PRICE-EFFICIENCY RESULTS

Summary Tables

The results of the Engineering Analysis are summarized in cost-efficiency tables

demonstrating the increased cost and efficiency due to each design option within each product

class. The design option combinations are shown in order of increasing efficiency.

Table la. Results for the 50-Gallon Electric Water Heater: HFC-245fa-Blown Foam

DO# Label Selected Design Option Combinations EF Total Installed

l_ l l___________________________________

I Cost

Existing Baseline 0.8600 345.66

0 12003 Baseline Baseline (245fa) 0.8601 349.01

1 .Heat Traps Baseline (245fa) + Heat Traps 0.8780 355.26

2 Insulated Tank Baseline (245fa)+ HeatTraps + nsulated Tank 0.8822 361.39

Bottom Bottom

3 2" Insulation Baseline (245fa) + Heat Traps + Insulated Tank 0.8967 388.77

Bottom + 2" Insulation

4 2.5" Insulation Baseline (245fa)+ HeatTraps+ Insulated Tank 0.9077 408.07

; i. Bottom + 2.5" Insulation

5 IPlastic Tank Baseline (245fa) + Heat Traps + 2.5" Insulation; 0.9099 444.50

..+ Plastic Tank

6 13" Insulation Baseline (245fa) + Heat Traps +3" Insulation + 0.9180 510.83

|I EP~~~~Plastic Tank

Table Ib. Results for the 50-Gallon Electric Water Heater: Water-Blown Foam

DO# Label Selected Design Option Combinations EF Total Installed

l_______I l_____ Jl__ l Cost

Existing Baseline 0.8600 345.66

0 2003 Baseline Baseline (Water-Blown) 0.8601 361.02

1 Heat Traps Baseline (Water-Blown) + Heat Traps 0.8780 367.27

2 Insulated Tank Baseline (Water-Blown) + Heat Traps + 0.8816 373.40

Bottom IInsulated Tank Bottom

3)2.5" Insulation Baseline (Water-Blown) + Heat Traps + 0.8895 394.82

|- |m> Insulated Tank Bottom + 2.5" Insulation

4 3" Insulation Baseline (Water-Blown) + Heat Traps + 0.8981 459.23

!~ i.~Insulated Tank Bottom + 3" Insulation

5iPlastic Tank Baseline (Water-Blown) + Heat Traps + 3" 0.9012 495.66

__ _____ I Insulation + Plastic Tank

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Table 2a. Results for the 40-Gallon Gas-Fired Water Heater: HFC-245fa-Blown Foam

DO# Label Selected Design Option Combinations EF Total Installed

IJ________ _Cost

Existing Baseline 0.544 330.15

0 !2003 Baseline iBaseline (245fa) 0.543 376.35

1 iHeat Traps !Baseline (245fa) + Heat Traps 0.552 380.57

2 !78% RE 'Baseline (245fa) + Heat Traps +78% RE 0.565 395.54

3 12" Insulation Baseline (245fa) + Heat Traps + 78% RE + 2"i 0.592 416.76

Insulation

4 2.5" Insulation Baseline (245fa) + Heat Traps + 78% RE + 0.599 431.47

2.5" Insulation

5 i80% RE Baseline (245fa) + Heat Traps + 80% RE + 0.615 468.25

S i2.5" Insulation

6 Side-Arm Baseline (245fa) + Heat Traps + 80% RE + 0.700 636.89

wI 2.5" Insulation + Side-Arm + Electronic Ignition 7 Plastic Tank Baseline (245fa) + Heat Traps + 80% RE + 0.709 654.60

2.5" Insulation + Side-Arm + Electronic Ignition

+ Plastic Tank

8 3" Insulation Baseline (245fa) + Heat Traps + 80% RE +3" 0.715 716.40

Insulation + Side-Arm + Electronic Ignition +;

tI iP~~~Plastic Tank

Table 2b. Results for the 40-Gallon Gas-Fired Water Heater: Water-Blown Foam

DO# Label Selected Design Option Combinations EF Total Installed

Cost

Existing Baseline 0.544 330.15

0 |2003 Baseline Baseline (Water-Blown) 0.544 380.30

1 hHeat Traps iBaseline (Water-Blown) + Heat Traps 0.552 384.53

2 78% RE Baseline (Water-Blown) + Heat Traps + 78% 0.565 399.50

RE

3 12" Insulation Baseline (Water-Blown) + Heat Traps + 78% 0.583 414.49

RE + 2" Insulation

4 2.5" Insulation Baseline (Water-Blown) + Heat Traps + 78% 0.591 430.58

RE + 2.5" Insulation

5 80% RE Baseline (Water-Blown) + Heat Traps + 80% 0.607 467.36

RE + 2.5" Insulation

6 Side-Arm Baseline (Water-Blown) + Heat Traps + 80% 0.691 635.99

j=i ~ XRE + 2.5" Insulation + Side-Arm + Electronic

Ignition

7 iPlastic Tank Baseline (Water-Blown) + Heat Traps + 80% 0.700 653.71

RE + 2.5" Insulation + Side-Arm + Electronic

|~<~~ Ignition + Plastic Tank

8 -3" Insulation Baseline (Water-Blown) + Heat Traps + 80%i 0.706 714.61

RE + 3" Insulation + Side-Arm + Electronic

"_______ l Ignition + Plastic Tank

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Table 3a. Results for the 32-Gallon Oil-Fired Water Heater: HFC-245fa-Blown Foam

DO# Label Selected Design Option Combinations EF Total Installed

Cost

Existing Baseline 0.529 936.60

0 2003 Baseline Baseline (245fa) 0.529 939.86

1 Heat Traps Baseline (245fa) + Heat Traps 0.539 954.81

2 2" Insulation Baseline (245fa) + Heat Traps+ 2" Insulation 0.555 1,007.11

3 i2.5" Insulation Baseline (245fa) + Heat Traps+ 2.5" Insulation 0.558 1,023.23

4 13" Insulation Baseline (245fa) + Heat Traps+ 3" Insulation 0.561 1,048.03

5 78% RE iBaseline (245fa) + Heat Traps+ 3" Insulation + 0.582 1,167.39

Ig 178% RE I

6 Interrupted Baseline (245fa) + Heat Traps+ 3" Insulation +| 0.586 1,223.39

Ignition 78% RE + Interrupted Ignition

7 82% RE Baseline (245fa) + Heat Traps + 3" Insulation + 0.616 1,434.34

Increased HX 78% RE + Interrupted Ignition + 82% REi

Area Increased HX Area i

Table 3b. Results for the 32-Gallon Oil-Fired Water Heater: Water-Blown Foam

DO# Label Selected Design Option Combinations EF Total Installed

JF| Cost

Existing Baseline 0.529 936.60

0 2003 Baseline Baseline (Water-Blown) 0.529 970.53

1 I Heat Traps Baseline (Water-Blown) + Heat Traps 0.539 985.48

2 2" Insulation Baseline (Water-Blown) + Heat Traps+ 2" 0.547 1,000.98

it gI' Insulation

3 J2.5" Insulation Baseline (Water-Blown) + Heat Traps + 2.5" 0.552 1,015.49

lji~~ Insulation

4 3" Insulation Baseline (Water-Blown) + Heat Traps + 3" 0.556 1,038.39

Insulation

5 78% RE Baseline (Water-Blown) + Heat Traps + 3" 0.577 1,157.75

Insulation + 78% RE

6 interrupted Baseline (Water-Blown) + Heat Traps + 3" 0.581 1,213.75

lgnition Insulation + 78% RE + Interrupted Ignition I

7 82% RE Baseline (Water-Blown) + Heat Traps + 3" 0.610 1,424.79

Increased HX Insulation + 78% RE + Interrupted Ignition +|

Area 82% RE Increased HX Area

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Overview of Engineering Analysis

The objective of the Engineering Analysis is to determine the costs of increased energy

efficiency for residential water heaters by developing price and efficiency data for design options

and combinations of design options for each product class. This information will be used in

subsequent components of the standards rulemaking process.

The Engineering Analysis uses computer simulation models and other analytical methods

to investigate the efficiency improvements of design options and interactions when multiple design

options are used. The Engineering Analysis is based on DOE's test procedure for residential

water heaters.

Manufacturer, distributor, and installer markups, as well as sales tax, are applied to factory

costs to arrive at the purchase price of the water heater. Additional installation costs required for

certain design options are included in the consumer price for these design options.

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Technological Issues

There are impending regulatory changes outside of the DOE energy efficiency standards

process that will impact the manufacture or installation of water heaters. Some of these changes

affect the efficiency of water heaters as well.

Insulation

Most residential water heaters are insulated with polyurethane foam in the space between

the tank and the jacket. The insulation is foamed into place using polyols and isocyanurate that

react to form a polyurethane foam. A blowing agent included in the mixture is vaporized by the

heat of the reaction, creating a frothy mass that hardens quickly into closed-cell foam insulation.

Currently, water heater manufacturers use HCFC-141b, an ozone-depleting substance, as a

blowing agent. As a result of the Montreal Protocol, the U.S. Environmental Protection Agency

has scheduled the phase-out of this blowing agent by the year 2003. Water heater manufacturers

must use another blowing agent after that time.

The industry is considering a number of blowing agents including HFC-245fa, HFC356mffm, HFC-134b, cyclo-pentane, and water-blown foam. Although the above blowing agents

are currently being investigated as possible replacements to HCFC-141b by the water heater

industry, the analysis presented in this report is based on two leading candidates, HFC-245fa and

water-blown foam. Water-blown foams are created when water is introduced into the chemical

mixture and participates in the reaction leading to polyurethane releasing CO2 which provides the

blowing activity.

The analysis for the DOE water heater energy efficiency standards is based on the

properties of insulation using these two technologies and the most realistic estimates of costs and

physical parameters available for each. The average increase in conductivity resulting from

replacing HCFC-141b with HFC-245fa is 3.0%, and replacing with water is 42.0%. Since the

efficiency and energy use characteristics of water heaters with HFC-245fa and water-blown

insulation are not the same as those with HCFC-141b insulation, it was necessary to compensate

for the higher k-factors. This was accomplished by modeling the water heaters with thicker

insulation. In addition to the extra volume and cost of insulation, the amount and cost of steel

used for the water heater jacket were also increased.

Flammable Vapor Ignition

Current designs for gas-fired water heaters rely on a standing pilot to ignite the main

burner. If flammable vapors are in the air near a water heater, there is the possibility of

unintended ignition. This is a potential safety problem because water heaters are often installed in

garages and basements, where flammable liquids such as gasoline or paint thinners may be used.

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The Consumer Product Safety Commission (CPSC) is working with GRI and the water

heater industry to develop a test procedure for gas-fired water heater designs that will prevent

ignition of flammable vapors. The Department expects the American National Standards Institute

(ANSI) will adopt a test procedure for water heater resistance to igniting flammable vapors in

1999.

From discussions with the Water Heater Industry Joint Research and Development

Consortium, DOE will use a placeholder value of $35 as additional cost for designs to prevent

ignition of flammable vapors. In this analysis, the extra $35 is applied to the manufacturer cost of

all design options for gas-fired water heaters, including the 2003 baseline design. Thus, the added

cost of preventing flammable vapor ignition does not impact the cost effectiveness of any energy

efficiency design improvement although it may have an effect on choice of energy source. The

design is assumed not to require electricity at the water heater or modifications of the venting

system. No changes in efficiency are expected from flammable vapor ignition resistant water

heater designs.

Venting

Use of gas-fired water heaters with flue-loss efficiency greater than 80% with existing

venting systems that are not designed for low temperature flue gases can potentially lead to

excessive corrosion and failure of the vent system in certain climates. Recovery efficiencies (RE)

beyond 80% are associated with flue-loss efficiencies exceeding 84%, resulting in flue gas

condensation within the water heater's flue, which leads to corrosion and a shortened life. To

ensure that condensation would not occur within the flue system, only flue baffle improvements

with maximum REs of 80% were included in design options selected for further analysis. By

keeping the RE ceiling at 80%, it was assumed that blowers would not be needed. However, the

Department recognizes that potential venting problems that may occur in the 78% to 80% RE

range could require type-B vent connectors and chimney relining. Therefore, where necessary,

the costs of venting modifications to gas water heater installation costs have been included.

According to the National Fuel Gas Code (ANSI Z223.1), Type-B vent connectors are

needed for any portion of the venting systems that are exposed to cold conditions (i.e.,

unconditioned spaces).

Type-B vent connectors are required only when recovery efficiency (RE) approaches the

78% level. It was estimated that, of homes with single wall vent connectors, 25% will require

Type-B connectors. Additional modifications, which include the relining of masonry chimneys,

will be needed when an 80% threshold is exceeded. This occurs in 25% of homes with masonry

chimneys.

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Baseline Models

The baseline unit represents the most common size water heater with an efficiency equal

to the minimum allowed by the current energy efficiency standards for each fuel type. The general

characteristics of the baseline model for each of the three primary product classes (i.e., electric,

gas-fired, and oil-fired) are provided below. An in-depth description of each of the baseline

models is provided in the Technical Support Document.

Electric Water Heaters

The baseline model is a 50-gallon (190-liter) glass-lined steel tank with 1/2 in. (3.8 cm) of

polyurethane foam insulation blown with HCFC-141b. The heater has two elements, each with an

input of 4,500 W. The elements are interlocked so that only one can be energized at a time. The

baseline energy factor is 0.86, the energy efficiency standard for this size and type of water

heater.

Gas-Fired Water Heaters

The baseline model of gas-fired water heaters is a bottom-fired, 40-gallon (150-liter),

glass-lined steel tank with a 4-in. (10-cm) center flue. The input rate is 40,000 Btu/hr (11,700

W), with a pilot rated at 450 Btu/hr (120 W). The tank is insulated with a nominal 1 in. (2.5 cm)

of polyurethane foam blown with HCFC-141b. The current energy efficiency standard for this

size and type of water heater is 0.54 EF. It has a recovery efficiency of 76%.

Oil-Fired Water Heaters

The baseline oil-fired water heater is a center-flue design. It has a rated volume of 32

gallons (120 liters), and is insulated with 1 in. (2.5 cm) of polyurethane foam blown with HCFC141b. The input rate is 0.65 gallons per hour (2.5 liters/hr) of oil or 90,000 Btu/hr (26,000 W). It

has an EF of 0.53, the current energy efficiency standard. The first hour rating is 105 gallons

(398 liters), and the RE is 75%. The burner motor, which powers both the blower and oil pump,

is rated at 1/8 hp (282 W). The baseline model uses an intermittent ignition system.

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Efficiency Calculations

The design options for each of the three classes of water heaters were modeled either with

computer simulation programs or an energy calculation method. The output from the computer

simulations was used to determine the energy efficiency characteristics of the water heater (e.g.,

the EF, RE, and standby heat loss coefficient (UA)), based on the DOE test procedure.

WATSIM Model for Electric Water Heaters

WATSIM is a detailed electric water heating simulation program developed by the

Electric Power Research Institute. WATSIM contains two simulation algorithms; one for the

detailed simulation of water heater tanks and the other for controlling water draw profiles for use

with the tank model. Since the simulation analysis must be performed according to the

requirements of the DOE test procedure, the water draw profile is specified to the 64.3 gallon

(243.4 liter) draw pattern in the test procedure. WATSIM does not include the EF, RE, and UA

calculations from the DOE test procedure. However, it does provide detailed temperature

profiles of the water inside the tank of the water heater during the simulation run. These

temperature readings are used to determine the EF and other parameters of the water heater using

the test procedure calculations. A spreadsheet calculates the efficiency characteristics according

to the DOE test procedure from the results from WATSIM.

TANK Model for Gas-Fired Water Heaters

TANK is a detailed gas-fired water heater simulation program developed by Battelle for

the Gas Research Institute. TANK calculates energy flows throughout the water heater including

heat gained or lost by the water, flue heat losses, jacket heat losses, fittings heat losses, and

combustion chamber heat losses. TANK calculates the EF, RE, and UA from the DOE test

procedure.

WHAM Energy Calculation for Oil-Fired Water Heaters

A simplified water heater analysis model (WHAM) was used for the engineering analysis

for oil-fired water heaters. WHAM is based on the DOE 24-hour test procedure. The model is

an equation to calculate average daily energy consumption from the RE, UA, and rated input

(Pon).

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Overall Analytic Approach

In this report, a distinction has been made between baseline models containing current

technologies and future baseline models which are expected to meet new mandated regulations.

The former are referred to as "existing" baseline models and the latter as "2003" baseline models.

An important energy-saving feature of existing water heater technology is the insulation based on

HCFC-141b as a blowing agent. The future regulatory phase-out of HCFCs by the year 2003

necessitate a replacement for HCFC-141b. The two strongest candidates for replacements are the

HFC-245fa blowing agent and water-blown foam insulation. Consequently, the engineering

analysis is performed on two parallel paths, one for HFC-245fa and one for water-blown foam

insulation. An ANSI test procedure covering the prevention of flammable vapor ignition,

expected in 1999, will require a change in the basic design of gas-fired water heaters. The

engineering analysis also addresses the cost of this change; we have assumed there is no effect on

water heater energy factor.

Additionally, for the purposes of the analysis, a representative, or "typical" tank size (rated

volumes of 50-gal for electric, 40-gal for gas-fired, and 32-gal for oil-fired) has been chosen from

all the standard sizes for each fuel type.

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Electric Water Heaters

Modeling Design Options

Four design options are being considered to improve the efficiency of electric water

heaters. Each design option is briefly discussed below.

2003 Baseline Models. As explained above in the Technological Issues section, HFC245fa blowing agent has a 3.0% higher conductivity than HCFC-141b and water-blown insulation

has a 42.0% higher conductivity than HCFC-141b. The thickness of the HFC-245fa foam

insulation surrounding the tank was increased to 1.55 in. (3.94 cm) to compensate for the

increased conductivity of the insulation. The thickness of the water-blown foam insulation

surrounding the tank was increased to 2.12 in. (3.38 cm) to compensate for the increased

conductivity of the insulation.

Heat Traps. The heat conducted and convected through the water pipes accounts for a

significant portion of the total standby loss in a typical residential-size water heater. A heat trap is

a device that keeps the buoyant hot water from circulating through a piping distribution system

because of natural convection. When there is no draw of hot water, this prevents water in the hot

water outlet line from settling back into the tank as it cools off; and prevents hot water in the tank

from circulating back out into the cold water inlet line. By containing the hot water in the storage

tank, the heat trap minimizes standby loss. Heat traps can be integral to the tank design or

independently attached to the inlet and outlet pipes during installation.

Increased Jacket Insulation. Most water heaters on the market today have at least 1-in.

(2.5 cm) thick jacket (sides and top) foam insulation, while some manufacturers provide 2- to 3-

in. (5.1 to 7.6 cm) thick insulation as well. Although increasing the insulation thickness reduces

the standby loss, the increase in the overall diameter of the water heater may pose some

installation problems. There will also be an increase in shipping costs because fewer heaters will

fit in a truck. Because of these potential installation problems, maximum insulation thicknesses

were limited to 3 in. (7.6 cm) for this analysis. In the HFC-245fa 2003 baseline model, we

simulated the performance of an electric water heater insulated with 2-, 21⁄2/, and 3-in. (5.1 cm, 6.4

cm, and 7.6 cm) foam insulation. In the water-blown 2003 baseline model, we used 2/2 and 3-in.

(6.4 cm and 7.6 cm). In particular, DOE would like comments and data on how the

manufacturers might deal with the increased insulation thicknesses in small places.

Insulating the Tank Bottom. The bottom of the tank of an electric water heater can be

insulated to reduce the standby heat losses. Currently, manufacturers may place fiberglass

insulation in the space beneath the concave bottom of the water heater tank. WATSIM models the

heat transfer through the bottom of the tank by two separate parallel heat transfer paths -

"bottom" and "support ring". The "bottom" represents the area of the concave dome and the

"support ring" represents the perimeter, which is a continuation of the tank wall below the bottom

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EE-RM-97-900 COMMENT 77F
of the tank. The "bottom insulation" portion of this assembly fills the domed space underneath

the tank. Putting insulation under the support ring breaks a major heat transfer path to the jacket.

The bottom insulation conductivity reflects the different characteristics of HFC-245fa and waterblown insulation.

Plastic Tank. This design is a thin steel shell with an internal plastic tank. To model this

tank with WATSIM, the tank wall thickness and conductivity were modeled as plastic instead of

steel. The conductivity of the plastic/steel composition is virtually identical to plastic. The

support ring material was changed from steel to foam insulation.

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Manufacturer Costs

Manufacturer cost estimates for a 50-gallon (190-liter) electric water heater were

disaggregated into variable (material, labor, transportation, overhead) and fixed (capital, product

design) costs. Design option variable costs and fixed costs were provided on a per unit basis and

expressed as an incremental increase over the existing baseline design. The breakdown of the

manufacturing costs for all design options are given in Tables 5a and 5b.

Existing Baseline Model. Cost estimates for the existing baseline model-a water heater

with 1 /2 in. (3.8 cm) of foamed jacket insulation using HCFC-141b as a blowing agent-were

supplied by GAMA. The material costs for a particular thickness of insulation were determined

by either subtracting from or adding to GAMA's baseline costs. The material costs of HCFC141b foam insulation and sheet metal were estimated by an independent consultant.

2003 Baseline Model. To convert the baseline manufacturer costs for foam insulation

blown with HCFC-141b to HFC-245fa or water-blown insulation, the amount and cost of

materials are used. Material costs associated with a particular level of HFC-245fa or water-blown

insulation were determined by adding to the baseline costs associated with a comparable level of

HCFC-141b foam insulation. Table 4 shows the calculation of the total foam cost for HFC-141b,

HFC-245fa, and water-blown insulation, based on the component cost estimates.

Table 4 Foam Components Cost Estimate

Foam Components Fraction Component Total Cost Total Cost Total Cost

of Foam Cost (141b) (245fa) (Water-Blown)

% $/lb $/lb $/lb $/lb

HCFC-141b 13.00% $1.50 $0.20

HFC-245fa 13.00% $4.00' - $0.52

Water-Blown 13.00% $1.502 - - $0.20

isocyanurate 51.00% $0.75 $0.38 $0.38 $0.38

polyols 31.00% $0.65 $0.20 $0.20 $0.20

catalysts, refractants, etc. 5.00% $4.50 $0.23 $0.23 $0.23

Total 100.00% _ $1.00 $1.32 $1.00

'Source: Allied Signal 2

Source: Consultant, manufacturers

Heat Traps. Manufacturer costs for metal and plastic heat traps were provided by

GAMA. The costs reflect the addition of heat traps to both the supply and draw lines.

Increased Jacket Insulation. GAMA provided variable cost and fixed cost data for

jacket insulation increases from a baseline level of l'/ 2 in. (3.81 cm) to a thickness of 2.0 in. (5.1

cm) only. To generate variable cost and fixed cost data for other thicknesses of insulation, the

data provided by a consultant was used to calculate ratios of variable and fixed cost for 2 in., 2/2

in., and 3 in. insulation compared to the baseline thickness. GAMA's costs for upgrading to 2.0

in. (5.1 cm) insulation, modified for both HFC-245fa and water-blown foam, were multiplied by

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EE-RM-97-900 COMMENT 77F
those ratios to approximate the variable and fixed costs for 2/2 in. (6.4 cm) and 3 in. (7.6 cm) of

insulation. The overhead portion of the variable cost for models with 3 in. (7.6 cm) jacket

insulation include 25% additional shipping cost due to reduced transport capacity.

Insulating the Tank Bottom. Manufacturer costs for insulating the tank bottom were

based on data from consultants.

Plastic Tank. Manufacturer costs for a plastic tank electric water heater design were

based on data provided by a consultant. The plastic tank design option fixed costs were provided

as the "lump sum" amount required to convert the baseline production to the new design. The

per unit cost was calculated by amortizing it over a five-year period and dividing it by the

assumed baseline model production volume of 40,000 units per year.

Design Option Retail Prices

For purposes of this analysis, the retail price is the cost to the consumer of only the water

heater. The cost of installing the water heater is not considered part of the retail price and is

discussed later.

The retail price for the existing baseline 50-gallon (190-liter) electric water heater (with

HCFC-141b foam insulation) was the median price from a large number of retailers, wholesalers,

plumbing contractors and utilities. This data can be found in the Water Heater Price Database

(http://www.eren.doe.gov/buildings/codes_standards/applbrf/waterheater.htm). This database was

developed from information gathered from over 130 contacts from all regions of the U.S. It

contains information on over 1100 models, including retail prices, fees (installation, delivery, etc.),

and warranties. Detailed product specification information (e.g., certified EF, 1st hour ratings)

from manufacturer's product literature and the GAMA and CEC directories were also included.

The price of a water heater depends on the length of the manufacturer's warranty. The

baseline models chosen for this analysis have up to 6-year warranties. The 5- to 6-year warranty

is the shortest warranty period offered by water heater manufacturers (although a 1-year warranty

is offered in special cases) and is typically reserved for those models which are produced in large

volumes (i.e., baseline models). A longer warranty, in addition to raising the price, may indicate

the presence of features not normally found in baseline models. The median retail price of

electric water heaters is $181.58.

Installation and Maintenance Costs

The installation cost is the cost to install the water heater and is not considered part of the

retail price. The cost of installation covers all labor and materials associated with replacing an

existing water heater. Delivery, removal, and permit fees are also included.

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Installation cost data for the 50-gallon (190-liter) baseline electric water heater came from

the Water Heater Price Database. The median installation cost is $155.00. None of the design

options considered for this analysis, with the exception of 3 in. insulation, increased the

installation cost. Design options that include 3 in. insulation require an additional cost to install

the wider units in narrow spaces (e.g., disassemble and reassemble doorjambs).

There is virtually no maintenance of residential electric water heaters. Thus, maintenance

costs were not included for the baseline model or for the different design options.

Cost-Efficiency Data

The results of the design option analysis for 50-gallon (190-liter) electric water heaters are

presented for the two 2003 baselines. Table 5a presents results using HFC-245fa-based blowing

agent and Table 5b results for water-blown insulation. Included in the cost-efficiency tables are

the following: disaggregated manufacturer costs, retail prices, installation costs, energy factor,

and energy use.

The existing baseline design with HCFC-141b foam insulation is also presented in the two

tables to show the manufacturer cost and retail price differences. Energy costs were from national

average energy prices for the year 2003 from DOE/EIA's Annual Energy Outlook 1999.

The results show that, for HFC-245fa-based blowing agent, the highest EF attainable is

0.918 which can be achieved through the use of plastic heat traps, 3 in. (7.6 cm) jacket insulation,

insulated tank bottom, and a plastic tank. This design saves 233 kWh/yr in electricity. For waterblown insulation, the highest EF attainable is 0.901, which can be achieved through the use of

plastic heat traps, 3 in. (7.6 cm) jacket insulation, insulated tank bottom, and a plastic tank.

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Table 5a. Cost-Efficiency Table for 50-gallon (190-liter) Electric Water Heaters - HFC-245a 2003 Baseline

Incremental Variable Costs Total Mfg to Energy Use Total Cost

Design Total Total Mfg Retail Retail Install. Maint. Energy Recovery UA Daily Yearly Installed Operating

No. Design Options Mat'l Labor Overhd Var. Fixed Cost Markup Price Ct Cot Factor Efficiency kWh/day kWh/yr $/yr $/yr

0 Existing Baseline S62.16 $10.57 $49.00 $121.73 $0.00 $121.73 1.57 $190.66 $155.00 $0.00 0.8600 98.00% 3.64 13.58 4958 345.66 390.72

Oa 2003 Baseline 64.30 $0.00 $0.00 $123.87 $0.00 $123.87 1.57 $194.01 $155.00 $0.00 0.8601 98.00% 3.64 13.58 4958 349.01 390.70

1 Heat Traps $2.59 $0.19 $0.82 $3.60 $0.39 $127.86 1.57 $200.26 $155.00 $0.00 0.8780 98.00% 3.06 13.34 4868 355.26 383.64

2 Insulated Tank $4.87 $0.31 $1.18 $6.36 $1.54 $131.77 1.57 $206.39 $155.00 $0.00 0.8822 98.00% 2.92 13.28 4846 361.39 381.94

Bottom

3 2" Insulation $13.54 $0.81 $4.88 $19.23 $6.15 $149.25 1.57 $233.77 $155.00 $0.00 0.8967 98.00% 2.46 13.08 4775 388.77 376.30

4 2.5" Insulation $19.36 $1.31 $8.58 $29.25 $8.46 $161.58 1.57 $253.07 $155.00 $0.00 0.9077 98.00% 2.13 12.94 4725 408.07 372.33

5 Plastic Tank $22.25 $1.99 $11.42 $35.66 $25.31 $184.84 1.57 $289.50 $155.00 $0.00 0.9099 98.00% 2.05 12.92 4717 444.50 371.73

6 3" Insulation $29.44 $2.49 $16.20 $48.13 $27.61 $199.61 1.57 $312.64 $198.19 $0.00 0.9180 98.00% 1.80 12.82 4678 510.83 368.70

Table 5b. Cost-Efficiency Table for 50-gallon (190-liter) Electric Water Heaters - Water-Blown 2003 Baseline

Incremental Variable Costs Total Mfg to Energy Use Total Cost

Design Total Total Mfg Retail Retail Install. Maint. Energy Recovery UA Daily Yearly Installed Operating

No. Design Options Mat'l Labor Overhd Var. Fixed Cost Markup Price Cost Cost Factor Efficiency kWh/day kWh/yr S/yr $/yr

0 Existing Baseline $62.16 $10.57 $49.00 $121.73 $0.00 $121.73 1.57 $190.66 $155.00 $0.00 0.8600 98.00% 3.64 13.58 4958 345.66 390.72

Oa 2003 Baseline $71.97 $0.00 $0.00 $131.54 $0.00 $131.54 1.57 $206.02 $155.00 $0.00 0.8601 98.00% 3.64 13.58 4957 361.02 390.68

1 HeatTraps $2.59 $0.19 $0.82 $3.60 $0.39 $135.53 1.57 $212.27 $155.00 $0.00 0.8780 98.00% 3.06 13.34 4868 367.27 383.64

2 Insulated Tank $4.87 $0.31 $1.18 $6.36 $1.54 $139.44 1.57 $218.40 $155.00 $0.00 0.8816 98.00% 2.94 13.29 4849 373.40 382.17

Bottom

3 2.5" Insulation $8.44 $0.69 $3.99 $13.12 $8.46 $153.12 1.57 $239.82 $155.00 $0.00 0.8895 98.00% 2.67 13.17 4809 394.82 378.98

4 3" Insulation $14.85 $1.19 $8.33 $24.37 $10.76 $166.67 1.57 $261.04 $198.19 $0.00 0.8981 98.00% 2.42 13.06 4769 459.23 375.81

5 PlasticTank $17.74 $1.87 $11.17 $30.78 $27.61 $189.93 1.57 $297.47 $198.19 $0.00 0.9012 98.00% 2.31 13.04 4760 495.66 375.13

Notes:

1) All costs and prices in 1998$.

2) Incremental variable and fixed costs are per unit costs and are relative to the 2003 baseline.

3) For the baseline model with HCFC-141b, the total variable costs are provided.

4) Retail prices are calculated based on the manufacturer cost-to-retail price markup of 1.56624 .

16

EE-RM-97-900 COMMENT 77F
Gas-Fired Water Heaters

Modeling Design Options

The following seven design options are being considered to improve the efficiency of gasfired water heaters:

* heat traps

* increased jacket insulation

* improved flue baffle

* electronic ignition

* flue damper

* side-arm heater

* plastic tank

Each design option is briefly discussed below along with a description of how it was

modeled with TANK. The discussion begins with the analysis of the baseline models using

polyurethane insulation blown with HFC-245fa and water-blown insulation. As noted above,

these baseline models are referred to as the two "2003" baseline models.

2003 Baseline Model. As discussed above in the section on the electric 2003 baseline

model, HFC-245fa blowing agent has a 3.0% higher conductivity than HCFC-141b and waterblown insulation has a 42.0% higher conductivity than HCFC-141b. To compensate for the

increased conductivity, the thickness of the HFC-245fa-based insulation and the thickness of the

water-blown insulation were increased accordingly.

Heat Traps. Metal and plastic heat traps were analyzed for gas-fired water heaters.

Both types of heat traps prevent the losses associated with the circulation of hot water into the

plumbing.

Increased Jacket Insulation. Most water heaters on the market today have at least 1-in.

(2.5 cm) thick jacket (sides and top) foam insulation, while some manufacturers provide 2- to 3-

in. (5.1 to 7.6 cm) thick insulation as well. Although increasing the insulation thickness reduces

the standby loss, the increase in the overall diameter of the water heater may pose some

installation problems. There will also be an increase in shipping costs because fewer heaters will

fit in a truck. Because of these potential installation problems, maximum insulation thicknesses

were limited to 3 in. (7.6 cm) for this analysis. In both 2003 baseline models, we simulated the

performance of an gas-fired water heater insulated with 2-, 2/2, and 3-in. (5.1 cm, 6.4 cm, and 7.6

cm) foam insulation. In particular, DOE would like comments and data on how the manufacturers

might deal with the increased insulation thicknesses in small spaces.

17

EE-RM-97-900 COMMENT 77F
Improved Flue Baffle. The standard flue baffle is a twisted strip of metal inserted into

the flue. It 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. An improved

flue baffle can increase the recovery efficiency (RE) from 76% to about 78-85%, depending on

the specific geometry. (See discussion of impacts of RE levels under Technological Issues

section). In this analysis, two levels of RE were considered: 78% and 80%. These RE levels are

achieved through the use of two types of improved flue baffle designs.

Electronic Ignition. This design option is an intermittent ignition device (IID) that lights

the main burner directly by generating a spark. It operates only at the beginning of each on-cycle

in contrast to the standing pilot ignition system which is constantly on.

Flue Damper (Electromechanical). Gas-fired water heaters are equipped with a draft

hood connecting the flue to a vent pipe or chimney. During off-cycle, the water heater loses heat

by natural convection up the flue. An electromechanical flue damper can be installed in the vent

pipe to minimize the off-cycle heat losses. The dampers open before combustion starts and close

immediately after combustion stops.

This design option always has an electronic ignition system associated with it. Since

electricity is required for the operation of the flue damper, it was assumed that the standing pilot

would be converted to an electronic ignition system in order to take advantage of the electrical

power that exists at the water heater.

Side-Arm Heater. The side-arm heater design avoids large flue losses through the

removal of the flue from the center of the tank. Water is withdrawn from the bottom of the tank

and heated over a burner in a small, separate heat exchanger. Water is returned to the top of the

tank. A small circulation pump moves water through the heat exchanger when the burner is on.

Plastic Tank. The lower heat conductivity of a plastic tank reduces the amount of heat

conducted through the tank wall to the insulation. Because plastic cannot withstand high

temperatures, it was only considered in conjunction with the side-arm water heater design.

18

EE-RM-97-900 COMMENT 77F
Manufacturer Costs

All manufacturing cost estimates for a 40-gallon (150-liter) gas-fired water heater were

disaggregated into variable (material, labor, overhead, transportation) and fixed (capital, product

design) costs. Design option variable and fixed costs were provided on a per unit basis and

expressed as an incremental increase over the existing baseline design. The breakdown of the

manufacturing costs for all design options are given in Tables 6a and 7a.

Existing Baseline Model. Cost estimates for the existing baseline model-a water heater

with 1 in. (2.5 cm) foamed jacket insulation using HCFC-141b as a blowing agent-were supplied

by GAMA. The material costs for a particular thickness of insulation were determined by adding

to or subtracting from GAMA's baseline costs. The material costs of HCFC-141b foam

insulation and sheet metal were estimated by an independent consultant.

2003 Baseline Model. To convert the baseline manufacturer costs for foam insulation

blown with HCFC-141b to HFC-245fa or water-blown insulation, the amount and cost of

materials are taken into account. Material costs associated with a particular level of HFC-245fa

or water-blown insulation were determined by adding to the baseline costs associated with a

comparable level of HCFC-141b foam insulation. The material costs of HFC-245fa foam

insulation and water-blown insulation were based on estimates by Allied Signal, see Table 4.

2003 Baseline Model with Flammable Vapor Ignition-Resistant Design. To prevent

the ignition of flammable vapors, gas-fired water heater manufacturers will need to redesign their

product. Based on discussions with the Water Heater Industry Joint Research and Development

Consortium, DOE added $35 to the total manufacturing cost ($15 variable costs and $20 fixed

cost) for product redesign.

Heat Traps. Manufacturer costs for metal and plastic heat traps were provided by

GAMA. The costs reflect the addition of heat traps to both the supply and draw lines.

Increased Jacket Insulation. GAMA provided variable and fixed cost data for jacket

insulation increases from a baseline level of 1.0 in. (2.54 cm) to a thickness of 2.0 in. (5.1 cm)

only. To generate variable cost and fixed cost data for other thicknesses of insulation, the data

provided by a consultant was used to calculate ratios of variable and fixed cost for 2 in., 2'/2 in.,

and 3 in. insulation compared to the baseline thickness. GAMA's costs for upgrading to 2.0 in.

(5.1 cm) insulation, modified for both HFC-245fa and water-blown foam, were multiplied by

those ratios to approximate the variable and fixed costs for 2/2 in. (6.4 cm) and 3 in. (7.6 cm) of

insulation. Note that the overhead portion of the variable cost for models with 3 in. (7.6 cm)

jacket insulation includes 25% additional shipping cost due to reduced transport capacity.

Improved Flue Baffle. Manufacturer costs for the improved flue baffle design were

based on data from GAMA. The costs were based on two flue baffle configurations, the first of

which increased the RE to 78%, and the second to 80%.

19

EE-RM-97-900 COMMENT 77F
Electronic Ignition. Manufacturer costs for electronic ignition were based on the

replacement of a standing pilot with an intermittent pilot ignition device. The cost of the

electronic ignition system was based on data from GAMA.

Flue Damper (Electromechanical). Manufacturer costs for including an

electromechanical flue damper with a gas-fired water heater were based on data from GAMA.

Because electromechanical flue dampers were analyzed only in conjunction with electronic

ignition systems, the incremental manufacturer costs of both design options are combined.

Because electricity is required for the operation of the flue damper, we assumed that the standing

pilot would be converted to an electronic ignition system in order to take advantage of the

electrical power at the water heater.

Side-Arm Heater and Plastic Tank. Manufacturer costs for the side-arm heater for a

gas-fired water heater design were based on data from a consultant. We included the costs for six

types of side-arm heater designs; 76%, 78 %, and 80% RE designs that use either metal or plastic

tank. For this analysis it was assumed that the cost difference between the three RE designs was

equal to the cost of the improved flue baffle design. Side-arm heaters were analyzed only in

conjunction with electronic ignition systems. Therefore, the incremental manufacturer cost of the

ignition system is also included. As discussed previously, plastic tanks cannot be considered as a

stand-alone design option for standard center-flue gas-fired water heaters due to the high

temperature of combustion. Thus, plastic tanks can only be considered with indirect heating

designs, such as a side-arm heater.

Design Option Retail Prices

The retail price is the cost to the consumer of only the water heater. The retail price for

an existing baseline 40-gallon (150-liter) gas-fired water heater (with HCFC-141b foam

insulation) was the median price from a large number of retailers, wholesalers, plumbing

contractors and utilities. This data can be found in the Water Heater Price Database (see

http://www.eren.doe.gov/buildings/codes_standards/applbrf/waterheater.htm).

The price of a water heater depends on the length of the manufacturer's warranty. The

baseline models chosen for this analysis have up to 6-year warranties. The 5- to 6-year warranty is

the shortest warranty period offered by water heater manufacturers (although 1-year warranties

have been offered in special cases) and is typically reserved for those models which are produced

in large quantities (i.e., baseline models). A longer warranty, in addition to raising the price, may

also indicate the presence of features not normally found in baseline models. The median retail

price for a baseline 40-gallon (150-liter) gas-fired water heater is $163 (without taxes).

20

EE-RM-97-900 COMMENT 77F
Installation and Maintenance Costs

The installation cost is the cost to the consumer of installing the water heater and is not

considered part of the retail price. The cost of installation covers all labor and material costs

associated with replacing an existing water heater. Delivery, removal, and permit fees are also

included. Installation cost for the 40-gallon (150-liter) baseline gas-fired water heater came from

the Water Heater Price Database. The median installation cost is $159.00.

Four design options were assumed to increase the cost of installing a gas-fired water

heater: the improved flue baffle, electronic ignition, the electromechanical flue damper, and the

side-arm heater. For several designs, the reported flue efficiency is close to 80%. For these

designs, it is assumed a Type-B vent connector or chimney relining may be required to ensure that

condensation does not occur in the vent system.

The three remaining design options (electronic ignition, electromechanical flue damper,

and side-arm heater) all require electricity to operate. The installation cost was increased in order

to include the cost of installing an electric circuit for these design options. This installation cost

estimate was also based on data from GRI.

The electromechanical flue damper was the only design option that was assumed to have a

maintenance cost. The maintenance cost of the flue damper was based on a prior DOE analysis.

Cost-Efficiency Data

The results of the design option analysis for 40-gallon (150-liter) gas-fired water heaters

are presented in Tables 6a, 6b, 7a, and 7b. Included in the cost and efficiency tables are

disaggregated manufacturer costs, retail prices, installation costs, maintenance costs, energyefficiency and energy use data.

The existing baseline design with HCFC-141b foam insulation is presented in Tables 6a

through 7b to show the manufacturer cost and retail price differences. Also presented are the

costs for incorporating a design to resist igniting flammable vapors. Energy costs were from

national average energy prices for 2003 from the Annual Energy Outlook 1999.

The costs for all the design option combinations are shown in Tables 6a and 7a and the

efficiency data is shown in Tables 6b and 7b. The results show that, for the HFC-245fa-based

blowing agent, the highest EF attainable is 0.7149, which can be achieved through the use of

plastic heat traps, 80% RE, 3 in. (7.6 cm) insulation, side-arm heater, electronic ignition, and

plastic tank. This design produces gas energy savings of 7.79 million Btu/year. For water-blown

insulation, the same design has an EF of 0.7062 and a gas energy savings of 7.53 million Btu/year.

21

EE-RM-97-900 COMMENT 77F
Table 6a. 245fa Insulation 40-gal (150-liter) Gas-Fired Water Heater: Cost Data

Incremental Costs Total Mfg to

Design Total Total Mfg Retail Retail Install. Maint.

No. Design Options Material Labor Overhead Variable Fixed Cost Markup Price Cost Cost

0 Existing Baseline $75.02 $10.74 $48.02 $133.78 $0.00 $133.78 1.28 $171.15 $159.00 $0.00

Oa Analytic Baseline $0.00 $.0 0.00 $0.00 $15.00 $20.00 $169.89 1.28 $217.35 $159.00 $0.00

I HeatTraps $2.75 $0.16 $0.19 $3.10 $0.20 $173.19 1.28 $221.57 $159.00 $0.00

2 78%RE $3.72 $1.41 $1.57 $6.70 $3.04 $179.63 1.28 $229.81 $165.73 $0.00

3 2" Insulation $13.33 $2.00 $6.53 $21.86 $4.47 $196.22 1.28 $251.03 $165.73 $0.00

4 2.5" Insulation $18.27 $2.59 $11.49 $32.35 $5.48 $207.72 1.28 $265.74 $165.73 $0.00

5 80%RE $18.27 $2.59 $11.49 $32.35 $5.48 $207.72 1.28 $265.74 $202.51 $0.00

6 Side-Arm $86.55 $6.46 $38.18 $131.19 $11.77 $312.85 1.28 $400.24 $236.64 $0.00

7 Plastic Tank $91.80 $7.26 $42.38 $141.44 $15.37 $326.70 1.28 $417.96 $236.64 $0.00

8 3" Insulation $97.86 $7.85 $49.26 $154.97 $16.38 $341.24 1.28 $436.56 $279.83 $0.00

Notes:

1) All costs and prices in 1998$.

2) Incremental variable and fixed costs are per unit costs and are relative to the 2003 baseline.

3) For the baseline model with HCFC-141b, the total variable costs are provided.

4) Retail prices are calculated based on the manufacturer cost-to-retail price markup of 1.27934 .

Table 6b. 245fa Insulation 40-gal (150-liter) Gas-Fired Water Heater: Efficiency Data

Fuel Energy Use Electrical Energy Use Total Cost

Design Energy Recovery UA Thermal Daily Yearly Daily Yearly Installed Operating

No. Design Options Factor Efficiency Efficiency Btu/day MBtu/year kWh/da kWh/year $/yr $/yr

0 Existing Baseline 0.5436 75.71% 13.99 78.10% 78558 28.67 0.00 0.00 330.15 184.04

Oa Analytic Baseline 0.5434 75.72% 14.02 78.08% 78579 28.68 0.00 0.00 376.35 184.09

1 HeatTraps 0.5523 75.61% 13.16 78.08% 77843 28.41 0.00 0.00 380.57 182.36

2 78%RE 0.5649 77.17% 12.79 79.80% 75644 27.61 0.00 0.00 395.54 177.21

3 2" Insulation 0.5921 77.99% 10.91 79.75% 73297 26.75 0.00 0.00 416.76 171.72

4 2.5" Insulation 0.5986 78.18% 10.53 79.74% 72787 26.57 0.00 0.00 431.47 170.52

5 80% RE 0.6146 80.22% 10.21 81.87% 70320 25.67 0.00 0.00 468.25 164.74

6 Side-Arm 0.6999 80.00% 4.79 78.00% 58438 21.33 0.08 29.32 636.89 139.21

7 Plastic Tank 0.7092 80.00% 4.29 80.00% 57671 21.05 0.08 29.32 654.60 137.42

8 3" Insulation 0.7149 80.00% 3.99 80.00% 57210 20.88 0.08 29.32 716.40 136.34

22

EE-RM-97-900 COMMENT 77F
Table 7a. Water-Blown Insulation 40-gal (150-liter) Gas-Fired Water Heater: Cost Data

Incremental Costs Total Mfg to

Design Total Total Mfg Retail Retail Install. Maint.

No. Design Options Material Labor Overhead Variable Fixed Cost Markup Price Cost Cost

0 Existing Baseline $75.02 $10.74 $48.02 $133.78 $0.00 $133.78 1.28 $171.15 $159.00 $0.00

Oa Analytic Baseline $0.00 $0.00 $0.00 $15.00 $20.00 $172.98 1.28 $221.30 $159.00 $0.00

1 HeatTraps $2.75 $0.16 $0.19 $3.10 $0.20 $176.28 1.28 $225.53 $159.00 $0.00

2 78% RE $3.72 $1.41 $1.57 $6.70 $3.04 $182.72 1.28 $233.77 $165.73 $0.00

3 2" Insulation $10.18 $1.82 $4.99 $16.99 $4.47 $194.44 1.28 $248.76 $165.73 $0.00

4 2.5" Insulation $14.48 $2.59 $11.49 $28.56 $5.48 $207.02 1.28 $264.85 $165.73 $0.00

5 80%RE $14.48 $2.59 $11.49 $28.56 $5.48 $207.02 1.28 $264.85 $202.51 $0.00

6 Side-Arm $82.76 $6.46 $38.18 $127.40 $11.77 $312.15 1.28 $399.35 $236.64 $0.00

7 Plastic Tank $88.01 $7.26 $42.38 $137.65 $15.37 $326.00 1.28 $417.07 $236.64 $0.00

8 3" Insulation $93.37 $7.85 $49.26 $150.48 $16.38 $339.84 1.28 $434.78 $279.83 $0.00

Notes:

1) All costs and prices in 1998$.

2) Incremental variable and fixed costs are per unit costs and are relative to the 2003 baseline.

3) For the baseline model with HCFC-141b, the total variable costs are provided.

4) Retail prices are calculated based on the manufacturer cost-to-retail price markup of 1.27934 .

Table 7b. Water-Blown Insulation 40-gal (150-liter) Gas-Fired Water Heater: Efficiency Data

Fuel Energy Use Electrical Energy Use Total Cost

Design Energy Recovery UA Thermal Daily Yearly Daily Yearly Installed Operating

No. Design Options Factor Efficiency Efficiency Btu/day MBtu/year kWh/day kWh/year $/yr $/yr

0 Existing Baseline 0.5436 75.71% 13.99 78.06% 78558 28.67 0.00 0.00 330.15 184.04

Oa Analytic Baseline 0.5436 75.91% 14.10 78.06% 78522 28.66 0.00 0.00 380.30 183.96

I HeatTraps 0.5523 75.80% 13.24 78.08% 77756 28.38 0.00 0.00 384.53 182.16

2 78% RE 0.5651 77.40% 12.86 79.77% 75625 27.60 0.00 0.00 399.50 177.17

3 2" Insulation 0.5829 77.89% 11.59 79.75% 74045 27.03 0.00 0.00 414.49 173.47

4 2.5" Insulation 0.5906 78.09% 11.08 79.74% 73384 26.79 0.00 0.00 430.58 171.92

5 80%RE 0.6066 80.13% 10.75 81.87% 70926 25.89 0.00 0.00 467.36 166.16

6 Side-Arm 0.6907 80.00% 5.30 - 59220 21.62 0.08 29.32 635.99 141.05

7 Plastic Tank 0.6997 80.00% 4.80 -58453 21.34 0.08 29.32 653.71 139.25

8 3" Insulation 0.7062 80.00% 4.45 57916 21.14 0.08 29.32 714.61 137.99

23

EE-RM-97-900 COMMENT 77F
Oil-Fired Water Heaters

Modeling Design Options

The following five design options are being considered to improve the efficiency of oil-fired

water heaters:

* heat traps

* increased jacket insulation

* improved flue baffle

* increased heat exchange surface area

* interrupted ignition

Each design option is briefly discussed below along with a description of how it was modeled.

Since there is no oil-fired water heater simulation model, the oil-fired water heater is analyzed using

spreadsheet-based calculations. The discussion begins with the analysis of the baseline models using

polyurethane insulation blown with HFC-245fa and water-blown insulation. As noted previously, these

baseline models are referred to as the two "2003" baseline models.

2003 Baseline Model. As discussed above in the sections on the electric and gas 2003 baseline

models, HFC-245fa blowing agent has a 3.0% higher conductivity than HCFC-141b and water-blown

insulation has a 42.0% higher conductivity than HCFC-141b. To compensate for the increased

conductivity, the thicknesses of the HFC-245fa-based insulation and the water-blown insulation were

increased in the 2003 baseline models to provide the same EF performance required by the present

standard.

Heat Traps. The impact of both metal and plastic heat traps were analyzed for oil-fired water

heaters. Both types of heat traps prevent the losses associated with the circulation of hot water into the

plumbing.

Increased Jacket Insulation. Most oil-fired water heaters on the market today provide at least

1-in. (2.5 cm) thick jacket (sides and top) insulation. The analysis assumes that polyurethane foam

insulation is used on the baseline performance model. Although increasing the insulation thickness

reduces the standby loss, it does affect manufacturing costs, shipping costs, and may present installation

problems. Because of these potential problems, the maximum insulation thicknesses were limited to 3

in. (7.6 cm) for this analysis. This appears to be the maximum thickness of insulation used by any

manufacturer of present residential electric, gas, or oil water heater models. For HFC-245fa foam

insulation, we simulated the performance of an oil-fired water heater insulated with 2, 2/2, and 3-in. (5.1

cm, 6.4 cm, and 7.6 cm) HFC-245fa-based insulation in addition to the 2003 baseline model. Similarly,

for water-blown foam insulation, we simulated the performance of an oil-fired water heater insulated

with 2, 21/2, and 3-in. (5.1 cm, 6.4 cm, and 7.6 cm) foam insulation in addition to the 2003 baseline

model. In this regard, DOE would like comments and data on how the manufacturers might deal with

24

EE-RM-97-900 COMMENT 77F
the increased insulation thicknesses in small spaces.

Improved Flue Baffle. The standard flue baffle is a twisted strip of metal inserted into the flue.

It 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. For present oil-fired water

heater designs, it is believed that an improved flue baffle can increase the recovery efficiency (RE) of a

baseline design from 76% to about 78% at relatively low cost. Efficiency improvements beyond this

are more difficult to achieve with a flue baffle due to the high heat rate of oil-fired water heaters and the

fast transit times for the flue gases. In this analysis, improvements to the flue baffle design were

assumed to bring the recovery efficiency to 78%.

Increase Heat Exchange Surface Area. This design option represents a number of possible

design modifications that would increase the surface area for heat exchange. Recovery efficiencies of

up to 82% are reported by the manufacturer for available products; 82% RE is used here to represent

the improvement offered by this design option. The use of this type of internally finned flue is assumed

to preclude the use of improved flue baffles, and hence the increased heat exchange surface area design

option is an alternative to the improved flue baffle design option.

Interrupted Ignition. This design option is an interrupted ignition device that ignites the

burner directly by generating a short-lived spark. This is in contrast to the intermittent ignition system

of the baseline model, which is constantly on during the on-cycle.

25

EE-RM-97-900 COMMENT 77F
Manufacturer Costs

All manufacturing cost estimates for a 32-gallon (120-liter) oil-fired water heater were

disaggregated into variable (material, labor, overhead, transportation) and fixed (capital, product

design) costs. Design option variable and fixed costs were calculated on a per unit basis and expressed

as an incremental increase over the existing baseline design. The breakdown of the manufacturing costs

for all design options are given in Tables 8a and 9a.

Existing Baseline Model. Cost estimates for the existing baseline model-a water heater with

1-in. (2.5 cm) foamed jacket insulation using HCFC-141b as a blowing agent-were provided by an

independent consultant. Industry estimates for manufacturers' costs of oil-fired water heaters were not

collected by GAMA.

2003 Baseline Model. To convert the manufacturer costs for the existing baseline model to

that of the 2003 baseline model with either HFC-245fa or water-blown insulation, the amount and cost

of materials are taken into account. The additional material costs (primarily foam and sheet metal costs)

associated with the 2003 baseline model level of HFC-245fa or water-blown insulation were determined

by adding to the baseline the costs associated with a comparable level of HCFC-141b foam insulation.

Heat Traps. Fixed and variable cost estimates for heat traps are based on data from

independent consultants.

Increased Jacket Insulation. Fixed and variable costs to increase HFC-245fa-based insulation

and water-blown insulation from the nominal 1 in. of the baseline 2003 designs to 2 in., 2'/2 in., and 3

in. were calculated based on the increased cost for the additional foam and jacket material as well as for

miscellaneous foaming materials, paint, shipping cartons, labor, and overhead. These latter costs were

based on data provided by independent consultants. Additional shipping costs were estimated based on

information for the same thickness increase provided by GAMA for gas-fired water heaters.

At least 50% of all installations of oil-fired water heaters are retrofits of a new water heater to

an existing oil burner. This creates an additional cost since the extra insulation thickness affects the

burner placement and hence the combustion characteristics of the water heater. The suggested solution

is a kit with replacement nozzle and blast tubes. Total manufacturer and installation cost for this kit was

estimated by an industry consultant and applied to 50% of installations of oil-fired water heaters with

insulation greater than 1 in. thick. We assumed that any cost to make existing oil burners work with

2003 baseline models could be attributed to the change in foam thickness caused by the 2003 phase-out

of HCFC-141b and not to efficiency improvements mandated by the standard.

Finally, an additional average installation cost of $8.00 was estimated for oil-fired water heaters

with 3 in. of insulation. This additional cost was added to reflect difficulties that may be encountered in

placing new oil-fired water heaters in existing construction.

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EE-RM-97-900 COMMENT 77F
Improved Flue Baffle. Estimated manufacturer variable and fixed costs for the improved flue

baffle design were based on data provided by an independent consultant.

Increased Heat Exchange Area. Costs were estimated for an enhanced heat exchange design

option that could provide 82% recovery efficiency. Estimated manufacturer variable and fixed costs for

the increased heat exchange area design were based on data provided by an independent consultant.

Interrupted Ignition. Manufacturer costs for interrupted ignition were based on the

replacement of the intermittent ignition system common in existing oil-fired burner designs with an

interrupted ignition system. Cost estimates for the interrupted ignition design option were based on

data provided by an independent consultant and a burner manufacturer.

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EE-RM-97-900 COMMENT 77F
Design Option Retail Prices and Installation and Maintenance Costs

The retail price is the cost to the consumer of just the water heater. The retail price for an

existing baseline 32-gallon (120-liter) oil-fired water heater (with HCFC-141b foam insulation) was

based on the data reported by 29 companies dealing in oil-fired water heating equipment. Based on this

data, the following costs were established: an average consumer cost for a base performance oil-fired

water heater without burner is $446; an average consumer cost for an oil burner for an oil-fired water

heater is $285; and an average installation cost for new oil-fired water heater is $491.

A typical manufacturer to consumer markup of 320% was used across all oil-fired water heater

design options based on the $446 figure for the existing baseline oil-fired water heater cost (without

burner), and the estimated manufacturing cost of $139.25. This is shown in Table 8a.

Cost-Efficiency Data

The results of the design option analysis for 32-gallon (120-liter) oil-fired water heaters are

presented in Tables 8a, 8b, 9a, and 9b. Included in the cost and efficiency tables are disaggregated

manufacturer costs, retail prices, installation costs, maintenance costs, and energy-efficiency and energy

use data.

The existing baseline design with HCFC-141b foam insulation is presented in Tables 8a through

9b to show the manufacturer cost and retail price differences. Energy costs were from national average

energy prices for 2003 from the Annual Energy Outlook 1999.

The costs for all the design option combinations are shown in Tables 8a and 9a and the

efficiency data is shown in Tables 8b and 9b. For the design options analyzed, the results suggest a

maximum EF of 0.6161 can be achieved through the use of plastic heat traps, increased heat exchange

surface area, 3 in. (7.6 cm) insulation, and interrupted ignition. This design produces energy savings of

3.80 million Btu/year of oil and 33.28 kWh/yr of electricity. Using water-blown insulation, the same

design has an EF of 0.6103 and an energy savings of 3.57 million Btu/year of oil and 31.53 kWh/yr of

electricity.

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EE-RM-97-900 COMMENT 77F
Table 8a. 245fa Insulation 32-gal (120-liter) Oil-Fired Water Heater: Cost Data

Incremental Costs Total Mfg to Total Cost

Design Total Total Mfg Retail Retail Install. Installed Operating Maint.

No. Design Options Material Labor Overhead Variable Fixed Cost Markup Price Cost $/yr S/yr Cost

0 Existing Baseline $85.00 $18.25 $36.00 $139.25 $0.00 $139.25 3.2 $445.60 $491.00 936.60 217.94 $97.14

Oa 2003 Baseline $1.02 $0.00 $0.00 $1.02 $0.00 $140.27 3.2 $448.86 $491.00 939.86 217.94 $97.14

1 Heat Traps $3.97 $0.15 $0.05 $4.17 $1.52 $144.94 3.2 $463.81 $491.00 954.81 213.96 $97.14

2 2" Insulation $10.59 $0.44 $3.24 $13.29 $3.04 $155.58 3.2 $497.86 $509.25 1,007.11 207.84 $97.14

3 2.5" Insulation $13.69 $0.59 $4.86 $18.16 $3.24 $160.65 3.2 $514.08 $509.25 1,023.23 206.46 $97.14

4 3" Insulation $16.96 $0.73 $6.47 $23.18 $3.44 $165.87 3.2 $530.78 $517.25 1,048.03 205.53 $97.14

5 78% RE $20.71 $1.28 $7.47 $28.48 $35.44 $203.17 3.2 $650.14 $517.25 1,167.39 197.96 $97.14

6 Interrupted Ignition $37.21 $1.28 $4.49 $44.98 $36.44 $220.67 3.2 $706.14 $517.25 1,223.39 194.03 $97.14

7 82% increased HX area $54.46 $3.03 $11.72 $62.93 $84.44 $286.62 3.2 $917.18 $517.25 1,434.43 184.66 $97.14

Notes:

1) All costs and prices in 1998$.

2) Incremental variable and fixed costs are per unit costs and are relative to the 2003 baseline.

3) For the baseline model with HCFC-141b, the total variable costs are provided.

Table 8b. 245fa Insulation 32-gal (120-liter) Oil-Fired Water Heater: Efficiency Data

Fuel Energy Use Electrical Energy Use

Design Energy Recovery UA Daily Yearly Daily Yearly

No. Design Options Factor Efficiency Btu/day MBtu/year kWh/day kWh/year

0 Existing Baseline 0.5290 75.00% 14.49 76860 28.05 0.241 88

Oa 2003 Baseline 0.5290 75.00% 14.49 76860 28.05 0.241 88

I Heat Traps 0.5388 75.00% 13.59 75456 27.54 0.236 86

2 2" Insulation 0.5547 75.08% 12.25 73298 26.75 0.230 84

3 2.5" Insulation 0.5584 75.09% 11.95 72812 26.58 0.228 83

4 3" Insulation 0.5610 75.10% 11.74 72482 26.46 0.227 83

5 78%RE 0.5824 78.00% 11.31 69814 25.48 0.219 80

6 Interrupted Ignition 0.5863 78.52% 11.23 69815 25.48 0.082 30

7 82% RE Increased HX 0.6161 82.54% 10.69 66438 24.25 0.078 28

Area

29

EE-RM-97-900 COMMENT 77F
Table 9a. Water-Blown Insulation 32-gal (120-liter) Oil-Fired Water Heater: Cost Data

Incremental Costs Total Mfg to Total Cost

Design Total Total Mfg Retail Retail Install. Installed Operating Maint.

No. Design Options Material Labor Overhead Variable Fixed Cost Markup Price Cost $/yr $/yr Cost

0 Existing Baseline $85.00 $18.25 $36.00 $139.25 $0.00 $139.25 3.2 $445.60 $491.00 936.60 217.94 $97.14

0 2003 Baseline $2.01 $0.13 $1.41 $3.54 $1.36 $144.15 3.2 $461.28 $509.25 970.53 217.94 $97.14

I Heat Traps $4.96 $0.28 $1.46 $6.69 $2.88 $148.82 3.2 $476.23 $509.25 985.48 213.96 $97.14

2 2" Insulation $7.64 $0.44 $3.30 $11.38 $3.04 $153.67 3.2 $491.73 $509.25 1,000.98 210.60 $97.14

3 2.5" Insulation $10.17 $0.59 $4.95 $15.71 $3.24 $158.20 3.2 $506.24 $509.25 1,015.49 208.78 $97.14

4 3" Insulation $12.84 $0.74 $6.60 $20.17 $3.44 $162.86 3.2 $521.14 $517.25 1,038.39 207.49 $97.14

5 78% RE $16.59 $1.29 $7.60 $25.47 $35.44 $200.16 3.2 $640.50 $517.25 1,157.75 199.83 $97.14

6 Interrupted Ignition $33.09 $1.29 $7.60 $41.97 $36.44 $217.66 3.2 $696.50 $517.25 1,213.75 195.87 $97.14

7 82% RE Increased HX $46.59 $2.49 $10.85 $59.92 $84.44 $283.61 3.2 $907.54 $517.25 1,424.79 186.41 $97.14

Area

Notes:

1) All costs and prices in 1998$.

2) Incremental variable and fixed costs are per unit costs and are relative to the 2003 baseline.

3) For the baseline model with HCFC-141b, the total variable costs are provided.

Table 9b. Water-Blown Insulation 32-gal (120-liter) Oil-Fired Water Heater: Efficiency Data

Fuel Energy Use Electrical Energy Use

Design Energy Recovery UA Daily Yearly Daily Yearly

No. Design Options Factor Efficiency Btu/day MBtu/year kWh/day kWh/year

0 Existing Baseline 0.5290 75.00% 14.49 76860 28.05 0.241 88

Oa 2003 Baseline 0.5290 75.00% 14.49 76860 28.05 0.241 88

1 Heat Traps 0.5388 75.00% 13.59 75456 27.54 0.236 86

2 2" Insulation 0.5474 75.04% 12.86 74270 27.11 0.233 85

3 2.5" Insulation 0.5522 75.06% 12.46 73629 26.87 0.231 84

4 3" Insulation 0.5556 75.09% 12.18 73176 26.71 0.229 84

5 78%RE 0.5769 78.00% 11.73 70473 25.72 0.221 81

6 Interrupted Ignition 0.5808 78.52% 11.65 70474 25.72 0.083 30

7 82% RE Increased 0.6103 82.54% 11.09 67066 24.48 0.079 29

HX Area

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EE-RM-97-900 COMMENT 77F