CHAPTER 3. MARKET AND TECHNOLOGY ASSESSMENT

TABLE OF CONTENTS

3.1 INTRODUCTION

................................ ................................ ................................ ........... 3

- 1 3.2 EQUIPMENT DEFINITIONS

................................ ................................ ......................... 3

- 1 3.3 EQUIPMENT CLASSES

................................ ................................ ................................ 3

- 3 3.4 EQUIPMENT TEST PROCEDURE

................................ ................................ ............... 3

- 4 3.5 MANUFACTURER TRADE ASSOCIATION

................................ .............................. 3

- 4 3.6 MANUFACTURER INFORMATION

................................ ................................ ........... 3

- 5 3.6.1 Manufacturers

................................ ................................ ................................ ...... 3

- 5 3.6.2 Potential Small Business Impacts

................................ ................................ ........ 3

- 5 3.7 REGULATORY PROGRAMS

................................ ................................ ....................... 3

- 6 3.7.1 Current Federal Energy Conservation Standards

................................ ................. 3

- 6 3.7.2 California Energy Commission

................................ ................................ ............ 3

- 6 3.7.3 ASHRAE Standard 90.1

................................ ................................ ...................... 3

- 7 3.8 MARKET DATA

................................ ................................ ................................ ............. 3

- 8 3.8.1 Efficiency Data

................................ ................................ ................................ .... 3

- 9 3.8.2 Capacity Data

................................ ................................ ................................ ..... 3

- 12 3.9 TECHNOLOGY ASSESSMENT

................................ ................................ .................. 3

- 14 3.9.1 Equipment Characteristics and Operation

................................ ......................... 3

- 14 3.9.2 Technology Options

................................ ................................ ........................... 3

- 16

LIST OF TABLES

Table 3.6.1 Major and other SPVU manufacturers

................................ ................................ ...... 3

- 5 Table 3.7.1 Federal Energy Efficiency Standards for SPVUs

................................ ..................... 3

- 6 Table 3.7.2 California Energy Commission Minimum Energy Efficiency Levels for SPVUs

... 3

- 7 Table 3.7.3 ASHRAE 90.1

- 2013 Addendum "i" Efficiency Levels for SPVUs

......................... 3

- 8 Table 3.8.1 Number of SPVU Models by Equipment Class

................................ ........................ 3

- 9 Table 3.9.1 Potential Technology Options for improved Energy Efficiency of SPVUs

........... 3

- 16

LIST OF FIGURES

Figure 3.8.1 EER ratings for SPVACs (<65,000 Btu/h)

................................ ............................ 3

- 10 Figure 3.8.2 EER Ratings for SPVACs ( ≥ 65,000 Btu/h and <135,000 Btu/h)

.......................... 3

- 10 Figure 3.8.3 EER Ratings for SPVHPs (<65,000 Btu/h)

................................ ........................... 3

- 11 Figure 3.8.4 EER Ratings for SPVHPs (<65,000 Btu/h)

................................ ........................... 3

- 11 Figure 3.8.5 Cooling inputs for SPVACs (<65,00 0 Btu/h)

................................ ....................... 3

- 12 Figure 3.8.6 Cooling inputs for SPVACs (≥65,000 Btu/h and <135,000 Btu/h)

....................... 3

- 13 Figure 3.8.7 Cooling inputs for SPVHPs (<65,000 Btu/h)

................................ ........................ 3

- 14 Figure 3.8.8 Heating inputs for SPVHPs (<65,000 Btu/h)

................................ ........................ 3

- 14 Figure 3.9.1 Histogram of Evaporator Motor Type of SPVACs and SPVHPs by EER

............ 3

- 21

3

- iCHAPTER 3. MARKET AND TECHNOLOGY ASSESSMENT

3.1 INTRODUCTION

This chapter details the market and technology assessment that the U.S. Department of Energy (DOE) conducted in support of the ongoing energy conservation standards rulemaking for single package vertical air conditioners (SPVACs) and single package vertica l heat pumps (SPVHPs ), or collectively single package vertical units ( SPVUs )

. The goal of the market assessment wa s to develop a qualitative and quantitative characterization of the SPVU industr y and market structure based on publicly available data and other information that DOE received directly from manufacturers and interested parties. DOE examined publicly available information from the Air Conditioning, Heating, and Refrigeration Institute ’s (AHRI) Directory of Certified Product Performance and from manufacturers’ websites and product literature

. The market and technology assessment covers manufacturer characteristics , existing regulatory efficiency improvement initiatives, equipment classes, and trends in product markets and characteristics. DOE per form ed the technology assessment to develop a list of technologies (referred to as technology options) that could be used to improve the energy efficiency of SPVUs

.

3.2 EQUIPMENT DEFINITION S

SPVUs a re a subset of commercial package air conditioning and heating equipment as defined by the Energy Policy and Conservation Act ( EPCA )

. SPVACs and SPVHPs are mainly used for cooling and heating classrooms, modular buildings, telecommunication shelters, and
po rtable buildings. Although th i s e quipment ha s similar cooling/heating capacities as products used in residential app lications, it is subject to different operational cycles and operating hours than are typically encountered i n residential applications.

EPCA defines both “single package vertical air conditioner” and “single package vertical heat pump,” and DOE has codified these definitions at 10 CFR 431.92. EPCA defines “ single package vertical air conditioners ” as :

“ A ir

- cooled commercia l package air conditioning an d heating equipment that

--- (A) is factory

- assembled as a single package that

— (i) has major components that are arranged vertically; (ii) is an encased combination of cooling and optional heating components; and (iii) is intended for exterior mounting on, adjacent interior to, or through an outside wall; (B) is powered by a single

- or 3

- phase current; (C) may contain 1 or more separate indoor grilles, outdoor louvers, various ventilation options, indoor free air discharges, ductwork, well plenum, or sleeve s; and (D) has heating components that may include electrical resistance, steam, hot water, or gas, but may not include reverse cycle refrigeration as a heating means. ”

(42 U.S.C. 6311(23))

3

- 1EPCA also defines “ single package vertical heat pump ” as :

“ A single package vertical air conditioner that

— (A) uses reverse cycle refrigeration as its primary heat source; and (B) may include secondary supplemental heating by means of el ectrical resistance, steam, hot water, or gas. ”

(42 U.S.C. 6311(24))

On March 16, 2011, ASHRAE released a draft of Proposed Addendum “i” to Standard 90.1

- 2010 for public review, which proposed to create a new equipment class in 90.1

- 2010 for SPVACs and SPVHPs used in space

- constrained applications. In this standard, s pace constrain ed applications are defined as:

(1) Indoor use; (2) A rated cooling capacity no greater than 36,000 Btu/h; (3) Single package unit requiring an opening in an exterior wall with overall exterior dimensions that require or use an existing sleeve that meets one of the following criteria:
1. Width of less than 32 inches and a height of less than 45 inches or
2. Fits inside an existing 1,310 in 2 opening. (4) Is commonly installed in site

- built commercial buildings; (5) Is of a similar cooling capacity and, if a heat pump, similar heating capacity; (6) Draws outdoor air for heat exchange directly through an existing opening, used for both inlet and outlet, in the exterior wall; (7) Is restricted to applications where an existing air conditioner, heat pump, or gas/electric unit, installed in an existing exterior wall opening, is to be replaced; and (8) Bears a permanent “Replacement” marking, conspicuously placed, and clearly indicating, that its application is limited to installations where an existing air conditioner or heat pump is to be repla ced.

In considering how to address the proposals contained in addendum “i”, DOE carefully considered the possibility of establishing an equipment class for space constrained SPVUs. After reviewing the SPVU market, DOE identified two distinct market segme nts: (1) traditional SPVUs, which are typically wall hung or installed indoors and intended for use in schools, telecommunications shelters, office buildings, and similar applications; and (2) through

- the

- wall units that are being classified as SPVUs and a re designed to be installed through

- the

- wall in hotels, apartments, dormitories, assisted living facilities, and other similar applications (i.e., “lodging” applications).

DOE discovered that many units characterized by industry as SPVUs, particularly t hose that are primarily used for lodging applications, are advertised for use in multiple applications including both commercial and residential applications. Upon discovering the dual

- market applications of these units, DOE considered whether the classifi cation of these products as

3

- 2SPVUs

– a type of commercial equipment

- is appropriate. SPVUs are classified as a type of commercial air conditioner under 42 U.S.C. chapter 77, subchapter III, Part A

- 1, “Certain Industrial Equipment.” Given the similarities be tween through

- the

- wall air conditioning units intended for installation in multi

- family residential applications and those intended primarily for installation in commercial lodging applications, DOE has tentatively concluded in the NOPR that the se units sh ould be treated the same under its regulatory scheme

.
A space

- constrained residential central air conditioner product class has already been established to account for products whose outer dimensions are severely limited by their application, and given t he similarities and overlap between models used in commercial lodging applications and models used in residential multi

- family applications, DOE believes that any single package vertical units that are “space

- constrained” are appropriately categorized as b elonging within the residential central air conditioner product class. As a result, any product which fits the definition of an SPVU under 10 CFR 431.92, but also falls under the “space

constrained” criteria set forth by the proposed Addendum “i” to ASHRAE Standard 90.1

- 2010, is currently not recognized by DOE as an SPVU in this rulemaking.

Additional details are available in the associated NOPR.

3.3 EQUIPMENT CLASSES

DOE generally divides covered cooling and heating equipment into classes by: (a) the type of energy used; (b) the cooling and/or heating capacity; or (c) any performance

- related features that affect customer utility or efficiency. (42 U.S.C. 6295(q)) Different energy efficiency standards may apply to diff erent equipment classes.

E PCA divide s s ingle p ackage v ertical u nits into equipment classes b ased on :

( 1 ) The t ype of system : air conditioner (cooling only) or heat pump (cooling and heating) ; ( 2 ) Type of electric current : single

- phase or three

- phase ; and ( 3 ) Cooling c apacity : (a) <65,000 British thermal units per hour ( Btu/h )

, (b) ≥65,000 Btu/h and < 135,000 Btu/h, and (c) ≥135,000 Btu/h and <240,000 Btu/h.

Although EPCA divided SPVACs and SPVHPs into equipment classes based on the phase of the electrical power , it set the same energy conservation standards for both single

- phase and three

- phase equipment . Therefore, e xisting energy conservation standards divide SPVUs into six equipment classes based on the cooling capacity and whether the equipment is an air conditioner or a heat pump. The existing equipment classes are :

• Single pac kage vertical air conditioner

, < 65,000 Btu/h

• Single pac kage vertical air conditioner, ≥65,000 Btu/h and < 1 35,000 Btu/h

• Single package vertical air conditioner, ≥ 135,000 Btu/h and < 240,000 Btu/h

• Sing le package vertical heat pump

, < 65,000 Btu/h

3

- 3• Singl e package vertical heat pump, ≥ 6 5,000 Btu/h and < 135,000 Btu/h

• Sing le package vertical heat pump, ≥ 135,000 Btu/h and < 240,000 Btu/h

I n the NOPR

, DOE is proposing to maintain the se existing equipment classes for its analysis.

3.4 EQUIPMENT TEST PROCEDURE

The statutory criteria for f ederal test procedures require that a test procedure be reasonably designed to produce test results which reflect energy efficiency, energ y use, and estimated operating costs of a type of industrial equipment (or class thereof) during a representative average use cycle (as determined by the Secretary), and shall not be unduly burdensome to conduct. (42 U.S.C. 6314 (a)(2))

On May 16, 2012
, D OE published a final rule that adopted the American National Standards Institute ( ANSI ) /AHRI 390

- 2003: Performance Rating of Single Package Vertical Air

Conditioners and Heat Pumps ( i.e., AHRI 390

- 2003 ) as the basis for Federal test procedure for SPVUs . 77 FR 28928

. AHRI 390

- 2003 provides a method for determining the energy efficiency ratio (EER) of SPVACs and SPVHPs
, and a method for determining the coefficient of performance (COP) for SPVHPs

. DOE uses t hese two metrics to set its energy conservation stand ards for SPVUs

.

3.5 MANUFACTURER TRADE ASSOCIATION

As part of its NOPR analysis, DOE sought to identify trade groups who represent manufacturers, distributors, and installers of the SPVU equipment analyzed in this rulemaking and found one trade association

, the Air

- Conditioning, Heating, and Refrigeration Institute (AHRI)

.
AHRI represent s more than 300 heating, water heating, ventilation, air conditioning and commercial refrigeration manufacturers within the global HVACR industry , and these manufacturers a ccount for more than 90 percent of the residential and commercial air conditioning, space heating, water heating, and commercial refrigeration equipment manufac tured and sold in North America

. a AHRI develops and publishes technical standards

, which use rat ing criteria and procedures for measuring and certifying performance for residential and commercial air conditioning, heating, and refrigeration equipment.

As noted previously, t he current Federal test procedure for SPVUs incorporates an AHRI standard

– AHRI 390

- 2003. AHRI also maintains the Directory of Certified Product Performance, which is a database of equipment ratings for all manufacturers who elect to participate in the program b . AHRI has two certified directories for SPVUs: “ s ingle p ackage

v ertical s ystems

– AC ” and “ s ingle p ackage v ertical s ystems

– HP. ” DOE used the data in th ese certification director ies in its market assessment.

a For more information see: http://www.ari.org/site/318/About

- Us
b http://www.ahridirectory.org/ahridirectory/pages/home.aspx

3

- 43.6 MANUFACTURER INFORMATION

The following section s detail information regarding manufacturers of SPVUs for sale in the United States.

3.6.1 Manufacture r s

DOE compiled data for SPVUs currently on the market by examining the AHRI Directory of Certified Product Performance. To suppleme nt the data in the AHRI database , DOE gathered additional information from the websites of individual manufacturers of SPVUs

. DOE identified manufacturers of SPVUs based on information in the AHRI directory, web

- based research, review of HVAC industry publications, and discussions with m anufacturers during the manufacturer interview process.

DOE identified seven manufacturers of SPVUs that market and sell equipment in the U.S

. As discussed in section III.B.1 in the NOPR, DOE also identified several additional manufacturers through the AH RI directory and through additional research that id entify their product as an SPVU; however, DOE has found that a significant portion of sales of the se products are to the residential market. Thus, these products are more appropriately classified as resid ential central air conditioners than as SPVUs, and DOE has not identified these manufacturers below with the other SPVU manufacturers listed in Table 3.6

. 1

.

Due to the small total size of the SPVU market , DOE i s unable to disc lose any market share data for SPVU manufacturers. However, in Table 3.6.1 below DOE divides manufacturers into “major” and “other” based on current industry characteristics, DOE research, and discussions with manufacturers about largest players in the SPVU market

. C ompanies designated as “major manufacturers” have larger market shares than “other manufacturers”

. Table 3.6

. 1 also includes several Canadian manufacturers that sell a notable amount of SPVUs to the U.S. market. DOE includes these manufacturers to show a complete picture of the competitors with in the U .S. market.

Table 3.6

. 1 Major and o ther SPVU m anufacturers Major Manufacturers Other Manufacturers Bard Manufacturing Company ChangeAir * Marvair, Division of Airxcel, Inc. Modine Manufacturing Company National Coil Company Temspec Incorporated* Emerson (“Liebert” Brand)

* Canadian manufacturer.

3.6.2 Potential Small Business Impacts

DOE also takes into consideration the impact of amended energy conservation standards

on domestic small businesses. Manufacturers of SPVUs are identified by North American Industry Classification System (NAICS) under code 333415, “ Air

- Conditioning and Warm Air Heating Equipment and Commercial and Industrial Refrigeration Equipment Manufacturing .”

3

- 5The Small Business Admi nistration (SBA) sets the threshold for manufacturers identified under NAICS code 333415 to be qualified as a small business as having 750 employees or fewer. c At thi s time, DOE has identified two domestic small business manufacturer s

– Bard Manufacturing Company and National Coil Company

– in the SPVU market that fall under the SBA’s definition

. DOE studie d the potential impacts on th ese small business manufacturer s , along with all other manufacturers, in detail during the manufacturer impact analysis ( MIA ), which is discussed in Chapter 12 of this TSD

.

3.7 REGULATORY PROGRAMS

3.7.1 Current Federal Energy Conservation Standards

EPCA contains mandatory energy conservation standards for commercial heating, air

conditioning, and water

- heating equipment, including SPV Us . (42 U.S.C. 6313(a)) The Energy Independence and Security Act of 2007 (EISA 2007) amended EPCA by prescribing definitions and setting minimum energy conservation standards for SPVACs and SPVHPs (42 U.S.C. 6313(a)(10)(A)). DOE codified the efficiency le vels contained in EISA 2007 for SPVUs as part of the March 2009 final rule technical amendment. 74 FR 12058 (March 7, 2009). The efficiency standards for SPVACs and SPVHPs established by EISA 2007 correspond to the levels contained in ASHRAE Standard 90.1

- 2004, which originated as addendum “d” to ASHRAE Standard 90.1

- 2001. The current standards are set forth in 10 CFR 431.97 (d), and described in Table 3.7.1.

Table 3.7

. 1 Federal Energy Efficiency Standards for SPVUs Equipment Class Cooling Capacity (Btu/h) Efficiency Level SPVAC <65,000 Btu/h EER = 9.0 SPVAC ≥65,000 Btu/h and <135,000 Btu/h EER = 8.9 SPVAC ≥135,000 Btu/h and <240,000 Btu/h EER = 8.6 SPVHP <65,000 Btu/h EER = 9.0 COP = 3.0 SPVHP ≥65,000 Btu/h and <135,000 Btu/h EER = 8.9 COP = 3.0 SPVHP ≥135,000 Btu/h and <240,000 Btu/h EER = 8.6 COP = 2.9

3.7.2 California Energy Commission

The California Energy Commission (CEC) is the state of California’s primary energy policy and planning agency. The CEC is responsible for promoting energy efficiency and conservation by setting the state’s appliance and building efficiency standards. On Fe bruary 12,
2014 , the CEC adopted amendments to its appliance efficiency regulations (California Code of Regulations Title 20, Sections 1601 through 1608) , to be made effective on July 1 st , 2014

. By

c For more information, see: http://ww w.sba.gov/sites/default/files/files/Size_Standards_Table.pdf

3

- 6definition of the CEC appliance efficiency regulations cod e, a single package vertical air conditioner means air

- cooled commercial package air conditioning and heating equipment that:

(1) Is factory

- assembled as a package that: (A) has major components that are arranged vertically; (B) is an encased combination of cooling and optional heating components; and (C) is intended for exterior mounting on, adjacent to, or through an outside wall; (2) is powered by a single

- or three

- phase current; (3) may contain one or more separate indoor grilles, outdoor louvers, various ventilation options, indoor free air discharges, ductwork, well plenum, or sleeves; and (4) has heating components that may include electrical resistance, steam, hot water, or gas, but may not include reverse cycle refrigeration as a heating means. In addition, a “ s ingle package vertical heat pump” means a single package vertical air conditioner that: (1) uses reverse cycle refrigeration as its primary heat source; and (2) may include secondary supplemental heating by means of electrical resistance, steam, hot water, or gas.

The current CEC SPVU standards , which are also the adopted standards effective on July
1 st , 2014, are depicted in Table 3.7

. 2

.

Table 3.7

. 2 Cal ifornia Energy Commission Minimum Energy Efficiency Levels for SPVUs 1
Appliance Cooling Capacity (BTU/hr) System Type Minimum E fficiency Cooling Mode Heating Mode

Single package vertical air conditioners <65,000 Single

- phase 9.0 EER N/A <65,000 3

- phase 9.0 EER N/A ≥ 65,000 and <135,000 All 8.9 EER N/A

≥ 135,000 and <240,000 All 8.6 EER N/A

Single package

vertical heat
pumps <65,000 Single

- phase 9.0 EER 3.0 COP <65,000 3

- phase 9.0 EER 3.0 COP ≥ 65,000 and <135,000 All 8.9 EER 3.0 COP

≥ 135,000 and <240,000 All 8.6 EER 2.9 COP

3.7.3 ASH RAE Standard 90.1

3

- 7ASHRAE Standard 90.1 is an energy standard for buildings except low

- rise residential buildings. On June 22, 2002, ASHRAE approved addendum “d” to include minimum efficiency level s for SPVUs a s part of ASHRAE Standard 90.1, and these levels were included in ASHRAE Standard 90.1

- 2004 (the first full release of ASHRAE Standard 90.1 after the approval of addendum d). Subsequent versions, ASHRAE 90.1

- 2007 (released January, 2008), ASHRAE 90.1

- 2010 (released October, 2010), and ASHRAE 90.1

- 2013 (released October, 2013) have since been published.

ASHRAE Standard 90.1 is sometimes adopted as part of State building code s , making certain parts or all of ASHRAE Standard 90.1 mandatory for compliance with the building codes in that State

. As a result

, although ASHRAE Standard 90.1 is a voluntary standard, SPVU manufacturers have to design their equipment to meet certain requirements for efficiency, ventilation and noise , contained in ASHRAE Standard 90.1 so they can be sold in certain States. Further, i f ASHRAE decides to increase the efficiency standard for SPVUs, then DOE, according to EPCA, is triggered to review the amended efficiency levels and is mandated to either adopt those levels as the Federal minimum efficiency standard or instead adopt a mo re

stringent standard if the more stringent standard would result in significant energy savings, be technologically feasible, and economically justified. (42 U.S.C. 6313(a)(6)(ii)) ASHRAE Standard 90.1

- 2013 (released October 2013) adopts addendum “i” , whic h increase s the minimum efficiency level for SPVUs as shown in Table 3.7

. 3 . As a result, these levels will likely be incorporated into future State building codes. Ad ditionally, DOE w as triggered to review these levels for consideration as minimum Federal standard levels

.

Table 3.7

. 3 ASHRAE 90.1

- 2013 Addendum "i" Efficiency Levels for SPVUs Equipment Type Size Category (I nput) Minimum Efficiency

SPVAC <65,000 Btu/h 10.0 EER ≥65,000 Btu/h and <135,000 Btu/h 10.0 EER ≥135,000 Btu/h and <240,000 Btu/h 10.0 EER

SPVHP <65,000 Btu/h 10.0 EER 3.0 COP ≥65,000 Btu/h and <135,000 Btu/h 10.0 EER 3.0 COP ≥135,000 Btu/h and < 240,000 Btu/h 10.0 EER 3.0 COP

3.8 MARKET DATA

Based on discussions with industry representatives during manufacturer interviews

, DOE estimate s that approximately 35 percent of the SPVU market goes to educational facilities, the majority of which is for space conditioning of modular classroom buildings. Another approximately 35 percent of the market go es to providing cooling for telecommunications and electronic encl osures. The remainder (30 percent) is used in a wide variety of commercial buildings

, and is expected to serve more niche applications, such as modular offices buildings.

3

- 8From the AHRI Directory d and manufacturers’ websites (of both AHRI

- member manufact urers and non

- AHRI

- member manufacturers) , DOE compiled a database of 30 1 SPVACs and 27 6 SPVHPs. Of the 57 7 total SPVUs, DOE was able to gather efficiency data from either the AHRI directory or manufacturer literature for 49 1 units (about 85 % of the DOE’s database). Table 3.8

. 1 shows the breakdown of models by equipment class for the models in DOE’s database. As shown in Table 3.8

. 1 , the majority of the models identified on the market are SPVUs with cooling capacities below 65,000 Btu/h, while a few are SPVACs with cooling capacities of 65,000 Btu/h or greater, but less than 135,000 Btu/h. DOE did not identify any SPVUs with cooling capacities greater than 135,000 Btu/h.

Table 3.8

. 1 Number of SPVU Models by Equipment Class Equipment Class Number of Models Percent of Total Models SPVAC, <65,000 Btu/h 288 49.9% SPVAC, ≥65,000 Btu/h and <135,000 Btu/h 13 2.3% SPVAC, ≥135,000 Btu/h and <240,000 Btu/h 0 0% SPVHP, <65,000 Btu/h 276 47.8% SPVHP, ≥65,000 Btu/h and <135,000 Btu/h 0 0% SPVHP, ≥135,000 Btu/h and <240,000 Btu/h 0 0%

3.8.1 Efficiency Data

DOE cha racterized the distribution of SPVUs currently available to customer s by dividing the models into bins based on their efficiency (both EER and COP efficiency metrics) and counting the number of models in each efficiency bin for each equipment class. For EER, each bin contains units whic h are no l ess than .05 EER lower than the defined EER of that bin and no greater than .04 EER higher than the defined EER of that bin. For COP, each bin contains units which are no l ess than

. 05 COP l o wer than the def ined COP of that bin and no greater than .04 COP higher than the defined EER of that bin. The figures below show the distribution of efficiencies for the various equipment classes of SPVUs. As shown in Table 3.8.1 above, there

are no equipm ent on the market for the following equipment classes: SPVACs ≥135,000 Btu/h and <240,000 Btu/h; SPVHPs ≥65,000 Btu/h and <135,000 Btu/h; and SPVHPs ≥135,000 Btu/h and <240,000 Btu/h.

d For more information see: http://www.ahridirectory.org/ahridirectory/pages/home.aspx ( Last accessed on August 13 th , 20 12 )

3

- 9Figure 3.8

. 1 EER ratings for SPVACs ( < 65,000 Btu/h)

Figure 3.8.1 shows that the e nergy e fficiency r atio for SPVACs < 65,000 Btu/h are mostly in the 9 to 10 EER range. The minimum efficiency rating is 9 EER and the maximum efficiency rating is 11.8 EER. The mean efficienc y for SPVAC units under 65,000 Btu/h is 9.8 EER and
t he mode is 9 EER.

Figure 3.8

. 2 E ER Ratings for SPVACs ( ≥ 65,000 Btu/h and <135,000 Btu/h )

Figure 3. 8.2 shows that the e nergy e fficiency r atio for SPVACs ≥ 65,000 Btu/h and <135,000 Btu/h are all found in the 9 to 10 EER range. The minimum efficiency is 9 EER and the maximum efficiency is 10 EER. The mean efficiency is 9.5 EER and the mode is 9.5 EER

. 48

7 11 37

0 10 5 0 7
0 37

5 3 0 2 12

0 3 3 0 18

0 3 9

0 6 0 0 6

0 10 20 30 40 50 60Number of Models

EER 

## SPVAC <65,000 Btu/h

2

0 0 0 0 3

0 0 0 0 2

0 0.5

1 1.5

2 2.5

3 3.5

9 9.1 9.2 9.3 9.4 9.5 9.6 9.7 9.8 9.9 10Number of Models

Energy Efficiency Ratio (EER) 

## SPVAC ≥65,000 Btu/h and <135,000 Btu/h

3

- 10Figure 3.8

. 3 EER Ratings for SPVHPs (<65,000 Btu/h)

Figure 3.8

. 4 EER Ratings for SPVHPs (<65,000 Btu/h)

Figure 3.8

. 3 shows that the e nergy e fficiency r atio for SPVHPs < 65,000 Btu/h are mostly concentrated in the 9 to 11 EER range. The minimum efficiency is 9 EER and the maximum efficiency is 12.3 EER . The m ean efficiency is 10.2 EER and the mode is 9 EER

. Figure 3.8

. 4 shows that the coefficient of performance for SPVHPs < 65,000 Btu/h are mainly at 3.0 COP. 44

7 5 16

3 11

2 3 10

0 21

2 3 6 14 21

0 6 6 3 39

3 0 9

0 6
0 3 0 0 3 3 0 3

0 10 20 30 40 50Number of Models

Energy Efficiency Ratio (EER) 

## SPVHP <65,000 Btu/h [EER]

140

9 27 43

7 11 3 3 0 9

0 20 40 60 80 100 120 140 160

3 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9Number of Models

Coefficient of Performance (COP) 

## SPVHP <65,000 Btu/hr [COP]

3

- 11The minimum COP is 3 and the maximum COP is 3.9 5 e . The mean COP is 3.15, and the mode COP is 3.

3.8.2 Capacity Data

DOE also characterized the SPVUs in its database based on their cooling capacity. Throughout the market analysis, DOE found that manufacturers tend to adver tise SPVU cooling and heating capacity by rounding it to the nearest cooling ton (a cooling ton is 12,000 Btu/h). As such, for the purposes of the NOPR analysis , DOE grouped units into bins with capacity ranges centered on multiples of 12,000 Btu/h cooling capacity. In other words, e ach bin contained units which were no less than 6,000 Btu/h lower than the associated tonnage, and no greater than 5,999 Btu/h higher than the associated tonnage.

As depicted in Table 3.8

. 1 , there are no SPVHPs in production with an input capacity ≥ 65,000 Btu/h and < 135,000 Btu/h, and there are also no SPVUs currently on the market with an input capacity ≥ 135,000 Btu/h, so DOE did not a nalyze capacity data for these equipment classes.

Figure 3.8

. 5 Cooling inputs for SPVACs (<65,000 Btu/h)

Figure 3.8

. 5 shows that the cooling capacities for equipment in the SPVAC <65,000 Btu/h equipment class are mostly in the 2 to 5 ton range, with the maximum amount of models in

e Even though there are some units on the market at an efficiency of 3.95 COP, DOE does not consider this to be the
true max

- tech efficiency level for SPVHP <65,000 Btu/h. In order to be considered the maximum technologically feasible efficiency level for an equipment class, DOE believes that equipment at such efficiency level must have proven performance at all operating capacities within that equipment class. Units at 3.95 COP only exist at one specific cooling capacity in the SPVHP <65,000 Btu/h equi pment class; therefore, 3.95 COP is not being considered the max

- tech efficiency level. DOE has determined the true max

- tech efficiency level for SPVHP <65,000 Btu/h to be 3.9 COP, and in order to avoid confusion has included the 3.95 COP efficiency units in the 3.9 COP bin in Figure 3.8

. 4

. 6 62 95

72

53

0 20 40 60 80 100

1 2 3 4 5Number of Units

Cooling Tons (12,000 Btu/h per ton) 

## SPVAC <65,000 Btu/h Cooling Capacity Data

3

- 12the 3 ton range. There are only 6 models within half a cooling ton of the 1 ton value

. Based on analysis of the DOE database, t he average cooling capacity of this equipment class is 39
, 586 Btu/h and the median cooling capacity is 39
, 000 Btu/h.

Figure 3.8

. 6 Cooling inputs for SPVACs (≥65,000 Btu/h and <135,000 Btu/h)

Figure 3.8

. 6 shows that the cooling capacities for equipment in the SPVAC ≥ 65,000 Btu/h equipment class are mostly within half a cooling ton of the 6 ton range, with 3 units also in the 7 ton range

. The m aximum input capacity in this data set is 84,000 Btu/h

. Based on analysis of the DOE database, the average cooling capacity of this equipment class is 72769 Btu/h , and the median cooling capacity is 70 ,000 Btu/h

. 10

3

0 2 4 6 8 10 12

6 7 8 9 10 11Number of Units

Cooling Tons (12,000 Btu/h per ton) 

## SPVAC ≥65,000 Btu/h Cooling Capacity Data

1 78 82
70

45

0 20 40 60 80 100

1 2 3 4 5Number of Units

Cooling Tons (12,000 Btu/h per ton) 

## SPVHP <65,000 Btu/h Cooling Capacity Data

3

- 13Figure 3.8

. 7 Cooling inputs for SPVHPs (<65,000 Btu/h)

Figure 3.8

. 7 shows that the cool ing capacities for equipment in the SPVHP <65,000 Btu/h equipment class are mostly in the 2 to 5 ton range, with the maximum amount of models in the 3 ton range. There is o nly 1 model in the 1 ton range. Based on analysis of the DOE database, the average cooling capacity of this equipment class is 3 90 21 Btu/h, and the median cooling capacity is 39 ,000 Btu/h.

Figure 3.8

. 8 He ating inputs for SPVHPs (<65,000 Btu/h)

Figure 3.8

. 8 shows that the heating capacities for equipment in the SPVHP <65,000 Btu/h equipment class are mostly in the 2 to 4 ton range, with the maximum amount of models in the 3 ton range. There is o nly 1 model in the 1 ton range and 24 models in the 5 ton range. Based on analysis of the DOE database, the average heating capacity of this equipment class is 3 7
, 330 4 Btu/h, and the median heating capacity is 3 6
, 0 00 Btu/h.

3.9 TECHNOLOGY ASSESSMENT

This se ction provides a technology assessment for SPVUs

. T his technology assessment presents details about equipment characteristics and operation

, and an examination of possible technological improvements for SPVACs and SPVHPs

.

3.9.1 Equipment C haracteristics and O peration

Air conditioners use a refrigeration cycle to cool an indoor space by moving heat from the cold location to a hotter location by means of evaporating and condensing a fluid, typically a 1 75 100

76

24

0 20 40 60 80 100 120

1 2 3 4 5Number of Units

Cooling Tons (12,000 Btu/h per ton) 

## SPVHP <65,000 Btu/h Heating Capacity Data

3

- 14refrigerant. An air conditioner typically has four major com ponents: a compressor, condens er coil, expansion valve, and an evaporator coil. During operation, the refrigerant cycles through these components in a closed loop. There are four main steps that the refrigerant passes through in this refrigerant cycle

. The cooling cycle is outlined below:

• Step 1: The refrigerant enters t he compressor as a low pressure gas. The compressor

compresses the refrigerant into a high pressure gas from a low pressure gas , which also raises the temperature of the gas.

• Step 2: T he o utdoor coil ( condens er coil ) removes heat from the high

- pressure gas

- phase refrigerant entering the coil , condens ing the gas into a liquid at high pressure

.

• Step 3: Th e liquid refrigerant goes through an expansion valve that lowers the refrigerant’s pressure and temperature before the refrigerant enters the indoor coil ( evaporator coil )

. As t he refrigerant passes through the expansion valve, it flashes into a mixture of low

- pressure gas and liquid.

• Step 4: The indoor coil cools the indoor air by transferring heat from the warmer indoor air to the colder refrigerant

, evaporat ing the refrigerant into a low pressure gas, whereby it enters the compressor starting the cycle a gain

.

In SPVUs , the major components must be arranged vertically , as stated by the definition described in section 3.2 . Typically, the outdoor coi l (condenser) and fan and the compressor are situated in the bottom of the cabinet with the supply

- air blower and indoor coil (evaporator) positioned directly above them.

H eat pump s operate using the same general principals and components as an air conditioner, but contain a reversing valv e that allow heat pumps to reverse the flow of the refrigerant to provide for a heating mode. During heating mode operation, the refrigerant flow travels through the major components in the opposite order with the i ndoor coil serving the function of the condenser coil and the outdoor coil serving the function of the evaporator coil

. During operation, the indoor coil rejects heat from the hot

- gas refrigerant to the interior space, which condenses the hot gas into a li quid; and the outdoor coil absorbs heat from the outside ambient air, which evaporates the liquid refrigerant into a gas.

Since January 1st, 2010, all newly manufactured SPVUs in the United States have no longer been allowed to use R

- 22 refrigerant per the Montreal Protocol. As result, the vast majority of SPVUs began using R410A refrigerant instead. DOE is aware of one alternative refrigerant, R407C, which can be used as a replacement for R410A in SPVUs. DOE is aware of some SPVUs which utilize R407C; however, these units are not offered for sale in the United States and therefore are not included among the products potentially regulated by this rule.

There are t hree primary sources of electric energy consumption in a package air conditioner or heat pu mp : the compressor , the supply

- air blower that operates to provide cooling (or in the case of the heat pump, reverse cycle heating), and the condenser fan . Because, in a commercial application, the supply blower generally runs continually during occupied h ours to provide for ventilation in the building, its energy consumption during the course of the year can

3

- 15be large relative to the compressor or condenser energy consumption. Auxiliary controls such as control boards, switches and LEDs can also contribute to the power consumption.

3.9.2 Technology Options In order to gain a deeper understanding of the technological improvements used to increase the efficiency of SPVUs , DOE examined the most common improvements used in today’s market , including both the SPVU market and other air conditioning markets

. DOE identified technologies to improve efficiency through examining equipment currently on the market (both SPVUs and other types of air conditioning or refrigeration equipment), reviewing industry publications, a nd discussing technology options with manufacturers

. The purpose of the technology assessment is to develop a list of technologies that could be used to improve the efficiency of SPVUs . The following assessment provides descriptions of technologies and designs grouped by four main categories : heat exchanger improvements

, indoor/outdoor fan improvements , compressor improvements , and others. Table 3.9

. 1 summarizes the technologies that were analyzed below.

Table 3.9

. 1 Potential Technology Options for improved Energy Efficiency of SPVUs Technology Options

Heat Exchanger Improvements Increased frontal coil area Increased depth of coil Increased fin density Improved fin design Improved tube design Hydrophilic film coating on fins Microchannel heat exchangers Dual condens er heat exchangers Indoor Blower and Outdoor Fan Improvements Improved fan motor efficiency
Improved fan blades
Compressor Improvements Improved compressor efficiency Multi

- speed Compressors

Other Improvements Thermostatic expansion valves Electronic expansion valves Thermostatic cyclic controls

3

- 163.9.2.1 Heat exchanger improvements

Increased frontal coil area

One of the most common ways of improving the heat exchanger effectiveness is increasing the heat transfer surface area by using a coil with a larger frontal area. With a larger condenser coil , heat can be rejected from the refrigerant t o the outside air stream at a lower condensing temperature. With a larger evaporator coil

, the evaporator can cool incoming air at a higher refrigerant temperature and still deliver the same cooling capacity

. With a lower condensing temperature and/or a higher evaporating temperature, t hese changes

can reduce the pressure difference between the low pressure and high pressure sides of the compressor, thus reducing the required compressor power.

Increases in heat exchanger area must be balanced due to tw o factors. The evaporator must still be able to dehumidify the air at the higher evaporating temperature, which may limit potential growth

. Also, there are physical limit s to increasing the frontal coil area due to existing cabinet dimensions , and larger units may incur additional costs beyond the larger heat exchanger.

I

ncreased depth of coil (additional tube rows)

Another way of increas ing the heat exchanger surface area is to add tube rows to the coil. Adding vertical tube rows will increase the depth of the coil, which would provide the same benefits as increasing the frontal area.

Increases in heat exchanger area must take into account a couple of factors. A dding more rows
may require an increase in the size of the unit due to physical constraints of the existing cabinet dimensions

, and increases may incur significant costs beyond just the costs of the larger heat exchanger. I ncreasing heat exchanger depth may also cause an increase in static pressu re that the fan motor must overcome to provide adequate air flow . This additional power to the fan must be considered in calculating the benefit associated with the additional heat exchanger surface area.

Increased fin density

Another method of increasing the heat exchanger surface area is to increase the fin density. H owever, increased fin density may have an effect on air flow, fan power, water drainage, and dirt build

- up . These factors must be considered in assessing the benefit of increased fin density

.

• Fan motor draw: Increasing the fin density increases the air

- side pressure drop over the coil, resulting in an increased power draw by the fan motor or reduced airflow through the coil

. This effect must be considered in calculating the benefit associated with the additional heat exchanger surface area.

• Draining condensate: Increased fin density also can decrease the ability of the evaporator to drain condensate . The condensate that forms on the eva porator usually flow s down to the drain pan by the effect of gravity. If restricted

, the

3

- 17condensate can restrict air flow and lead to entrainment of water droplets in the discharge air flow.

• Dirt build

- up: The build

- up of dirt on heat exchanger surfaces is also accelerated by an increase in fin density. Smaller air passageways through the coils are more likely to retain dirt which, if allowed to accumulate

, may decrease the system performance if taken too far

. Taking these factors into consideration the maximum fin density is a function of the type of coil ( i.e. , evaporator or condenser), the fin type ( i.e. , wavy, louvered, or enhanced), the number of tube rows, and the tube diameter. From physical teardowns, DOE found that almost all SPVU heat exchange rs have a fin density between 12 and 15 fins per inch.

Improved fin design

Improvements to the fin design may have the effect of improving the coil’s air

- side heat transfer coefficient and thus improving the overall heat

- transfer capability of the coil. Th e s e improved designs may increase the air turbulence over the coil. Enhanced fin designs are generally achieved by using wavy, louvered, lanced, or slit

- type fin surfaces. From physical teardowns, DOE found that m ost fins used in SPVU heat exchangers are the wavy

- fin design

.

Improved tube design

Improvement of the refrigerant

- side heat transfer coefficient is accomplished by augmenting the interior surface of the refrigerant tubes wit h spiral grooves. This typ e of refrigerant tubing is known as rifled or grooved tubi ng. Research has shown that the refrigerant side heat

- transfer coefficient for grooved tubing can increase by 80% to 140% compared to that of conventional smooth tubing. 2
, 3
, 4 As seen with fin enhancements, manufactur ers of refrigerant tubing have developed various types of grooved tubing to improve the heat

- transfer c apability of air conditioning coils. Improvement to the refrigerant

- side heat

- transfe r coefficient is a function of the width, he ight, and spacing of the grooves as well as the concen tration of lubricant oil being circulated within the refrigerant.

From physical teardowns, DOE found that nearly all SPVU heat exchangers that were inspected use rifled tubing.

Hydrophilic film coati ng on fins

The condensate water that forms on heat exchanger fins may adhere to the surface as droplets and cause bridging of the fin spacing, resulting in decreased heat transfer performance and increased air pressure drop. Adding a hydrophilic coating to heat exchanger fins allows
water not only to better adhere to the surface , which reduces the condensate layer thickness , but also to flow down the fins and fall off the evaporator quickly, resulting in reduced air

- side pressure drops across the heat exc hanger. Hydrophilic film coating on heat exchanger fins have been shown to reduce air

- side pressure drop 20 to 50 percent when operating with high

- humidity

room

- side air. 5 However, DOE is unaware of any publicly available data quantifying the energy

3

- 18efficiency enhancement associated with hydrophilic

- film coating on fins under n DOE test procedure conditions.

M icrochannel H eat E xchangers

Unlike a conventional tube

- and

- coil heat exchanger ( coil tube with several attached plate fin s) , microchannel heat exchangers have a rectangular aluminum cross

- section containing several small channels (typically less than 1 millimeter across) through which refrigerant passes. Aluminum fins are brazed between the rectangular tubes. Microchannel can increase heat transfer while reducing pressure drop as compared with conventional coils. Microchannel heat exchangers also generally weigh less and hold significantly less refrigerant than conventional heat exchangers.

Currently

, there are several manufacturers of micr ochannel heat exchangers. The technology was first widely adopted for use in automobile air conditioning systems, where it is used a lmost exclusively for condens er heat exchangers because of difficulty in evaporator applications as explained below . Other air

- conditioning applications have adopt ed microchannel heat exchangers, such as military environmental control units (ECUs), air

- cooled chillers for commercial buildings, and some residential central air conditioning systems.

However, microchann el heat exchangers have not yet been adopted by SPVU manufacturers. In manufacturers interviews, m ost SPVU manufacturers noted that they have experimented with microchannel heat exchangers in prototypes; however, SPVU manufacturers note that there are some issues that prevent microchannel heat exchangers from being widely adopted , such as the high investment cost required for the equipment needed to fabricate these heat exchangers ( i.e. , brazing ovens).

Microchannel heat exchangers may also have difficult y in evaporator applications, because their geometry is less amenable to condensate removal than conventional heat exchangers.. F or heat pumps, where the outdoor coil is the evaporator coil, any condensate that forms can turn into frost in cold ambient conditions. Defrosting a microchannel evaporator coil is also a concern for heat pumps for the same reason as stated above, the hor izontal flat fins block the gravitational flow of condensate.

Dual Condens er Heat Exchangers

In air conditioning eq uipment, the effectiveness of a heat exchanger at discharging heat into the outdoor air stream is directly related to the amount of surface area of the heat exchanger coils.

In order to continue improving the efficiency of the condenser section of the unit when increasing the size of the condenser coil is uneconomical, SPVU manufacturers have utilize d two separate condensing heat exchangers operating in series, rather than just one. Doing so allows the manufacturer to achieve the desired incre ase in total condenser coil surface area, without the fabrication cost constraints of manufacturing a single, large condenser coil as an alternative.

3

- 193.9.2.2 I ndoor B lower and O utdoor F an Improvements

Improved fan motor efficiency

SPVUs primarily use permanent split capacitor (PSC) motors for their fans and blowers

. These motors range in efficiency from 50 to 70 percent. While larger motors are generally more efficient, there is a range of efficiency for any given power level.

Electric motors operate based on the interaction between a field magnet and a magnetic rotor. However, single

- phase motors only pro duce a rotating magnetic field when the rotor is rotating, and simply powering the electromagnet is therefore not sufficient to start such a motor. One of the most significant differences between different types of single

- phase motors is the way in which t hey handle start

- up. In a PSC motor, a small start

- up winding is present which is energized out of phase with the main winding. The start

- up winding is electrically connected in parallel with the main winding and in series with a capacitor. At start

- up, th e interactions between the magnetic field generated by the start

- up winding and that generated by the main winding induce rotation. As the capacitor charges, the current flowing through the start

- up winding decreases, and the start

- up winding becomes an au xiliary winding after the motor reaches running speed. Consequently, the current to the start

- up winding is cut off once the capacitor is fully charged and the motor reaches steady

- state speed. 6

Permanent magnet motors have higher efficiencies than PSC m otors and are known as brushless DC (BLDC) motors , electronically commutated motors ( ECMs ) , brushless permanent magnet (BPM) motors, and electronically

- commutated permanent magnet (ECPM) motors. BLDC motors convert single

- phase AC input power into DC power and achieve the commutation required for operation of DC motors by electronic switching r ather than through use of a conventional mechanical commutator. The commutation is coordinated through use of sensor technology that determines when the motor is at the proper angle for switching the power. BLDC motors (less than 1 horsepower) offer effici ency gains of at least 10% more than similarly

- sized PSC motors and offer even greater efficiency gains at part

- load performance than PSC motors

. 7 However, BLDC motors can weigh more than PSC motors of the same shaft power, potentially necessitating some s ystem redesign to accommodate the increased weight.

When surveying the SPVU market, DOE found that PSC motors are the dominant motor design in lower efficiency units and that BLDC motors are commonly found in higher efficiency equipment. Figure 3.9

. 1 below shows the frequency of each motor type by EER of all the models of SPVACs and SPVHPs in DOE’s compiled database. At 10 EER , the market data shows a transition fro m using a PSC blower motor to a BLDC motor. However, of the 27 models that use PSC motors at 10 EER, 18 of them are units with gas

- heating, which makes up a very small part of the overall SPVU shipments. Thus, DOE determined that majority of SPVUs at 10 EER are likely to be shipped with BLDC motors.

3

- 20Figure 3.9

. 1 Histogram of Evaporator Motor Type of SPVACs and SPVHPs by EER

Improved fan blades

Air system efficiency c an be improved through more advanced fan and blower design and by reducing the restrictions to air flow. The air delivery system of a n SPVU typically consists of two motor s driving three fans

- two indoor blower s ( which move air across the evaporator coil ) and an outdoor fan (which m oves air across the condenser coil) . The evaporator blower s are typically centrifugal blower s , while the condenser fan is typically a propeller

- type fa n

. Improvements to the fan blade designs could increase the overall efficiency by decreasing the power de mands for the fan motor. Most SPVUs use forward curved blowers, which typically have a n overall efficiency between 55 and 65 percent. Some manufacturers have b een experimenting with backward

- curved blowers for their quieter performance and higher efficie ncies (up to 85 percent when using airfoil blades). 8 However, the space limitations within SPVUs make reduction of flow resistance difficult. Backwards

- curved fan blades were found in SPVUs at the max tech efficiency level. DOE has not found any data quan tifying the efficiency improvement of a backward

- curved blower in SPVU models.

3.9.2.3 C ompressor Improvements

Improved Compressor Efficiency

The compressors used in SPVUs are almost exclusively scroll compressors, which use two interleaving scrolls to pump refrigerant through out the sealed system. These compressors 0 10 20 30 40 50 60 70 80 90

9 9.2 9.4 9.6 9.8 10 10.2 10.4 10.6 10.8 11 11.2 11.4 11.6 11.8 12 12.2 12.4Number of Models

Energy Efficiency Ratio (EER ) 

## Market Saturation of PSC and ECM motors by SPVU EER rating

PSC Motors

ECM Motors

3

- 21effectively have identical designs, but vary in efficiency as a function of manufacturing tolerances. The scroll compressors found in SPVUs range in efficiency from about 2.80 to 3.25 COP.
, T he c ompressor consumes the majority of the electrical input to an SPVU (indoor and outdoor blower fans and the central controls account for the remainder) . As such, utilizing a higher efficiency compressor yields a significant improvement to the EER/COP of an SPVU

. Based on physical teardowns, baseline efficiency SPVUs used single

- speed compressors with lower peak

- load EERs, whereas more efficient SPVUs incorporated two

- speed compressors with higher EERs in their designs.

Multi

- Speed compressors

Most con ventio nal single

- speed compressors run at a constant speed and respon d to signals from the thermostat by cycling on and off

. During the initial start

- up of the system after the compressor turns on, the system does not operate at peak efficiency (until it reaches steady

state performance) . The energy expended while the system is not achiev ing peak performance is known as cycling losses.

Because of these cycling losses, the efficiency of systems using these compressors is typically lower than fu ll

- capacity efficiency at part load, due to off

- cycle losses.

. Multi

- speed
compressors (two

- speed or variable

- speed) are typically implemented through the use of an electronic control that varies the input frequency of the power supply for the compressor m otor. Multi

- speed compressors enable modulation of the refrigeration

- system cooling capacity, allowing the air conditioner to match the cooling load. This modulation can improve efficiency by reducing off

- cycle losses and by operating at a lower mass flow rate at part

- load conditions

, which reduces the load on the compressor . There are also non

- e fficiency

- related advantages to multi

- speed control, including quieter operation at low speeds, enhanced comfort by eliminating temperature fluctuations in the room, and potentia l for improved dehumidification.

3.9.2.4 Other Improvements

Capillary Tubes

Manufacturer interviews and DOE’s reverse engineering indicate that the capillary tube is the flow control device currently used in baseline SPVUs; however, more efficient SPVUs tend to use TXVs as their flow control device. The capillary tube is a pressure

- reducing device that consists of a small

- diameter tube that connects the outlet of the condenser to the inlet of the evaporato r. The very large pressure drop as refrigerant flows through the capillary allows the high and low pressures in the system to be maintained. Since it is a mechanically fixed device, the capillary tube provides optimum system operating parameters over only a narrow range of operating conditions.

3

- 22Thermostatic expansion valves

The ther mostatic expansion valve (TXV)

– a flow

- control alt ernative to the capillary tube

– is commonly used in higher

- efficiency air

- conditioning systems. TXVs regulate the flow of liquid refrigerant entering the evaporator in response to the superheat temperature of the refrigerant leaving it. TXVs can adapt better to changes in operating condi tions, such as variations in ambient temperature, which affect the condensing temperature. As a result, TXVs can control for optimum system operating parameters over a wider range of operating conditions, and can thus improve seasonal efficiency.

Electron ic expansion valves

Electronic expansion valves (EEVs) serve a similar purpose as TXVs, but they operate using electronic (microprocessor) control. The EEV uses a pulse motor, which rotates based on an electronic signal from a microcomputer , which determi n es the desired valve position from measured system parameters. While a TXV is limited due to its thermo

- mechanical design, EEVs have a greater flexibility for operation. Research has demonstrated t hat, when incorporated into air

- conditioning systems using inverter

- driven variable

- speed compressors, EEVs can improve seasonal energy efficiency beyond that of systems using conventional TXVs. As with variable speed compressors, the main benefit of EEVs is to improve efficiency on a seasonal basis.

Thermostati c cyclic controls

Remote thermostatic cyclic controls can monitor room temperature more accurately than typical built

- in thermostats can . Research has been conducted to investigate the use of fuzzy logic controllers for HVAC applications. These controller types have been shown to improve the performance of HVAC systems over that of conventional controllers. Thermostatic controls could offe r seasonal energy savings.

As with variable speed compressors and expansion valves, the DOE test procedure for SPVUs can only measure energy efficiency improvements based on steady

- state conditions. In addition, no data were found or presented that indic ated how the steady

- state performance of SPVUs could be enhanced with thermostatic cyclic controls.

3

- 23REFERENCES

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. A. Cavallini, D. Del Col, L. Doretti, G.A. Longo, L. Rossetto, “ Review P aper H eat T ransfer and P ressure D rop D uring C ondensation of R efrigerants I nside H orizontal
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. LBNL and Resource Dynamics Corporation. U.S. Department of Energy. Improving Fan System Performance: a Sourcebook for Industry. April 2003 : p p. 19

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3

- 24