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 (<65,000 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

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CHAPTER 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 vertical heat pumps

(SPVHPs), or collectively single package vertical units (SPVUs).

The goal of the market assessment was to develop a qualitative and quantitative 

characterization of the SPVU industry 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 performed 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 DEFINITIONS

SPVUs are 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 

portable buildings. Although this equipment has similar cooling/heating capacities as products 

used in residential applications, it is subject to different operational cycles and operating hours 

than are typically encountered in 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:

“Air-cooled commercial package air conditioning and 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 sleeves; 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))

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EPCA 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 electrical 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, space constrained 

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 in2 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 replaced. 

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 segments: (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 are 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 those 

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 classification of these products as 

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SPVUs – 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 between 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 

these units should 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 the 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 

belonging 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 “spaceconstrained” 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 different equipment classes.

EPCA divides single package vertical units into equipment classes based on:

(1) The type 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 capacity: 

(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, existing 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 package vertical air conditioner, <65,000 Btu/h

• Single package vertical air conditioner, ≥65,000 Btu/h and <135,000 Btu/h

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

• Single package vertical heat pump, <65,000 Btu/h

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• Single package vertical heat pump, ≥65,000 Btu/h and <135,000 Btu/h

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

In the NOPR, DOE is proposing to maintain these existing equipment classes for its 

analysis.

3.4 EQUIPMENT TEST PROCEDURE 

The statutory criteria for federal test procedures require that a test procedure be 

reasonably designed to produce test results which reflect energy efficiency, energy 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, DOE published a final rule that adopted the American National 

Standards Institute (ANSI)/AHRI 390-2003: Performance Rating of Single Package Vertical AirConditioners 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 these two metrics to set its energy conservation 

standards 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 represents more than 300 heating, water heating, ventilation, air conditioning and 

commercial refrigeration manufacturers within the global HVACR industry, and these

manufacturers account for more than 90 percent of the residential and commercial air 

conditioning, space heating, water heating, and commercial refrigeration equipment 

manufactured and sold in North America.

a AHRI develops and publishes technical standards,

which use rating criteria and procedures for measuring and certifying performance for residential 

and commercial air conditioning, heating, and refrigeration equipment. 

As noted previously, the 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 programb. AHRI has two certified directories for SPVUs: “single package 

vertical systems – AC” and “single package vertical systems – HP.” DOE used the data in these

certification directories 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

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3.6 MANUFACTURER INFORMATION

The following sections detail information regarding manufacturers of SPVUs for sale in 

the United States. 

3.6.1 Manufacturers 

DOE compiled data for SPVUs currently on the market by examining the AHRI 

Directory of Certified Product Performance. To supplement 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 manufacturers 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 AHRI directory and through additional research that identify their 

product as an SPVU; however, DOE has found that a significant portion of sales of these 

products are to the residential market. Thus, these products are more appropriately classified as 

residential 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 is unable to disclose 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. Companies designated 

as “major manufacturers” have larger market shares than “other manufacturers”. Table 3.6.1also 

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 within 

the U.S. market. 

Table 3.6.1 Major and other SPVU manufacturers

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.” 

3-5
The Small Business Administration (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 

this time, DOE has identified two domestic small business manufacturers – Bard Manufacturing 

Company and National Coil Company – in the SPVU market that fall under the SBA’s 

definition. DOE studied the potential impacts on these small business manufacturers, 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, airconditioning, and water-heating equipment, including SPVUs. (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 levels 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 February 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 1st, 2014. By 

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

3-6

 
definition of the CEC appliance efficiency regulations code, 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 “single 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 

1st, 2014, are depicted in Table 3.7.2.

Table 3.7.2 California Energy Commission Minimum Energy Efficiency Levels for SPVUs1

Appliance Cooling Capacity 

(BTU/hr) System Type Minimum Efficiency

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 ASHRAE Standard 90.1

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ASHRAE 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 

levels for SPVUs as 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 codes, 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, if 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 morestringent 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”, which increases 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. Additionally, DOE was 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 (Input) 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

estimates 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 goes to providing cooling for telecommunications and 

electronic enclosures. 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.

3-8
From the AHRI Directoryd and manufacturers’ websites (of both AHRI-member 

manufacturers and non-AHRI-member manufacturers), DOE compiled a database of 301

SPVACs and 276 SPVHPs. Of the 577 total SPVUs, DOE was able to gather efficiency data 

from either the AHRI directory or manufacturer literature for 491 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 characterized the distribution of SPVUs currently available to customers 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 which are no less 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 less than .05 COP lower than the defined 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 equipment 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 

13th, 2012)

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

Figure 3.8.1 shows that the energy efficiency ratio 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 efficiency for SPVAC units under 65,000 Btu/h is 9.8 EER and

the mode is 9 EER.

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

Figure 3.8.2 shows that the energy efficiency ratio 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

60

Number 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 10

Number of Models

Energy Efficiency Ratio (EER)

SPVAC ≥65,000 Btu/h and <135,000 

Btu/h

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Figure 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 energy efficiency ratio 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 mean 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

50

Number 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 3.9

Number of Models

Coefficient of Performance (COP)

SPVHP <65,000 Btu/hr [COP]

3-11
The minimum COP is 3 and the maximum COP is 3.95e

. 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 advertise 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, each 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 analyze 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 equipment 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 5

Number of Units

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

SPVAC <65,000 Btu/h Cooling 

Capacity Data

3-12

 
the 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, the 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 maximum input capacity in this data set is 84,000 Btu/h. Based on analysis 

of theDOE 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 11

Number 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 5

Number of Units

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

SPVHP <65,000 Btu/h Cooling 

Capacity Data

3-13
Figure 3.8.7 Cooling inputs for SPVHPs (<65,000 Btu/h)

Figure 3.8.7 shows that the cooling 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 only 1 model in the 1 ton range. Based on analysis of the DOE database, 

the average cooling capacity of this equipment class is 39021 Btu/h, and the median cooling 

capacity is 39,000 Btu/h.

Figure 3.8.8 Heating 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 only 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 37,3304

Btu/h, and the median heating capacity is 36,000 Btu/h.

3.9 TECHNOLOGY ASSESSMENT

This section provides a technology assessment for SPVUs. This technology assessment 

presents details about equipment characteristics and operation, and an examination of possible 

technological improvements for SPVACs and SPVHPs.

3.9.1 Equipment Characteristics and Operation

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 5

Number of Units

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

SPVHP <65,000 Btu/h Heating 

Capacity Data

3-14
refrigerant. An air conditioner typically has four major components: a compressor, condenser

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 the 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: The outdoor coil (condenser coil) removes heat from the high-pressure gas-phase

refrigerant entering the coil, condensing the gas into a liquid at high pressure. 

• Step 3: The 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 the 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, evaporating the refrigerant into a low pressure gas, whereby 

it enters the compressor starting the cycle again.

In SPVUs, the major components must be arranged vertically, as stated by the definition 

described in section 3.2. Typically, the outdoor coil (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.

Heat pumps operate using the same general principals and components as an air 

conditioner, but contain a reversing valve 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 indoor 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 liquid; 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 three primary sources of electric energy consumption in a package air 

conditioner or heat pump: 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 hours to 

provide for ventilation in the building, its energy consumption during the course of the year can 

3-15
be 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, and 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 condenser 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

3-16
3.9.2.1 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 to 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, these 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 two 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 limits to increasing the frontal coil area due to existing cabinet 

dimensions, and larger units may incur additional costs beyond the larger heat exchanger.

Increased depth of coil (additional tube rows)

Another way of increasing 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. Adding 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. Increasing heat exchanger depth may also cause an increase in static pressure 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. However, 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 evaporator 

usually flows down to the drain pan by the effect of gravity. If restricted, the 

3-17
condensate 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 exchangers 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. These 

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 most 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 with spiral grooves. This type of 

refrigerant tubing is known as rifled or grooved tubing. 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, manufacturers of refrigerant 

tubing have developed various types of grooved tubing to improve the heat-transfer capability of 

air conditioning coils. Improvement to the refrigerant-side heat-transfer coefficient is a function 

of the width, height, and spacing of the grooves as well as the concentration 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 coating 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 exchanger. 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 

3-18
efficiency enhancement associated with hydrophilic-film coating on fins under n DOE test 

procedure conditions.

Microchannel Heat Exchangers

Unlike a conventional tube-and-coil heat exchanger (coil tube with several attached plate 

fins), 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 microchannel heat exchangers. The 

technology was first widely adopted for use in automobile air conditioning systems, where it is 

used almost exclusively for condenser heat exchangers because of difficulty in evaporator 

applications as explained below. Other air-conditioning applications have adopted microchannel 

heat exchangers, such as military environmental control units (ECUs), air-cooled chillers for 

commercial buildings, and some residential central air conditioning systems. 

However, microchannel heat exchangers have not yet been adopted by SPVU 

manufacturers. In manufacturers interviews, most 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 difficulty in evaporator applications, 

because their geometry is less amenable to condensate removal than conventional heat 

exchangers.. For 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 horizontal flat fins 

block the gravitational flow of condensate.

Dual Condenser Heat Exchangers

In air conditioning equipment, 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 utilized two 

separate condensing heat exchangers operating in series, rather than just one. Doing so allows the 

manufacturer to achieve the desired increase in total condenser coil surface area, without the 

fabrication cost constraints of manufacturing a single, large condenser coil as an alternative. 

3-19
3.9.2.2 Indoor Blower and Outdoor Fan 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 produce 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 they 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, the 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 auxiliary 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 motors 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 rather 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 efficiency 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 system 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 from 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. 

3-20
Figure 3.9.1 Histogram of Evaporator Motor Type of SPVACs and SPVHPs by EER

Improved fan blades

Air system efficiency can be improved through more advanced fan and blower design 

and by reducing the restrictions to air flow. The air delivery system of an SPVU typically 

consists of two motors driving three fans - two indoor blowers (which move air across the 

evaporator coil) and an outdoor fan (which moves air across the condenser coil). The evaporator 

blowers are typically centrifugal blowers, while the condenser fan is typically a propeller-type 

fan. Improvements to the fan blade designs could increase the overall efficiency by decreasing 

the power demands for the fan motor. Most SPVUs use forward curved blowers, which typically 

have an overall efficiency between 55 and 65 percent. Some manufacturers have been 

experimenting with backward-curved blowers for their quieter performance and higher 

efficiencies (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 quantifying the efficiency 

improvement of a backward-curved blower in SPVU models. 

3.9.2.3 Compressor Improvements

Improved Compressor Efficiency

The compressors used in SPVUs are almost exclusively scroll compressors, which use 

two interleaving scrolls to pump refrigerant throughout 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 10.210.410.610.8 11 11.211.411.611.8 12 12.212.4

Number of Models

Energy Efficiency Ratio (EER)

Market Saturation of PSC and ECM motors by 

SPVU EER rating

PSC Motors

ECM Motors

3-21
effectively 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. , The compressor 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 conventional single-speed compressors run at a constant speed and respond 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 steadystate performance). The energy expended while the system is not achieving peak performance is 

known as cycling losses.

Because of these cycling losses, the efficiency of systems using these compressors is 

typically lower than full-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 motor. 

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-efficiency-related advantages to 

multi-speed control, including quieter operation at low speeds, enhanced comfort by eliminating 

temperature fluctuations in the room, and potential 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 

evaporator. 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.

3-22
Thermostatic expansion valves

The thermostatic expansion valve (TXV) – a flow-control alternative 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 conditions, 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.

Electronic 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 determines 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 that, 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.

Thermostatic 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 offer 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 indicated how the steady-state performance of 

SPVUs could be enhanced with thermostatic cyclic controls.

3-23
REFERENCES

1. California Code of Regulations, Title 20: Division 2, Chapter 4, Article 4, Sections 1601-

1608: Appliance Efficiency Regulations. December 2013: pp 19-20, 115. Available 

online at: http://www.energy.ca.gov/2013publications/CEC-400-2013-015/CEC-400-

2013-015-45DAY.pdf

2. A. Cavallini, D. Del Col, L. Doretti, G.A. Longo, L. Rossetto, “A New Computational 

Procedure for Heat Transfer and Pressure Drop During Refrigerant Condensation Inside 

Enhanced Tubes,” Enhanced Heat Transfer, vol. 6 (1999): pp. 441–456.

3. A. Cavallini, D. Del Col, L. Doretti, G.A. Longo, L. Rossetto, “Review Paper Heat 

Transfer and Pressure Drop During Condensation of Refrigerants Inside Horizontal 

Enhanced Tubes,” International Journal of Refrigeration, vol. 23 (2000): pp. 4–25.

4. J. Yu, S. Koyama, “Condensation Heat Transfer of Pure Refrigerants in Microfin Tubes,” 

Proceedings of the 1998 International Refrigeration Conference, Purdue University, 

1998, pp. 325–330.

5. Mimaki M. 1987. “Effectiveness of Finned-Tube Heat Exchanger Coated Hydrophilic

Type Film,” ASHRAE Transactions, vol. 93, pt. 1 (1987): pp. 62-71.

6. U.S. Department of Energy – Office of Energy Efficiency and Renewable Energy. 

“Preliminary Technical Support Document for Residential Furnace Fans,” July 2012. 

Washington D.C. Available online at: http://www1.eere.energy.gov/buildings/appliance_standards/residential/furnace_fans_ptsd.html

7. K. Roth, A. Chertok, J. Dieckmann, J. Brodrick, “Electronically Commutated Permanent 

Magnet Motors,” ASHRAE Journal, March 2004: pp. 77-76.

8. LBNL and Resource Dynamics Corporation. U.S. Department of Energy. Improving Fan 

System Performance: a Sourcebook for Industry. April 2003: pp. 19-21. Available online 

at: www1.eere.energy.gov/manufacturing/tech_deployment/pdfs/fan_sourcebook.pdf

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