to which man has been reported to have been exposed for any given time that

has been reported to have caused death in man or any concentration to which animals have been exposed for eight hours or less and that has been

reported to have caused death in animals.

Lethal Dose (LP) : Any dose of a substance introduced by any route other

than inhalation over any given period of time and reported to have caused

death in man or a single dose introduced in one or more divided portions

and reported to have caused death in animals

Load factors : Multipliers by which design loads are increased in order

to obtain the loads to be used in ultimate strength design of structural

elements

Maximum "flow" temperature : The maximum temperature that will be obtained

in a component when the heat transfer medium is flowing through the system.

Maximum "no-flow" temperature : The maximum temperature that will be obtained

in a component when the heat transfer medium 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 medium.

MPS 4900.1 : PHA "Minimum Property Standards For One And Two Family

Dwellings"

MPS 4910.1 : FHA "Minimum Property Standards For Multifamily Housing".

No-Flow Condition : The condition obtained when the heat transfer fluid

is not flowing through the collector array due to shut-down or malfunction.

Outgassing : The emission of gases by materials and components , usually

during exposure to elevated temperature, or reduced pressure.

Passive Solar System : An assembly of collectors, thermal storage device(s),

and transfer media which converts solar energy into thermal energy and in

which no energy in addition to solar is used to accomplish the transfer of

thermal energy. The prime element is a passive solar system is usually

some form of thermal capacitance.

D-3
Physical Compatibility : The ability of materials and components in contact

with each other to resist degradation such as that caused by differential

coefficients of thermal expansion.

pphm : Parts per hundred million

Safety glass : Glazing materials predominantly inorganic in character,

which meets the appropriate requirements of this 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

Service loads : Loads which are expected during the service life of a structure and upon which the design of the structure is based.

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 2.4 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 auxiliary 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 the sun reaches

its maximum altitude for that day.

Storage subsystem : The assembly used for storing thermal energy so that

it can be used when required.

Subsystem : One of several major elements of a solar heating system, such

as collectors, thermal storage device (s), heaters, etc.

System : The complete assembly necessary to supply heat to the dwelling

in which it is installed.

Sustained load : A load that is considered to be applied to the structure

over a projected period of time

Thermal Energy : Heat possessed by a material resulting from the motion of

molecules and which can do work.

Toxic fluids : Gases or liquids which are poisonous, irritating and/or

suffocating, as classified in the Hazardous Substances Act, Part 191,

Chapter I. Title 21.

Ultimate strength design : A method of proportioning structures or members

for failure at a specified multiple of working loads, and assuming nonlinear

distribution of flexural stresses.

UV: Ultra-violet

D-4
Water Hammer : The term used to identify the hammering noises and severe

shocks that may occur in a pressurized water supply system 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.

Working stress design : A method of proportioning structures or members

for prescribed working loads at stresses well below the ultimate, and

assuming linear distribution of flexural stresses

D-5

APPENDIX E

REFERENCED STANDARDS

AASHO H20-44 Standard Specification for Highway Bridges

ANSI A13.1 (1956) Scheme for the Identification of Piping Systems

ANSI A58.1 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 S2.8 (1972) Guide for Describing the Characteristics of Resilient

Mountings

ANSI Z95.1 (1974) Oil Burning Equipment (NFPA 31-1972)

ANSI Z97.1 (1972) Performance Specifications and Methods of Test for

Safety Glazing Material Used in Buildings

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 610 Standard for Central Humidifiers (1974)

ARI Standard 620 Standard for Self-Contained Humidifiers (1974)

ARI Standard 760 Standard for Solenoid Valves for Use with Volatile

Refrigerants and Water, 1975

ASHRAE 55-74 (1974) Thermal Environmental Conditions for Human Occupancy

ASHRAE 90-75 (1975) Energy Conservation in New Building Design

E-1
ASHRAE Handbook of Fundamentals, Chapter 14

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 739-73, Section 10.4 (1973) Flame Resistance Permanency

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 E 108-75 (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 F82-67 (1973) Recommended Practice for Fast Quality Check on Immersion

for Nonmetallic Gasket Materials

AWWA C506-69 Backflow Prevention Devices-Reduced Pressure Principle and

Double Check Valve Types

AWWA DlOO (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 Labeling Act - Public Law 86-613, 12 July 1960

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

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 Ball Valve

E-3
lAPMO PS 31-74 Specification for backflow Prevention Devices

lAPMO PSI Prefabircated 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

NEMA MGl-18.615 Hydraulic Institute Standards for Centrifugal, Rotary and

Reciprocating Pumps

NFPA 26 (1958) Supervision of Valves

NFPA 30 (1973) Flammable and Combustible Liquids Code

NFPA 31 Standard for the Installation of Oil Burning Equipment

NFPA 54 (1974) National Fuel Gas Code

NFPA 70, Section 240.24 Attachment Plugs

NFPA 72A (1974) Local Protective Signaling Systems

NFPA 89M-71 (1971) Heat Producing Appliance Clearances

NFPA 90B Standard for the Installation of Warm Air Heating and Air Conditioning

Systems

NFPA 211 Standard for Chimneys, Fireplaces, and Vents

NFPA 321 (1973) Classification of Flammable 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

SAE J20e(1974) Coolant System Hoses

Threshold Limit Values for Chemical Substances and Physical Agents in the Work- room 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)

E-4
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 American Association of State Highway Officials

AGA American Gas Association

AMCA Air Moving and Conditioning Association, Inc. ANSI American National Standards Institute

ARI Air-Conditioning and Refrigeration Institute

ASHRAE American Society of Heating, Refrigerating, and Air

Conditioning Engineers

ASME American Society of Mechanical Engineers

ASSE American Society of Sanitary Engineering

ASTM American Society for Testing and Materials

AWWA American Water Works Association, Inc. BMC Basic Mechanical Code (Division of BOCA)

BOCA Building Officials and Code Administrators International, Inc. CISPI Cast Iron Soil Pipe Institute

CPSC Consumer Product Safety Commission

CS Commercial Standard

FCCCHR Foundation for Cross-Connection Control and Hydraulic Research

FHSLA-1960 Federal Hazardous Substances Labeling Act, Public Law 86-613

July 12, 1960

FS Federal Specifications

HUD Department of Housing and Urban Development

HVI Home Ventilating Institute

lAPMO International Association of Plumbing and Mechanical Officials

IBR Institute of Boiler and Radiator Manufacturers

ICBO International Conference of Building Officials

lEC International Electrotechnical Commission

ISO International Standards Organization

MCA Mechanical Contractor's Association

MSS Manufacturer's Standardization Society of the Valve and

Fitting Industry

NACE National Association of Corrosion Engineers

NAS/NRC National Academy of Science/National Research Council

NBS The National Bureau of Standards

NEMA National Electrical Manufacturer's Association

NESCA National Environmental Systems Contractors Association

NFO National Forest Products Association

NFPA National Fire Protection Association

NPC National Plumbing Code

NRCA National Roofing Contractor's Association

NSF National Sanitation Foundation Testing Laboratory, Inc. NSPC National Standard Plumbing Code

PL Public Law

SAE Society for Automotive Engineers

SBI Steel Boiler Institute

SPMA Sump Pump Manufacturer's Association

TEMA Tubular Exchanger Manufacture's Association, Inc. UBC Uniform Building Code

UPC Uniform Plumbing Code

UMC Uniform Mechanical Code

UL Underwriter's Laboratories, Inc.

F-1

NBS.114A (REV. 7-73)

U.S. DEPT. OF COMM. BIBLIOGRAPHIC DATA

SHEET

1. PUBLICATION OR REPORT NO. NBSIR 76-1059

2. Gov't Accession

No.

3. Recipient's Accession No.

4. TITI.r-: AND SUBTITLE

Intermediate Minimum Property Standards for Solar Heating

and Domestic Hot Water Systems

5. Publication Date April 1976

6. Performing Organization Code

460.03

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. 4606500

11. Contract/Grant No. IAA-H-38-76

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

Interim

14. Sponsoring Agency Code

15. SUPPLEMENTARY NOTES

16. ABSTRACT (A 200-word or less factual summary of most significan' :i formation. 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 pra: t tce and on nationally recognized standards including

the Ml and 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;

18. AVAILABILITY |

| Unlimited

[X] For Official Distribution. Do Not Release to NTIS

1 1 Order From Sup. of Doc, U.S. Government Printing Office Washineton. D.C. 20402. SD Cat. No. C13

1

! Order From National Technical Information Service (NTIS)

Springfield, Virginia 22151

19. SECURITY CLASS

(THIS REPORT)

UNCL ASSIFIED

21. NO. OF PAGES

171

20. SECURITY CLASS

(THIS PAGE)

UNCLASSIFIED

22. Price

USCOMM-DC 29042-P74
I