3-i CH APTER 3. MARKET AND TECHNOLOGY ASSESSMENT

TABLE OF CONTENTS

3.1 INTRODUCTION .................................................................................................. 3-1

3.1.1 Description of Products............................................................................... 3-1

3.1.2 Definitions................................................................................................... 3-3

3.1.3 Product Classes ........................................................................................... 3-5

3.1.4 Product Test Procedures ............................................................................. 3-7

3.2 MARKET ASSESSMENT ..................................................................................... 3-8

3.2.1 Trade Associations ...................................................................................... 3-8

3.2.1.1 Air-Conditioning, Heating, and Refrigeration Institute ............... 3-8

3.2.1.2 Hearth, Patio & Barbecue Association ........................................ 3-9

3.2.1.3 Association of Pool and Spa Professionals .................................. 3-9

3.2.2 Manufacturer Information ......................................................................... 3-10

3.2.2.1 Manufacturers and Market Shares ............................................. 3-10

3.2.2.2 Small Business Impacts ............................................................. 3-13

3.2.3 Distribution Channels ............................................................................... 3-14

3.2.4 Regulatory Programs ................................................................................ 3-16

3.2.4.1 Current Federal Energy Conservation Standards ....................... 3-17

3.2.4.2 State Energy Conservation Standards ........................................ 3-18

3.2.4.3 Canadian Standards Association ................................................ 3-19

3.2.4.4 Mexico ....................................................................................... 3-20

3.2.5 Voluntary Programs .................................................................................. 3-20

3.2.5.1 American Council for an Energy Efficient Economy ................ 3-21

3.2.5.2 Consortium for Energy Efficiency ............................................. 3-21

3.2.5.3 ENERGY STAR ........................................................................ 3-21

3.2.5.4 Federal Energy Management Program ...................................... 3-22

3.2.5.5 Rebate Programs ........................................................................ 3-23

3.2.5.6 Super-Efficient Gas Water Heating Appliance Initiative .......... 3-23

3.2.6 Historical Shipments ................................................................................. 3-24

3.2.6.1 New Home Starts ....................................................................... 3-24

3.2.6.2 Shipments ................................................................................... 3-25

3.2.6.3 Water Heater Unit Shipments .................................................... 3-25

3.2.6.4 Water Heater Value of Shipments ............................................. 3-26

3.2.6.5 Direct Heating Equipment Shipments ....................................... 3-27

3.2.6.6 Pool Heater Shipments ............................................................... 3-28

3.2.7 Industry Cost Structure ............................................................................. 3-28

3.2.8 Equipment Lifetime .................................................................................. 3-29

3.2.9 Market Performance Data ......................................................................... 3-30

3.2.9.1 Residential Water Heaters.......................................................... 3-30

3.2.9.2 Direct Heating Equipment ......................................................... 3-42

3.2.9.3 Pool Heaters ............................................................................... 3-48

3.3 TECHNOLOGY ASSESSMENT ......................................................................... 3-48

3.3.1 Baseline Equipment Components and Operation ..................................... 3-49

3.3.1.1 Baseline Residential Water Heaters ........................................... 3-493-ii 3.3 .1.2 Baseline Direct Heating Equipment........................................... 3-50

3.3.1.3 Baseline Pool Heaters ................................................................ 3-50

3.3.2 Technology Options .................................................................................. 3-51

3.3.2.1 Water Heaters............................................................................. 3-51

3.3.2.2 Direct Heating Equipment ......................................................... 3-64

3.3.2.3 Pool Heaters ............................................................................... 3-71

3.3.3 Technologies That Do Not Affect Energy Efficiency as Measured ......... 3-74

3.3.3.1 Water Heaters............................................................................. 3-74

3.3.3.2 Direct Heating Equipment ......................................................... 3-75

3.3.3.3 Pool Heaters ............................................................................... 3-75

L I ST OF TABLES

Table 3.1.1 Product Classes for Residential Water Heaters ............................................ 3-5

Table 3.1.2 Proposed Product Classes for Direct Heating Equipment ............................ 3-6

Table 3.2.1 Manufacturers Whose Products Are Included in the AHRI Directory ......... 3-9

Table 3.2.2 Major and Other Residential Water Heater Manufacturers ........................ 3-10

Table 3.2.3 Residential Water Heater Manufacturers by Technology Type ................. 3-12

Table 3.2.4 Gas-Fired Traditional Direct Heating Equipment Manufacturers .............. 3-12

Table 3.2.5 Gas Hearth DHE Direct Heating Equipment Manufacturers ...................... 3-13

Table 3.2.6 Gas-Fired Pool Heater Manufacturers ........................................................ 3-13

Table 3.2.7 Small Business Manufacturers of Residential Water Heaters, Direct Heating

Equ ipment, and Pool Heaters ......................................................................................... 3-14

Table 3.2.8 Federal Energy Conservation Standards for Residential Water Heaters .... 3-17

Table 3.2.9 Federal Energy Conservation Standards for Direct Heating Equipment* .. 3-18

Table 3.2.10 California State Efficiency Standards for Residential Water Heaters ...... 3-19

Table 3.2.11 California State Energy Conservation Standards for Pool Heaters .......... 3-19

Table 3.2.12 Canadian Efficiency Standards for Residential Water Heaters ................ 3-20

Table 3.2.13 Mexican Efficiency Standards for Water Heaters .................................... 3-20

Table 3.2.14 ENERGY STAR Residential Water Heater Criteria Issued on April 1, 2008

............................................................................................................................... ......... 3-22

Table 3.2.15 FEMP Gas Water Heater Performance Requirements .............................. 3-23

Table 3.2.16 FEMP Electric Water Heater Performance Requirements ....................... 3-23

Table 3.2.17 Sample Rebate Programs .......................................................................... 3-23

Table 3.2.19 Residential Water Heater Value of Shipments by Year ........................... 3-27

Table 3.2.20 AHRI and HPBA Residential Direct Heating Equipment Industry Estimated

Sh ipment Data (New Construction and Replacement)* ................................................ 3-28

Table 3.2.21 Residential Gas-Fired Pool Heater Shipments*........................................ 3-28

Table 3.2.22 Industry Cost Structure Using SEC Data .................................................. 3-29

Table 3.2.23 Equipment Lifetimes................................................................................. 3-30

LI ST OF FIGURES

Fi g ure 3.2.1 2006 Market Shares for the Domestic Residential Water Heaters ............ 3-113-iii

Fi gure 3.2.2 Water Heaters Distribution Channel ......................................................... 3-15

Figure 3.2.3 Direct Heating Equipment Distribution Channel ...................................... 3-16

Figure 3.2.4 Pool Heater Distribution Channel ............................................................. 3-16

Figure 3.2.5 New Privately Owned Single-Family and Multifamily Housing Unit Starts in

t h e United States, 1990-2008 ......................................................................................... 3-25

Figure 3.2.6 Residential Water Heater Industry Shipments (Domestic and Imported) . 3-26

Figure 3.2.7 Distribution of Gas Storage-Type Water Heater Models by Energy Factor for

Al l Storage Volumes, All Burner Types ........................................................................ 3-31

Figure 3.2.8 Distribution of Gas-fired Storage Water Heater Models by Rated Storage

V o lume, All Burner Types ............................................................................................. 3-32

Figure 3.2.9 Distribution of Gas-Fired Storage-Type Water Heater Models by Storage

Ca pacity, All Burner Types ........................................................................................... 3-33

Figure 3.2.10 Distribution of Ultra Low NO X Gas-Fired Storage-Type Water Heater

Mo dels by Energy Factor for All Storage Volumes ...................................................... 3-34

Figure 3.2.11 Distribution of Ultra Low NO X Gas-Fired Storage Water Heater Models by

St orage Capacity ............................................................................................................ 3-35

Figure 3.2.12 Distribution of Electric Storage-Type Water Heater Models by Energy

Fa ctor for All Storage Volumes ..................................................................................... 3-36

Figure 3.2.13 Distribution of Electric Storage Water Heater Models by Rated Storage

Vo lume ........................................................................................................................... 3-37

Figure 3.2.14 Distribution of Electric Storage-Type Water Heater Models by Storage

Ca pacity ......................................................................................................................... 3-38

Figure 3.2.15 Distribution of Oil-Fired Storage-Type Water Heater Models by Energy

Fa ctor for All Storage Volumes ..................................................................................... 3-39

Figure 3.2.16 Distribution of Oil-Fired Storage-Type Water Heater Models by Storage

Ca pacity ......................................................................................................................... 3-40

Figure 3.2.17 Distribution of Instantaneous Gas-Fired Water Heater Models by Energy

F a ctor, All Input Capacity Ratings ................................................................................ 3-41

Figure 3.2.18 Distribution of Instantaneous Gas-Fired Water Heater Models by Input

Ca pacity ......................................................................................................................... 3-42

Figure 3.2.19 Distribution of Wall Furnace Fan-Type Models by Input Rating and AFUE

............................................................................................................................... ......... 3-43

Figure 3.2.20 Distribution of Wall Furnace Gravity-Type Models by Input Rating and

AF UE ............................................................................................................................. 3-44

Figure 3.2.21 Distribution of Floor Furnace Models by Input Rating and AFUE......... 3-45

Figure 3.2.22 Distribution of Room Heater Models by Input Rating and AFUE .......... 3-46

Figure 3.2.23 Distribution of Hearth Models by Input Rating and AFUE .................... 3-47

Figure 3.2.24 Distribution of Pool Heater Models by Input Capacity and Thermal

Eff iciency ....................................................................................................................... 3-48CHAPTER 3. MARKET AND TECHNOLOGY ASSESSMENT

3.1 INTRODUCTION

This chapter details the market and technology assessment that the U.S.

Department of Energy (DOE) has conducted in support of the ongoing energy

conservation standards rulemaking for residential water heaters, direct heating

equipment, and pool heaters.

This chapter consists of the market assessment and the technology assessment.

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

characterization of the residential water heater, direct heating equipment, and pool heater

industries and market structures based on publicly available information and data and

other information that DOE received directly from manufacturers and other interested

parties. DOE examined publicly available information from the Air­Conditioning,

Heating, and Refrigeration Institute (AHRI) Consumers' Directory of Certified Efficiency

Ratings for Heating and Water Heating Equipment (formerly the Gas Appliance

Manufacturers Association (GAMA) a equipment certification directory), as well as U.S.

Census Bureau Current Industrial Reports (CIR) and Annual Survey of Manufacturers

(ASM), the appliance database from the California Energy Commission (CEC)

, and

information from the Federal Trade Commission (FTC). The market and technology

assessment addresses manufacturer characteristics and market shares, existing regulatory

and non­regulatory efficiency improvement initiatives, product classes, and trends in

product markets and characteristics. DOE performs the technology assessment to develop

a preliminary list of technologies (referred to as technology options) that could be used to

improve the efficiency of residential water heaters, direct heating equipment, and pool

heaters.

3.1.1 Description of Products

Residential water heaters primarily provide hot water to residences for consumer

use, appliances, and other functions. Some residential water heaters may also provide

heated water to radiant heating systems. A basic gas storage residential water heater is

comprised of a standing pilot ignition system, a burner, a combustion chamber, a flue

baffle, a flue, an insulated water tank, a cold water inlet and hot water outlet, a sacrificial

anode, a gas valve, a temperature and pressure relief valve, a thermostat, heat traps, and

an outer case. A basic electric storage residential water heater is comprised of an electric

resistance heating element, a sacrificial anode, an insulated water tank, a cold water inlet

and a hot water outlet, a temperature and pressure relief valve, a thermostat with wire

harness, heat traps, and an outer case. A basic oil storage residential water heater is

comprised of a combustion chamber, a flue baffle, a flue, an insulated water tank, a cold

water inlet and hot water outlet, a sacrificial anode, a power burner system, a thermostat,

a The Air­Conditioning and Refrigeration Institute (ARI) and GAMA merged on January 1, 2008 to

become the Air­Conditioning, Heating, and Refrigeration Institute (AHRI). For more information, please

visit www.ahrinet.org.

3­1a temperature and pressure relief valve, and an outer case. A basic gas instantaneous

residential water heater is comprised of a combustion chamber, a burner, a heat

exchanger, a vent, a cold water inlet and hot water outlet, a gas valve, a standing pilot

ignition system, a burner control thermostat, a flow detector, and an outer case.

In the United States, 99.9 percent (110 million) of homes have water heaters (as

of 2005). Energy consumption attributable to water heater operation represents 1.7

percent (1.68 quads) of total U.S. energy consumption. Within individual homes, water

heating represents, on average, 17 percent of total annual household energy

consumption. 1

Direct heating equipment (DHE) typically provides primary or supplemental

space heating within a single room in a building. Some direct heating equipment,

including gas hearth DHE, serves an aesthetic purpose in addition to being used for space

heating. A basic residential gas wall fan­type heater consists of an outer case, an air

circulation fan, a burner, a combustion chamber/heat exchanger, a standing pilot ignition

system, a pilot light sensing control valve, a flue, a draft diverter, an air intake, and a

burner control thermostat. A basic residential gas wall gravity­type heater consists of an

outer case, a burner, a combustion chamber/heat exchanger, a standing pilot ignition

system, a pilot light sensing control valve, a flue, a draft diverter, an air intake, and a

burner control thermostat. Gravity provides air circulation as warm air rises ( i.e.

, warm

air, which is less dense, rises and cool air, which is more dense, descends due to

buoyancy effects). A basic residential gas floor heater consists of an outer case, a burner,

a combustion chamber/heat exchanger, a standing pilot ignition system, a pilot light

sensing control valve, a flue, a draft hood, an air intake, a burner control thermostat, and

a floor grate. A basic residential gas room heater consists of an outer case, a burner, a

combustion chamber/heat exchanger, a standing pilot ignition system, a pilot light

sensing control valve, a flue, a draft hood, an air intake, a burner control thermostat, and

an outer case. Basic residential gas floor and basic gas room heaters rely on gravity for

air circulation. Basic residential wall gravity, floor, and room heaters differ primarily in

the enclosure design and how they are installed. Vented gas hearth DHE, sold as

fireplaces, fireplace inserts, or gas stoves, can be used to provide residential space

heating, while also simulating wood­burning products. A basic vented hearth product

consists of a heat exchanger, a standing pilot ignition system, a burner, a pilot light

sensing control valve, a combustion chamber, a flue/vent, an air intake, a burner control

thermostat, ceramic logs, an outer case, and a glass viewing pane.

Residential pool heaters raise the water temperature in pools, allowing use of the

pool when ambient temperatures are low. A basic residential gas pool heater is comprised

of an outer case, a combustion chamber with refractory, a standing pilot ignition system,

a pilot light sensing control valve, a burner, a heat exchanger, an air intake, a flue/vent, a

cold water inlet and hot water outlet, pressure and water safety switches, and a burner

control thermostat with user interface.

3­23.1.2 Definitions

The National Appliance Energy Conservation Act (NAECA) established the

definition of a “residential water heater” (42 United States Code (U.S.C.) 6291(27)) as

follows:

Residential water heater means a product that uses oil, gas, or electricity to heat

potable water for use outside the heater upon demand, including

–

1. Storage­type units which heat and store water at a thermostatically controlled

temperature, including gas storage water heaters with an input of 75,000

British thermal units [Btu] per hour [h] or less, oil storage water heaters with

an input of 105,000 Btu per hour or less, and electric storage water heaters

with an input of 12 kilowatts [kW] or less;

2. Instantaneous­type units which heat water, but contain no more than one

gallon of water per 4,000 Btu per hour of input, including gas instantaneous

water heaters with an input of 200,000 Btu per hour or less, oil instantaneous

water heaters with an input of 210,000 Btu per hour or less, and instantaneous

electric water heaters with an input of 12 kilowatts or less; and,

3. Heat pump­type units, with a maximum current rating of 24 amperes at a

voltage no greater than 250 volts, which are products designed to transfer

thermal energy from one temperature level to a higher temperature level for

the purpose of heating water, including all ancillary equipment such as fans,

storage tanks, pumps, or controls necessary for the device to perform its

function. Section 430.2 of 10 Code of Federal Regulations (CFR).

The definition of a residential water heater is further described in appendix E to

subpart B of part 430 of 10 CFR as follows:

1. Gas­Fired Storage­Type Water Heater means a water heater that uses gas as

the energy source, is designed to heat and store water at a thermostatically

controlled temperature of less than 180 °F [degrees Fahrenheit] (82 °C

[degrees Celsius]), has a nominal input of 75,000 Btu (79 MJ [megajoules])

per hour or less, and has rated storage capacity of not less than 20 gallons (76

liters) nor more than 100 gallons (380 liters);

2. Oil­Fired Storage­Type Water Heater means a water heater that uses oil as the

energy source, is designed to heat and store water at a thermostatically

controlled temperature of less than 180 °F (82 °C), has a nominal input of

105,000 Btu/h (110 MJ/h) or less, and has a manufacturer’s rated storage

capacity of 50 gallons (90 liters) or less;

3. Electric Storage­Type Water Heater means a water heater that uses electricity

as the energy source, is designed to heat and store water at a thermostatically

controlled temperature of less than 180 °F (82 °C), has a nominal input of 12

kilowatts (40,956 Btu/h) or less, an has a rated storage capacity of not less

than 20 gallons (76 liters) nor more than 120 gallons (450 liters);

3­34. Tabletop Water Heater means a water heater in a rectangular box enclosure

designed to slide into a kitchen countertop space with typical dimensions of

36 inches high, 25 inches deep and 24 inches wide;

5. Instantaneous Gas­fired water heater means a water heater that uses gas as the

energy source, initiates heating based on sensing water flow, is designed to

deliver water at a controlled temperature of less than 180 °F (82 °C), has an

input greater than 50,000 Btu/h (53 MJ/h) but less than 200,000 Btu/h (210

MJ/h), and has a manufacturer’s specified storage capacity of less than 2

gallons (7.6 liters); and,

6. Instantaneous Electric Water Heater–Reserved

The energy conservation standards for residential water heaters are represented in

terms of the energy factor (EF) in appendix E of subpart B, section 430 of 10 CFR. (42

U.S.C. 6295(e)(1)) The EF is the ratio of the heat delivered to the energy consumed

according to the specific test procedure for residential water heaters. The EF accounts for

both recovery efficiency and standby losses at prescribed patterns of hot­water draws

totaling 64.3 gallons per day.

In DOE’s existing regulations, four types of residential heating equipment are

referred to as direct heating equipment. DOE refers to these four types of heating

equipment ( i.e.

, wall fan DHE, wall gravity DHE, floor DHE, and room DHE) as

“traditional” DHE in the NOPR associated with this TSD. In the NOPR, DOE proposes

to define a fifth type of direct heating equipment—gas hearth DHE. DOE defines vented

home heating equipment as “home heating equipment, not including furnaces, designed

to furnish warmed air to the living space of a residence, directly from the device, without

duct connections (except that boots not to exceed 10 inches beyond the casing may be

permitted) and includes: vented wall furnace, vented floor furnace, and vented room

heater.” Section 430.2 of 10 CFR.

Section 430.2 defines a vented wall furnace (gravity type and fan type), vented

floor furnace, and vented room heater:

1. Vented wall furnace means a self­contained vented heater complete with

grilles or the equivalent, designed for incorporation in, or permanent

attachment to, a wall of a residence and furnishing heated air circulated by

gravity or by a fan directly into the space to be heated through openings in

the casing.

2. Vented floor furnace means a self­contained vented heater suspended from

the floor of the space being heated, taking air from combustion from

outside this space. The vented floor furnace supplies heated air circulated

by gravity or by a fan directly into the space to be heated through openings

in the casing.

3. Vented room heater means a self­contained, free standing, nonrecessed,

vented heater for furnishing warmed air to the space in which it is

installed. The vented room heater supplies heated air circulated by gravity

or by a fan directly into the space to be heated through openings in the

casing.

3­4Before the enactment of NAECA, EPCA included home heating equipment in

DOE’s appliance standards program. DOE construed this term as covering unvented as

well as vented products, and prescribed a separate test procedure for each. 43 FR 20128,

20132 (May 2, 1978). However, when NAECA replaced the term “home heating

equipment” with “direct heating equipment” in NAECA’s amendments to EPCA in 1987

(42 U.S.C. 6295(e)(3)), the new energy conservation standards for this equipment

affected only gas products. The statutorily prescribed standards used the AFUE

descriptor, which applies only to vented equipment. The AFUE represents the heat

transferred to the conditioned space divided by the fuel energy supplied. Because of the

limitation imposed by the statute's use of the AFUE descriptor, subsequent DOE actions

concerning direct heating equipment have focused solely on vented products.

DOE defines a pool heater under NAECA as “an appliance designed for heating

nonpotable water contained at atmospheric pressure, including heating water in

swimming pools, spas, hot tubs and similar applications.” (42 U.S.C. 6291(25))

The energy conservation standard for pool heaters is represented by the thermal

efficiency. Section 430.32(k) of 10 CFR. (42 U.S.C. 6295(e)(2)) Thermal efficiency

represents the heat transferred to the nonpotable water divided by the fuel energy

supplied.

3.1.3 Product Classes

DOE categorized the product types ( i.e.

, residential water heaters, residential

direct heating equipment, and pool heaters) into product classes and will formulate a

separate energy conservation standard for each class. The criteria for separation into

different classes are type of energy used, capacity, and other performance­related features

such as those that provide utility to the consumer or others deemed appropriate by the

Secretary that would justify the establishment of a separate energy conservation standard.

(42 U.S.C. 6295(q) and 6316(a)) For residential water heaters, the product classes are

based on energy source ( i.e.

, gas or electric) and design ( i.e.

, storage­type, tabletop, and

instantaneous or “tankless”). The product classes shown in Table 3.1.1 were established

by the January 17, 2001, Energy Conservation Standards for Water Heaters Final Rule

(the January 2001 final rule) amending the energy conservation standards for residential

water heaters and incorporated into section 430.32(d). 66 FR 4474, 4497 (January 17,

2001).

Table 3.1.1 Product Classes for Residential Water Heaters

Residential Water Heater Type Characteristics

Gas­Fired Storage Type Nominal input of 75,000 Btu/h or less; rated storage volume from 20 to

100 gallons

Oil­Fired Storage Type Nominal input of 105,000 Btu/h or less; rated storage volume of 50

gallons or less

Electric Storage Type Nominal input of 12 kW (40,956 Btu/h) or less; rated storage volume

from 20 to 120 gallons

Tabletop Dimensions of 36 inches high, 25 inches deep, and 24 inches wide

3­5Instantaneous Gas­Fired Nominal input of over 50,000 Btu/h up to 200,000 Btu/h; rated storage

volume of 2 gallons or less

Instantaneous Electric Input of 12 kW or less; contains no more than one gallon of water per

4,000 Btu/h of input

Table 3.1.2 shows the product classes for direct heating equipment established by

NAECA. (42 U.S.C. 6295(e)(3)) However, DOE has proposed reducing the number of

heating capacity ranges for direct heating equipment to better reflect the distribution of

direct heating equipment available on the market. In addition, DOE has proposed adding

a separate product class of direct heating equipment–gas hearth DHE (Table 3.1.2).

Table 3.1.2 Proposed Product Classes for Direct Heating Equipment

Direct Heating Equipment Type Heating Capacity (Btu/h)

Gas Wall Fan Type Up to 42,000

Over 42,000

Up to 27,000

Gas Wall Gravity Type Over 27,000 up to 46,000

Over 46,000

Gas Floor Up to 37,000

Over 37,000

Up to 20,000

Gas Room Over 20,000 up to 27,000

Over 27,000 up to 46,000

Over 46,000

Up to 20,000

Gas Hearth Over 20,000 up to 27,000

Over 27,000 up to 46,000

Over 46,000

Gas hearth direct heating equipment class description. Vented gas hearth

products, sold as fireplaces, fireplace inserts, or gas stoves, can be used to provide

residential space heating. When used to furnish heat to a living space, vented gas hearth

DHE provides the same function and utility as vented heaters. The definition for vented

home heating equipment (or vented heater) in 10 CFR 430.2 states that this equipment is

“... a class of home heating equipment, not including furnaces, designed to furnish

warmed air to the living space of a residence, directly from the device, without duct

connections (except that boots not to exceed 10 inches beyond the casing may be

permitted) and includes: vented wall furnace, vented floor furnace, and vented room

heater.” Vented gas hearth DHE furnish warmed air to the living space of a residence,

directly from the device, without duct connections. Therefore, the vented heater

definitions stated previously include vented hearth products.

The energy conservation standards for direct heating equipment apply to a vented

hearth product if the product is designed to provide the same function and utility as

vented heaters by supplying heat to the space in which it is installed. In addition to space

heating, gas hearth DHE also provide aesthetic utility. When compared to gas wall

furnaces or gas room heaters, they must use different technologies to achieve improved

efficiency than traditional DHE. The constraints placed on gas hearth DHE, such as the

3­6glass viewing panes and consumer demand for a “yellow­flame” that simulates a woodburning fireplace make it difficult for hearth product manufacturers to achieve the same

efficiency increases with the same methods used by gas wall furnace and gas room heater

manufacturers. Therefore, DOE is proposing in the NOPR to include the following

definition for vented gas hearth direct heating equipment: “Vented hearth heater means a

vented, freestanding, recessed, zero clearance fireplace heater, a gas fireplace insert or a

gas­stove, which simulates a solid fuel fireplace and is designed to furnish warm air,

without ducts to the space in which it is installed.”

For pool heaters, the only product class is gas­fired pool heaters, which is

established by NAECA. (42 U.S.C. 6295(e)(2))

3.1.4 Product Test Procedures

Test procedures already exist for all three products covered by this rulemaking.

DOE established test procedures for residential water heaters, residential direct heating

equipment, and pool heaters through the rulemaking process, initially established by a

final rule published on October 17, 1990, and codified in appendix E to subpart B of 10

CFR part 430. 55 FR 42163. DOE amended the residential water heater test procedure on

May 11, 1998, by adding the following provisions: (1) a revision to the method used in

determining the first hour rating of storage­type water heaters, (2) an additional rating for

electric and instantaneous gas­fired water heaters, and (3) a revision to the definition of a

heat pump water heater. 63 FR 25996. On July 20, 1998, DOE published in the Federal

Register a correction to the May 1998 final rule, which added residential water heater

testing schematics. 63 FR 38737. Along with the amended energy conservation standards

published in the January 2001 final rule, DOE also amended the test procedure by adding

a definition for tabletop water heaters and reaffirming the test methods specified in

appendix E to subpart B of 10 CFR Part 430. 66 FR 4476.

DOE prescribed a test procedure for vented types of gas­fired direct heating

equipment in a notice published in the Federal Register on May 2, 1978. 43 FR 20182.

On May 12, 1997, DOE published a final test procedure rule that amended the test

procedures for direct heating equipment, and, in particular, vented home heating

equipment. 62 FR 26140. The May 1997 final rule included modified calculation

procedures for the weighted­average steady­state efficiency and AFUE for certain

manually controlled heaters, and added a procedure for calculating the annual energy

consumption of fossil fuel and auxiliary electrical energy for these types of products.

On May 12, 1997, DOE also published in the Federal Register a final rule that

amended the test procedure for pool heaters. 62 FR 26140. The May 1997 final rule

updated the referenced American National Standards Institute (ANSI) standard for pool

heaters from ANSI Standard Z21.56­1986, Gas­Fired Pool Heaters, to ANSI Standard

Z21.56­1994, Gas­Fired Pool Heaters. This update added a procedure for calculating the

annual energy consumption of fossil fuel auxiliary electrical energy for pool heaters and a

seasonal efficiency descriptor. 62 FR 26141.

3­73.2 MARKET ASSESSMENT

The following market assessment identifies the manufacturer trade associations;

domestic and international manufacturers of residential water heaters, direct heating

equipment and pool heaters, and their corresponding market shares; and regulatory and

non­regulatory programs. The market assessment also provides historical shipment data;

describes the cost structure for the residential water heater, direct heating equipment, and

pool heater industries; and summarizes relevant market performance data for each

product type.

3.2.1 Trade Associations

DOE recognizes the importance of trade groups in disseminating information and

providing growth to the industry they support. To gain insight into the residential water

heater, direct heating equipment, and pool heater industries, DOE researched various

associations available to manufacturers, suppliers, and users of such equipment. DOE

also used the member lists of these groups to construct a database of domestic

manufacturers.

DOE identified several trade groups that support or have an interest in the

residential water heater, direct heating equipment, and pool heater industries, including

AHRI, the Hearth, Patio & Barbecue Association (HPBA), and the Association of Pool

and Spa Professionals (APSP).

3.2.1.1 Air­Conditioning, Heating, and Refrigeration Institute

AHRI b is a national trade association of manufacturers of residential, commercial,

and industrial appliances and equipment, components and related products. AHRI was

established in January of 2008, when the Air­Conditioning and Refrigeration Institute

(ARI) merged with the Gas Appliance Manufacturers Association (GAMA). AHRI's

scope includes gas­fired, oil­fired, and electric products and equipment. “(AHRI)

members are responsible for more than 90 percent of space and water heating shipments

in the United States” during 2007. 2 “[AHRI] helps its members stay abreast of relevant

legislative and regulatory developments; supports the development of improved products

and installation procedures; compiles statistical reports of industry shipments; sponsors

and coordinates advertising and consumer education programs; and sponsors efficiency

certification programs for space heating, water heating, air­conditioning, and refrigeration

products and equipment.” 3 AHRI maintains the AHRI Efficiency Certification Program.

AHRI also maintains a database of products and equipment tested under its certification

program on its website. The majority of heating products currently manufactured by

member and non­member manufacturers are included in this database. c Table 3.2.1 shows

manufacturers of products covered by this rulemaking represented in AHRI’s Consumers'

Directory of Certified Efficiency Ratings for Heating and Water Heating Equipment

(hereafter the AHRI directory).

b For more information, please visit www.ahrinet.org.

c For more information, please visit www.gamapower.org.

3­8Table 3.2.1 Manufacturers Whose Products Are Included in the AHRI Directory d

Residential Water Heaters Direct Heating Equipment Pool Heaters

A.O. Smith Corporation CFM Corporation Hayward Industries, Inc.

Bock Water Heaters, Inc. Empire Comfort Systems,

Inc. Jandy Pool Products, Inc.

Bradford White Corporation Lennox Hearth Products Lochinvar Corporation

Bosch Water Heating Louisville Tin and Stove

Co. Pentair, Inc.

ECCOTEMP, LLC Rinnai Corporation Raypak

Heat Transfer Products, Inc. Williams Furnace Company

Lochinvar Corporation

Rheem­Ruud

Rinnai America

Corporation

Takagi Industrial Co. USA

Vaughn Manufacturing

Corporation

The majority of residential water heater, direct heating equipment, and pool heater

manufacturers identified in section 3.2.2.1 are represented by AHRI.

3.2.1.2 Hearth, Patio & Barbecue Association

HPBA “includes manufacturers, retailers, distributors, manufacturers'

representatives, service and installation firms, and other companies and individuals ­ all

having business interests in and related to the hearth, patio, and barbecue products

industries.” 4e

3.2.1.3 Association of Pool and Spa Professionals

APSP is an “international trade association and leading industry advocate

representing the swimming pool, spa, and hot tub industry.” 5 APSP also delivers public

relations, advertising, and water safety messages to consumers, and maintains industry

data and statistics on the pool and spa industries. Members can obtain information on the

products available to consumers, historical and geographical pool and spa installation

statistics, and other types of data. Additionally, the APSP offers pool and spa

professionals resources and tools to assist in business operations.

d A.O Smith Water Corporation refers to A. O. Smith Water Products Company, A. O. Smith Water

Heaters, State Water Heaters, Reliance Water Heater Company, Apollo Hydroheat and Cooling, Maytag

Water Heaters, American Water Heater Company, GSW Water Heating, and John Wood Water Heaters.

Bosch Water Heating is a division of Bosch USA, which is a branch of Bosch Group. Rheem­Ruud refers

to Rheem Manufacturing Company, Ruud Water Heating, the Paloma Group, and Paloma Tankless. Rinnai

America Corporation and Rinnai Corporation are subsidiaries of Rinnai Japan. Takagi Industrial Company

USA is a division of Takagi. Lennox Hearth Products refers to Lennox International, Incorporated.

Williams Furnace Company is a subsidiary of Continental Materials Corporation. Pentair refers to Pentair

Water Pool and Spa, Incorporated. Raypak refers to Raypak, Incorporated.

e For more information, visit www.hpba.org/index.php?id=46.

3­93.2.2 Manufacturer Information

The following section provides information about manufacturers of residential

water heaters, direct heating equipment, and pool heaters, including estimated market

shares, potential small business impacts, and product distribution channels.

3.2.2.1 Manufacturers and Market Shares

Using publicly available data ( e.g.

, Appliance Magazine and market assessments

from third parties), DOE estimated the market shares for manufacturers of each of the

three products contained in this standards rulemaking. Manufacturers may offer multiple

brand names.

DOE estimates that there are approximately 26 domestic manufacturers of

residential water heaters. 6 The large majority of the domestic market is controlled by

three U.S. manufacturers: Rheem­Rudd, A.O. Smith Corporation (including State

Industries and American Water Heater), and Bradford­White. 7 Five manufacturers hold

most of the remaining domestic market share, including: Bock Water Heaters, Inc.;

Bosch Water Heating; Noritz America; Rinnai America Corporation; and Takagi

Industrial Co. USA. Table 3.2.2 lists these manufacturers.

Table 3.2.2 Major and Other Residential Water Heater Manufacturers

Major Manufacturers* Other Manufacturers

Rheem­Ruud Bock Water Heaters, Inc.

A. O. Smith Corporation Bosch Water Heating

Bradford White Corporation Noritz America

Rinnai America Corporation

Takagi Industrial Co. USA

* Manufacturers with 10 percent or more of market share.

Figure 3.2.1 shows the 2006 market shares for domestic residential water heater

manufacturers as depicted in the September 2007 f issue of Appliance Magazine

, except

that A.O. Smith and American Water Heater’s market shares are combined. As noted

above, A.O. Smith acquired GSW Inc., the parent company of American Water Heater,

on April 3, 2006. A.O. Smith’s market share now includes the market share once held by

American Water Heater, and thus, DOE combined A.O. Smith and American Water

Heater’s market share using the most recent data available to represent the current water

heater market shares.

f Appliance Magazine last published market share figures for the residential water heater market in

September 2007.

3­10Figure 3.2.1 2006 Market Shares for the Domestic Residential Water Heaters 8

The residential water heater market can be further divided into manufacturers of

gas, oil­fired, and electric storage water heaters, and gas or electric instantaneous water

heaters. Table 3.2.3 shows manufacturers that produce these types of residential water

heaters.

3­11Table 3.2.3 Residential Water Heater Manufacturers by Technology Type

Manufacturer Residential Water Heater Type

Gas

Storage Oil­Fired

Storage Electric

Storage Instantaneous Gas Instantaneous

Electric

A. O. Smith Corporation X X X X

Bock Water Heaters, Inc. X X

Bosch Water Heating X X

Bradford White

Corporation X X X

ECCOTEMP, LLC X

Heat Transfer Products,

Inc. X

Lochinvar Corporation X X

Noritz X

Rheem­Ruud X X X

Rinnai America

Corporation X

Takagi Industrial Co.

USA X

Vaughn Manufacturing X

TOTALS 5 4 5 6 1

DOE estimates that there are four domestic manufacturers of traditional direct

heating equipment and 16 manufacturers of gas hearth DHE. g Table 3.2.4 and Table 3.2.5

list these manufacturers.

Table 3.2.4 Gas­Fired Traditional Direct Heating Equipment Manufacturers

Major Manufacturers* Other Manufacturers

Empire Comfort Systems, Inc. Monitor Products, Inc.

Louisville Tin and Stove Co. United States Stove Company

Williams Furnace Company**

*Major manufacturers have at least 10% market share.

** Williams Furnace Company is a subsidiary of Continental Materials Corporation.

g Estimate based on membership in AHRI (former GAMA members), membership in HPBA, and online

product searches.

3­12Table 3.2.5 Gas Hearth DHE Direct Heating Equipment Manufacturers h

Major Manufacturers Minor Manufacturers

Hearth & Home Technologies, Inc. Blaze King Industries

Lennox International Inc Buck Stove Corporation

Monessen Hearth Systems Co Breckwell Hearth Products

Empire Comfort Systems Inc

Golden Blount, Inc

Hearthstone Quality Home Heating

Products, Inc.

Hussong Mfg. Co., Inc.

Jøtul North America, Inc.

Mendota Hearth Products

Thelin Co. Inc

Travis Industries, Inc.

Wolf Steel Inc. (Napoleon Fireplaces)

Due to the small total size of the traditional direct heating equipment market and

confidentiality concerns, DOE was unable to disclose any market share data for

traditional direct heating equipment manufacturers or hearth equipment manufacturers.

DOE divided manufacturers into “major” and “other” based on the current industry

characteristics, DOE research, and discussions with manufacturers. Major companies

have larger market shares.

DOE identified five domestic manufacturers of residential gas­fired pool heaters.

Table 3.2.6 lists these manufacturers.

Table 3.2.6 Gas­Fired Pool Heater Manufacturers i

Major Manufacturers* Other Manufacturers

Hayward Industries, Inc. Lochinvar Corporation

Jandy Pool Products, Inc.

Raypak

Pentair

*Major manufacturers have at least 10% market share.

Due to the small total size of the pool heater market and confidentiality concerns,

DOE was unable to disclose any market share data for residential pool heater

manufacturers. DOE divided pool heater manufacturers into “major” and “other”

categories based on the current industry characteristics, DOE research, and discussions

with manufacturers. Major companies have larger market shares.

3.2.2.2 Small Business Impacts

h Lennox Hearth Products refers to Lennox International, Incorporated. Hearth and Home Technologies is a

subsidiary of HNI Corporation.

i Raypak refers to Raypak, Incorporated. Pentair refers to Pentair Water Pool and Spa, Incorporated.

3­13DOE realizes that small businesses may be disproportionately affected by the

promulgation of energy conservation standards for residential water heaters, direct

heating equipment, and pool heaters. The Small Business Administration (SBA) defines

small business manufacturing enterprises for residential water heaters, direct heating

equipment, and pool heaters as those having 500 employees or fewer. 9 SBA lists small

business size standards for industries as they are described in the North American

Industry Classification System (NAICS). The size standard for an industry establishes the

largest size that a for­profit entity can be while still qualifying as a small business for

Federal Government programs. These size standards are generally expressed in terms of

the average annual receipts or the average employment of a firm. Residential water heater

and pool heater manufacturing are classified under NAICS 335228, “Other Major

Household Appliance Manufacturing,” and direct heating equipment is classified under

NAICS 333414, “Heating Equipment (except warm air furnaces) Manufacturing.” The

size standard is 500 employees or fewer for both NAICS codes.

DOE studied the potential impacts on these small businesses as a part of the

manufacturer impact analysis (chapter 12). Table 3.2.7 lists the small business residential

water heaters, direct heating equipment, and pool heating manufacturers that DOE

identified.

Table 3.2.7 Small Business Manufacturers of Residential Water Heaters, Direct

Heating Equipment, and Pool Heaters

Water Heaters Direct Heating Equipment Pool Heaters

Bock Water Heaters Empire Comfort Systems, Inc. Lochinvar Corporation

ECCOTEMP SYSTEMS, LLC Louisville Tin and Stove Co.

Heat Transfer Products, Inc. Blaze King Industries

Therma­Flow, Inc. Breckwell Hearth Products

Vaughn Manufacturing

Corporation Buck Stove Corporation

Golden Blount, Inc

Hearthstone Quality Home Heating

Products, Inc.

Hussong Mfg. Co, Inc. (Kozy Heat)

Mendota Hearth Products

Thelin Co. Inc

Travis Industries, Inc

United States Stove Company

3.2.3 Distribution Channels

Analysis of the distribution channels of products covered by this rulemaking is an

important facet of the market assessment. DOE gathered information from publicly

available sources regarding the distribution channels for residential water heaters, direct

heating equipment, and pool heaters.

3­14The residential water heater market can be divided into two areas: replacement of

existing units and new construction. Between 49 and 59 percent of residential water

heaters are distributed through wholesalers. 10 These wholesalers then resell residential

water heaters to contractors and plumbers, plumbing supply houses, local hardware

stores, and other retail channels. For gas instantaneous water heaters in particular, the

wholesale distribution channel accounts for an even larger percentage. Residential water

heaters are also sold through retail distribution (between 41 and 51 percent). 11 These

residential water heaters are sold directly by residential water heater manufacturers to

home improvements stores, chain hardware stores, and other large retailers. According to

DOE’s 2000 water heater technical support document (TSD), approximately 60 percent

of replacements were sold through the retail distribution channel. 12 Alternatively,

customers may purchase a residential water heater and install it themselves or hire a

contractor to complete the installation. Homebuilders, contractors, and plumbers purchase

residential water heaters for new construction.

Appliance Magazine’s 56 th annual statistical review stated that 8.19 million

residential water heaters were shipped in 2008. 13 According to the Northwest Energy

Efficiency Alliance (NEEA)’s analysis of residential water heater distribution channels,

20 percent were purchased by homebuilders for use in new construction. The remaining

80 percent of sales were retrofit units replacing existing residential water heaters. Of

these retrofit units, approximately 52 percent were purchased and installed by consumers,

and approximately 48 percent were installed by contractors and plumbers. 14

For analysis purposes, DOE defined four distribution channels for residential

water heaters: Replacement A, Replacement B, New Homes A, and New Homes B.

(Figure 3.2.2).

Figure 3.2.2 Water Heaters Distribution Channel

Consumer purchases and installations typically do not play a role in the

established distribution channels of direct heating equipment. For replacement

3­15applications, most sales go through distributors to contractors, and then to consumers. In

new home applications, most sales go through distributors to contractors hired by the

builder. Thus, DOE defined two distribution channels for analysis purposes: Replacement

and New Homes (Figure 3.2.3).

Figure 3.2.3 Direct Heating Equipment Distribution Channel

For pool heaters in replacement applications, most sales go through distributors or

retailers to pool service companies. In most new home applications, the pool builder

purchases the equipment from a distributor or wholesaler. Thus, DOE defined two

distribution channels for analysis purposes: Replacement and New Homes (Figure 3.2.4).

Figure 3.2.4 Pool Heater Distribution Channel

3.2.4 Regulatory Programs

The following section details current regulatory programs mandating energy

conservation standards for residential water heaters, direct heating equipment, and pool

heaters. Section 3.2.4.1 discusses current Federal energy conservation standards, and

section 3.2.4.2 provides an overview of existing State standards. Sections 3.2.4.3 and

3.2.4.4 review standards in Canada and Mexico that may affect companies servicing the

domestic market.

3­163.2.4.1 Current Federal Energy Conservation Standards

NAECA established energy conservation standards for residential water heaters,

direct heating equipment, j and pool heaters, and required that DOE conduct two cycles of

rulemakings to determine if more stringent standards are economically justified and

technologically feasible for these products. (42 U.S.C. 6295 (e)(1) and (4)) On February

7, 1989 and October 17, 1990, DOE issued a final rule codifying the standards prescribed

by NAECA, and thereby established the first set of energy conservation standards for

residential water heaters, direct water heating equipment, and pool heaters. 54 FR 6077

(February 7, 1989) and 55 FR 42163 (October 17, 1990).

Pursuant to 42 U.S.C. 6295(e)(4)(A), on January 17, 2001, DOE published in the

Federal Register the January 2001 final rule, effective January 20, 2004, amending the

energy conservation standards for residential water heaters. 66 FR 4474.

Table 3.2.8 Federal Energy Conservation Standards for Residential Water Heaters

Residential Water Heater Class Minimum Energy Factor (EF)

Gas­Fired Storage Type 0.67

– (0.0019 x Rated Storage Volume in gallons)

Oil­Fired Storage Type 0.59

– (0.0019 x Rated Storage Volume in gallons)

Electric Storage Type 0.97

– (0.00132 x Rated Storage Volume in gallons)

Instantaneous Gas­Fired Type 0.62

– (0.0019 x Rated Storage Volume in gallons)

Instantaneous Electric Type 0.93

– (0.00132 x Rated Storage Volume in gallons)

Tabletop 0.93

– (0.00132 x Rated Storage Volume in gallons)

DOE initially analyzed energy conservation standards for direct heating

equipment as part of an eight­product standards rulemaking. When DOE analyzed direct

heating equipment in these earlier proceedings, it considered only products categorized as

vented home heating equipment. DOE issued a notice of proposed rulemaking (NOPR)

on March 4, 1994, proposing to amend the energy conservation standards for direct

heating equipment and other consumer products. 59 FR 10464. The Department of

Interior and Related Agencies Appropriations Act for Fiscal Year 1996 (P.L. 104­134)

imposed a moratorium on proposing or issuing final rules for appliance standards

rulemakings for the remainder of Fiscal Year 1996, thereby preventing DOE from

finalizing the 1994 proposed standards and leaving the existing NAECA efficiency levels

in place. Table 3.2.9 presents these energy conservation standards for direct heating

equipment.

j Initially, EPCA included vented and unvented home heating equipment in DOE’s appliance standards

program. However, EPCA did not specifically use the term direct heating equipment. NAECA prescribed

energy conservation standards for direct heating equipment instead of vented and unvented home heating

equipment, but NAECA did not include a definition of the products covered under the direct heating

equipment category. Since DOE has established test procedures to measure the energy efficiency of vented

home heating equipment and the test procedures for unvented home heating equipment do not have an

energy efficiency measure, DOE has determined that direct heating equipment only refers to vented home

heating equipment for the purpose of this rulemaking.

3­17Table 3.2.9 Federal Energy Conservation Standards for Direct Heating Equipment*

Direct Heating Equipment Design Type Product Class, by Input Rating

(Btu/h) AFUE

%

Gas Wall Fan Up to 42,000 73

Over 42,000** 74

Gas Wall Gravity Up to 10,000 59

Over 10,000 up to 12,000 60

Over 12,000 up to 15,000 61

Over 15,000 up to 19,000 62

Over 19,000 up to 27,000 63

Over 27,000 up to 46,000** 64

Over 46,000 65

Gas Floor Up to 37,000 56

Over 37,000** 57

Gas Room Up to 18,000 57

Over 18,000 up to 20,000 58

Over 20,000, up to 27,000 63

Over 27,000 up to 46,000 64

Over 46,000** 65

*Includes all of the product classes set forth in the Energy Policy and Conservation Act ( EPCA) and codified

at 10 CFR Part 430.32(i).

**Representative product classes that DOE intends to analyze.

As with direct heating equipment, DOE initially analyzed standards for pool

heaters as part of the eight­product standards rulemaking of 1994, 59 FR 10464, but

never finalized the proposed standards (for reasons explained above). DOE has not

amended the energy conservation standards for pool heaters since NAECA established

them in 1987. 42 U.S.C 6295 (e)(2) Existing energy conservation standards for

residential pool heaters specify a thermal efficiency for pool heaters of no less than 78

percent. 10 CFR part 430.32(k).

3.2.4.2 State Energy Conservation Standards

The following States have established appliance energy efficiency regulations:

Arizona, California, Connecticut, Maine, Maryland, Massachusetts, Minnesota, New

Hampshire, New Jersey, New York, Oregon, Pennsylvania, Rhode Island, Vermont, and

Washington. Of these, California is the only State that explicitly regulates equipment

covered in this rulemaking. 15

The State of California mandates energy conservation standards for residential

water heaters. State standard levels are identical to Federal standard levels for each

covered product. California regulations extend the scope of Federal standards, including

standards for products outside of the rated storage capacity range and input capacity

range stated for the product types covered by Federal standards. Additionally, California

has specific regulations for instantaneous oil­fired water heaters, which are similar to the

Federal standards for oil­fired storage water heaters. 16 Table 3.2.10 presents California’s

water heater standards.

3­18Table 3.2.10 California State Efficiency Standards for Residential Water Heaters 17

Appliance Energy

Source Input Rating Rated

Storage

Volume

gallons Minimum Energy Factor

Storage Water

Heaters Gas ≤ 75,000 Btu/h < 20 0.62

– (0.0019 x Volume)

Storage Water

Heaters Gas ≤ 75,000 Btu/h > 100 0.62

– (0.0019 x Volume)

Storage Water

Heaters Oil ≤ 105,000 Btu/h > 50 0.59

– (0.0019 x Volume)

Storage Water

Heaters Electricity ≤ 12 kW > 120 0.93

– (0.00132 x Volume)

Instantaneous

Water Heaters Gas ≤ 50,000 Btu/h Any 0.62

– (0.0019 x Volume)

Instantaneous

Water Heaters Gas ≤ 200,000 Btu/h ≥ 2 0.62

– (0.0019 x Volume)

Instantaneous

Water Heaters Oil ≤ 210,000 Btu/h Any 0.59

– (0.00132 x Volume)

Instantaneous

Water Heaters Electricity ≤ 12 kW Any 0.93

– (0.00132 x Volume)

The State of California also mandates energy conservation standards for direct

heating equipment. These standard levels are identical to Federal energy conservation

standard levels. 18

California mandates energy conservation standards for pool heaters as well. The

State’s gas­fired pool heater standard is identical to the Federal standard level with an

additional requirement that prohibits the use of constant burning pilots. 19 California also

issues standards for oil­fired and electric heat pump pool heaters. Table 3.2.11 provides

these pool heater standards. 20

Table 3.2.11 California State Energy Conservation Standards for Pool Heaters 21

Residential Pool Heater Type Standard Level

Oil Fired Thermal Efficiency: 78%

Heat Pump Average Coefficient of Performance: 3.5

3.2.4.3 Canadian Standards Association

The Canadian Standards Association (CSA) is an independent standards­setting

agency that establishes test procedures and efficiency standards that are typically adopted

by the Canadian Government.

Residential Water Heaters. CSA has specified energy conservation standards for

residential water heaters. The CSA standards divide residential water heaters into several

categories and subcategories, summarized in Table 3.2.12.

3­19Table 3.2.12 Canadian Efficiency Standards for Residential Water Heaters 22

Water Heater Type Product Class Efficiency Standard

Description

Gas­Fired Storage Input rating ≤ 21.98 kW

(75,000 Btu/h) and storage

capacity 76 to 380 liters Minimum EF:

0.67

– 0.0005V

Oil­Fired Storage Input rating ≤ 30.5 kW

(107,000 kJ/h) and storage

capacity ≤ 190 liters Minimum EF:

0.59

– 0.0005V

Bottom Inlet

50 to 270 liters Maximum Standby Loss:

40 + (0.20V)

Electric Storage > 270 to 454 liters Maximum Standby Loss:

(0.472V)

– 33.5

Top Inlet

50 to 270 liters Maximum Standby Loss:

35 + (0.20V)

> 270 to 454 liters Maximum Standby Loss:

(0.472V)

– 38.5

Note: V=rated storage capacity in liters; EF=energy factor as defined by CSA P.3­04 for gasfired water heaters and CAN/CSA­B211­00 for oil­fired water heaters.

Direct Heating Equipment

. Canada has product classes for vented gas fireplaces

and fireplace heaters. Vented gas fireplaces are primarily used for aesthetic purposes,

whereas vented gas fireplace heaters are designed to provide heat to the space where they

are installed. Canada has not issued energy conservation standards for either of these

products classes and did not appear to have plans to issue standards as of April 2009. 23

Pool Heaters. CSA has specified an energy conservation standard for gas pool

heaters similar to Federal energy conservation standards. This standard sets a minimum

thermal efficiency of 78 percent.

3.2.4.4 Mexico

Mexico has specified energy conservation standards for gas water heaters. The

Mexican standards divide gas water heaters into domestic and commercial categories,

summarized in Table 3.2.12.

Table 3.2.13 Mexican Efficiency Standards for Water Heaters 24

Water Heater Type Product Class Efficiency Standard

Description

Gas Fired Domestic Hot Water Heaters Minimum Thermal Efficiency: 72%

Commercial Hot Water Heaters Minimum Thermal Efficiency: 77%

3.2.5 Voluntary Programs

DOE reviewed several voluntary programs promoting energy efficient residential

water heaters, direct heating equipment, and pool heaters in the United States, including

the American Council for an Energy Efficiency Economy (ACEEE), the Consortium for

3­20Energy Efficiency (CEE), the Environmental Protection Agency (EPA) ENERGY STAR

program, the Federal Energy Management Program’s (FEMP) procurement program for

energy­efficient products, various rebate programs offered by local utilities, and the

Super Efficient Gas Water Heating Appliance Initiative (SEGWHAI).

3.2.5.1 American Council for an Energy Efficient Economy

ACEEE k is “dedicated to advancing energy efficiency as a means of promoting

economic prosperity, energy security, and environmental protection.” ACEEE conducts

technical and policy assessments, advises policy makers and program managers, works

collaboratively with businesses and public interest groups, organizes conferences,

publishes books, conference proceedings, and reports, and educates consumers and

businesses. 25

ACEEE works with industry to maintain a database of high­efficiency residential

water heaters and offers guidance to consumers on how to improve the efficiency of their

residential water heaters.

3.2.5.2 Consortium for Energy Efficiency

CEE l

, “a nonprofit public benefits corporation, develops initiatives for its North

American members to promote the manufacture and purchase of energy­efficient

products and services. The goal of the organization is to induce lasting structural and

behavioral changes in the marketplace, resulting in the increased adoption of energyefficient technologies.” 26

CEE organizes a summary of utility­sponsored rebate and incentive programs for

efficient residential water heaters. This summary is available online to encourage

consumers to purchase efficient residential water heaters and take advantage of utility

rebates.

3.2.5.3 ENERGY STAR

ENERGY STAR, m a voluntary labeling program backed by the U.S.

Environmental Protection Agency (EPA) and DOE, identifies energy efficient products

through a qualification process. To qualify, a product must exceed Federal energy

efficiency standards by a specified amount, or if no Federal standard exists, exhibit

selected energy­saving features. The ENERGY STAR program qualifies the top quartile

of products on the market, meaning that approximately 25 percent of products on the

market meet or exceed the ENERGY STAR levels. On April 1, 2008, ENERGY STAR

set requirements for gas storage water heaters, whole­home gas tankless water heaters,

gas condensing water heaters, heat pump water heaters, and solar water heaters.

k For more information, please visit www.aceee.org.

l For more information, please visit www.cee1.org.

m For more information, please visit www.energystar.gov.

3­21ENERGY STAR released the criteria on April 1, 2008. They took effect on

January 1, 2009. Table 3.2.14 summarizes the requirements.

Table 3.2.14 ENERGY STAR Residential Water Heater Criteria Issued on April 1,

2008 27

Product Type Cr iteria

Gas Storage Water Heater •

•

• Minimum EF of 0.62 (0.67 beginning September 1,

2010)

Minimum first hour rating of 67 gallons

Minimum 6­year warranty on sealed system

Whole­Home Gas Tankless Water Heater •

•

• Minimum EF of 0.82

Minimum gallons per minute of 2.5 over a 77 oF rise

Minimum 10­year warranty on heat exchanger and 5

years on parts

Gas Condensing Storage Water Heater •

•

• Minimum EF of 0.80

Minimum first hour rating of 67 gallons

Minimum 8­year warranty on sealed system

Heat Pump Water Heater •

•

• Minimum EF of 2.0

Minimum first hour rating of 50 gallons per hour

Minimum 6­year warranty on sealed system

Solar Water Heater •

•

• Minimum Solar Fraction of 0.5

OG­300 certification from the SRCC (Solar Rating

and Certification Corporation)

Minimum 10­year warranty on solar collector, 6 years

on storage tank, 2 years on controls, and 1 year for

piping and parts

3.2.5.4 Federal Energy Management Program

“DOE’s FEMP n works to reduce the cost and environmental impact of the

Federal Government by advancing energy efficiency and water conservation, promoting

the use of distributed and renewable energy, and improving utility management decisions

at Federal sites.” 28 FEMP helps Federal buyers identify and purchase energy­efficient

equipment.

FEMP designates standards for water heaters purchased by the Federal

Government. The designated FEMP gas water heater standards levels appear in Table

3.2.15, and the FEMP electric water heater standards appear in Table 3.2.16.

n For more information, please visit www.eere.energy.gov/femp.

3­22Table 3.2.15 FEMP Gas Water Heater Performance Requirements 29

Storage Tank Volume Energy Factor

50 gallons or less 0.62 or higher

Table 3.2.16 FEMP Electric Water Heater Performance Requirements 30

Storage Tank Volume Energy Factor

Less than 60 gallons 0.93 or higher

60 gallons or more 0.91 or higher

3.2.5.5 Rebate Programs

Several utilities offer rebate programs for high­efficiency residential water

heaters. A small sample of these programs is listed in Table 3.2.17.

Table 3.2.17 Sample Rebate Programs

State Utility Product Requirement Value

$

California Pacific Gas and Electric

Company (PG&E) 31 Water Heaters Gas Storage: EF ≥ 0.62 and

capacity ≥ 30 gallons

Electric Storage: EF ≥ 0.93 and

capacity ≥ 40 gallons $30

Florida Central Florida Gas 32 Gas Water

Heaters Storage and tankless installation

or replacement $350­$525

Illinois City Water Light and Power 33 Water Heaters New electric installation or gas

replacement and capacity ≥ 30

gallons $200

Texas Austin Energy 34 Water Heaters New replacement $100

3.2.5.6 Super­Efficient Gas Water Heating Appliance Initiative

The Super­Efficient Gas Water Heating Appliance Initiative (SEGWHAI) states

that it “will develop and implement the next generation of cost­effective and highefficiency storage­type gas water heater. SEGWHAI will facilitate the development and

commercialization of this next generation of standard water heater. SEGWHAI will

develop a well funded incentive program to make mass commercialization possible for

gas storage water heater units that meet SEGWHAI performance specifications.” 35

3­233.2.6 Historical Shipments

Annual product shipment trend data are an important aspect of the market

assessment and development of the standards rulemaking. Such data are used in the

shipments analysis (chapter 9). The number of unit shipments is expected to follow a

trend similar to that of new home starts. However, the percentage of consumers with

multiple units of some appliances is expected to rise, causing unit shipments of certain

appliances to increase, or not to drop as quickly as they otherwise would have.

3.2.6.1 New Home Starts

Trends in new home starts may directly affect shipments of residential water

heaters, direct heating equipment, and pool heaters. While there is a market for both

replacement and remodeling for some of these products, residential water heaters are

fixtures in virtually all new homes.

Figure 3.2.5 presents the number of new single­family and multifamily housing

units started in the United States from 1990 to 2007. Between 2000 and 2005, singlefamily home starts increased 39.4 percent and peaked at 1,716,000 units annually. This

trend reversed to a 63.8 percent decrease from 2005 to 2008, when home starts fell to

622,000 units. o The result is an overall decrease in new home starts of 51 percent

between 2000 and 2008. Multifamily unit starts have remained relatively steady over the

past 7 years, hovering around 350,000 units annually. 36

o Fourth quarter 2008 data are preliminary.

3­240 200 400 600 800 1000 1200 1400 1600 1800 2000

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008**Housing Units** **Started (thousands)** 

**Year** Single­Family Units

Multi­Family Units

Figure 3.2.5 New Privately Owned Single­Family and Multifamily Housing Unit

Starts in the United States, 1990­2008 37

3.2.6.2 Shipments

Information about annual equipment shipment trends allows DOE to estimate the

impacts of energy conservation standards on the residential water heater, direct heating

equipment, and pool heater industries. DOE has examined unit shipments and value of

shipments for residential water heaters, direct heating equipment, and pool heaters using

publicly available data from the U.S. Census Bureau’s Annual Survey of Manufacturers

(ASM) and Current Industrial Reports (CIR), and the American Society of Heating,

Refrigerating, and Air­Conditioning Engineers (ASHRAE) and AHRI estimates.

3.2.6.3 Water Heater Unit Shipments

The U.S. Census Bureau’s annual CIR provides annual unit shipments and value

of shipments for various industries, including the residential water heater industry. The

CIR however, does not distinguish between shipments for new construction and

replacement.

Figure 3.2.6 presents the annual shipments of residential water heaters (domestic

and imported shipments) from 2001 to 2007 based on the annual CIRs. 38

The numbers show two trends that affect the residential water heater industry.

Overall, shipments of electric and non­electric water heaters have declined since 2001.

However, shipments of non­electric water heaters have declined more rapidly than

shipments of electric water heaters. In 2006 and 2007, shipments of electric water heaters

exceeded shipments of non­electric water heaters.

3­253,000,000 4,000,000 5,000,000 6,000,000 7,000,000 8,000,000 9,000,000 10,000,000

2001 2002 2003 2004 2005 2006 2007**Units Shipped** 

**Year** Total

Non­electric Water Heaters

Electric Water Heaters

Figure 3.2.6 Residential Water Heater Industry Shipments (Domestic and

Imported) 39

Table 3.2.18 presents the annual shipments of the residential water heater industry

from 2003 to 2007 as estimated by AHRI.

Table 3.2.18 AHRI Residential Water Heater Industry Estimated Shipment Data

(New Construction and Replacement)* 40

Year Electric,

Storage Water

Heaters

units Gas, Storage

Water

Heaters

units Oil­Fired,

Storage Water

Heaters**

units Gas

Instantaneous

Water Heaters †

units Total

units

2007 4,470,000 4,384,000 24,000 322,000 9,200,000

2006 4,792,000 4,654,000 22,000 242,000 9,710,000

2005 4,519,000 4,801,000 26,000 156,000 9,502,000

2004 4,573,000 5,054,000 23,000 85,000 9,735,000

2003 4,430,000 5,124,000 24,000 N/A 9,578,000

* Shipments rounded to nearest 1,000 units.

** Only showing shipments for 30­ and 32­gallon models.

† Shipment data not available for all years.

3.2.6.4 Water Heater Value of Shipments

Table 3.2.19 provides the value of shipments for the residential water heater

industry from 2000 to 2007 using the U.S. Census Bureau CIRs. 41 The CIR expresses all

dollar values in current dollars ( i.e.

, 2003 data are expressed in 2003$, etc.). Using the

Gross Domestic Product (GDP) Deflator, DOE converted each year’s shipment values to

2008$; 2007 was the last year included in the CIR data set.

3­26Table 3.2.19 Residential Water Heater Value of Shipments by Year 42

Year Value of Shipments

$ millions Value of Shipments in 2008$

$ millions

Non­Electric Electric Total Non­Electric Electric Total

2007 863.0 622.5 1485.5 887.4 640.1 1527.5

2006 902.8 651.9 1,554.7 947.3 684.0 1631.4

2005 970.2 638.4 1,608.6 1050.9 691.5 1742.4

2004 884.1 545.3 1,429.4 988.9 609.9 1598.8

2003 985.6 569.5 1,555.1 1138.4 657.8 1796.2

2002 842.0 576.0 1,418.0 990.3 677.5 1667.8

2001 799.3 555.7 1,355.0 955.6 664.4 1620.0

2000 843.6 572.7 1,416.3 1032.8 701.1 1734.0

According to the data, non­electric and electric water heaters have had a relatively

constant value of shipments between 2000 and 2007. Although the number of electric

water heater shipments exceeded the number of non­electric water heater shipments in

2006, the value of non­electric water heater shipments continued to exceed the value of

electric water heater shipments even as the number of non­electric water heater shipments

declined.

3.2.6.5 Direct Heating Equipment Shipments

The direct heating industry does not report information about direct heating

equipment shipments in as much detail as the water heater industry due to confidentiality

concerns. DOE received shipment data from AHRI on traditional types of direct heating

equipment ( i.e.

, wall furnaces, floor furnaces, and room heaters). Information is not

available for every year, and some information was omitted to preserve confidentiality.

Generally, the traditional direct heating product industry had small sales volumes and a

decline in shipments. Some products, e.g.

, floor furnaces, are sold strictly as replacement

products. Expansion of the consumer base to increase shipments is unlikely because in

recent years more consumers are installing central heating systems instead of using direct

heating methods to heat their homes. In contrast, there are much higher shipment

volumes for gas hearth DHE, which are installed in new construction. Gas hearth DHE

are desirable because of their aesthetic appeal in addition to their heating capabilities.

DOE obtained the shipments data for gas­fired fireplaces from HPBA. 43

Table 3.2.20 presents the annual shipments of the residential direct heating

equipment industry from 2002 to 2006 as estimated by AHRI and HPBA.

3­27Table 3.2.20 AHRI and HPBA Residential Direct Heating Equipment Industry

Estimated Shipment Data (New Construction and Replacement)* 44

Year Vented

Wall

Furnace*

* Direct Vent

Wall

Furnace** Floor

Furnaces Vented

Room

Heaters**

*

, †† Vented Gas

Hearth

DHE ††,†††

2006 80,000 54,000 4,000 N/A 1,728,000

2005 81,000 65,000 4,000 18,000 2,141,000

2004 88,000 66,000 5,000 21,000 2,104,000

2003 85,000 66,000 5,000 23,000 1,810,000

2002 84,000 61,000 6,000 21,000 1,716,000

* Shipment totals are rounded to nearest 1,000 units.

** Not specific to only fan­type or gravity­type direct heating equipment.

*** Shipment data not available for all years.

† Includes certain fireplaces that are AHRI certified

†† Shipment data from HPBA.

††† Includes gas log sets, which are not a covered product.

3.2.6.6 Pool Heater Shipments

The pool heater industry does not report information about pool heater shipments

in as much detail as the water heater industry due to confidentiality concerns. However,

some information is available. DOE estimated shipments for pool heaters in the national

impacts analysis (NIA, chapter 10 of this TSD) and presents a sample of those shipments

in Table 3.2.21. Generally, shipments increase between 2003 and 2010 at an average rate

of approximately 13,000 units each year.

Table 3.2.21 Residential Gas­Fired Pool Heater Shipments*

Year Pool Heater Shipments

2010 357,000

2009 338,000

2008 322,000

2007 314,000

2006 309,000

2005 297,000

2004 280,000

2003 262,000

* Shipments rounded to nearest 1,000 units.

3.2.7 Industry Cost Structure

DOE developed the residential water heater, direct heating equipment, and pool

heater industry cost structures from publicly available information from the ASM, and

from Security Exchange Commission (SEC) 10­K reports filed by publicly owned

manufacturers. Companies subject to SEC regulations must report sales, costs of goods

sold, gross profits, and various overhead costs, in addition to overall performance and

operations for the year. DOE analyzed SEC reports and developed a representative cost

structure for the industries of each product type.

3­28DOE examined SEC 10­K reports from 2000 to 2006. The cost of materials as a

percentage of revenue for each product can fluctuate as raw material costs change from

year to year. The cost of payroll for production workers as a percentage of revenue for

each product type has declined, pointing to the possibility of increased production

automation in the heating products industry. Finally, selling, general, and administrative

costs have declined as manufacturers cut costs by reducing the non­production, support,

and administrative employee base.

Table 3.2.22 presents the industry cost structure derived from the SEC 10­K

reports. p Each financial statement entry is presented as a percentage of total revenue.

Table 3.2.22 Industry Cost Structure Using SEC Data

Financial Statement Entry Percent of Total Revenue for Each Product Type

Water Heaters Direct Heating Equipment Pool Heaters

Profit before Financing 6.0 9.2 7.2

Selling, General, and Administrative Expenses 14.0 12.5 16.0

Research and Development 2.1 2.0 2.5

Overhead 15.4 16.0 16.0

Labor 10.1 9.4 10.0

Material 52.4 50.9 48.3

Total 100.0 100.0 100.0

The manufacturer impact analysis (MIA) (chapter 12 of this TSD) presents a

detailed financial analysis of each of the three product types covered by this rulemaking.

This analysis identifies key financial inputs, such as the cost of capital, working capital,

depreciation, and capital expenditures.

3.2.8 Equipment Lifetime

DOE reviewed available literature and consulted with manufacturers to establish

typical equipment lifetimes. (See the life­cycle cost analysis, chapter 8 of this TSD, for

additional details and sources used to determine the typical equipment lifetimes.) DOE

combined these sources to develop average estimated lifetimes of the equipment covered

by this rulemaking (Table 3.2.23).

p For more information, please visit www.sec.gov.

3­293-30

Ta ble 3.2.23 Equipment Lifetimes

Equipment Average Lifetime

years

Residential Water Heaters

Gas Storage-Type Water Heater 13

Oil-Fired Water Heater 13

Electric Storage-Type Water Heater 13

Gas Instantaneous Water Heater 20

Direct Heating Equipment

Traditional and Hearth Direct Heating Equipment 15

Pool Heaters

Gas Pool Heater 8

Chapter 8 of the TSD provides more information about residential water heater,

direct heating equipment, and pool heater lifetimes.

3.2.9 Market Performance Data

DOE combined information from the AHRI directory, 45 the CEC, 46 and the FTC

wi th other publicly available data from manufacturers’ catalogs of residential water

heaters, direct heating equipment, and pool heaters to develop an understanding of these

industries and their markets. These databases contain information such as manufacturer

name, model number, and efficiency.

3.2.9.1 Residential Water Heaters

Figure 3.2.7 through Figure 3.2.18 show the distribution of energy factors and

capacities of gas storage, oil-fired storage, electric storage, and instantaneous gas water

heaters in the AHRI directory. DOE created separate market performance plots for ultra

low NO X gas storage water heaters because currently available ultra low NO X gas storage

w a ter heaters exhibit difference performance characteristics than gas storage water

heaters with a standard burner, due primarily to reduced air flow. Ultra low NO X burners

ar e required on water heaters in certain areas of the United States that restrict nitrous

oxide emissions of certain consumer appliances. Consequently, in the engineering

analysis, DOE analyzed two representative gas storage water heaters

 one with a

standard burner and one with an ultra low NO X burner. (See chapter 5 of the NOPR TSD

fo r more details.)

Figure 3.2.7 shows the number of gas storage water heaters at each energy factor

rating from 0.48 to 0.67. The figure contains data for all volumes of storage capacity.3-31 18

- 3

- - 50

9 57 57 56 407 520

196 248 431

106

75 67 76

9

- 100 200 300 400 500 6000.480.490.500.510.520.530.540.550.560.570.580.590.600.610.620.630.640.650.660.67Count

Energy Factor

Count: 2386

Average Gas EF: 0.60 Federal Standard for 40 Gallon Models

(Representative Rated Capacity)

Figure 3.2.7 Distribution of Gas Storage-Type Water Heater Models by Energy

Factor for All Storage Volumes, All Burner Types

Gas-fired water heater energy factors are concentrated between 0.58 and 0.63 EF.

The minimum standard level listed in Figure 3.2.7 represents the Federal standard for a

40-gallon gas water heater, the representative volume for gas water heaters. Chapter 5 of

the NOPR TSD discusses the analysis of the representative volume.

Figure 3.2.8 shows the number of gas-fired storage water heaters at each rated

storage volume.3-32

Figure 3.2.8 Distribution of Gas-fired Storage Water Heater Models by Rated

Storage Volume, All Burner Types

Gas-fired storage water heaters are mainly concentrated at the 40 and 50 gallon

storage volumes. Based on the “large” and “small” product class division used for TSL 5

(i.e., water heaters above 55 gallons are classified as “large” and all others are classified

as “small”), 11.5% of gas-fired storage water heater models would fall into the “large”

category and 88.5% of gas-fired storage water heater models would be considered

“small.”

Figure 3.2.9 shows the distribution of efficiencies at various capacities for gasfired storage water heaters and how the Federal standard, defined by energy factor,

relates to rated storage capacity based on the equation in Table 3.2.8.3-33 0.45 0.50 0.55 0.60 0.65 0.70

20 30 40 50 60 70 80 90 100Energy Factor

Rated Volume (Gallons) Federal

Sta ndard

Figure 3.2.9 Distribution of Gas-Fired Storage-Type Water Heater Models by

Storage Capacity, All Burner Types

Gas-fired water heaters are mainly distributed between 30 and 75 gallons of

storage capacity. Generally, energy factor decreases as storage capacity increases due to

increased standby losses at higher gallon sizes.

Figure 3.2.10 shows the number of ultra low NO X gas-fired storage water heaters

a t each energy factor rating, from the minimum rating on the market of 0.56 to the

maximum available rating of 0.62. The figure contains data for the all volumes of storage

capacity.3-34 2

0 7

5 8

3 13

0 2 4 6 8 10 1 2 14

0.56 0.57 0.58 0.59 0.6 0.61 0.62 C o u n t

Energy Factor Count: 38

Average EF: 0.60 Federal Standard Level

fo r 40 Gallon Models

(Representative Rated

Gallon Capacity)

Figure 3.2.10 Distribution of Ultra Low NO X Gas-Fired Storage-Type Water Heater

Mo dels by Energy Factor for All Storage Volumes

Ultra low NO X gas-fired water heater energy factors are concentrated between

0.5 8 and 0.62 EF. The minimum standard level listed in Figure 3.2.10 represents the

Federal standard for a 40-gallon gas-fired water heater, the representative volume for gasfired water heaters.

Figure 3.2.11 shows the distribution of efficiencies at various capacities for ultra

low NO X gas-fired storage water heaters, and how the Federal standard, defined by

e n ergy factor, relates to rated storage capacity based on the equation in Table 3.2.8.3-35 0.45 0.5 0.55 0.6 0.65 0.7

20 30 40 50 60 70 80 90 100 E n e r g y F a c t o r

Rated Volume (Gallons) Federal Standard

Fi gure 3.2.11 Distribution of Ultra Low NO X Gas-Fired Storage Water Heater

Mo dels by Storage Capacity

Ultra low NO X gas-fired water heaters are mainly distributed between 30 and 60

g a llons of storage capacity. Generally, energy factor decreases as storage capacity

increases.

Figure 3.2.12 shows the distribution of electric storage water heater models by

energy factor for all storage volumes.3-36 7

- 9 5 12 23

14 15 12 75 140 245 243

40 55

0 50 100 150 200 250 300

0.81 0.82 0.83 0.84 0.85 0.86 0.87 0.88 0.89 0.90 0.91 0.92 0.93 0.94 0.95 C o u n t

Energy Factor Count: 895

Average EF: 0.92 Federal Standard for 50 Gallon Models

(Representative Rated Capacity)

F i gure 3.2.12 Distribution of Electric Storage-Type Water Heater Models by Energy

Factor for All Storage Volumes

Electric water heater energy factors are concentrated between 0.90 and 0.93. The

Federal standard level listed in Figure 3.2.12 represents the current Federal standard for a

50-gallon electric water heater, the representative volume for electric water heaters.

Chapter 5 of the TSD discusses the analysis of the representative volume.

Figure 3.2.13 shows the distribution of electric storage water heaters at each

storage volume.3-37

Figure 3.2.13 Distribution of Electric Storage Water Heater Models by Rated

Storage Volume

Electric storage water heaters are concentrated primarily at the 40 and 50 gallon

storage volumes. Based on the “large” and “small” product class division used for TSL 5

in the NOPR (i.e., storage water heaters above 55 gallons are classified as “large” and all

others are classified as “small”), 27.4% of electric storage water heater models would fall

into the “large” category and 72.6% of electric storage water heater models would be

considered “small.”

Figure 3.2.14 shows another distribution of models and how the Federal standard,

defined by energy factor, relates to rated storage capacity based on the equation in Table

3.2.8.3-38 0.70 0.90 1.10 1.30 1.50 1.70 1.90 2.10 2.30 2.50

0 20 40 60 80 100 120 140Energy Factor

Rated Volume (Gallon) Federal Standard

Figure 3.2.14 Distribution of Electric Storage-Type Water Heater Models by

Storage Capacity

Figure 3.2.14 shows an obvious trend of electric storage water heater efficiency

decreasing as storage capacity increases. There is a wide variety of electric storage water

heater volume capacities available to consumers, from 27 to 120 gallons.

Figure 3.2.15 shows the distribution of oil-fired storage water heater models by energy

factor and storage capacity for all storage volumes.3-39 0 0 0 2

0 0 4

2

0 0 0 0 2

0 3

0 0 0 1

0 1

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5

0 . 4 8

0 . 4 9

0 . 5 0

0 . 5 1

0 . 5 2

0 . 5 3

0 . 5 4

0 . 5 5

0 . 5 6

0 . 5 7

0 . 5 8

0 . 5 9

0 . 6 0

0 . 6 1

0 . 6 2

0 . 6 3

0 . 6 4

0 . 6 5

0 . 6 6

0 . 6 7

0 . 6 8 C o u n t

Energy Factor Count: 15

A v erage Oil EF: 0.58 Federal Standard for 32 Gallon Models

(Representative Rated Capacity)

F i gure 3.2.15 Distribution of Oil-Fired Storage-Type Water Heater Models by

Energy Factor for All Storage Volumes

Oil-fired water energy factors are more diffuse. The Federal standard level listed

on Figure 3.2.15 represents the current Federal standard for a 32-gallon oil-fired water

heater, the representative volume for oil-fired water heaters. Chapter 5 of the NOPR TSD

discusses the analysis of the representative volume.

Figure 3.2.16 shows another distribution of the oil-fired storage water heater

models and how the Federal standard, defined by energy factor, relates to rated storage

capacity based on the equation in Table 3.2.8.3-40 0.45 0.50 0.55 0.60 0.65 0.70

30 32 34 36 38 40 42 44 46 48 50Energy Factor

Rated Volume (Gallons) Federal Standard

Fi gure 3.2.16 Distribution of Oil-Fired Storage-Type Water Heater Models by

Storage Capacity

Figure 3.2.16 shows that oil-fired storage water heaters are concentrated around

30 to 32 gallons and 50 gallons of storage capacity. The energy factor decreases as

volume increases.

Figure 3.2.17 shows the distribution of energy factors of instantaneous gas-fired

water heaters in the AHRI, CEC, and FTC directories.3-41 6

4

2 2 4 4

2 5 4 6 6 5 20 55

1 19

17

5 9

4

2

- 10 20 30 40 50 60Count

Energy Factor Count: 182

Average EF: 0.79 Federal Standard for 0 gallon models

(Representative Rated Capacity)

F i gure 3.2.17 Distribution of Instantaneous Gas-Fired Water Heater Models by

Energy Factor, All Input Capacity Ratings

The instantaneous gas-fired water heater market is concentrated around units with

energy factors ranging from 0.80 to 0.84. Figure 3.2.18 shows another distribution of

instantaneous gas-fired water heaters and how energy factors relate to input capacity. The

Federal standard line is based on the equation in Table 3.2.8 for existing Federal energy

conservation standards. The line is horizontal because energy factor does not depend on

input capacity and because the rated storage volume for all instantaneous water heaters is

0 gallons.3-42 0.6 0.65 0.7 0.75 0.8 0.85 0.9 0.95 1

0 50 100 150 200 250Energy Factor

Input (kBtu/h) Count: 737

Average EF: 0.83

Federal Standard

Figure 3.2.18 Distribution of Instantaneous Gas-Fired Water Heater Models by

Input Capacity

3.2.9.2 Direct Heating Equipment

Figure 3.2.19, Figure 3.2.20, Figure 3.2.21, Figure 3.2.22 and Figure 3.2.23 show

the input rating and AFUE of wall furnace fan-type, wall furnace gravity-type, floor

furnace, room heater, and hearth-type direct heating equipment, respectively. DOE

obtained this information from the AHRI directory and other publicly available product

literature.3-43 72 74 76 78 80 82 84

0 10000 20000 30000 40000 50000 60000 70000AFUE (percent)

Input Rating (Btu/hour) Count: 82

Average AFUE: 77.3

Federal Standard

Figure 3.2.19 Distribution of Wall Furnace Fan-Type Models by Input Rating and

AFUE

Some fan-type wall furnaces just meet the Federal standard, while some exceed

the Federal standard by more than 10 absolute percentage points. There is no

concentration of efficiencies. When fan-type wall furnaces are analyzed by input rating,

efficiency varies across the range of AFUEs. For low-efficiency products, efficiency

increases with increased input rating. For high-efficiency products, efficiency decreases

with increased input rating.3-44 55 60 65 70 75 80 85

0 10000 20000 30000 40000 50000 60000AFUE (percent)

Input Rating (Btu/hour) Count: 54

Average AFUE: 66.6

Federal Standard

Figure 3.2.20 Distribution of Wall Furnace Gravity-Type Models by Input Rating

and AFUE

Some gravity-type wall furnaces just meet the Federal standard, while some

exceed the Federal standard by more than 20 absolute percentage points. The majority of

gravity-type wall furnaces have efficiencies below 70 percent AFUE. There is no

discernible relationship between input rating and efficiency.3-45 55.5 56 56.5 57 57.5 58 58.5

0 10000 20000 30000 40000 50000 60000 70000 80000AFUE (percent)

Input Rating (Btu/hour)

Count: 15

Average AFUE: 57.5

Federal Standard

Figure 3.2.21 Distribution of Floor Furnace Models by Input Rating and AFUE

Some floor furnaces just meet the Federal standard, while some exceed the

Federal standard by only one absolute percentage point. Floor furnaces have efficiencies

in a narrow range between 56 and 58 percent AFUE, with an increase in efficiency as

input rating increases.3-46

Figure 3.2.22 Distribution of Room Heater Models by Input Rating and AFUE

Some room heaters just meet the Federal standard, while some exceed the Federal

standard by approximately 25 absolute percentage points or more. Room furnaces have

efficiencies in a range between 57 and 83 percent AFUE, with an increase in efficiency as

input rating increases. The room heaters rated at 83 percent AFUE were identified by

DOE through review of publicly available product literature. Although AHRI does not

list this product in its directory, it is available to consumers.3-47 55 60 65 70 75 80 85 90 95

0 10000 20000 30000 40000 50000 60000 70000 80000 A F U E ( p e r c e n t )

Input Rating (Btu/hour) Count: 296

Average AFUE: 67.4

F i gure 3.2.23 Distribution of Hearth Models by Input Rating and AFUE

Hearth models have efficiencies between 57 and 93 percent AFUE. AHRI does

not list gas hearth DHE in its directory as a separate product type, but does include

certain certified gas hearth DHE listed as various types of traditional direct heating

equipment. DOE identified products currently in the AHRI database that would be

classified as gas hearth DHE and separated them into their own product class. DOE found

through a review of product literature that additional gas hearth DHE models are

available to consumers.3-48 3.2 .9.3 Pool Heaters

Figure 3.2.24 shows the distribution and thermal efficiency of gas-fired pool

heaters in the CEC and FTC directories.

75 80 85 90 95 100

0 200,000 400,000 600,000 800,000 1,000,000 1,200,000Thermal Efficiency (percent)

Input Rating (Btu/hour) Count: 409

Average Thermal

Efficiency: 82.7

Federal Standard

Figure 3.2.24 Distribution of Pool Heater Models by Input Capacity and Thermal

Efficiency

The majority of pool heaters are rated with an input capacity of 400,000 Btu/h or

less. Of these pool heaters, all models exceed the Federal standard. The pool heaters rated

at input capacities above 400,000 Btu/h are typically not marketed for residential use.

3.3 TECHNOLOGY ASSESSMENT

The purpose of the technology assessment is to develop a list of technology

options manufacturers can use to improve the efficiency of residential water heaters,

direct heating equipment, and pool heaters. The following assessment provides

descriptions of those technology options that apply to all product classes.

In preparation for the screening and engineering analyses, DOE identified several

possible technology options and examined the most common efficiency-improving

technologies used today. These technology options provide insight into the technological

improvements typically used to increase the energy efficiency of residential water

heaters, direct heating equipment, and pool heaters.3-49

3.3 .1 Baseline Equipment Components and Operation

The baseline model for each product class serves as a reference point for

measuring changes resulting from energy conservation standards. DOE defines the

baseline model in each product class as a product having an efficiency that just meets the

existing Federal energy conservation standards. DOE also defines baseline models as

having commonly available features.

3.3.1.1 Baseline Residential Water Heaters

Gas-Fired Storage Water Heaters. The baseline gas-fired storage water heater is

a water heater that incorporates a complete gas-fired water heating system in an

individual package. Each baseline gas-fired water heater consists of a glass-lined

corrosion-resistant steel tank, insulation surrounding the top and sides of the tank, a dip

tube that directs cold entering water to the bottom of the tank, a hot water outlet pipe,

heat traps, a gas burner, a standing pilot ignition, a combustion chamber, a burner control

thermostat, a gas valve, a sacrificial anode, a flue within the water tank, a baffle-type heat

exchanger within the flue, a temperature and pressure-relief valve, an outer case, and

packaging for shipment. Manufacturers may differentiate gas-fired water heaters by

efficiency rating, input to burners, and storage capacity.

Oil-Fired Storage Water Heaters. The baseline oil-fired storage water heater is a

water heater that incorporates a complete oil-fired water heating system in an individual

package. Each baseline oil-fired water heater consists of a glass-lined corrosion-resistant

steel tank, insulation surrounding the top and sides of the tank, a dip tube that directs cold

entering water to the bottom of the tank, a hot water outlet pipe, a combustion chamber, a

sacrificial anode, a flue within the water tank, a baffle-type heat exchanger within the

flue, an oil-fired power burner system, a burner control thermostat, a temperature and

pressure-relief valve, an outer case, and packaging for shipment. Manufacturers may

differentiate oil-fired water heaters by efficiency rating, input to burners, and storage

capacity.

Electric Storage Water Heater. The baseline electric storage water heater is a

water heater that incorporates a complete electric powered water heating system in an

individual package. Each baseline electric water heater consists of a glass-lined

corrosion-resistant steel tank, insulation surrounding the top and sides of the tank, a dip

tube that directs cold entering water to the bottom of the tank, a hot water outlet pipe,

heat traps, electric resistive heating elements, a control thermostat and wire harness, a

sacrificial anode, a temperature and pressure-relief valve, an outer case, and packaging

for shipment. Manufacturers may differentiate electric water heaters by efficiency rating,

input to the heating elements, and storage capacity.

Instantaneous Gas-Fired Water Heaters. The baseline instantaneous gas-fired

water heater is a water heater that incorporates a complete instantaneous gas-fired water

heating system in an individual package. Each baseline instantaneous gas-fired water

heater consists of a cold water inlet, a hot water outlet, a combustion chamber, a heat

exchanger, a burner, a vent, a standing pilot ignition, a flow detection device, a gas valve,3-50

a b urner control thermostat, an outer case, and packaging for shipment. Manufacturers

may differentiate instantaneous gas-fired water heaters by efficiency rating and input to

the burners.

3.3.1.2 Baseline Direct Heating Equipment

Gas Wall Fan Type. The gas wall fan-type heater is a heater that incorporates a

complete gas heating system in an individual package. Each baseline gas wall fan-type

heater consists of a heat exchanger, a room air circulation blower, a standing pilot

ignition system, a burner, a pilot light sensing control valve, a combustion chamber, a

flue, an intake, a burner control thermostat, an outer case, and packaging for shipment.

Manufacturers may differentiate gas wall fan-type heaters by efficiency rating and input

rating.

Gas Wall Gravity Type. The gas wall gravity-type heater is a heater that

incorporates a complete gas heating system in an individual package. Each baseline gas

wall gravity-type heater consists of a heat exchanger, a standing pilot ignition system, a

burner, a pilot light sensing control valve, a combustion chamber, a flue, an intake, a

burner control thermostat, an outer case, and packaging for shipment. Manufacturers may

differentiate gas wall gravity-type heaters by efficiency rating and input rating.

Gas Floor Type. The gas floor-type heater is a heater that incorporates a complete

gas heating system in an individual package. Each baseline gas floor-type heater consists

of a heat exchanger, a standing pilot ignition system, a burner, a pilot light sensing

control valve, a combustion chamber, a flue, an intake, a burner control thermostat, a

floor grate, an outer case, and packaging for shipment. Manufacturers may differentiate

gas floor-type heaters by efficiency rating and input rating.

Gas Room. The gas room-type heater is a heater that incorporates a complete gas

heating system in an individual package. Each baseline gas room-type heater consists of a

heat exchanger, a standing pilot ignition system, a burner, a pilot light sensing control

valve, a combustion chamber, a flue, an intake, a burner control thermostat, an outer case,

and packaging for shipment. Manufacturers may differentiate gas room-type heaters by

efficiency rating and input rating. Manufacturers may also differentiate by outer case.

Room heaters can be packaged as console and hearth-type heaters.

Gas Hearth. A gas hearth heater simulates a wood-burning device. Each baseline

vented gas hearth product consists of a heat exchanger, a standing pilot ignition system, a

burner, a pilot light sensing control valve, a combustion chamber, a flue, an intake, a

burner control thermostat, ceramic logs, an outer case, and a tempered glass viewing

pane. Manufacturers may differentiate vented gas hearth DHE by efficiency rating and

input rating.

3.3.1.3 Baseline Pool Heaters

A gas-fired pool heater incorporates a complete pool heating system in an

individual package. Each baseline gas pool heater consists of a cold water inlet pipe, a3-51

ho t water outlet pipe, a heat exchanger, a standing pilot ignition system, a burner, a pilot

light sensing control valve, a combustion chamber, a flue/vent, an air intake, a burner

control thermostat, an outer case, and packaging for shipment. Manufacturers may

differentiate gas-fired pool heaters by efficiency rating or input rating.

3.3.2 Technology Options

3.3.2.1 Water Heaters

DOE identified the following technology options as having the potential to

improve the efficiency of water heaters:

1. Heat traps

2. Insulation improvements

3. Power vent (gas-fired and oil-fired only)

4. Heat exchanger improvements

5. Flue damper (electromechanical)

6. Side arm heater

7. Electronic (or interrupted) ignition

8. Heat pump water heater (electric only)

9. CO 2 heat pump water heater

1 0

. Flue damper (buoyancy operated)

11. Directly fired

12. Condensing

13. Condensing pulse combustion

14. Thermophotovoltaic and thermoelectric generators

15. Reduced burner size (slow recovery)

16. Timer control

17. Two-phase thermosiphon (TPTS)

18. Modulating controls

19. Intelligent controls

20. Self-cleaning.

Heat Traps (Oil Fired). Residential water heaters lose heat by conduction and

convection through the fittings (water pipes, drain valve, pressure relief valve, and

thermostat), which contributes to standby losses. A heat trap is a device or arrangement

of piping that keeps the buoyant hot water from circulating to the piping distribution

system by natural convection, which leads to heat loss through uninsulated pipes to the

surroundings. When there is no draw of hot water, a heat trap prevents water in the hot

water outlet line from getting back into the tank as it cools off, and prevents hot water in

the tank from circulating back into the cold water inlet line. Thus, by containing hot

water in storage tanks, heat traps minimize standby loss. These devices can be integral to

tank design or independently attached to inlet and outlet pipes during installation at the

site. Insulating its exposed portion can increase the effectiveness of a heat trap. Multiple

manufacturers include heat traps on their water heater models.3-52 Co nventional heat traps come in two styles. In the first style, a floating plastic ball

blocks the cold water inlet. The buoyancy of the plastic holds it in place until water is

drawn. The force of water is strong enough to push the ball out of the way as water enters

the tank.

The second style is used for the hot water outlet. In this heat trap, the ball is

denser than water, and the weight of the ball seals the outlet until hot water is drawn and

the water pressure lifts it out of the way. A small bypass channel is left for water to

escape back into the inlet line from the tank after a large draw fills the tank with cold

water. Heat traps can also be made of metal. Manufacturing costs appear to be roughly

comparable between metal and plastic heat traps, but plastic heat traps are considerably

more effective in reducing water heater standby losses.

Other heat trap designs include U-shaped pipes, flexible seals, flaps, and springs.

Insulation Improvements (Gas-Fired, Oil-Fired, Electric Storage). Standby

losses can be reduced by improving water heater tank insulation. Increasing the thermal

resistivity of the water heater jacket to reduce the amount of heat loss during standby

periods increases the water heater energy factor.

Insulation can be improved by modifying the baseline design of the standard gasfired storage water heater using (1) increased jacket insulation, (2) a plastic tank, (3) an

insulated tank bottom (electric only), (4) advanced forms of insulation, and (5) foam

insulation.

Increased Jacket Insulation . Manufacturers insulate gas-fired, electric, and oilfired storage water heaters by filling the cavity between the jacket and the tank (top and

sides) with insulation. Most storage water heaters on the market today have at least 1-

inch thick insulation; some models have 2- or 3-inch thick insulation. Increasing the

diameter of the jacket insulation will reduce standby losses by increasing the thermal

resistivity of the water heater jacket. Jacket losses represent a majority of the standby

losses. Some manufacturers produce water heaters with increased insulation. Aftermarket insulating blankets are also commercially available to increase water heater

insulation.

Plastic Tank (electric only) . Plastic water heater storage tanks can be constructed

using a seamless, blow-molded polybutylene inner tank with a filament-wound fiberglass

outer tank. A second method involves constructing a thin steel shell with an internal

plastic tank. The steel exterior is constructed first, then plastic powder is injected into the

shell and the tank is rotated in a furnace to coat the interior with the plastic. The steel

exterior serves as the primary structural support for the tank. The lower heat conductivity

of plastic compared to metal reduces the amount of heat conducted through the tank wall

to the insulation and to the feed-throughs. However, the plastic tank cannot be used with

standard center-flue gas-fired storage water heaters or with oil-fired storage water heaters

because the plastic cannot withstand the high temperatures produced by the flames.3-53 Ins ulated Tank Bottom (electric only) . Insulated tank bottoms increase water

heater efficiency by reducing standby losses. The standard water heater tank is not

insulated on the bottom, where water temperature is lowest. However, the tank bottom is

still conductive; therefore, adding insulation will reduce heat dissipation through the

bottom of the tank.

Advanced Forms of Insulation . Alternate ways of reducing the jacket losses

without increasing the diameter of gas-fired, electric, and oil-fired storage water heaters

include using advanced insulation materials or evacuated panels. Some of the advanced

materials or methods of insulation considered here involve using vacuum insulation, inert

gases, aerogel insulation, or partial vacuums.

Vacuum Insulation. A “hard” vacuum between internal reflective surfaces

is a very good insulator. It has been used for years in Thermos bottles and Dewar

tanks for cryogenic applications. Durability and the difficulty of maintaining the

seal over the life of the storage water heater are some manufacturing problems

that have to be resolved.

Gas-Filled Panels . Gas-filled panels are thermal insulating devices that

retain a high concentration of a low-conductivity gas at atmospheric pressure

within a multilayer infrared reflective baffle. The thermal performance of the

panels depends on the type of gas fill and the baffle configuration. Gas-filled

panels are flexible and self-supporting, and can be made in a variety of shapes and

sizes to thoroughly fill most types of cavities. This technology has not been

demonstrated for water heater applications. 47

A e rogel Insulation. An example of advanced insulation materials is silica

aerogel, which is composed of 96 percent air and 4 percent silicon dioxide.

Aerogels are more efficient and weigh less than the polyurethane foam currently

used in most water heaters. The R-value of the aerogel at atmospheric pressure is

comparable to that of the polyurethane foam, but when 90 percent of the air is

evacuated from a plastic-sealed aerogel packet, its resistance nearly triples.

Another advantage of aerogel insulation over foam insulation is avoiding the use

of chlorofluorocarbons to blow the polyurethane foam into the heater jacket. New

manufacturing processes have been developed that can produce flexible blankets

or clamshell forms of this material. The aerogel material is vulnerable to shock

and vibration, however, and material handling is an issue. Because the aerogel is

hygroscopic, it requires a thorough sealing of the cavity between the water heater

tank and the outside cover. The material has not been demonstrated for use with

water heaters.

Evacuated Panels. Other materials with a lightweight open structure can

provide effective insulation combined with “soft” or low vacuums. The materials

can be enclosed with metals or plastic. A vacuum is drawn in this panel before

sealing, and a lightweight, rigid foam keeps the vacuum from compressing the

panel. This technology has not been demonstrated for storage water heater

applications.3-54 Fo am Insulation . Foam insulation can be used as an alternative to fiberglass

insulation. Chlorofluorocarbon-free, water-blown polyurethane foam is a common

alternative to high-density fiberglass blankets. Incorporating foam insulation of the same

thickness in place of fiberglass insulation can increase overall efficiency of the storagetype water heater. Foam typically has an R-value up to two to three times greater than

fiberglass. Additionally, foam can be blown into the cavity between the tank and the

outer case and does not need to be cut to form as required by some fiberglass installation

methods. This facilitates the filling of small spaces and constrictive geometries where the

potential for heat loss still exists, and which would be difficult to fill with fiberglass batts.

Finally, manufacturing processes that use foam-blowing techniques are better suited for

production line changes due to the shape-conforming characteristics of the foam. This

allows additional technology options, methods, and advances to be incorporated into

current designs with minimal impacts on insulation installation techniques.

Power Vent (Gas-Fired and Oil-Fired Storage). The power vent technology

option can increase the recovery efficiency, depending on the specific set-up of the

technology. Power vents can be designed as either induced or forced draft systems. An

induced draft fan is installed downstream of the draft diverter in the venting system and

pulls flue gases through the flue. A forced draft fan is upstream of the combustion

chamber and supplies the correct fuel-to-air ratio for combustion. Both methods improve

efficiency by increasing turbulence in the flue gases.

Typically, this technology is incorporated with a flue baffle that has a more

restricted flow path. Induced and forced draft fans can transmit air through the restricted

flue baffle, where a natural venting system would not be possible. This restriction of air

flow increases mixing, which increases heat transfer, thermal efficiency, and recovery

efficiency. When recovery efficiencies reach above 80 percent, condensation of flue

gases is likely. Water heaters obtaining recovery efficiencies above 80 percent should

include methods to properly dispose of condensate and be made of materials that resist

corrosion caused by condensate.

In addition to an increase in efficiency, there is also a reduction in standby loss.

The restrictions created by the stationary blower installed in either the intake or flue paths

reduce the off-cycle standby loss. The blowers act like dampers.

Some manufacturers make water heaters with induced draft fans that, in addition

to pulling the combustion products through the water heater, also draw excess air into the

flue gases before venting. This is similar to a vent hood used in natural venting

applications. Adding ambient air cools flue gases leaving the water heater to a low

enough temperature so that standard plastic piping can be used for venting. This

eliminates any problems with metal vent pipe corrosion. Plastic piping is often cheaper

and easier to install than sheet metal or masonry chimneys.

Heat Exchanger Improvements (Gas-Fired, Oil-Fired Storage, and

Instantaneous). Heat transfer from the flue gases to the water can be enhanced by

improving the flue baffle or heat exchanger. The improved heat transfer leads to an

increase in the thermal efficiency of the water heater. If the thermal efficiency is3-55

in creased to about 84 percent, condensation of the flue gases begins to occur in the flue

or vent pipe. Condensation may cause the surfaces of the flue and vent pipe to corrode.

To avoid such problems, materials that resist corrosion and methods to properly collect

and dispose of condensate are incorporated into water heater designs.

The heat exchanger can be improved by modifying the baseline gas-fired storage

water heater using (1) increased heat exchanger surface area, (2) an improved flue baffle,

(3) a submerged combustion chamber, (4) multiple flues, (5) alternative flue geometry

(helical), or (6) a u-tube flue. These approaches can increase recovery efficiency

significantly, but may also cause condensation (and hence corrosion) to occur in venting

systems.

Increased Heat Exchanger Surface Area . The baseline design consists of a

vertical flue in the center of the gas-fired or oil-fired storage water heater tank. This

design can be improved by increasing the surface area of the flue, which increases the

amount of heat transfer and thermal efficiency. One way to accomplish this is by

increasing the diameter of the flue. The overall tank diameter would need to be increased

to maintain consistent volume. Tank height could also be increased to maintain the same

volume, which would also add surface area to the flue. The flue baffle would most likely

require modification in order to maintain the same amount of air flow restriction.

Enhanced Flue Baffle . The standard flue baffle of a gas-fired and oil-fired storage

water heater is a twisted strip of metal inserted into the flue that increases the turbulence

of flue gases and improves heat transfer to the walls of the flue. The geometry of the flue

baffle can be modified to increase its effectiveness. Improving the flue baffle so that air

flow becomes more restricted and more turbulent can increase the amount of heat

transfer, which increases the thermal efficiency. Increasing the length of the path that the

flue gases travel and including more turns in the flue gas path can improve the flue

baffling. This can be accomplished by including fins or some other form of extrusion

from the flue wall, or by increasing the number of flow altering features in the baffle,

which is typically constructed from a flat piece of sheet metal and inserted into the flue.

These methods to enhance the flue baffle, which increase air flow restriction and

turbulence, may also result in an increased surface area, which also increases heat

transfer. Enhanced flue baffle technology can also reduce standby losses. Enhancements

to the flue baffle typically create restrictions to the air flow, which decreases convective

heat loss during standby periods.

Submerged Combustion Chamber. The combustion chamber in a standard gasfired and oil-fired storage water heater is below the water tank, and the bottom of the tank

(below the burners) is seldom insulated. Therefore, the water heater loses heat from

below the tank. The sides and bottom of the combustion chamber are not surrounded by

water. By inserting the combustion chamber into the storage tank, more of the

combustion energy can be recovered. Standby losses are reduced somewhat because of

restrictions on air flow through the combustion chamber and flue.

Multiple Flues. The multiple flue design uses several smaller flues in place of one

large central flue in the middle of the storage tank. The increased surface area for heat3-56

ex change between the flue gases and the water in the tank yields an increase in recovery

efficiency.

Alternative Flue Geometry (Helical) . This technology option is most often

associated with condensing gas-fired storage water heaters, but it also applies to oil-fired

storage water heaters. The technology incorporates both a helical or spiraling flue and a

u-tube flue. This technology contributes to increased efficiency in two distinct ways. The

surface area of the flue is increased, since it runs a helical path considerably longer than

the height of the water tank, increasing heat transfer during steady-state operations. Also,

when the burner is not operating, the multiple turns in the flue resist heat convection out

of the flue, reducing standby losses. Directing the flue downward with a “U” shape

allows the forming condensate to drain from the water heater flue properly. The flue

usually exits the sidewall of the water heater. Safety concerns exist due to the corrosive

and acidic nature of the flue gas condensate; corrosion-resistant materials are used to

mitigate this damage.

U-Tube. A u-tube flue for a gas-fired or oil-fired storage water heater is a flue

shaped like an inverted “U” within the water heater tank. This shape contributes to

increased efficiency in two distinct ways. The surface area of the flue is increased, as it

runs twice the height of the water tank, increasing heat transfer during steady-state

operation. This effect is similar to the increased heat exchanger surface area technology

option. When the burner is not operating, the inverted u-shaped flue resists heat

convection out of the flue, reducing standby losses. This effect is similar to the flue

damper technology options.

Direct Vent . Another method to increase surface area includes a secondary heat

exchanger. Combustion gases exiting through the vent preheat incoming air before it

passes through the primary heat exchanger. Manufacturers currently produce

instantaneous water heaters that accomplish this by running the inlet and exhaust vents

concentrically. This venting configuration is known as direct-vent. This set-up is similar

to a shell-in-tube heat exchanger.

Manufacturers currently produce water heaters with heat exchanger improvement

technologies.

Electromechanical Flue Damper (Gas-Fired Storage). Gas-fired storage water

heaters are typically equipped with a draft hood connecting the flue pipes to a vent pipe

or chimney. During off-cycle, the water heater loses heat by natural convection and

conduction through the vent pipe or chimney. Installing a damper at the flue exit or in the

vent pipe can minimize the off-cycle heat losses. A flue damper is installed upstream of

the draft diverter, while the vent damper is installed downstream of the draft diverter.

Electric flue dampers are activated by an external source of electricity. The

dampers open when combustion starts and close immediately after combustion stops.

Therefore, there is a greater reduction in off-cycle losses compared to buoyancy-activated

dampers. When the damper reaches the open position, an interlock switch energizes the

solenoid and enables the gas ignition circuit. Therefore, the burner cannot be ignited3-57

wh en the damper is in the closed position. Because the dampers open and close

immediately, no bypass is needed. However, a knockout vents the flue gases from a

standing pilot. The electric flue damper needs an electric hookup and consumes power

when the gas supply is off.

Flue and vent dampers have no effect on the steady-state performance of the

water heater. However, flue and vent dampers can reduce standby losses of gas-fired

storage water heaters, yielding improved energy efficiency. Some commercial water

heaters use flue dampers.

Side Arm Heater (Gas-Fired, Oil-Fired Storage). The side arm heater technology

option for gas-fired and oil-fired storage water heaters avoids large flue losses by

removing the flue from the center of the storage tank. Water is withdrawn from the

bottom of the tank, heated over a burner in a small, separate heat exchanger, and returned

to the top of the tank. A small circulation pump moves water through the heat exchanger

when the burner is on. The burner could have electronic ignition, which would reduce

pilot light losses. A low-voltage transformer, fed by a standard 120-volt wall connection,

supplies auxiliary power. Water heaters using this design are not currently on the market.

Electronic (or Interrupted) Ignition (Gas-Fired, Oil-Fired Storage, and

Instantaneous). The most commonly used ignition system in gas-fired and oil-fired

storage water heaters and instantaneous water heaters is a standing pilot ignition system.

The disadvantage of these water heaters is that they burn gas continuously at a rate of

about 1000 Btu/hr, and only part of this heat is converted to useful energy. As an

alternative to standing pilots, three electronic ignition devices are sometimes used in gasfired and oil-fired storage water heater and instantaneous water heater products:

Intermittent Pilot Ignition. This is a device that lights a pilot by generating a

spark, which in turn lights the main burner.

Intermittent Direct Ignition. This system lights the main burner directly by

generating a spark.

Hot Surface Ignition. This system lights the main burner directly via a sufficiently

hot surface.

Hydroelectric ignition is another form of electronic ignition used in gas-fired

products, particularly instantaneous water heaters. However, it is not as common as the

three forms of ignitions above. For hydroelectric systems, a small turbine is spun by

flowing water to produce electricity, which ignites a pilot. This is similar to intermittent

pilot ignition.

Unlike standing pilot ignition systems that consume gas continuously,

hydroelectric devices operate only at the beginning of each on-period. Although there is

no increase in the steady-state efficiency with the use of electronic ignition devices, they

reduce overall fuel consumption. Burner on-time may increase, however, to make up for

the heat the standing pilot would have supplied during standby periods.3-58 The “interrupted ignition” system for an oil-fired burner activates the spark only

until a steady flame is established. This differs from “intermittent ignition” for oil-fired

burners, where the energy source is activated during the entire burner operating cycle.

Interrupted ignition does not affect oil consumption, and there is no improvement in the

recovery efficiency of the water heater. However, this technology option not only reduces

the igniter’s electricity consumption, but also reduces its maintenance costs because the

electrodes do not have to be replaced as often. In addition to changes in controls, the

igniter can be made from solid-state electronics, instead of an iron core transformer. This

improves performance and also reduces power consumption. Manufacturers produce

water heaters with electronic ignition.

Heat Pump Water Heater (Electric Storage). A heat pump water heater

represents a merging of two otherwise unrelated technologies: an electric resistance

storage water heater with tank and controls, and a refrigeration circuit similar to that

found in a residential air-conditioner. Heat pump water heaters use existing heat pump

technology to extract heat from the surroundings for heating stored water. For electric

water heaters, this is an alternative to resistive heating. Heat pump water heaters transfer

heat from air, typically at room temperature, to water at a higher temperature. The heated

water can then be used to provide the residential hot water supply. Since heat does not

naturally transfer from a low temperature to a higher temperature, a mechanical system

consisting primarily of a closed refrigeration loop containing a refrigerant vapor

compressor, an evaporator (a type of heat exchanger), a condenser (another heat

exchanger), and an expansion device is used to transfer the heat. The working fluid in the

loop, the refrigerant, extracts heat from the surrounding air. Typically, the evaporator

captures heat from the ambient air, and the condenser delivers this heat to the water

inside of a storage tank. The pump and expansion device facilitate pressure and phase

changes to allow for these heat transfer processes.

When used continuously, typical heat pumps appear to heat water at roughly two

and a half to three times the rate of energy input (in the form of electricity). In practice,

actual tested residential heat pump water heater designs typically yield energy factors

from approximately 1.0 to 3.0, 48 while a baseline electric storage water heater has an

e n ergy factor of 0.90. An energy factor range exists because of variations in design and

ambient conditions. For example, differences in piping between the heat pump and

storage tank, efficiencies of the individual components of the heat pump loop, and

storage tank characteristics affect EF.

It should be noted that most U.S. homes are heated for substantial portions of the

year, and operating a heat pump water heater typically extracts heat from the household

air and increases the load on the home heating system during these periods. Energy

factors for heat pump water heaters, or any water heaters, do not consider home heating

loads. For this reason, accounting for the net energy or energy cost impact of the heat

pump water heater requires analyzing the energy cost impact on the entire house, not just

the electrical energy input to the water heater.

There are two basic designs for residential heat pump water heaters: add-on and

integral. An add-on heat pump water heater is designed to be added to a separately3-59

ma nufactured storage tank, often a standard electric resistance water heater. A small

pump circulates water from the tank through the heat pump. The heat pump and storage

tank are combined in the field during installation. The second type of heat pump water

heater is an integral heat pump water heater. In an integral design, the heat exchanger

(condenser) is combined with the storage tank design during the manufacturing process.

This eliminates the need for a circulation pump and increases efficiency. Both heat pump

configurations typically supplement resistive, or traditional electric, storage water heaters

where the elements operate only when the demand for hot water is greater than what the

heat pump can supply.

Both designs have a refrigeration subsystem composed of at least an expansion

device, evaporator, compressor, and a fan (to force air over the evaporator and enhance

heat transfer). The refrigerant condenser, also part of the refrigeration loop, can be

located with the rest of the subsystem as a separate unit (as is done with the add-on-type

heat pump water heater), or be integral to the tank as with the integral heat pump water

heater design. In the add-on heat pump water heater, cold water is removed from the tank,

heated, and pumped back into the tank. In the integral design, the heat pump compressor

moves refrigerant from the condenser coil to the evaporator coil. The condenser coil is

typically either inside the tank or wrapped around the tanks exterior ( i.e. , between the

tank wall and the insulation). The evaporator coil is typically housed on top of the tank

along with the remaining heat pump components. The compressor, evaporator coil, and

evaporator fan mounted on top of the storage tank will add approximately 12 inches to

the height of a traditional electric water heater tank. Regardless of design, the expansion

device, evaporator, fan, and compressor must be located outside the tank. In the add-on

design, components can be mounted on top of the tank or as a completely separate unit

that can be placed on the floor or mounted on the wall. For higher efficiencies, the add-on

heat pump water heater should be placed relatively close to the tank. As the unit is placed

farther from the tank, the water heating efficiency degrades due to piping losses,

predominantly the result of warm water left in the piping between on-cycles that results

in heat transfer to the surroundings.

The heat pump water heater also produces condensate at the evaporator coil

during operation. Like all refrigeration devices, the evaporator coil must be cold to

extract heat from the surrounding air. When air blows across the coil, moisture in the air

is condensed to liquid. The amount of liquid produced is a function of the humidity in the

air blown across the coil, the temperature of the evaporator coil, and the hot water load.

Locating the heat pump in the conditioned space of a residence does not eliminate all the

condensate buildup unless the air conditioning system can be counted on to dehumidify

all house air to a dew point below the coil temperature. Therefore, condensate drains are

typically required to remove condensation that collects as a result of operation. A pump

may also be needed to move condensate to a drain.

Most residential heat pump water heater designs need back-up electric resistance

heating elements because cost and space considerations limit the heating capacity of the

refrigeration system. Typical heat pump water heaters have between 40 and 80 percent of

the heating capacity of typical electric resistance storage water heaters. To compensate

for this reduced heating capacity and allow faster water heating and shorter recovery3-60

pe riods for the heat pump water heater during periods of high use, electric resistance

heaters are employed that can heat the water in the tank faster than the heat pump unit.

The cost of larger capacity systems generally outweighs the energy efficiency benefits to

the average consumer. Additionally, removing large amounts of heat from a conditioned

space during high use periods with a larger system may create unfavorable conditions in a

residence. Instead, practical systems are designed to heat water gradually using the higher

efficiency heat pump, but can, when required by the heating load, use a higher capacity

electric resistance backup.

Finally, the space in which the heat pump water heater is located must be large to

provide adequate air flow and must provide ready access for regular air filter changes on

the heat pump evaporator coil. The refrigeration subsystem of a heat pump water heater

needs sufficient flow of warm air across the evaporator coils to serve as a heat source.

Without this heat source, the heat pump cannot function and must revert to electric

resistance operation. Operation in heat pump mode will generally require about 100 cubic

feet per minute or more of warm air. Multiple manufacturers produce heat pump water

heaters. Multiple manufacturers produce heat pump water heaters, conduct heat pump

research, and develop prototype designs.

Carbon Dioxide (CO 2

) Heat Pump Water Heater (Electric Storage). C O 2 h eat

pu mp water heaters are similar to the aforementioned heat pump water heater technology.

This technology uses carbon dioxide as a natural refrigerant to transfer heat from the

surrounding air to the water stored in the tank through a heat pump loop. Current

products and prototypes can achieve coefficients of performance as high as 3.0, 49 which

re sult in EFs ranging from approximately 1.0 to 3.0. This range accounts for differences

in ambient air conditions, storage tank efficiency, and efficiencies of the components that

make up the heat pump loop. Additionally, some products installed outdoors can function

in cold weather without freezing pipes or frosting evaporators. Typically, this technology

is installed outdoors due to the size of components. Typical installations include a

separately packaged heat pump and a separately packaged storage unit consisting of two

tanks and supporting hardware. CO 2 heat pump water heaters also take advantage of load

s h ifting strategies by heating water at night and storing it for use during the day. Products

are predominantly available outside of U.S. markets where products have been made

available by government subsidy rebate programs. 50

Bu oyancy Operated Flue Damper (Gas-Fired Storage). This flue damper is a

small, very lightweight aluminum dome-shaped poppet that slides up and down in an

enclosure placed at the top of the flue of a gas-fired water heater. The buoyancy of the

combustion products lifts the poppet, allowing flue gases to enter the venting system.

This technology option would reduce off-cycle standby losses by sealing the flue

and preventing convection to the venting system, but would have no effect on recovery

efficiency because it does not affect the rate of heat transfer. This flue damper may not

work with high recovery efficiency water heaters because there may not be enough waste

heat in the combustion products to provide sufficient buoyancy to lift the poppet.3-61 The safety standard 51 for gas water heaters requires the burner to shut off if the

f l ue gets blocked for some reason. Thus, the effects of a failure of the flue damper to

open should be mitigated by the burner controls.

Directly Fired (Gas-Fired, Oil-Fired Storage). In this technology option, water is

sprayed through a series of baffles above the burner of gas-fired and oil-fired storage

water heaters. Burner flame and flue products are in direct contact with the water, which

is re-pressurized by a circulating pump and returned to the storage tank. The direct

contact process allows for more efficient heat transfer than conventional shell-and-tube

gas-fired and oil-fired storage water heaters because the heat resistive barrier between the

water and the flue products is eliminated. However, direct contact with flue products can

lead to contamination of the domestic water. This can potentially cause health and safety

problems for end users. This technology option can also cause conflict with local and

uniform plumbing codes ( e.g. , International Association of Plumbing and Mechanical

Officials (IAPMO) 1991) with respect to water quality.

Co n densing (Gas-Fired, Oil-Fired Storage, and Instantaneous). Energy

efficiency of gas-fired and oil-fired storage and instantaneous water heaters can be

increased by extracting more heat from the flue gases. More energy can be extracted by

condensing the combustion products in the flue gas, which extracts more heat in the form

of latent energy, leading to an increase in the thermal efficiency of the gas-fired and oilfired storage and instantaneous water heater. Water heater technology options or a

combination of technology options can be added to a water heater design to condense the

combustion gases.

The flue-gas condensate is often acidic and corrosive. Therefore, special

corrosion-resistant heat exchangers and vent linings are required for safe and reliable

operation of the water heater. Corrosion due to condensation of combustion gases limits

the thermal efficiency of a fuel-fired water heater with a standard flue and vent system.

Using corrosion-resistant heat exchangers or sidewall venting, and lining the

vent/masonry systems with corrosion-resistant material can extend the thermal efficiency.

Condensing gas appliances can be fully condensing or near condensing. Fully

condensing appliances have flue gas temperatures less than the dew point (130 oF to 140

oF) of the flue products. Condensation is expected in both the heat exchanger and the vent

system. Near-condensing appliances have flue gas temperatures approaching the dew

point of the flue gases, but still greater than the dew point. Condensation is expected in

the vent system but not in the heat exchangers. The thermal efficiency of fully

condensing water heaters can be as high as 99 percent. For near-condensing water

heaters, thermal efficiency is generally between 84 and 90 percent. Manufacturers

produce residential and commercial condensing water heaters.

Condensing Pulse Combustion (Gas-Fired, Oil-Fired Storage, and

Instantaneous). Pulse combustion burners for gas-fired and oil-fired storage and

instantaneous water heaters are another condensing technology. Pulse combustion

burners operate on self-sustaining resonating pressure waves that alternately rarefy the

combustion chamber (drawing a fresh fuel/air mixture into the chamber) and pressurize it3-62

(c ausing ignition by compression heating of the mixture to its flash point). This process is

initiated by a blower supplying an initial fuel and air mixture to the combustion chamber.

A spark ignites the mixture. Once resonance is initiated, the process becomes selfsustaining.

Pulse combustion systems feature high heat transfer rates, can self-vent, and can

draw outside air for combustion even when installed inside. Because the pulse

combustion process is highly efficient, the burners are generally used with condensing

appliances.

Thermophotovoltaic and Thermoelectric Generators (Gas-Fired, Oil-Fired

Storage, and Instantaneous). Heat and light energy can be extracted from the

combustion process of gas-fired and oil-fired storage and instantaneous water heaters and

converted into useful electrical energy. Thermophotovoltaic generator technology uses a

special light-emitting burner coupled with silicon photovoltaic cells that generate

auxiliary power that can run a fan, operate the electronic ignition and controls, and charge

a battery. This avoids the requirement of an auxiliary electrical supply, while offering the

efficiency advantages of electronic ignition and forced-draft combustion.

Another method of generating electricity at the water heater is based on

thermoelectric technology. Thermoelectric generators use semiconductors to convert a

temperature differential into a voltage source. This voltage source can provide power to

run a fan, operate the electronic ignition and controls, and charge a battery, similar to the

thermophotovoltaic generator. Thermoelectric generators are available, but none have

been used to generate auxiliary power for water heaters.

Reduced Burner Size (Slow Recovery) (Gas-Fired, Oil-Fired Storage, and

Instantaneous). Reducing burner size for gas-fired and oil-fired storage and

instantaneous water heaters while keeping flue baffle and tank geometry the same will

increase the ratio of heat transfer surface area to energy input, thereby increasing the

recovery efficiency. The lower energy input means that recovery would be slower than

with conventional burners.

Timer Control (Electric Storage). This technology option limits the time of day

when the elements of an electric storage water heater may be energized. This is most

often used as part of an electric utility demand-side management program for load

shifting (“demand avoidance strategy”). Energy savings are possible because the water in

the tank remains at a reduced temperature for part of the day. However, the actual energy

savings will depend on the end-use profile, lifestyle of the consumer, and a basic desire to

save energy. Savings will be greater for water heaters where standby loss levels are high

because the electric consumption, in response to the standby losses, shifts from on-peak

to off-peak times when electricity costs less.

After-market timer controls for water heaters are commercially available. Some

utilities also offer load-shifting controls for water heaters to reduce peak daytime

demand.3-63 Two -Phase Thermosiphon (Gas-Fired, Oil-Fired Storage). Two-phase

thermosiphon (TPTS) technology removes the flue from the center of gas-fired and oilfired storage water heaters and places a heat exchanger outside the storage tank, reducing

standby losses. This is similar to the side-arm heater technology option. TPTSs are heatpipe mechanisms that transfer heat from the external burner to the storage tank. The

TPTS is a closed loop device consisting of an evaporator, in which the working fluid

(water) is heated by the burner, percolating liquid and vapor into the condenser where

heat is transferred into the water storage tank. At the condenser, which is inside the

storage tank, the vaporized working fluid is condensed and drains back through a separate

restricted tube to the evaporator, where it is reheated. The restriction prevents the heated

vapor and liquid from flowing to the condenser through the return path. During off-cycle,

there is very little heat transfer through the TPTS system. This reduces standby losses to

levels similar to those of electric water heaters.

Modulating Controls (Instantaneous). Modulating controls within an

instantaneous water heater can reduce energy consumption, improve efficiency, and

improve overall performance by changing the operating conditions in response to

household demand. Basic controls ( i.e. , those without modulation) operate at either the

minimum or the maximum output levels, based on simple inputs from either the user or

the water heater. Alternatively, modulating controls can reduce output so that excess

energy is not wasted when only small temperature differentials or low flow rates need to

be satisfied. By modulating the controls, the demand can be met more precisely by the

appropriate outputs. For example, a control will not open fully to correct a small

differential; rather, the control will modulate to a lower, or stepped, position to avoid

wasting energy. An added benefit to modulation is the elimination of stacking, the effect

of overheating due to a succession of short hot water draws. Stacking can lead to scalding

and other safety issues. Finally, duty cycling can be reduced, which can reduce the total

amount of energy consumed. Several manufacturers currently include modulating

controls in instantaneous water heaters.

Intelligent Controls (Gas-Fired, Oil-Fired, Electric Storage, and

Instantaneous). Intelligent controls, self diagnostics, and electronic controls for storage

and instantaneous water heaters minimize energy consumption and maximize hot water

output. Monitoring functions typically operate to minimize operating cost while still

meeting household demand. This works by tracking usage patterns and adjusting water

heater operations to maximize efficiency. Also, water heaters may employ economizer

modes to limit the maximum temperature to reduce energy consumption. Smart vacation

settings operate to minimize energy usage while maintaining temperatures above

freezing. Diagnostic software may also maintain the optimal burner conditions, valve

positions, and air-to-fuel ratios to maximize efficiency, for example. Several storage- and

instantaneous-type water heaters incorporate intelligent, self-diagnostic, and electronic

controls.

Self-Cleaning (Gas-Fired, Oil-Fired, Electric Storage). This technology option

for storage water heaters is a modification of the conventional dip tube associated with

the baseline storage water heater. Water exits a conventional dip tube with a weak

diffusing action. Self-cleaning technology incorporates a method to introduce the inlet3-64

wa ter at high turbulence. This is accomplished by modifying the exit orifice at the end of

the dip tube to increase the inlet velocity of the water and create a spray pattern. Designs

may also incorporate orifices along the length of the dip tube. These introduce inlet water

at various points within the tank to increase mixing and overall tank turbulence. Further

designs may turn the flow path of the inlet water to a horizontal angle to increase the

amount of swirling, or rotational turbulence. This can be accomplished by simply

bending the dip tube.

This technology has the benefit of self-cleaning, but this does not contribute to an

increase in energy efficiency as measured by the DOE test procedure. By introducing the

inlet water at higher velocities and with turbulence, naturally occurring sediment in the

water is forced to remain in suspension. Therefore, the sediment can be drawn out of the

tank when there is a call for hot water, instead of settling to the bottom. If long standby

periods occur, the dip tube is designed to unseat any settled particles so that they can be

withdrawn from the tank. This prevents the formation of permanent deposits, which

degrade heat transfer. Deposits decrease water heater performance, can cause leaks, and

reduce tank volume.

3.3.2.2 Direct Heating Equipment

DOE identified the following technology options that might improve the

efficiency of direct heating equipment:

1. Heat exchanger improvements

2. Electronic ignition

3. Thermal vent damper

4. Electrical vent damper

5. Power burner

6. Induced draft

7. Two stage and modulating operation

8. Improved fan or blower motor efficiency

9. Increased insulation (floor furnaces only)

10. Condensing

11. Condensing pulse combustion

12. Air circulation fan

13. Sealed combustion

Heat Exchanger Improvements (Fan Wall, Gravity Wall, Floor, Room,

Hearth). Improving the heat exchanger for fan wall, gravity wall, floor, room, and hearth

heaters can improve heat transfer from combustion gases to the air. The improved heat

transfer leads to an increase in the thermal efficiency and AFUE of direct heating

equipment. If the AFUE increases to about 90 percent, condensation of the combustion

gases begins to occur in the heat exchanger or vent pipe. Condensation typically occurs

when the combustion gases are cooled to approximately 130 oF. Condensation may cause

corrosion to the surfaces of the heat exchanger and vent pipe. To avoid such problems,

direct heating equipment designs incorporate materials that resist corrosion and methods

to properly collect and dispose of condensate. If the design does not include a means to3-65

ma nage condensate, the use of this technology option will be limited to an AFUE below

90 percent to avoid damage.

The technology option of improved heat exchanger can be achieved by modifying

baseline designs of standard gas-fired direct heating equipment using (1) increased heat

exchanger surface area, (2) multiple flues, (3) multiple turns in flue, (4) direct vent, and

(5) increased heat transfer coefficient.

Increased Heat Exchanger Surface Area . The performance of the heat exchanger

can be improved by simply increasing its surface area, which increases the amount of

heat transfer occurring in the direct heating equipment. This, in turn, improves the direct

heating equipments’ ability to extract heat from combustion gases. The result is an

increase in the steady-state efficiency of the unit, and thus, the AFUE.

Multiple Flues . Incorporating a multiple flue design can increase heat exchanger

surface area. The heat exchanger heats room air by passing it through multiple tubes

instead of a single tube. One manufacturer incorporates 15 tubes to increase the surface

area and increase the rate of heat transfer.

Multiple Turns in Flue . This technology increases heat exchanger surface area by

including multiple turns in the flue pipe. Overall dimensions of the outer case do not

necessarily need to increase to accommodate a longer flue path. The longer flue path

increases heat exchanger surface area, which increases steady-state efficiency and AFUE

of the unit. One manufacturer incorporates turns in a heat exchanger to increase surface

area and AFUE.

Direct Vent . Another method to increase surface area includes a secondary heat

exchanger. Combustion gases exiting through the vent are used to preheat incoming air

before it passes through the primary heat exchanger. Manufacturers currently produce

direct heating equipment that accomplishes this by running the inlet and exhaust vents

concentrically. These units are known as direct-vent heaters. This set up is similar to a

shell-in-tube heat exchanger.

Increased Heat Transfer Coefficient . An alternative to increasing the size of the

heat exchanger is enhancing the inside and outside heat transfer coefficients of the heat

exchanger. This can be accomplished by modifying the surface of the heat exchanger

material for the purpose of increasing turbulence in the air passing close to the

exchanger’s surface, for example. Incorporating dimples or some other surface feature to

enhance turbulence can increase the heat transfer coefficient when correctly designed.

Also, the heat exchanger may be constructed of a material with a higher thermal

conductivity than the standard copper that is typically used.

Electronic Ignition (Fan Wall, Gravity Wall, Floor, Room, Hearth). All gravitytype heaters and the majority of fan-type heaters have a standing pilot ignition system. In

direct heating equipment, standing pilots continuously burn gas. The efficiency of the fan

wall, gravity wall, floor, room, and hearth heaters can be improved by simply replacing3-66

th e standing pilot ignition system with an electronic one, such as an intermittent pilot

system or a hot surface ignition system. This eliminates the need for the standing pilot.

In assessing the impact on energy consumption, it is important to account for the

added electrical energy consumption of the electronic ignition device in addition to the

reduction in gas energy consumption that results from eliminating the standing pilot.

The two standing pilot ignition systems for gravity heaters, hydraulic and

millivolt, do not require an outside source of electricity to operate. Consequently, these

gas valves are more complex and more costly than those of an ignition system requiring a

separate power source. For both the hydraulic and millivolt systems, the small amount of

electricity that is required by the gas valve and thermostat is generated by either a

thermocouple or thermopile. The thermocouple or thermopile draws its power from the

burning pilot, and only a small fraction of the heat energy is converted to electricity. The

pilot burns at approximately 775 Btu/hr constantly, and the electrical power typically

required is only around 1 Watt, or 3.5 Btu/hr. The remaining heat is lost or transferred to

th e room (even when there is no call for heating).

For fan wall furnaces that already require an outside source of electricity to

operate the fan, the electronic ignition system is powered off the fan power supply. The

power draw of the fan power supply transformer occurs continuously. For direct heating

equipment that does not already require electricity, a means to supply power must be

included in the design.

Both hot surface and intermittent pilot electronic ignitions require an outside

source of electricity to operate. The gas valve for each electronic ignition system

typically only consumes power during a call for heat. The control module, which houses

the electronic circuitry required to control the entire ignition system, typically only

consumes power during a call for heat. Finally, the electronic thermostat draws power

continuously (regardless of whether heat is needed). These power requirements in total

are typically less than the pilot burn rate. Manufacturers currently produce direct heating

equipment with electronic ignition.

Thermal Vent Damper (Fan Wall, Gravity Wall, Floor, Room, Hearth). Vent

dampers are installed between the draft hood and the vent pipe of fan wall, gravity wall,

floor, or room heaters. Vent dampers improve efficiency primarily by reducing off-cycle

infiltration and off-cycle sensible heat losses. Vent dampers have no effect on steadystate efficiency because they do not improve heat transfer.

A pair of bi-metal coil springs activate thermal vent dampers. Heat created by

combustion gases causes the two coil springs to contract and open the damper blade.

After heating discontinues, the springs cool and expand, closing the damper. Response

time to open and close the damper varies and may be slow because the bi-metal coil

spring does not heat up or cool down instantaneously. Thermal vent dampers can be

installed on units using either a standing pilot or an electronic ignition system. In the

closed position, thermal vent dampers allow some bypass to ensure that combustion gases

will not be trapped within the heat exchanger during start up. The bypass also allows the3-67

ve nting of flue gases from a standing pilot. Adding a bypass reduces off-cycle losses

because the damper is only partially closed.

Combustion products must maintain a certain amount of heat in order to expand

the bi-metal coil springs of the thermal vent damper. If a high efficiency heater transfers

nearly all heat to a room and an insufficient amount of heat remains in the combustion

gases on contact with the thermal vent damper, there will not be enough heat to open the

damper.

Electrical Vent Damper (Fan Wall, Gravity Wall, Floor, Room, Hearth). In

direct heating equipment, vent dampers are installed between the draft hood and the vent

pipe of fan wall, gravity wall, floor, room, and hearth heaters. Vent dampers improve

efficiency primarily by reducing off-cycle infiltration and off-cycle sensible heat losses.

Vent dampers have no effect on steady-state efficiency. Vent dampers have no affect on

steady-state efficiency because they do not improve heat transfer.

An external source of electricity is needed for electrical vent damper operation.

Sensors indicate when the burner is off, allowing for fast closure of the damper. This

results in a greater reduction in off-cycle losses than can be achieved with thermally

activated vent dampers. Electric vent dampers include safety interlocks to prevent burner

operation when the damper is not fully open. Unlike thermal dampers, electric dampers

do not allow for bypass since they can open immediately upon burner operation, unless

standing pilot ignition is employed. When standing pilots are in use, a knockout on the

damper allows standing pilot combustion gases to vent when the damper is fully closed.

Safety concerns do exist. A power failure may cause the electrical damper to

remain closed and not cycle open while the heater operates to meet heating demands.

This issue is mitigated by including safety interlocks that allow operation of the burner

only when the damper is in the open position. Also, a spring return actuator that fails in

the open position can be used. In this case, when the electric vent damper experiences a

power loss, a spring forces the damper to the open position.

Electrical dampers require an electrical connection, but use only a nominal

amount of power during opening and closing. Spring return dampers, if installed, require

only a nominal amount of power as well. Power is required while opening and holding

closed during standby periods (to overcome the return spring).

Power Burner (Fan Wall, Gravity Wall, Floor, Room, Hearth). Fan-assisted

combustion systems for fan wall, gravity wall, floor, room, and hearth heaters can be

designed with power burner technology. Power burners use blowers upstream of the

combustion zone to supply a more efficient fuel-air mixture to the burner. Power burners

also reduce off-cycle losses by restricting air flow and convection of warm air to the vent

system, similar to a vent or combustion box damper.

Increasing the amount of primary air to the burner will also increase the

accompanying steady-state efficiency. This is accomplished without further design

modifications to the heater. Because the power burner can be designed to overcome3-68

re latively large pressure drops within the heat exchanger, further increases in steady-state

efficiency can be attained by redesigning the heat exchanger system. The heat exchanger

can be designed to be more compact with more restrictions so that more heat can be

extracted from the combustion gases. As efficiency increases, condensation of

combustion gases within the vent system becomes more likely. Condensation of

combustion gases should be avoided unless the system is specifically designed as fully

condensing direct heating equipment.

Induced Draft (Fan Wall, Gravity Wall, Floor, Room, Hearth). Fan-assisted

combustion systems for fan wall, gravity wall, floor, room, and hearth heaters can be

designed with induced draft technology. Induced draft fans are located downstream of the

combustion zone (at the exit of the heat exchanger) and regulate the amount of primary

air at the burner resulting in a higher combustion efficiency. Induced draft systems also

reduce off-cycle losses. Since induced draft fans are located at the exit of the heat

exchanger, they tend to reduce off-cycle infiltration losses more than power burners. The

induced draft fan essentially acts as a vent damper to prevent heated room air from being

drawn into the vent system.

The space allocated for the draft hood is large enough to accommodate an induced

draft fan. The induced draft fan could also be located anywhere along the length of the

vent pipe as long as a draft can be maintained. Some installations may even incorporate a

fan in the vent cap at the end of the venting system. Besides increasing AFUE, the

steady-state efficiency will also increase because of the increasing amount of primary air

to the burner. This increase is accomplished without further design modifications to the

heater. Because the induced draft fan can be designed to overcome relatively large

pressure drops within the heat exchanger, further increases in steady-state efficiency can

be attained by redesigning the induced draft heat exchanger system. The heat exchanger

can be redesigned to be more compact with more restrictions so that a greater amount of

heat can be extracted from the flue gases. As efficiency increases, condensation of

combustion gases within the vent system becomes likely. Condensation of combustion

gases should be avoided unless the system is specifically designed as fully condensing

direct heating equipment.

Two-Stage and Modulating Operation (Fan Wall, Gravity Wall, Floor, Room,

Hearth). Two-stage or modulating operation allows fan wall, gravity wall, floor, room,

and hearth heaters to meet heating load requirements more precisely. When low heating

load conditions exist, the heater can operate at a reduced burner rate. This reduces cycling

of the unit, which in turn, reduces large fluctuations in room temperature.

Two-stage or modulating burners attempt to reduce cycling of the heater by

reducing the flow rate of gas at lower heating loads. These burners regulate gas flow but

not air flow. Excess air is induced at lower gas flow rates, resulting in lower combustion

efficiencies when compared to a normal or maximum gas flow rate. Because of this,

heaters equipped with two-stage or modulating burners will always have a lower energy

efficiency, as measured by the DOE test procedure, than heaters equipped with singlestage burners.3-69 To o vercome this lower efficiency and achieve efficient two-stage or modulating

operation, an induced draft or forced draft system using a two-speed or variable speed

combustion fan must incorporate the two-stage or modulating burner. With the multispeed combustion fan, the excess air drawn into the burner at low gas flow rates can be

reduced so that there is no decrease in the steady-state efficiency of the heater. The aircirculation fan on forced-air two-stage and modulating direct heaters must also be

capable of two-stage or variable speed operation to avoid a similar decrease in energy

efficiency.

Improved Fan or Blower Motor Efficiency (Fan Wall, Hearth). For fan wall and

hearth heaters equipped with air circulation fans, the fan or blower motor efficiency can

be increased to reduce the electrical energy consumption of the unit.

Typical fan motor sizes are 1/20 horsepower. Since the motor is so small,

increased efficiency would yield extremely small electrical energy savings. Direct

heating manufacturers typically use permanent split capacitor (PSC) fan motors. The next

jump in motor efficiency would be a permanent magnet brushless DC (BLDC) motor. A

brushless DC motor uses electronic controls to commutate the motor, eliminating brush

friction and losses, and therefore increasing motor efficiency. BLDC motors also have

longer lifetimes than electric motors containing brushes.

Increased Insulation (Floor). Floor furnaces are the only heater types installed

directly in an unconditioned space. Floor furnaces are typically installed where the

majority of the unit is below the subfloor of the first floor and in the crawlspace of a

home. DOE considered increasing or improving the insulation of a heater only for this

product class of DHE. Since room heaters and wall furnaces are installed in the

conditioned space, insulation in the cabinet would only serve to minimize cabinet hot

spots and reduce the amount of radiated heat coming off the heater. Additionally, the

DOE test procedure calls for the measurement of jacket losses only for floor furnaces.

Increased or improved insulation would reduce the jacket losses of this type of DHE and

increase the overall AFUE. Insulation is installed in a floor furnace at the perimeter of the

cabinet.

Condensing (Fan Wall, Gravity Wall, Floor, Room, Hearth). If fan wall, gravity

wall, floor, room, and hearth heaters are designed to have high steady-state efficiencies,

enough heat will be extracted from the combustion gases so that condensing will occur

within the heat exchangers. This type of heater is typically termed a condensing heater

and AFUEs generally exceed 90 percent. One typical condensing design uses a high

efficiency fan-assisted combustion system with additional heat exchanger surface area.

This heater system can be designed to achieve high efficiencies that are much

higher than non-condensing systems. In the power burner or induced draft technology

option description, condensation of the combustion gases within the vent system was not

desired. Since condensation is now desired, the fan-assisted system is designed to extract

as much heat from the combustion gases as possible. Typically, condensing systems

exhaust their combustion gases through a direct vent. Positive pressure can be maintained

within the vent system to exhaust the low temperature combustion gases with a fan3-70

in stalled upstream of the combustion zone. Conversely, negative pressure can be

maintain within the vent system to draw combustion gases from the combustion chamber

with a fan installed downstream of the combustion zone. The combustion gases can be

passed through a larger or improved heat exchanger to extract as much heat as possible.

Condensing systems require some means to collect and drain the condensate that

develops within the heat exchangers. Condensing systems can be designed to use

secondary heat exchangers and air circulation fans as well.

Condensing Pulse Combustion (Fan Wall, Gravity Wall, Floor, Room, Hearth).

If a fan wall, gravity wall, floor, room, or hearth heater is designed to have a high steadystate efficiency, enough heat will be extracted from the flue gases so that condensing

occurs within the heat exchanger. This type of heater is typically termed a condensing

heater and AFUEs generally exceed 90 percent. One typical condensing design uses pulse

combustion with additional heat exchanger area.

This heater system can be designed to achieve very high efficiencies. In the power

burner or induced draft technology option description, condensation of the combustion

gases within the vent system was not desired due to the corrosive nature of the

condensate. However, to achieve high AFUEs, enough heat must be extracted from the

combustion gases to cause the combustion gases to condense. Condensing pulse

combustion systems are designed to extract as much heat from the combustion gases as

possible. Pulse combustion systems, like a direct-vent type heater, draw combustion air

from the outside. Once ignition is accomplished, the pulse combustion process is selfsustaining. The turbulent nature of the pulse combustion process requires no mechanical

devices ( e.g. , induced draft fans or power burners) to vent the combustion products to the

outside. Pulse combustion designs may use a secondary heat exchanger and an air

circulation fan to increase steady-state efficiency. The secondary heat exchanger is

usually located at the forced air blower outlet and before the combustion air enters the

combustion chamber. Part of the efficiency gain comes from capturing the heat of

vaporization of the combustion gases before they are expelled to the outside. Combustion

gases condense because the temperature of the vented gases falls to about 130 °F. A

condensate drain is usually needed to route the condensed moisture into a floor drain.

Air Circulation Fan (Floor, Room). Air circulation fans improve the steady-state

efficiency of floor and room heaters by circulating air in a counter-current mode to the

flow of combustion products. In gravity-type heaters, room air circulates co-current with

the combustion products, driven only by the thermal buoyant forces. Counter-current heat

exchangers are inherently more efficient than co-flowing types. In addition, the higher air

flow rates that occur in forced-air heaters result in higher heat transfer coefficients than

gravity-type heaters can achieve.

AFUE increases due to air circulation fans result solely from improving the

steady-state efficiency of the heater. This technology is only considered for room heaters

and floor furnaces. Air circulation fans are known to be easily incorporated into currently

available room heater models as manufacturers already provide consumers with the

option of purchasing fans for these units. Though floor furnaces do not currently have the3-71

opt ion of adding a circulation fan, DOE believes the cabinet is large enough to

incorporate a fan without having to enlarge the cabinet.

Sealed Combustion (Fan Wall, Gravity Wall, Floor, Room, Hearth). Fan wall,

gravity wall, floor, room, and hearth heaters that pull air from the conditioned space to

use for the combustion process waste heat. Removing energy in the form of heated air

and exhausting it outside of the conditioned space is inherently less efficient than

drawing outside air for the combustion process. Fan wall, gravity wall, floor, and room

direct heating equipment with sealed combustion chambers prevents heat rejection from

occurring. Using outside air for heating ensures that air within the conditioned space is

not used for combustion.

Unlike sealed combustion heaters (which do not induce any pressure), non-sealed

combustion heaters induce negative pressure during operation. When air is exhausted

from a conditioned space, the removed air must be replaced to satisfy the induced

pressure differential. This happens naturally by infiltration, or leaking, of cool outside air

into the conditioned space. Sealed combustion does not contribute to exchanges of air

between the interior conditioned spaces and exterior unconditioned spaces.

Sealed combustion provides inherent safety benefits. Sealing the combustion

process prevents harmful combustion gases from mixing and accumulating in the

conditioned space. Combustion products are exhausted outside the space.

3.3.2.3 Pool Heaters

The following technology options could improve the efficiency of pool heaters:

1. Electronic ignition

2. Improved heat exchanger design

3. More effective insulation (combustion chamber)

4. Power venting

5. Sealed combustion

6. Condensing pulse combustion

7. Condensing

Electronic Ignition. One of the most common ways to reduce energy

consumption of pool heaters is to eliminate the standing pilot light as a method of

igniting the main burner. Pool heater manufacturers already make heaters with electronic

ignition and many different variations in models are available. Since February 1984,

California has required that pool heaters use electronic ignition instead of standing pilot

lights. Three electronic ignition devices are used in gas-fired pool heaters:

Intermittent Pilot Ignition. This device lights a pilot by generating a spark, which

in turn lights the main burner.

Intermittent Direct Ignition. This system lights the main burner directly by

generating a spark.3-72 Hot Surface Ignition. This system lights the main burner directly from a

sufficiently hot surface.

Unlike standing pilot ignition systems that consume gas continuously, these

devices operate only at the beginning of each on-period. Although there is no increase in

the steady-state efficiency when using electronic ignition devices, the overall fuel

consumption is reduced. Pool heater pilot lights typically consume approximately 1,100

Btu/hr on average.

Improved Heat Exchanger Design. Pool heaters are currently capable of reaching

the steady-state efficiency level where potentially damaging condensation will start to

form on the heat exchanger. A small increase in heat exchanger size may be possible

without causing condensation of the combustion gases by increasing the heat exchanger

surface area. The burner configuration might also require adjustment. No blower would

be required for this technology option.

The heat exchanger size can also be increased while preventing condensation

from forming by using a governor. The governor maintains pool water temperature and

water flow to prevent condensation of combustion gases. The governor limits the

efficiency of the heat exchanger so that the latent heat of the combustion gases is not

transferred to the pool water. At least one manufacturer makes a pool heater with a

condensing governor.

If condensation is desired to achieve a high steady-state efficiency, then the pool

heater design must properly manage and dispose of the potentially damaging condensate.

This can be accomplished with corrosion-resistant materials and a condensate drain.

More Effective Insulation (Combustion Chamber). Combustion chambers for

pool heaters are insulated with fiberglass blankets to prevent heat loss through the walls

of the combustion chamber to the exterior of the pool heater. Manufacturers reduce the

amount of heat loss to increase the thermal efficiency by using materials with more

effective insulation properties. Pool heater manufacturers currently produce products that

use Fiberfrax panels and refractory tiles to reduce the amount of heat loss through the

combustion chamber walls. By lining the sides and bottom of the heat exchanger with

these materials, manufacturers increase the amount of heat that is transferred from the

combustion chamber to the heat exchanger. DOE identified several manufacturers that

use insulation that is more effective than fiberglass blankets for pool heater combustion

chambers.

Power Venting. Fan-assisted combustion systems for pool heaters can be

designed with power venting technology. Induced draft fans located downstream of the

combustion zone (at the exit of the heat exchanger) or forced draft fans located upstream

of the combustion zone (at the entrance to the combustion chamber) regulate the amount

of primary air at the burner resulting in a higher combustion efficiency.

To increase the energy efficiency, a larger heat exchanger surface area (which

increases the heat transfer rate) is required. The larger heat exchanger typically increases3-73

th e amount of restriction to the air flow path and the combustion gases are typically not

buoyant enough to provide adequate draft. Therefore, the power vent forces combustion

gases through the restricted heat exchanger area. Forcing the air increases turbulence,

which increases the rate of heat transfer. The increased rate of heat transfer will in turn

increase steady-state efficiency and energy efficiency. Configuration of other parts of the

pool heater, such as the combustion chamber and burner, can remain constant with this

technology option. However, additional alterations of the heat exchanger may be needed

if condensing occurs, which can corrode the heat exchanger.

Sealed Combustion. Pool heater combustion processes require a regulated ratio of

fuel to air to be efficient. The primary air for the combustion chamber must be supplied at

a constant rate without any fluctuations. To maintain a specific supply of primary air,

manufacturers seal the combustion chamber of the pool heater. Manufacturers produce

pool heaters with seal combustion chambers and air intakes that operate at consistent

energy efficiency levels regardless of outside conditions. Pool heaters, particularly those

installed outdoors, without seal combustion chambers are susceptible to reductions in

thermal efficiency in high winds. Pressure and air flow variations caused by ambient

conditions can vary the amount of primary air supplied to the burners, which can reduce

burner efficiency. Several manufacturers produce pool heaters with sealed combustion

chambers.

Condensing Pulse Combustion. To increase the energy efficiency of a pool

heater, the water vapor in the combustion gases must be condensed to capture the heat of

vaporization. The heat exchanger must be altered for condensing operations to prevent

the acidic condensate from corroding the heat exchanger. A condensate drain is also

required.

Condensing can be accomplished by using pulse combustion burners. These

burners operate with self-sustaining resonating pressure waves that alternately ratify the

combustion chamber (causing a fresh fuel/air mixture to enter the chamber) and

pressurize it (causing ignition by compression of the mixture to its flash point). This

process is initiated by a blower that supplies the initial fuel and air mixture to the

chamber. The fuel and air mixture is ignited with a spark igniter. Once resonation is

established, the process becomes self-sustaining. Pulse combustion systems feature high

heat transfer rates through the heat exchanger due to increased turbulence of combustion

gases. High-efficiency gas-fired boilers using pulse combustion are currently available.

Condensing. To increase the efficiency of a pool heater, the water vapor in the

combustion gases must be condensed in order to capture the heat of vaporization. The

heat exchanger must be altered for condensing operations to prevent condensate from

corroding the heat exchanger. A condensate drain is also required.

This technology option uses a radiant burner, a modified heat exchanger to

condense the combustion gases, and a burner located above the heat exchanger to prevent

corrosion from contact with condensate. A ceramic matrix radiant burner is located above

a series of finned heat exchanger tubes. A blower forces an air and gas mixture through

the ceramic matrix burner and down past the heat exchanger. Most of the heat is radiated3-74

to the heat exchanger. By locating the burner above the heat exchanger and out of the

way of any condensation, the burner does not require corrosion protection. The heat

exchanger must still be corrosion-resistant, however, and a condensate drain must be

installed.

3.3.3 Technologies That Do Not Affect Energy Efficiency as Measured

DOE reviewed the technologies presented in the previous assessment and

considered their impacts on DOE’s test procedure results as well as their impacts on

energy use. Since EF, AFUE, and thermal efficiency are the relevant performance metrics

in this rulemaking, DOE did not consider the technologies discussed in section 3.3.2 that

have no effect on EF, AFUE, or thermal efficiency during the screening analysis.

However, DOE does not discourage manufacturers from using these technologies

because they might reduce annual energy consumption. In this section, DOE explains

why these technologies do not affect EF, AFUE, or thermal efficiency.

3.3.3.1 Water Heaters

The following technology options either do not effect or do not increase the EF of

residential water heaters: timer controls, self-cleaning, intelligent controls, and

modulating controls.

Timer Controls (Electric). Timer controls affect the time of day when the

elements of an electric storage water heater may be energized. This feature has the

potential to reduce energy use because the water in the tank remains at a reduced

temperature for part of the day. 52 These savings are achieved because the electric

c o nsumption, in response to the standby losses, is shifted from on-peak to off-peak times

when electricity costs less.

However, the DOE test procedure for electric storage water heaters does not show

the effects of timer controls because the test specifies normal operation for the water

heater during the entire testing period. Additionally, this technology affects the energy

consumption pattern of the water heater and not energy efficiency because load is shifted,

not reduced. The typical use of the average consumer is specified by the test procedure,

and time of day and conditions of an electrical supply grid (on-peak or off-peak) are not

factors. Although this technology can reduce peak energy demand and reduce overall

energy costs to the consumer throughout the year, it does not increase EF under the DOE

test procedure for electric storage water heaters because of the specified test conditions.

Therefore, DOE does not consider timer controls as a technology for improving EF of

electric storage water heaters.

Self Cleaning (Gas, Oil, Electric Storage). Self-cleaning incorporates a method

to introduce the inlet water at high turbulence so that the sediment occurring naturally in

the water remains in suspension and does not settle to the bottom of the tank.

Additionally, a self-cleaning dip tube unseats sediment that accumulates during long

standby periods. Tank cleaning does not improve EF as measured by the DOE test

procedure. The test procedure to determine EF is 24 hours, and testing immediately3-75

fo llows manufacture. Sediment build-up can reduce EF over the life of the water heater,

but the amount of build-up that could occur in a 24-hour period, if any, would not be

enough to affect the test results. This technology facilitates the removal of deposits,

which can build up over the life of a water heater, which is typically 9 to 15 years.

Deposits decrease water heater performance, reduce tank volume, and can cause leaks.

Self-cleaning improves tank life and reduces the required maintenance, but these are not

determinants for EF. Therefore, DOE does not consider self-cleaning as a technology for

improving EF of electric, gas, or oil storage water heaters.

Intelligent Controls (Gas, Oil, Electric Storage). Intelligent controls and selfdiagnostics minimize energy consumption and maximize hot water output. Several

storage and instantaneous type water heaters currently on the market include selfdiagnostics and electronic controls. Typically, varying the temperature of the heated

water based on the household demand minimizes energy consumption. However, the

DOE test procedure has a set draw pattern and usage for the water heater, and specifies

an inlet and outlet temperature for the water. As a result, there is no opportunity for

varying temperatures to affect the EF calculation. Consequently, DOE does not consider

intelligent controls as a technology for improving EF of electric storage, gas storage, and

gas instantaneous water heaters.

Modulating Controls (Instantaneous). Modulating water heater controls can

reduce energy consumption, improve energy efficiency, and improve overall performance

by changing the operating conditions in response to household demand. Modulating

controls can also reduce output so that excess energy is not wasted when only small

temperature differentials or low flow rates need to be satisfied. Although modulating

controls can increase energy efficiency over a broad operating range, they do not affect

EF as measured by the DOE test procedure. Due to the specified test conditions, ( i.e. , no

variability in demand or delivery), there is no opportunity for varying operating

conditions to affect the EF calculation. Therefore, DOE does not consider modulating

controls as a technology for improving EF of instantaneous water heaters.

3.3.3.2 Direct Heating Equipment

DOE has not identified any technologies that do not affect or do not increase

AFUE for residential direct heating equipment as measured by DOE’s test procedure.

3.3.3.3 Pool Heaters

Only one technology option has no effect on the thermal efficiency of residential

pool heaters: electronic ignition.

Electronic Ignition. Electronic ignition (intermittent pilot, intermittent direct, and

hot surface ignition) reduces the energy consumption of gas-fired pool heaters by

eliminating the standing pilot. Pool heater pilot lights burn continuously with a burn rate

ranging from 1,000 Btu/h to 2,000 Btu/h during the pool heater operating season.

Electronic ignition uses energy only when there is a call for heating and only until a

flame has been established.3-76 Ele ctronic ignition can be used to replace the standing pilot and reduce the overall

energy consumption of the pool heater. However, the thermal efficiency descriptor

specified by EPCA and measured by DOE’s test procedure, does not take into account

the energy efficiency benefits of ignition sources that are alternatives to standing pilots

( e.g. , electronic ignition). The thermal efficiency descriptor, as measured by the DOE test

procedure, does not account for additional energy consumption of a continuous, standing

pilot light when the burner is off because it is a steady-state test procedure and thermal

efficiency is determined when the burner is on. That is, thermal efficiency only captures

energy efficiency impacts that affect combustion and the transfer of energy to the water.

The thermal efficiency descriptor does not account for any energy that a pool heater may

use in the standby period. Therefore, standards expressed in terms of this descriptor

cannot require use of such alternative ignition sources or capture the full energy savings

benefit of their use. Therefore, DOE does not consider electronic ignition as a technology

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