### RESULTS AND METHODOLOGY OF THE ENGINEERING ANALYSIS FOR RESIDENTIAL WATER HEATER EFFICIENCY STANDARDS

Submitted to the U.S. Department ofEnergy Office ofCodes and Standards (OCS) November 2, 1998Addendum The following changes have been madeto the mainreport: Page 11 Referenced Appendices A-G Page 11 Referenced Appendix D Page 12 Referenced Appendix F Page 17 Referenced Appendix G Page 27 Changed text from Table 5to read "Table 7" Page 74 Added Table 50a. Cost Table for40 gallon (150 liter) Gas-Fired Storage Water Heater

- Selected Design Option Combinations Page 81 Changed text from Appendix D to read "Appendix E"

The following Appendices Athrough G are also available on the web page as .pdffiles that can de downloaded and printed: APPENDIX A: "WATSIM-DOE TEST.XLS"

- SPREADSHEET TOOL TO DETERMINE THE ENERGY PERFORMANCE CHARACTERISTICS OF ELECTRIC STORAGE WATER HEATERS BASED ON OUTPUT FILES FROM THE WATSIM COMPUTER SIMULATION MODEL APPENDIX B: WATER HEATER ANALYSIS MODEL (WHAM)

- METHOD FOR DETERMINING WATER HEATER ENERGY CONSUMPTION APPENDIX C: VENTING ISSUES IN GAS-FIRED WATER HEATERS APPENDIX D: MANUFACTURER COST DATA FOR RESIDENTIAL ELECTRIC AND GAS-FIRED WATER HEATERS APPENDIX E: OIL-FIRED WATER HEATERS CONDUCTIVE HEAT LOSS CALCULATION APPENDIX F: ESTIMATES OF MANUFACTURING COSTS AND ENERGY CHARACTERISTICS FOR ELECTRIC AND GAS-FIRED STORAGE WATER HEATERS

- DATA FROM MAX MINNIEAR APPENDIX G: DESIGN OPTION COMBINATIONSCONTENTS

OVERVIEW

................................................................. 7 REQUEST FOR STAKEHOLDER COMMENTS

................................. 7 LIST OF ACRONYMS

................................................... 9 INTRODUCTION

.................................. ................. ..... 11 INFORMATION SOURCES

.................................................. 11 BASELINE MODELS

.................................................... 13 SCREENING ANALYSIS OF THE DESIGN OPTIONS

........................... 14 EFFICIENCY CALCULATIONS

............................................ 18 TECHNOLOGICAL ISSUES ................................................ 21 OVERALL ANALYSIS APPROACH

........................................... 26 ELECTRIC WATER HEATERS

.............................................. 26 GAS-FIRED WATER HEATERS

.............................................. 45 OIL-FIRED WATER HEATERS

.............................................. 76 REFERENCES

.............................................................. 97Table 27. TANKInput Values providing acceptable EF and RE values

............... 49 Table 28. Gas-Fired Water Heater Baseline Model Characteristics

.................. 49 Table 29. Gas-Fired Water Heater Modeling Differences: Existing BaselineModel vs. Analytic Baseline M odel ................................................ 51 Table 30. Gas-Fired Water Heater Modeling Differences: Analytic Baseline Model vs. Models with Metal and Plastic Heat Traps

................................ 51 Table 31. Gas-Fired Water Heater Modeling Differences: Analytic Baseline Model vs. Models w/2 & /2 nominal in. offoam insulation

.......................... 52 Table 32. Gas-Fired Water Heater Modeling Differences Analytic Baseline Model vs. Model with Improved Flue Baffle

......... ................... ..... 54 Table 33. Gas-Fired Water Heater Modeling Differences Analytic Baseline Model vs. Model with Electronic Ignition

......... .............................. 55 Table 34. Gas-Fired Water Heater Modeling Differences: Analytic Baseline Model vs. Model with Electromechanical Flue Damper

............................... 56 Table 35. Side-Arm 40 gallon (150 liter) Gas-Fired Water Heater: Energy Factor Estimates

............... .......................................... . 57 Table 36. Side-Arm 40 gallon (150 liter) Gas-Fired Water Heater, Plastic Tank: Energy Factor Estimates

...................................................... 58 Table 37. Gas-Fired Water Heater Existing Baseline Model: Manufacturer Costs

...... 59 Table 38. Gas-Fired Water Heater Material Costs Associated with varying thicknesses of HCFC-141b Foam Insulation

......... ................................ 59 Table 39. Gas-Fired Water Heater Material Costs Associated with varying thicknesses of HFC-245fa Foam Insulation

............................................. 60 Table 40. Gas-Fired Water Heater Baseline Model with HCFC-141b and HFC-245fa: Manufacturer Costs

.................................................... 60 Table 41. Gas-Fired Water Heater Analytic Baseline Model with Resistant Flammable Vapor Ignition Design: Manufacturer Costs

................ ............. 61 Table 42. Heat Traps for Gas-Fired Water Heaters: Incremental Manufacturer Costs

..................................................................... 61 Table 43. Increased Jacket Insulation for Gas-Fired Water Heaters: Incremental Manufacturer Costs

.................................................... 62 Table 44. Improved Flue Baffle for Gas-Fired Water Heaters: Incremental Manufacturer Costs

................................................................ 62 Table 45. Electronic Ignition for Gas-Fired Water Heaters: Incremental Manufacturer Costs

................................................................ 62 Table 46. Flue Damper w/ Electronic Ignition for Gas-Fired Water Heaters: Incremental Manufacturer Costs

................ ........... .................. ..... 63 Table 47. Side-Arm Heaters for Gas-Fired Water Heaters: Incremental Manufacturer Costs

................................................................ 63 Table 48. 40-Gallon (150 liter)Gas-Fired Storage Water Heater Retail Prices

......... 65 Table 49. 40-Gallon (150 liter) Gas-Fired Storage Water Heater Installation Costs

..... 66 Table 50. Cost Table for 40 gallon (150 liter) Gas-Fired Storage Water Heater

........ 71 Table 50a. Cost Table for 40 gallon (150 liter) Gas-Fired Storage Water Heater

- Selected Design Option Combinations

............................................ 72 Table 51. Efficiency Table for 40 gallon (150 liter) Gas-Fired Storage Water Heater

.... 73 Table 51a. Efficiency Table for 40 gallon (150 liter) Gas-Fired Storage Water Heater

-TABLES

Table 1. Design Options Used in theEngineering Analysis

......................... 17 Table 2. Design Options Eliminated from Further Consideration

.................... 17 Table 3. NAECA Minimum Efficiency Standards

................................. 19 Table 4. Conductivity Comparisons between Foam Insulation Blown with HCFC-141b and HFC-245fa

........................................................... 22 Table 5. Summary ofGeneral Recommendations for Relining Exterior Masonry Chimneys forResidential Installations in a Two-Appliance Configuration

............... 25 Table 6. Summary ofGeneral Recommendations for Relining Exterior Masonry Chimneys for Residential Installations in a One-Appliance Configuration

................ 26 Table 7. Initial Existing Electric Water Heaters Baseline Characteristics*

............ 27 Table 8. Electric Water Heater Existing Baseline Model Characteristics*

............. 28 Table 9. Electric Water Heater Modeling Differences: Existing vs. Analytic Baseline Model

- Insulation Conductivity*

........................................ 30 Table 10. Electric Water Heater Modeling Differences: Analytic Baseline Model vs. Models with Metal andPlastic Heat Traps*

............................... 32 Table 11. Electric Water Heater Modeling Differences: Analytic Baseline Model vs. Models w/ 2 & 2V in. offoam insulation

.................................. 32 Table 12. Electric Water Heater Modeling Differences: Analytic Baseline Modelvs. Model with Foamed Bottom Insulation*

......................................... 33 Table 13. Electric Water Heater Modeling Differences: Analytic Baseline Model vs. Plastic Tank*

............................................................... 34 Table 14. Existing Electric Water Heater Material Costs Associated with varying thicknesses ofHCFC-141b Foam Insulation

............................... 35 Table 15. Foam Components CostEstimate

...................................... 36 Table 16. Analytic Electric Water Heater Material Costs Associated with varying thicknesses ofHFC-245fa Foam Insulation

................................ 36 Table 17. Electric Water Heater Baseline Model with HCFC-141b and HFC-245fa: Manufacturer Costs

.................................................... 37 Table 18. Heat Traps for Analytic Electric Water Heaters: Incremental Manufacturer Costs

.......................................................... ...... 37 Table 19. Increased Jacket Insulation for Analytic Electric Water Heaters: Incremental Manufacturer Costs .................................................... 38 Table 20. Insulating the Tank Bottom for Analytic Electric Water Heaters: Incremental Manufacturing Costs ................................................... 38 Table 21. Plastic Tank Design for Electric Water Heaters: Incremental Manufacturer Costs

................................................................ 39 Table 22. 50-Gallon (190 liter) Electric Storage Water Heater Retail Prices ........... 39 Table 23. 50-Gallon (190 liter) Electric Storage Water Heater Installation Costs

....... 41 Table 24. Cost-Efficiency Table for 50 gallon (190 liter) Electric Storage Water Heaters

..................................................................... 44 Table 25. Battelle Baseline Model Characteristics as presented at November 1997 GRI TAG meeting ....................................................... 46 Table 26. TANK Input Variables: Approximate Impact on EF and RE

............... 48Figures Figure 1. 50 gallon (190 liter)Electric Storage Water Heaters: Total Consumer Cost and Operating Cost vs. Energy Factor

........................................ 45 Figure 2. Energy Factor and Recovery Efficiency vs. Flue Baffle Effectiveness and Excess Combustion Air

....................................................... 47 Figure 3. Gas Fired Water Heaters Design Option Selection Process

................. 71 Figure 4. 40 gallon (150 liter) Gas-Fired Storage Water Heaters: Total Consumer Cost and Operating Cost vs. Energy Factor for Selected Design Options Combinations

.... 76Selected Design Option Combinations

..................................... 74 Table 52. Oil-Fired Water Heater Baseline Model Characteristics

................... 76 Table 53. Performance Characteristics for Existing Baseline Oil-Fired Water Heater

... 78 Table 54. Oil-Fired Water Heater Modeling Differences: Existing Model with HCFC-141b vs. Analytic Modelwith HFC

............................................ 79 Table 55. Performance Characteristics forAnalytic Oil-Fired Water Heater

.......... 79 Table 56. Analysis Results for Design Option #1 (Heat Traps)

...................... 79 Table 57. Analysis Results for Design Options 2

- 2" Jacket Insulation

.............. 82 Table 58. Analysis Results for Design Option 3

- Improved Flue Baffle

............... 82 Table 59. Analysis Results for Design Option 4

- Increased Heat Exchanger Area

...... 84 Table 60. Analysis Results for Design Option 5

- Interrupted Ignition

................ 87 Table 61. Cost Table for 32 gallon Oil-Fired Storage Water Heater Design Options

.... 91 Table 62. Energy Impact and Simple Payback ofOil-Fired Water Heater Design Options

..................................................................... 94 Table 62a. Energy Impact and Simple Payback ofSelected Oil-Fired Water Heater Design Options

............................................................. 948 gas-fired water heaters

- manufacturer cost-to-retail price markup value

- incremental manufacturing cost for "Side-Arm Heater" design option

- issues regarding the use ofametal or plastic tank for "Side-Arm Heater" designs

- maintenance costs for "Side-Arm Heater" designs, due to fouling oftheheat exchanger

- 10-year life for mechanical flue dampers in residential applications

- should fixed costs for 2.5 in. insulation scale with material cost? oil-fired water heaters

- extended characterization ofthe baseline model characteristics

- manufacturer cost-to-retail price markup value.9 LIST OF ACRONYMS
AGA American Gas Association ADL Arthur D. Little, Inc. AE098 Energy Information Administration's Annual Energy Outlook ANOPR Advance Notice ofProposed Rulemaking ANSI American National Standards Institute ARI Air-Conditioning and Refrigeration Institute Btu British thermal unit CPI Consumer Price Index CPSC Consumer Product Safety Commission DOE U.S. Department ofEnergy EF energy factor (from DOE's water heatertestprocedure) EIA Energy Information Administration EPACT Energy Policy Act of 1992 EPCA Energy Policy Conservation Act EPA U.S. Environmental Protection Agency EPRI Electric Power Research Institute FR Federal Register GAMA Gas Appliance Manufacturers' Association GRI Gas Research Institute GRIM Government Regulatory Impact Model HCFC hydrochlorofluorocarbon HFC hydrofluorocarbon HSI hot surface ignition IRR Internal Rate ofReturn LBNL Lawrence Berkeley National Laboratory LCC life-cycle cost LPG liquefied petroleum gas MMBtu million Btu MCF thousand cubic feet NAECA National Appliance Energy Conservation Act NES National Energy Savings NFGC National Fuel Gas Code NIST National Institute of Standards and Technology NOAA National Oceanic & Atmospheric Administration PNNL Pacific Northwest National Laboratory PVC polyvinylchloride RE recovery efficiency (ofa water heater) RECS Residential Energy Consumption Survey SCF standard cubic foot SG&A Cost Selling, General &Administration Cost TAG Technical Advisory Group TSD Technical Support Document UA Standby Heat LossCoefficient UEC unit energy consumption USC United States Code WHAM Water Heater Analysis Model10 This page intentionally left blank.11 INTRODUCTION The Energy Policy and Conservation Act, as amended, provides energy conservation standards for water heaters among other products and authorizes the Secretary ofEnergy to prescribe amended or new energy standards for each type ofcovered product. This is a preliminary Engineering Analysis; it ispart ofthe analyses the Department will conduct forthe water heater rulemaking. The preliminary life-cycle cost analysis will be provided later this month. The objective ofthe Engineering Analysis isto determine the costs ofincreased energy efficiency for residential water heaters bydeveloping price and efficiency data for design options and combinations ofdesign options for each product class. This information willbe used in subsequent components ofthe standards rulemaking process. The results ofthe Engineering Analysis are summarized in cost-efficiency tables demonstrating the increased cost and efficiency due toeach design option within each product class. Appendices A through G that are referenced in thisreport. This reportdescribes the analysis ofcost and efficiency impacts ofspecific design options and combinations ofdesign options. Design options used in this analysis are the results ofa technology assessment and screening analysis, and comments from stakeholders. The Engineering Analysis uses computer simulation models and other analytical methods to investigate the efficiency improvements ofdesign options and interactions when multiple design options are used. The Engineering Analysis is based on the U.S. DOE Test Procedure for residential water heaters with a daily draw of64.3 gallons (243.4 liters), a setpoint of 135°F (57.2 C), an inlet water temperature of58°F (14.4°C), and an ambient air temperature of67.5°F (19.70C) 2 Manufacturer, distributor and installer markups are applied to factory costs as is sales tax to arrive atthe purchase price ofthewater heater. A fixed markup isderived from retail price data for existing baseline water heater models and applied to manufacturer costs in order to determine consumer prices ofdesign options. Additional installation and costs required for certain design options are also included in the final price for these design options. Energy prices are the current national average energy prices from the Energy Information Administration's Annual Energy Outlook 1998 (AE098) 3. INFORMATION SOURCES The primary source ofboth manufacturer cost and efficiency data for this analysis was the Gas Appliance Manufacturers' Association (GAMA) (See Appendix D). GAMA collected cost and efficiency data from water heater manufacturers. The data was aggregated to protect the confidentiality ofthe individual manufacturers. GAMA did not provide data for three ofthe design options being considered (2.5 in. ofinsulation, plastic tank & side-arm heater). The12 missing data was supplemented by cost and efficiency information obtained from Max E. Minniear, former Vice President ofEngineering at A. O. Smith Water Products Company. Mr. Minniear was contracted byLawrence Berkeley National Laboratory (LBNL) to provide disaggregated cost and efficiency data for baseline designs and various design options (See Appendix F). Some ofthe cost data was also compared with data obtained from Eugene West, formerly ofBradford-White Corporation, who was under contract with Pacific Northwest National Laboratory (PNNL). Mr. Minniear and Mr. West were both recommended by the Gas Appliance Manufacturers Association (GAMA). Although computer simulation models were used to generate the efficiency gains expected from design options, GAMA and Mr. Minniear's efficiency estimates were used to confirm the reasonableness ofthe models' estimates. Other sources ofinformation were used as well. One key source ofefficiency data was the GAMA directory 4. The directory lists energy factor (EF), recovery efficiency (RE), rated input, and first hour rating for residential water heating equipment. The Department accepts listing in the GAMA directory as certification that a model meets theminimum allowable efficiency. Manufacturers' product literature was also collected. Itprovided additional information about certain design features (e.g., heattraps and thickness offoam insulation). Product literature data were mapped to listings in the GAMA directory to determine what efficiency improvements were employed to reach particular efficiency levels. Independent confirmation ofmanufacturer cost data was conducted for certain design options by contacting component manufacturers. Inparticular, this was done forheat traps and foam insulation. Anupper limitto the factory cost ofbaseline model water heaters was extracted from census data5

. Factory cost is the manufacturer's cost to make water heaters and includes material, labor, and overhead. The Census Bureau Survey ofManufacturers, Major Household Appliances (MA36F), 1995, reports total value ofgas-fired and electric water heaters as $920 million for 8.07 million units sold. This gives an average price per unit of$114. Since this data includes premium models and the manufacturer's markups, as well aswarranty costs, freight, profits and commissions, itwill be higher than the baseline model factory cost, but itprovides an upper limit. The cost to the consumer for the water heater equipment and the installation cost was established by contacting various plumbing contractors and large retail chains (e.g., The Home Depot, Lowe's, Ferguson, Orchard) throughout the United States. Other reports, such as the Gas Research Institute (GRI) report,AssessmentofTechnology forImprovingtheEfficiency of Residential Gas WaterHeaters 6 and the Arthur D. Little report, MarketDispositionof High-Efficiency WaterHeatingEquipment 7 , were used to confirm the reasonableness ofthe cost, price, and efficiency data. The above GRI report was specifically used to establish the installation cost ofgas-fired water heaters requiring an electrical hookup and to estimate the maintenance cost associated with electromechanical flue dampers.13 BASELINE MODELS The determination ofproduct classes and selection ofbaseline units for the analysis is based on existing DOE water heater efficiency standards 8 and stakeholder comments. The baseline unit represents the most common size water heater with an efficiency equal to the minimum allowed by the existing energy efficiency standards. The general characteristics of eachbaseline model for each ofthe three primary product classes (i.e., electric storage, gas-fired storage, and oil-fired storage) are provided below. An in-depth description ofeach ofthe baseline models is provided later inthisreport. Electric Storage WaterHeaters The baseline model is a 50gallon (190 liter) glass-lined steel tank with 1/ 2in. (3.8 cm) of polyurethane foam. The heater has two elements, each with an input of4500 W. The elements are interlocked so that only one can be energized at a time. The baseline energy factor is 0.86, the National Appliance Energy Conservation Act (NAECA) minimum forthis size and type of water heater. Gas-Fired Storage Water Heaters The baseline model ofgas-fired storage water heaters isa 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 pilotrated at 400 Btu/hr (120 W). Thetank is insulated with 1in. (2.5 cm) of polyurethane foam. The heater has theminimum efficiency allowed byNAECA with an energy factor of0.549. It has a recovery efficiency of76%. Oil-Fired Storage Water Heaters The baseline oil-fired water heater is a center-flue design. Ithas arated volume of32 gallons (120 liters), and is insulated with 1in. (2.5 cm) ofpolyurethane foam insulation. The input rate is 0.65 gallons per hour(2.5 liters/hr) ofoil or 90,000 Btu/hr (26,000 W). It has an EF of0.53, the minimum allowed by NAECA. The firsthour rating is 105 gallons (398 liters), and the RE is 75%. The tank is a cylinder 18 in. (46 cm) in diameter and 32.7 in. (83.1 cm) high, pierced by a 6 in. diameter (15 cm) flue along the central axis. The burner motor, which powers both the blower and oil pump, is rated at 1/8 hp (282 W). No auxiliary power is consumed during standby. The ignition system on the baseline model is assumed to be the intermittent type and uses a conventional magnetic transformer to achieve the high voltage spark.14 

### SCREENING ANALYSIS OFTHE DESIGN OPTIONS The first step in the rulemaking process is the screening ofdesign options. The purpose ofscreening is to identify those design options that the Department will consider forthe engineering analysis. The screening analysis also provides a discussion ofthe criteria for eliminating certain design options from further consideration. On July 15, 1996, the Department issued the Process Improvement (Interpretive) Rule (61 FR 36974, July 15, 1996) which establishes the factors DOE uses for screening design options. The factors are as follows: * Technological feasibility. * Practicability to manufacture, install and service. * Adverse impacts on product utility or product availability. * Adverse impacts on health and/or safety. In accordance with the Process Improvement Rule, the Department published the results ofapreliminary screening ofthe water heater design options in "Technology Assessment andScreening Analysis, Appendix B Supplement to the WaterHeater Rulemaking Framework",January 1998. Stakeholders were notified ofthe availability of this document in the Federal Register on January 14, 1998 (63 FR 2186). The Notice further requested comments on the Technology Assessment and Screening Analysis document. Comment Summary: DOE received 28 comments on the Technology Assessment and Screening Analysis document. Six stakeholders including GAMA supported, with modifications, theDepartment's position regarding the screened design options. The comments addressed air atomized oil burners, power vents and tank bottom insulation for gas or oil-fired water heaters. The majority ofcomments dealt withthe Department's decision to eliminate the heat pump water heater design option from consideration. Those comments from the American Gas Association (AGA) and some gas utilities claimed that DOE must consider all technologically feasible design options to comply with the law (42 U.S.C. Section 

### 6295). Changes to the Screened Design Options: The baseline electric unit for the present analysis has been assumed to have 1.5 in. of jacket insulation (rather than the 1.0 in. assumed for gasand oil-fired water heaters) in orderto achieve the baseline EF levels. Increasedjacket insulationlevels will be considered in the engineering analysis based on these baseline assumptions. Heattrapscould be either ofplastic or metallic design. Manufacturing costs appear to be roughly comparable between the two, but plastic heat traps are considerably more effective in reducing the water heater standby losses. Therefore, the present engineering analysis will only consider plastic heat traps as a design option. AirAtomizedBurnerswere included in the set ofdesign options DOEproposed for consideration in the rulemaking for oil-fired water heaters. However, based on stakeholder comments, the Department has decided not to consider air atomized burners further because they aren't practical to manufacture. A prototype ofthe air atomized burner has been developed for oil-fired furnaces but the design has not yet been applied to water heaters and the work is being closely followed15 by the oil-fired water heater industry. A power vent design was included as part ofthe discussion ofthe ImprovedFlue Baffle design option. However, DOE will not consider the power vent design because it requires special venting systems that may not be practical in all situations. Although the American Council for an Energy Efficient Economy claims that this design can go above the 80% RE limit without requiring corrosion resistant flues, the Department believes that any designs above 80 % RE could result in corrosion insidethe water heater in colder climates. Increased HeatExchangerSurfaceAreawas included in the set ofdesign options the Department proposed to consider. Manufacturers stated that the same efficiency improvement can be achieved byImprovedFlueBaffles and that this is the preferred approach for residential water heaters. Additionally, Increased HeatExchangerSurfaceAreainthe form offinned flue surfaces, is being considered as adesign option for oil-fired water heaters. Because oil-fired units have a higher input capacity, they can benefit from both improved flue baffles and increased heat exchanger surface areas. Electric utilities requested that the Department consider the TankBottomInsulation option for gas or oil-fired water heaters as well. However, DOEhas decided not to consider it for safety reasons. The tankbottom is the burner enclosure for gas or oil-fired water heaters, and the high temperatures would pose a safetyhazard due to melting insulation. The gas utility industry would like DOE to consider theHeatPump WaterHeater design option. However, the gasutility industry didn't provide any new information to cause DOE toreconsider its earlier decision. The Interpretive Rule addresses how those design options, that are not practicable to manufacture, install and service, should be eliminated from consideration inthe engineering analysis. Inparticular, there are three different sections ofthe Rule that urge the Department to: (III)(l)(d) "eliminate problematic design options early in the process;" (j) "reduce time and cost ofdeveloping standards;" and (III)( 11) "be sensitive to first cost increases...avoiding negative impacts to identifiable population groups." Further, the design is not to have adverse impacts onproduct utility. Providing an equivalent capacity unit (equal to the base case capacity forthe electric water heater design) would increase the first cost ofthe electric water heater significantly. This is also truebecause heat pumps, in general, are not very efficient at low temperatures < 50°F (<10°C) and present designs may not have sufficient capacity to meet normal hot water loads, and hence, may require an electric resistance backup. A Federal Technology Alert'° issued on the use ofresidential heat pump water heaters at federal sites shows that theyare cost-effective only in select regions ofthe United States when compared to electric resistance water heating. Since a standard can only cover products which can be practically applied to all situations, the heat pump water heater's adverse impact on consumer utility and lack ofadequate servicing infrastructure weighed heavily in the earlier recommendation. Surveys from the Georgia Power and Alabama Power companies reported that over 50 % oftheir customers would have difficulty installing a heat16 pump water heater because ofspace limitations (Arthur D. Little, Inc. 1996"). Additionally, many comments to the 1994 Notice ofProposed Rulemaking (59 FR 10464, March 4, 1994) claimed that itwas difficult to find people trained to service a heat pump water heater in rural and low-income areas. AGA argues that DOE relied on "unsubstantiated and uncorroborated" explanations by interested parties inreversing its decision, when in fact, the proposal to keep electric heat pump water heaters as a design option prompted an unprecedented torrent ofnegative comments following the issuance ofthe proposed rule in 1994. They are summarized as follows:* 33 comments questioned the reliability ofheatpump water heaters. * 15 comments citedthe space restrictions ofsmall homes, and the increased payback time due to reduced water use. * 216 comments cited the immature infrastructure formanufacturing, sales and repair, especially in rural areas. * 66 comments questioned the inconvenience and possible price hikes for larger tank size due to the lowerrecovery rate, 40 % slower than conventional electric water heaters. * 21 comments believed itwould distort the marketplace and lessen competition among fuel sources. * 33 comments expressed concerns about increased noise. * 107 comments feared increased electric rates due to loss ofrevenues in rural electric cooperatives. * 22 comments claimed under-the-counter applications would not be cost effective. Since the late 1970s, when efforts to develop and commercialize heatpump water heaters began, annual sales have not exceeded 10,000 heat pump water heaters (<0.33% of electric water heater sales, <0.17% ofall water heater sales). Sales have declined drastically since the mid-1980s, and recent sales are less than 0.1% ofall electric water heaters sold. No mass market distribution, sales, installation and servicing infrastructure exists. There is no precedent in the history ofthe U.S. major appliance industries to suggestthat a complete reversal ofthis situation, onthe scale ofseveral million units peryear, in only a few years, and in the absence ofconsumer demand, ispossible. Such a reversal would be required ifan energy efficiency standard at the heat pump water heater level for electric water heaters is proposed.17 The heat pump waterheater being developed by DOE does not overcome all ofthe consumer utility issues because it isdesigned with a lowerrecovery rate foraverage to low hot water usage households. Finally, the Department isconcerned that including the heat pump water heater design option could interfere in the market balance between gas and electric utilities. Table 1is alist ofdesign options being considered forthe engineering analysis (for discussion ofoptioncontraints considered seeAppendix G) and Table 2 is a listofdesign optionsthat have been eliminated from further consideration. Table 1. Design Options Used in the Engineering Analysis 

### Design Options - Description Gas Electric Oil Heat Traps X X X Plastic Tank X( X Increased Jacket Insulation X X X Insulatingthe Tank Bottom X Improved Flue Baffle X X Increased HeatExchanger Surface Area X Flue Damper (Electromechanical) X Side-Arm Heater X Electronic (or Interrupted) Ignition X X (1) used in conjunction with the side-armheater option

Table 2. Design Options Eliminated from Further Consideration Design Options -- Description Criteriafor Elimination Flue Damper (Buoyancy Operated) Safety issues and lack oflong-term use data Submerged Combustion Conflict with health and safety codes Directly Fired Conflict with health and safety codes Condensing Option Venting application restrictions Condensing Pulse Combustion Venting application restrictions18 Design Options - Description CriteriaforElimination Power Vents Venting application restrictions Advanced Forms ofInsulation Fails the practicability to manufacture criterion U-Tube Flue Lack ofworking prototypes and conflictwith safety codes Thermophotovoltaic and Thermoelectronic Lack ofapplication to waterheaters Generators Reduced Burner Size (Slow Recovery) Adverse impact on product utility and venting application restrictions Heat Pump Water Heater Options Lack ofservice and installation infrastructure andproduct utility concerns Timer Controlled Not an efficiency improvement option System Application Options System installation feature Increased Heat Exchanger Surface Area Not as cost effective asthe ImprovedFlue Baffle design option for gas-fired units Air-Atomized Oil Burner Not practical to manufacture and lack of application to water heaters Sediment Removal Features Not an efficiency improvement option Two-Phase Thermosyphon (TPTS) Design Fails the practicability to manufacture EFFICIENCY CALCULATIONS The energy performance ofthe baseline unit ismandated bythe NAECA minimum efficiency standards, which have been in effect since 199112 (Table 3).19 Table 3. NAECA Minimum Efficiency Standards
Product Class Minimum Allowable Energy Factor (as ofApril 15, 1991) Gas-fired Water Heater 0.62

- (.0019 x Rated Storage Volume in gallons) Oil-fired Water Heater 0.59

- (.0019 x Rated Storage Volume in gallons) Electric Water Heater 0.93

- (.00132 x Rated Storage Volume in gallons) Note: Rated Storage Volume =the water storage capacity ofa water heater,in gallons, as specified by the manufacturer.

The design options for each ofthe three classes ofwater 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 ofthe water heater (e.g., the EF, RE, and standby heat loss coefficient (UA)), based upon the DOEtest procedure. The simulation models and energy calculation methods that were used are discussed briefly below. WATSIM Model forElectric Storage WaterHeaters WATSIM is a detailed electric water heating simulation program developed by EPRI'3

. WATSIM contains two simulation algorithms; one for the detailed simulation ofwaterheater tanks and the other for controlling water draw profiles for use with thetank model. Since the simulation analysis mustbe performed according to the requirements ofthe DOE test procedure, the water draw profile is specified to the 64.3 gallon (243.4 liter) draw pattern in thetest procedure. The output ofWATSIM does not include theEF, RE, andUA calculations from the DOE testprocedure. However, it does provide detailed temperature profiles ofthe water inside the tank ofthe water heater during the simulation run (the temperature profile is provided in a standard WATSIM output file called tw_vs_tl.out). These temperature readings are used to determine the EF and other parameters ofthe water heater using the testprocedure calculations. A spreadsheet tool has been developed to calculate the efficiency characteristics per the specifications ofthe DOE testprocedure from the output contained in the tw_vstl.outfile. Appendix A provides a detailed description ofthe procedure to determine the efficiency characteristics using the WATSIM output. TANK Model for Gas-Fired Storage WaterHeaters TANK is a detailed gas-fired storage water heater program developed by Battelle for the GRI'4

. TANK calculates energy flows throughout the waterheater including heat gained or lost by the water, flue heat losses,jacket heat losses, fittings heat losses, and combustion chamber heat losses. Unlike WATSIM, the outputs ofTANK include the EF, RE, and UA20 from the DOE test procedure. Therefore, calculations outside ofTANK are not necessary for determining the gas-fired water heater's energy efficiency characteristics under DOE test procedure. As will be discussed in more detail later, there are limits to how high the flue-loss efficiency can be increased before changes are required ofthe vent system to prevent flue gas condensation. Recent discussions with Battelle'5 indicate that TANK may provide inaccurate estimates ofthe flue-loss efficiency. However, because ofinsufficient data, DOE has decided, fornow, to rely on TANK predictions. Therefore the Engineering Analysis will continue to use TANK's estimates ofthe flue-loss efficiency to indicate whether modifications to the vent system are necessary. WHAM Energy Calculation for Oil-Fired Storage WaterHeaters A simplified water heater analysis model (WHAM) was used for the Engineering Analysis for oil-fired water heaters. WHAM is based onthe 24 hour simulated use test portion ofthe DOE testprocedure. The model is an equation to calculate energy consumption from the RE, UA, and rated input (Pon) 16. The WHAM energy calculations have been checked against both the WATSIM and TANK simulation models to verify that the energy consumption calculations are sufficiently accurate. The WHAM energy calculation isbased on an idealized version ofa water heater. The water temperature is assumed to remain atthe setpoint throughout the tank. Also RE and UA are assumed tobe constant. The equation is listedbelow. 

## Q vol dens- Cp (Ttank

- Tin)

.[ UA (Ttank
- Tmb)
where; Qin = average daily energy input, RE = recovery efficiency from test procedure, UA = standby heat loss coefficient from test procedure, Pn, = rated input, vol =average volume ofwater drawn in 24 hours, T,,,k =tank thermostat set point, T

m = inletwater temperature, Tamb = ambient air temperature surrounding the water heater dens =density ofwater, and Cp = specific heat ofwater. Daily energy use predictions from WHAM for oil-fired water heaters were not directly compared against daily use predictions from any oil-fired water heater simulation model (such as TANK or WATSIM) as no simulation model exists for oil-fired water heaters. However, the results ofthe WHAM equation have been compared against results ofdetailed simulation models ofresidential electric and gas-fired storage water heaters with excellent agreement. A21 detailed explanation ofthe WHAM approach is included in Appendix B. It is believed that WHAM is a good predictor ofdaily energy use for oil-fired water heaters because one of the simplifying assumptions is that all the water drawn from the tank is atthe setpoint temperature. Fora given drawvolume (such as the separate 10.7 gallon (40.5 liter) draws ofthe DOE test),the oil-fired water heater will fire at approximately the same time as would a gas-fired waterheater ofsimilar volume. However, since therecovery rate ofoil-fired waterheaters istypically over twice that ofresidential gas fired water heaters, the temperature ofthe water being drawn from the heater will, on average, be closer to the water heater set point temperature. TECHNOLOGICAL ISSUES There are impending regulatory changes outside ofthe NAECA efficiency standards process that will impact the manufacture or installation ofwater heaters. Some ofthese changes affect the efficiency ofwaterheaters aswell. These issues are described here, along with the methods that were used to address each issue. Insulation Mostresidential water heaters are insulated with polyurethane foam in the space between the tank and thejacket. The insulation is foamed inplace using polyols and isocyanates that react to form a polyurethane foam. Ablowing agent included in themixture is vaporized by the heat ofreaction creating a frothy mass that hardens quickly into closed-cell foam insulation. Currently, water heater manufacturers use HCFC-141b, an ozone depleting substance, as ablowing agent. As aresult oftheMontreal Protocol, the U.S. Environmental Protection Agency has scheduled the phase out ofthis blowing agent bytheyear 2003 7

. Water heater manufacturers must use another blowing agent after that time. One ofthe leading alternatives for use as ablowing agent appears to be HFC-245fa. This blowing agent is being adopted bythe refrigerator industry and should be available in sufficient quantity by 2003. At thetemperatures found in water heaters, information from Bayer and Battelle reports shows that itdoes have a slightly higher k-factorthan the current blowing agent' 8 '9. Based on this information, Table 4 presents conductivity comparisons of foam insulation blown with HCFC-141b and HFC-245fa. The average increase in conductivity resulting fromreplacing HCFC-141b with HFC-245fa is 3.0%.22 Table 4. Conductivity Comparisons between Foam Insulation Blown with HCFC-141b and HFC-245fa Conductivity @ 100°F (37.8°C) HCFC-141b HFC-245fa Source Type of Foam Panel Btu-in/hrft-°F (W/m-K) Btu-in/hrft °F (W/m-K) Bayer 5% pack, 2 in. (5.1 cm) panel 0.149 (0.0214) 0.151 (0.0218) Bayer 10% pack,2 in. (5.1 cm) panel 0.148 (0.0212) 0.154 (0.0221) Bayer 5% pack, 3 in. (7.6 cm) panel 0.152 (0.0220)' 0.155 (0.0223) Bayer 10% pack, 3in. (7.6 cm) panel 0.150 (0.0217)' 0.154 (0.0221) Bayer not specified 0.146 (0.0211) 0.154 (0.0221) Battelle not specified 0.166 (0.0239) 0.172 (0.0247) Average Conductivity Increase 3.0% The analysis forthe DOE water heater energy efficiency standards is based on the properties ofinsulation blown with HFC-245fa andthe most realistic estimates ofcosts and physical parameters available for HFC-245fa. In orderto keep the efficiency and energy use characteristics ofwater heaters with HFC-245fa insulation the same as those with HCFC-141b insulation, itwas necessary to compensate forthe 3.0% higher k-factor. This was accomplished by modeling the water heaters with slightlythicker insulation. In addition to the extra volume and cost ofinsulation, the amount and cost ofsteel used for the water heater jacket were also increased. The industry is also considering other blowing agents in addition to HFC-245fa including HFC-356mffm, HFC-134b, cyclo-pentane, and water blown foams. Water blown foams are created whenwater is mixed into one ofthe components and participates in the chemical reaction leading to polyurethane causing the release ofCO2 which provides the blowing activity. Although the above blowing agents are currently being investigated as possible replacements to HCFC-141b bythe water heater industry, the analysis presented in this report is based on the use ofHFC-245fa. DOE, in collaboration with the National Institute ofStandards and Technology (NIST) and Pacific Northwest National Laboratory, is testing the relative performance ofHCFC-141 b, HFC-245fa and water-CO2 foam blowing agents on water heater performance. The approach ofthe analysis is to measure the thermal conductivity ofblocks foamed with each blowing agent in a guarded hot plate test, and perform a DOE 24-hour simulated use test on tanks foamed with each blowing agent. Twelve 50-gallon (190 liter), dual-element electric water heater tanks were provided by Bradford White and shipped to BASF, a foaming supplier for foaming. BASF foamed a set offour samples (consisting offour tanks and four blocks) with each blowing agent. The foaming oftanks with each blowing agent was timed to ensure a similar aging period has passed prior to the time they are tested. The foaming was carried out, to the extent possible, in accordance with standard industry practices. BASF, on the basis of their expertise and experience, and in consultation with industry experts, determined the23 appropriate parameters regarding the formulation ofthe resin and blowing agent material. The samples, consisting offoam blocks and tanks were shipped to NIST where the following tests were conducted: Guarded Hot Plate: Aone meter guarded hot plate operated in two-sided mode was used to measure the thermal conductivity oftheinsulation blocks. The cold plates were setto 67.5 F (19.7 C). Thermal conductivity measurements were made at hot plate temperatures of 100.0°F (37.8°C), 120.0°F (48.9°C), and 140.0°F (60.0°C). DOE 24-HourTest: NIST usedthe DOE 24-hour simulated usetest to determine EF. The EF testwas conducted on at least three ofthe fourtanks. An infrared camera was used during the DOE testto inspect forgross voids or bridges inthe tankinsulation. If the infrared inspections and EF results were consistent between samples ofa given blowing agent type, NIST could, at itsdiscretion, eliminate the fourth tank from the testing sequence. All final results ofthetests will be fully documented and provided to theDOE. The test results will be used to verify the assumed thermal conductivities ofthe foam insulations used in the Engineering Analysis. Subsequent revisions to the Engineering Analysis will update the insulation conductivities as dictated bythe test results. Flammable Vapor Ignition Current designs for gas-fired water heaters rely on a standing pilot to ignite the main burner. Ifflammable vapors are inthe 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 orpaint thinners may be used. The Consumer Product Safety Commission (CPSC) is working with GRI and the water heater industry to develop atest procedure for gas-fired water heater designs that will prevent ignition offlammable vapors 20

. American National Standards Institute (ANSI) is anticipated to adopt atest procedure regarding 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 fordesigns to prevent ignition offlammable vapors. Inthis analysis, the extra $35 is applied to the manufacturer cost ofall design options for gas-fired water heaters, including the baseline design. Thus, the added cost ofpreventing flammable vapor ignition does not impact the cost effectiveness of any energy efficiency design improvement. The design is also assumed not to require electricity at the water heater or modifications ofthe venting system. No changes in efficiency are expected from flammable vapor ignition resistant water heater designs. This situation will24 be monitored to verify these assumptions or to update the analysis as designs meeting the ANSI standard become available. Venting Useofgas-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 ofthe vent system2122 in certain climates. The Department has recognized this potential problem and decided to incorporate, where necessary, the costs ofventing modifications to gas water heater installation costs. Inthis section, recommendations derived from previous studies conducted by the gas industry are outlined. Appendix C ofthis report provides more details on the impacts ofusing high-efficiency water heaters on vent system corrosion and itsprevention. GRI has estimated that 53% ofU.S. residences have common vent systems for water heaters and furnaces (Paul 1991). With increased minimum furnace efficiency requirements (since 1992), mostreplacement furnaces have a higher efficiency than the existing units they are replacing. Although masonry chimneys are quite resilient to corrosion, relining may be necessary when an existing low flue-loss efficiency (<80%) furnace is replaced with a high flue-loss efficiency furnace (>80%). Because furnace on-times are significantly higher than water heater on-times, the furnace usually dries any condensate deposited in the masonry chimney by the water heater. With the use ofhigh flue-loss efficiency furnaces, the flue gas temperatures are lower, increasing chimney wet-times. Most water heaters sold today are for the replacement market. In almost allreplacement situations, there are vent systems and reliners available in the market to meet the venting requirements forinstalling high flue-loss efficiency water heaters. Hence, there is no technological barrier to use a high flue-loss efficiency waterheater in a replacement situation. Table 5 summarizes the recommendations for atwo-appliance configuration. A base case configuration is assumed to have two natural draft appliances (a furnace and a water heater, for example) venting into a common vent system. The flue-loss efficiency ofeach of these units is assumed to be less than 80%. Thevent connectors are assumed to be single wall metallic connectors and the vent is assumed to be an exterior masonry chimney that is properly sized. Table 6 summarizes the recommendations for a one-appliance configuration. A base case configuration isassumed to have a natural draft water heater venting into an exterior masonry vent system. The flue-loss efficiency ofthe unit is assumed to be less than 80%. The vent connectors are assumed to be single wall metallic connectors and the vent is assumed to be an exterior masonry chimney that is properly sized. This table shows that design options and combinations ofdesign options, which result in a flue-loss efficiency of80% or less can be vented into systems that follow the National Fuel Gas Code 23 standards for venting systems with no additional cost.25


### Table 5. Summary ofGeneral Recommendations forRelining Exterior Masonry Chimneys for Residential Installations in a Two-Appliance Configuration Option Comment Base case: both furnace and water heater flue-loss efficiency less than 80% No relining isnecessary Replace base case water heater with 80.5% efficient (flue-loss) unit No relining is necessary Replace base case water heater with 83% Relining may be needed in most DOE efficient (flue-loss) unit regions Replace base case furnace with 83% Relining ofthe chimney is recommended in efficient (flue-loss) unit (fan-assisted) all regions except DOE region I (Phillips 1994) Ifthe flue-loss efficiency isbetween 80.5% and 83%, chimneys in some DOEregions Replace base case water heater and furnace may need relining. Ifthe flue-loss with highflue-loss efficient units efficiency is above 83%, relining is recommended in all regions except region DOE region I. "Orphaned" water heater Relining is recommended in all DOE regions26 Table 6. Summary ofGeneral Recommendations for Relining Exterior Masonry Chimneys for Residential Installations in a One-Appliance Configuration Option Comment Base case: flue-loss efficiency ofthe water heater is less than 80% No relining is necessary Replace base case water heater with 80.5% efficient (flue-loss) unit No relining isnecessary Replace base case water heater with 83% Relining may be needed in most DOE efficient (flue-loss) unit regions, except DOE region I Another important consideration is the configuration ofthe vent connector

- the portion ofthe vent system connecting the gas appliance flue collar ordraft hood to the vent. A single wall ventconnector limits the flue-loss efficiency ofgas appliances to 80% in aworst case installation. Therefore, ifthe flue-loss efficiency ofthe water-heater orthe furnace (twoappliance configuration) exceeds 80% it isrecommended that a double wall vent connector be used (Paul et al. 1992, Talbert et al. 1995). OVERALL ANALYSIS APPROACH Inthis report, a distinction hasbeen made between baseline models containing current technologies and future baseline models which are expected to incorporate new mandated features. The former are referred to as "existing" baseline models and the latter as "analytic" baseline models. An important feature ofexisting water heater technology is the insulation based onHCFC-141b as ablowing agent. Additionally, for the purposes ofthe analysis, a representative, or "typical" tank size (rated volumes of50-gal for electric, 40-gal for gas-fired, and 32-gal for oil-fired) has been chosen from all the standard sizes foreach fuel type. The first halfofthis discussion concerning costs and prices will address only the typical existing baseline models. ELECTRIC WATER HEATERS The Engineering Analysis models the design options for electric water heaters using WATSIM, a detailed computer simulation model for water heaters developed by EPRI. A 50 gallon (190 liter) rated volume electric resistance water heater is used as the existing baseline model forthis analysis.27 Existing Typical Baseline Model In using WATSIM to establish the typical existing baseline model, the goal was to establish the characteristics ofa 50 gallon (190 liter) baseline electric waterheater which would yield a 0.86 EF (the minimum EF allowed byNAECA for a 50 gallon electric water heater). GAMA's directory ofcertified water heaters and product literature from various manufacturers showsthree models of50 gallon (190liter) electric water heaters with an energy factor of0.86. Two models accomplished this through the use ofheat traps and 1in. (2.5 cm) offoam insulation (American E51-50H-045D andBradford White M-I-50T6DS) while one model achieved a 0.86 EF solely throughthe use of 1in. (2.5 cm) offoam insulation (Rheem 81V52D). It should be noted that the foam insulation in the above models is blown with HCFC-141b. Since the literature indicated that a 0.86 EF was achievable solely through the use of 1in. (2.5 cm) offoam insulation, thefirst typical existing baseline water heater modeled incorporated only this single energy-efficiency design feature. Table 7 summarizes the primary characteristics ofthetypical existing baseline water heater first simulated with WATSIM. Table 7. Initial Existing Electric Water Heaters Baseline Characteristics*
Tank Diameter 15.84 in. (40.23 cm) Tank Length 54.48 in. (138.38 cm) Insulation Thickness

- Sides 1.00 in. (2.54 cm) Insulation Thickness

- Top 1.00 in. (2.54 cm) Conductivity ofFeed-Throughs (equivalent to steel) 0.40 Btu/ft-min °F (41.54 W/mnK) Natural Convection UA for Feed-Through calcs (noheat traps) 0.578 Btu/hr- F (default in WATSIM) Note: *Units inthe table are consistent with the units used bythe WATSIM simulation model. Simulations ofa water heater with the baseline characteristics listed in Table 7 yielded a surprisingly low EF of0.805. WATSIM's simulation results were then compared to those from TANK (GRI's gas-fired water heating simulation model) to determine the cause ofits low EF estimate. Forcomparably sized water heaters, WATSIM's pipe heat loss estimates were approximately twice that ofTANK's. Since during TANK's development its performance was validated against actual test data, WATSIM's method for calculating feedthrough losses was suspected ofbeing inaccurate. To confirm this, additional simulations were conducted to determine whether any specific water heater characteristics could significantly impact EF, thereby ruling out the high feed-through losses as being the cause of the low EF estimate. But the simulations could not identify any physical parameters, besides the addition ofheat traps or an increase inthe thickness ofthe foam insulation, which could reduce water heater losses enough to yield a significantly large impact on EF. Thus,28 WATSIM's default feed-through losses were concluded to be the likely cause for its low EF estimates. EPRI confirmed that WATSIM's feed-through loss estimates were indeed too high, although no indication was given as to the magnitude ofthe error24

. New simulations were conducted after reducing WATSIM's feed-through loss estimates to those predicted by TANK. Lower feed-through losses were realized by lowering the natural convection UA values at the supply and draw lines and byadding 1/8" pipe insulation for modeling purposes only. By using the same initial baseline characteristics as listed previously with the exception ofa UA value of0.185 Btu/hr-°F rather than 0.578 Btu/hr'°F, fornatural convection feed-through losses, a 0.830 EF was predicted. Because the EF estimate was still 0.030 points lower than the target value of0.860 EF,the thickness ofthe foam insulation was increased from 1to '/2 in. (2.5 to 3.8 cm). An 0.858 EF was achieved as aresult ofmaking this change. Thus, the typical existing baseline model as simulated by WATSIM was able to achieve theminimum allowable NAECA efficiency of0.86 EFthrough the use of 1 /2 in. (3.8 cm) offoam insulation. Table 8 describes the physical details ofthetypical existing baseline model electric water heater used in this analysis. These values describe the water heater in engineering terms foruse in the WATSIM simulation model. Table 8. Electric Water Heater Existing Baseline Model Characteristics*

Descriptive parameter Value tank: diameter 15.8 in. (40.1 cm) height 54.5 in. (138.4 cm) wall thickness 0.063 in. (0.16 cm) wall conductivity 0.40 BTU/ftmin- F (41.5 W/m-K) support ring conductivity 0.40 BTU/ftmin-°F (41.5 W/m-K) height ofconcave bottom dome 1.5 in. (3.8 cm) heattransfer coefficient for tank wall film 20.0 BTU/hr-ft 2-F (113.5 W/m2 K) tank insulation

- thickness top: 1.5 in. (3.8 cm) side: 1.5 in. (3.8 cm) bottom: 0.75 in. (1.91 cm) tank insulation

-conductivity top: 0.000233 BTU/ft-min- F (0.0242 W/m-K) side: 0.000233 BTU/ft-min- F (0.0242 W/m-K) bottom: 0.000333 BTU/ft-min- F (0.0346 W/m-K) cold water inlet height 7.5 in. (19 cm) hot water outlet height 54.5 in. (138 cm) heater elements

- height 1: 7.44 in. (18.9 cm) 2: 38.9 in. (98.8 cm) heater elements

- power 1: 4.50 kW 2: .4.50kW29
heater elements

- efficiency 1: 100% 2: 100% thermostats - height 1: 12.0 in. (30.5 cm) 2: 43.7in. (111 cm) feed-throughs

-height 1: 54.5 in. (138 cm) 2: 54.5 in. (138 cm) 3: 1.56 in. (3.96 cm) 4: 54.5 in. (138 cm) feed-throughs

- conductivity 1: 0.40 BTU/ft-min-°F (41.5 W/m-K) 2: 0.40BTU/ft-min °F (41.5 W/m-K) 3: 0.0018 BTU/ft-min-°F (0.1869 W/m-K) 4: 0.40 BTU/ft-min °F (41.5 W/m-K) feed-throughs

- insulation thickness 1: 0.12 in. (0.30 cm) 2: 0.12 in. (0.30 cm) 3: 0 4: 0 feed-throughs

- orientation I: vertical 2: vertical 3: horizontal 4: vertical feed-throughs

-radius 1: 0.5 in. (1.3 cm) 2: 0.5 in. (1.3 cm) 3: 0.5 in. (1.3 cm) 4: 0.5 in. (1.3 cm) feed-throughs

- length 1: 24.0 in. (61.0 cm) 2: 24.0 in. (61.0 cm) 3: 6.0 in. (15.2 cm) 4: 3.6 in. (9.1 cm) feed-throughs

- wall thickness 1: 0.036 in. (0.091 cm) 2: 0.036 in. (0.091 cm) 3: 0.036 in. (0.091 cm) 4: 0.036 in. (0.091 cm) feed-throughs

- insulation conductivity 1: 0.000233 BTU/ft-min °F (0.024196 W/mrK) 2: 0.000233 BTU/ft-min-°F (0.024196 W/m-K) 3: 0 4: 0 feed-throughs

- natural convection pipe loss 1: 0.185 BTU/hr °F 2: 0.185 BTU/hr-°F 3: 0.0 4: 0.0 Note: *Units inthe table are consistent with the unitsused bythe WATSIM simulation model.30 Modeling Design Options As listed in Table 1,there are only four design options that are being considered to improve the efficiency ofelectric storage water heaters. Each design option is briefly discussed below along withhow itwas modeled with WATSIM. The discussion begins with the analysis ofthe baseline model using foam insulation blown with HFC-245fa rather than HCFC-141b. As noted before this baseline model is referred to as an "analytic" baseline model. Analytic Baseline Model. The blowing agent currently utilized bythe water heater industry for foam insulation, HCFC-141b, is scheduled to be phased out by 2003. Because new energy-efficiency standards are expected to take effect near the phase out date ofHCFC141b, the baseline model forthis analysis must utilize foam insulation blown with an acceptable alternative blowing agent. The most likely alternative to replace HCFC-141b appears to be HFC-245fa. According to published reports, HFC-245fa has a 3.0% higher conductivity than HCFC-141b. Thus, the conductivity value ofthe foam insulation in the existing baseline model listed in Table 8 was increased by 3.0% to a value of0.000240 Btu/ft-min- F (0.0249 W/m-K) (the conductivity increase was also applied to the feed-through insulation). In addition, the thickness ofthe foam insulation surrounding the tank was increased to 1.55 in. (3.94 cm) to compensate for the increased conductivity ofthe insulation. This increase in insulation thickness alsoresulted in an increase ofjacket material. Table 9 summarizes the changes that were made to the insulation conductivity ofa typical existing baseline model with HCFC-141b in order to simulate itsperformance with HFC-245fa. Table 9. Electric Water Heater Modeling Differences: Existing vs. Analytic Baseline Model

- Insulation Conductivity*

Baseline Baseline Descriptive parameter

_ __ w/ HFC-141b w/ HFC-245fa 0.000233 BTU/ft-min-°F 0.000240 BTU/ft-min-°F insulation conductivity (0.02420 W/m-K) (0.024922 W/m-K)
Note: *Units in the table are consistent withthe units used by the WATSIM simulation model. HeatTraps. The heat conducted and convected through the fittings (water pipes, drain valve, pressure reliefvalve, andthermostat) accounts for a significant portion ofthe total standby loss in atypical residential-size waterheater25

. Aheat trap isa device or arrangement ofpiping that keeps the buoyant hot water from circulating through a piping distribution system because ofnatural convection. When there is no draw ofhot water, this device 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 out into the cold water inlet line. Thus,31 by containing the hotwater inthe storage tank, the heattrap minimizes standby loss. These devices canbe integral to the tank design or independently attached to the inlet and outlet pipes during installation. Conventional heat traps are currently made in two styles. In the first style, a floating plastic ball blocks the cold water inlet. The buoyancy oftheplastic holds it in place until water is drawn. The force ofwater is strong enough topush the ball out ofthe way as water entersthe tank. The second style is used forthe hot water outlet. In thisheat trap,the ball is denser than water, and the weight ofthe ball seals the outlet until hot water is drawn and the water pressure lifts it out ofthe way. A small bypass channel is left for water to escape back into the inlet line from the tank. This isnecessary because after alarge draw fillsthe tank with cold water,the water expands as it isheated. Otherheat trap designs have also been invented and produced. These include U-shaped pipes 26,flexible seals27, flaps, springs, and other mechanisms. Forthis analysis, heat traps were analyzed as being either metal or plastic. Both types ofheat traps prevent the losses associated withthe circulation ofhot water into the piping distribution system. For purposes ofthis analysis, metal heattraps are considered to bethose devices which are attached tothe inlet and outlet pipes. Plastic heat traps are considered to be those devices which are integral to the tankdesign. On the inlet side, the plastic heat trap ispart ofa plastic dip tube assembly where the heat trap mechanism resides near the top ofthe water heater but within the tank. On the outlet side, the plastic heattrap ispart ofa heat trap/anode device where the heattrap mechanism ispart ofa plastic cartridge enclosed within the steel pipe that houses the entire heattrap/anode device. To simulate the performance ofheat traps,the UA values for calculating the natural convection heat transfer losses atthe supply and draw lines were lowered bya magnitude of 0.122 Btu/hr-°F28

. The above procedure models the heat losses associated with hot water recirculation. TANK, the simulation tool forthe modeling ofgas-fired storage heaters, models both metal andplastic heat traps. Based upon modeling the performance ofa40 gallon (150 liter) gas-fired water heater with TANK, plastic heat traps prevent losses of approximately 500 Btu/day (530 kJ/day) relative to metal heat traps. To model plastic heat traps in WATSIM, the conductivity ofthe insulation surrounding the supply and draw lines was decreased to achieve the 500 Btu/day (530 kJ/day) savings. Table 10 summarizes the changes made to the analytic baseline model (with HFC-245fa) in order to simulate the performance ofmetal and plastic heat traps.32 Table 10. Electric Water Heater Modeling Differences: Analytic Baseline Model vs. Models withMetal and Plastic Heat Traps*
with Metal with Plastic Descriptive parameter Analytic Baseline with Metal th ast Heat Traps HeatTraps feed-throughs

- insulation I 0.000240 BTU/ft-min-°F 0.000240 BTU/ftmin-F 0.000010 BTU/fimin-°F (0.024922 W/m-K) (0.024922 W/m-K) (0.001308 W/m-K) 0.000240 BTU/ft-min-°F 0.000240 BTU/ft-min-°F 0.000010 BTU/ft-min-°F conductivity 2: (0.024922 W/m-K) (0.024922 W/m-K) (0.001308 W/m-K) feed-throughs

-natural convection 1: 0.185 BTU/h °F 0.063 BTU/h °F 0.063 BTU/h-°F pipe loss 2: 0.185 BTU/h-°F 0.063 BTU/h-°F 0.063 BTU/h °F Note: *Units in the table are consistent with theunits used bythe WATSIM simulation model. Increased JacketInsulation. Thejacket (sides and top) ofthe water heater is insulated with polyurethane foam or fiberglass. Because polyurethane foam has a lower thermal conductivity than fiberglass and is cheaper to install in large volume manufacturing, it is used almost exclusively. Most water heaters on the market today have atleast 1-in. (2.5 cm) thick foam insulation, while some manufacturers provide 2- or 3-in. (5.1 or 7.6 cm) thick insulation, as well. Although increasing the insulation thickness reduces the standby loss, the increase inthe overall diameter ofthe water heater may pose someinstallation problems. There will also be an increase in shipping costs because fewer heaters will fit in a truck. Because ofthese potential installation problems, maximum insulation thicknesses were limited to 21/2 in. (6.4 cm) forthis analysis. Table 11 summarizes the changes made to the analytic baseline model (with HFC245fa) to simulate the performance ofan electric water heater insulated with 2- and 22-in. (5.1 cm and 6.4 cm) offoam insulation. Table 11. Electric WaterHeater Modeling Differences: Analytic Baseline Model vs. Models w/ 2 & 21/2 in. offoam insulation
with 2 in. of with 2/2 in. offoam Descriptive parameter Analytic Baseline foam insulation insulation tank insulation

-thickness top: 1.55 in. (3.94 cm) 2.00 in. (5.08 cm) 2.50 in. (6.35 cm) side: 1.55 in. (3.94 cm) 2.00 in. (5.08 cm) 2.50 in. (6.35 cm) Insulating theTank Bottom. The bottom ofthe tank ofan electric water heater can be insulated with polyurethane foam to reduce the standby heat losses. The use of polyurethane foam insulation underneath the tank bottom is not conventional practice. Currently, manufacturers might place fiberglass insulation inthe space allotted underneath the bottom ofthe water heater due to the concaveness ofthe tank. For this analysis, the height of the baseline model's concave dome is assumed to be 1 /2 in. (3.8 cm) with 3 Ain. (1.9 cm) of fiberglass insulation stuffed below it.33 Inmodeling foam insulation for the tank bottom it was assumed that a foamed "disk/bottom insulation" assembly would be used. WATSIM models the heat transfer through the bottom ofthe tank by two separate parallel heattransfer paths

- "bottom" and "support ring". The "bottom" represents the area ofthe concave dome and the "support ring" represents the perimeter, which is a continuation ofthe tank wall below the bottom ofthe tank. The "bottom insulation" portion ofthis assembly fills the domed space underneath the tank. The "disk" portion is assumed to lieunderneath both the support ring and the "bottom insulation". Although the "disk" portion ofthis assembly is assumed to be only 1/a in. (3.2 mm)thick, water heater construction practices prevent the support ring from deforming it, when thetank is filled withwater. The adhesive and structural properties ofthe foam insulation keep the tank from crushing the bottom insulation. The bottom insulation portion ofthe "disk/bottom insulation" assembly reduces the heat losses from the bottom ofthe tank, while the disk portion reduces the conduction heat losses throughthe support ring. Table 12 summarizes the changes made to the analytic baseline model to simulate the performance ofelectric water heaters with bottominsulation. The support ring conductivity is assumed to be 50% steel and 50% foam insulation. As aresult, its conductivity was twice that offoam insulation. Table 12. Electric Water Heater Modeling Differences: Analytic Baseline Model vs. Model withFoamed Bottom Insulation* Descriptive parameter Analytic Baseline Foamed Bottom Insulation tank:support ring conductivity 0.40 BTU/ft-min °F(41.54 W/m-K) 0.000472 BTU/ft-min- F (0.0490 W/m-K) tank insulation

- thickness bottom: 0.75 in. (1.91 cm) 1.5 in.(3.8 cm) tank insulation

- conduct.bottom: 0.000333 BTU/ft-min-°F (0.0346 W/m-K) 0.000240 BTU/ft-min- F (0.0249 W/m-K) *Units inthe table are consistent with use by WATSIM. Plastic Tank. There are at least two methods for constructing plastic water heater tanks. One method uses a seamless, blow-molded polybutylene inner tank with a filamentwound fiberglass outertank, similar to the fabrication oftanks forwater softeners 29

. Another method consists ofconstructing a thin steel shell with an internal plastic tank. The tank is fabricated by first constructing the steel exterior, injecting plastic powder within the steel shell, and thenrotating the tank within a furnace, thereby, coating the interior with the plastic. The steel exterior serves as the primary structural support for the tank. It isapproximately 1/16 in. (1.6 mm) thick while theplastic interior, 1/16 in. to 1 /s in. (1.6 mm to 3.2 mm) thick, provides a non-corrosive surface in addition to some structural support. In both types of plastic tanks, the lower heat conductivity ofthe plastic compared to steel reduces the amount ofheat conducted through the tank wall to the insulation. Both ofthe plastic tank construction methods enable an improved process ofinsulating the tank bottom. In typical electric water heaters utilizing metal tanks, the metal ofthe tank wall extends below the bottom ofthe tank and acts as a support ring. This support ring has direct contact through the bottomjacket with the floor and provides a path for conduction heat losses to the floor. Since the plastic tanks34

are completely insulated, standby losses from the bottom ofthe tank are significantly reduced. The "steel shell/plastic interior" tank was the plastic tanktype modeled forthis analysis as itis the least expensive to manufacture. Inmodeling this plastic tanktype with WATSIM, the tank wall thickness and conductivity were modified to correspond to the plastic instead of steel. (The conductivity ofthe plastic/steel composition atthe thickness levels described above is virtually identical to plastic.) In addition, the support ring material was changed from steel to foam insulation and the bottom insulation was increased to 1in. (2.5 cm) offoaminsulation. Table 13 summarizes the changes made tothe analytic baseline model to simulate the performance ofa plastic tank. Table 13. Electric Water HeaterModeling Differences: Analytic Baseline Model vs. Plastic Tank* Descriptive parameter Analytic Baseline Plastic Tank tank:wall thickness 0.063 in. (0.16 cm) steel 0.0853 in. (0.16 cm) plastic 0.126 in. (0.32 cm) wall conductivity 0.40 BTU/ft-min-°F (41.54 W/m-K) 0.0018 BTU/ft-min-°F (0.1869 W/m-K) support ring conductivity 0.40 BTU/ft-min-°F (41.54 W/m-K) 0.000236 BTU/ft-min °F (0.024507 W/m-K) tank insulation

- thickness bottom: 0.75 in. (1.91 cm) 1.0 in. (2.54 cm) tank insulation

- conduct. bottom: 0.000333 BTU/ft-min-°F (0.0346 W/m-K) 0.000240 BTU/ft-min-°F (0.0249 W/m-K) Note: *Units in the table are consistent with the unitsused bythe WATSIM simulation model. Design Option ManufacturerCosts Manufacturer costs wereprimarily based upon dataprovided by GAMA with the exception ofthe plastictank design option, which were provided byMax Minniear. The cost estimates were based upon the production ofa 50 gallon (190 liter) electric water heater were disaggregated into variable (material, labor, transportation, overhead) and fixed (capital, product design) costs. Design optionvariable costs (from GAMA and Mr. Minniear) and fixed costs (from GAMA) wereprovided as a per unit cost andexpressed as an incremental increase over the baseline design. The plastic tank design option fixed costs were provided as the "lump sum" amount required to convert the baseline production to the new design and the "lump sum" amount was converted to a per unit costby amortizing itover a five year period and dividing it by Mr. Minniear's assumed baseline model production volume of40,000 units per year.35 Existing Baseline Model. GAMA's existing baseline model cost estimates were based upon awater heater with 1I2in. (3.8 cm) offoamedjacket insulation using HCFC-141 b as ablowing agent. Forthe other levels ofinsulation, the amount and cost ofmaterials associated with varying thicknesses ofHCFC-141b foam insulation were developed. Thus, the material costs associated with aparticular level ofinsulation could easilybe determined by either subtracting from or adding to GAMA's baseline costs. Table 14 summarizes the material costs associated with varying levels offoam insulation blown with HCFC-141b. The material costs ofHCFC-141b foam insulation ($1/lb or $2.2/kg) and sheet metal ($0.30/lb or $0.66/kg) were based on estimates by Mr. Minniear30

. Table 14. Existing Electric Water Heater Material Costs Associated with varyingthicknesses ofHCFC-141b Foam Insulation Polyurethane Foam 141b JacketSheet Metal Misc Total thickness volume' weight2 cost3 area thickness weight' cost5 cost 6 cost

in. (cm) ft' (m 3 ) lb (k) ft2 (m 2 ) ft3(m3 ) lb (kg) 1.0(2.5) 1.83 (0.05) 3.65 (1.66) $3.65 23.99(2.23) 0.038(0.001) 18.57(8.42) $5.57 $0.00 $9.23 1.5(3.8) 2.84(0.08) 5.68(2.58) $5.68 25.66(2.38) 0.041(0.001) 19.87(9.01) $5.96 $0.00 $11.64 2.0(5.1) 3.92(0.11) 7.84(3.56) $7.84 27.37(2.54) 0.043(0.001) 21.19(9.61) $6.35 $5.67 $19.86 2.5(6.4) 5.07(0.14) 10.14(4.60) $10.14 29.12(2.71) 0.046(0.001) 22.54(10.22) $6.76 $8.04 $24.94 3.0(7.6) 6.29(0.18) 12.59(5.71) $12.59 30.90(2.87) 0.049(0.001) 23.92(10.85) $7.18 $11.59 $31.35 50 gallon (190 liter) tank dimensions: diameter = 15.8 in. (40.1 cm), length = 54.5 in. (138.4 cm), dome height = 1.5 in. (3.8 cm) 2Foam density = 2 Ib/ft 3 (32 kg/m') Foam cost= $1/lb ($2.2/kg) Sheet metal density = 489 Ib/ft' (7833 kg/m3) Sheet metal cost = $0.30/lb ($0.66/kg) 6Miscellaneous cost includes additional cost for dams to contain the insulation in a larger cavity during foaming. Analytic Baseline Model. In order to convert the baseline manufacturer costs associated with foam insulation blown with HCFC-141b to that blown with HFC-245fa, the amount and cost ofmaterials associated with varying thicknesses ofHFC-245fa foam insulation were developed. Thus, thematerial costs associated with aparticular level ofHFC245fa insulation could easily be determined by addingto the baseline costs associated with a comparable level ofHCFC-141b foam insulation. Table 16 summarizes the material costs associated with varying levels ofHFC-245fa foam insulation. The material costs ofHFC245fa foam insulation ($1.32/lb or $2.9/kg) were based onestimates by Allied Signal31

. Table 15 shows the calculation of the total foam cost forHFC-141b and HFC-245fa foam insulation, based on the component cost estimates.36 Table 15. Foam Components Cost Estimate
Foam Components Fraction Component Total Cost Total Cost Cost (141b) (245fa) % $/lb $/lb $/lb blowing agent (141b) 13.00% $1.50 $0.20 blowing agent (245fa) 13.00% $4.00

- $0.52 isocyanurate 51.00% $0.75 $0.38 $0.38 polyols 31.00% $0.65 $0.20 $0.20 catalysts, refractants, etc. 5.00% $4.50 $0.23 $0.23 Total 100.00% $_1.00 $1.32 Table 16. Analytic Electric Water Heater Material Costs Associated with varying thicknesses ofHFC-245fa Foam Insulation Polyurethane Foam 245fa Jacket Sheet Metal i Misc Total thickness' volume2 weights cost 4 area thickness' weight5 cost' cost 7 cost in.(cm) ft3 (m 3 ) lb (kg) (m2) ft l (m) lb (kg) 1.0(2.5) 1.83(0.05) 3.65(1.66) $4.82 23.99(2.23) 0.038(0.001) 18.57(8.42) $5.57 $0.00 $10.39 1.55(3.94) 2.95(0.08) 5.90(2.68) $7.78 25.84(2.40) 0.041(0.001) 20.00(9.07) $6.00 $0.00 $13.78 2.0 (5.1) 3.92 (0.11) 7.84 (3.56) $10.35 27.37 (2.54) 0.043 (0.001) 21.19(9.61) $6.35 $5.67 $22.37 2.5 (6.4) 5.07 (0.14) 10.14 (4.60) $13.39 29.12 (2.71) 0.046(0.001) 22.54 (10.22) $6.76 $8.04 $28.19 3.0 (7.6) 6.29 (0.18) 12.59 (5.71) $16.61 i30.90 (2.87) 0.049 (0.001) 23.92 (10.85) $7.18 $11.59 $35.38 'Thickness increased dueto increased conductivity of245farelative to 141b. 250 gallon (190 liter) tank dimensions: diameter = 15.8 in. (40.1 cm), length = 54.5 in.(138.4 cm), domeheight = 1.5 in.(3.8 cm) 3Foam density = 2 Ib/ft 3 (32 kg/m') 4Foam cost = $1.32/lb ($2.9/kg) 5

Sheet metal density= 489 Ib/ft3 (7833 kg/m') 6 Sheet metal cost =$0.30/lb ($0.66/kg) 7Miscellaneous cost includes additional cost for dams tocontain the insulation inalarger cavity during foaming. As noted in Table 16, the actual thickness level for 1.5 in. (3.8 cm) ofHFC-245fa foam insulation was assumed to be slightlygreater than that for HCFC-141b foam insulation due to HFC-245fa's higher conductivity. For this analysis it was assumed that manufacturers would retain the same level ofinsulation thermal resistance for their baseline model when switching from HCFC-141b to HFC-245fa foam insulation. Table 17 presents the manufacturer cost estimates for a 50 gallon (190 liter) electric water heater with 1/2 in. (3.8 cm) ofHCFC-141b foam insulation and the costs associated with the same baseline model foamed with HFC-245fa insulation. The material costs for the HCFC-141b baseline model were adjusted upward by the difference in material costs ($2.14) calculated between the HCFC-141b and HFC-245fa models.37 Table 17. Electric Water Heater Baseline Model with HCFC-141b and HFC-245fa: Manufacturer Costs
Variable Costs (per unit) Fixed Costs (perunit) Total Product Mfg Design Material Labor Overhead Total Capital Design Total Cost Baseline w/141b- 1.5 in (3.8 cm) $62.16 $12.41 $50.99 $125.56 $0.00 $0.0 0.00 $125.56 Baselinew/245fa- 1.55in (3.94 cm) $64.30 $12.41 $50.99 $127.70 $00.00 $.00 $0.00 $127.70 Heat Traps. Manufacturer costs for metal and plastic heat traps were based upon data 

### provided by GAMA. GAMA's data didnotprovide separate costs for metal and plastic heat traps. Data from the heat trap manufacturer Perfection, Inc.32 

### was used as areference. Metal heat trap material costs for boththe supply and draw lines were based on a%-in. (1.9 cm)by 3-in. (7.6 cm) pipe nipple assembly design. Plastic heat trap material costsfor the supply line were based on aplastic drop-in-tube design while those for thedraw line were based on a plastic cartridge heat trap design within a combined outlet and anoderod assembly. Table 18 summarizes the incremental manufacturer costs for incorporating metal and plastic heat traps into an electric water heater. GAMA didnot disagregate the capital cost and theproduct design cost butprovided a total fixed cost.The costs reflect theaddition ofheat traps to both the supply and draw lines. Table 18. Heat Traps for Analytic Electric Water Heaters: Incremental Manufacturer Costs |Incremental Variable Costs (per unit) Incremental Fixed Costs (per unit)j Total Product Incremental Design IMaterial Labor Overhead Total Capital Design Total ! Mfg Cost Heat Traps (metal) $2.59 $0.20 $0.83 $3.62 $0.00 $0.00 $0.39 $4.01 Heat Traps (plastic) \ $2.59 $0.20 $0.83 $3.62 $0.00 $0.00 $0.39 $4.01 Note: 1)Perfection Inc.'s datawasalmost identical forboth types($3.00 forplastic and $2.95 formetal heat traps); 2)Note that GAMA's heattrap variable costs are different for electric water heaters and gas-firedwater heaters. IncreasedJacket Insulation. Since the analytic baseline model for the Engineering Analysis assumes foam insulationbased on HFC-245fa, manufacturer cost estimates for increases in thejacket insulation were based upon insulation blown with HFC-245fa. All foam cost data were based on information provided by Allied Signal. As presented earlier, Table 14 depicted the material costs for varying levels ofHFC-245fa foam insulation. GAMA provided variable cost and fixed cost data forjacket insulation increases from abaseline level of 1.5 in. (3.81 cm) to a thickness of2.0 in. (5.1 cm) only. In order to generate variable cost and fixed cost datafor the next level ofinsulation, the data provided by M. Minniear was used to calculate ratios ofvariable and fixed cost for2" insulation to 2.5" insulation. GAMA's costs for 2.0 in. (5.1 cm) insulation modified for 245fa blowing agent, were multiplied by those ratios to approximate the variable and fixed costs for 2.5 in. (6.4 cm) ofinsulation. Table 18 summarizes the incremental manufacturer costs forjacket insulation increases from a baseline level of 1.5 in. (3.81 cm) to a thickness of2.0 in. (5.1 cm) and 2.5 in. (6.4 cm) (using38 material cost provided in Table 16). As stated earlier, insulation thicknesses were limited to 2/2 in. (6.4 cm) due to installation and shipping concerns. Table 19. Increased Jacket Insulation for Analytic Electric Water Heaters: Incremental Manufacturer Costs
Incr. Variable Cost(per unit) Incr.Fixed Costs (perunit) Total Product Incremental Design Material Labor Overhead Total Capital Design Total MfgCost Incr. Insulation

- 2.0 in (5.1 cm) $8.59 $0.51 $3.66 $12.76 $0.00 $0.73 $0.73 $13.49 Incr. Insulation

- 2.5 in(6.4 cm) $14.41 $1.02 $7.32 $22.75 $0.00 $1.02 $1.02 $23.77 

### Insulatingthe TankBottom. Manufacturer costs for insulating thetank bottom were based on data from GAMA, which included total incremental variable cost and total fixed cost only. Table 20 summarizes the incremental manufacturing costs for insulatingthe tank bottom. The modeling ofthis design option is based on the following considerations: The bottom insulation is assumed to fill the entire space covered bythe concave dome. Since the bottom insulation also consists ofan 1 /s-in. (3.2 mm) foamed disk which the water heater "stands" on,the overall height ofthe water heater is increased by 1/8ofan in. (3.2 mm). It is important to note, that atthis time no explanation ofthe design assumptions associated with insulating the tank bottom was provided by GAMA. Other sources (Max Minniear and Eugene West), provided an incremental total cost almost a magnitude lower than GAMA's. Forcomparison, Mr. Minniear's total manufacturing cost estimate is $4.25 and Mr. West's estimate for material cost only is $0.85. Table 20. Insulating the Tank Bottom for Analytic Electric Water Heaters: Incremental Manufacturing Costs iIncremental Variable Costs (per unit)lIncremental Fixed Costs (per unit): Total Product Incremental Design I Material Labor Overhead Total Capital Design Total MfgCost Insulate Tank Bottom ' $0.00 $0.00 $0.00 $26.98 i $0.00 $0.00 $3.39 $30.37 Plastic Tank. Manufacturer costs for a plastic tank electric storage water heater design were based ondata provided by Mr. Minniear. The plastic tank design isbased on the "steel shell/ plastic interior" tank type discussed earlier and assumes a tank wall thickness of 0.20 in. (5.1 mm). Table 21 summarizes the incremental manufacturer costs for switching from a metal tank to a plastic tank design.39 

### Table 21. Plastic Tank Design for Electric Water Heaters: Incremental Manufacturer Costs
IncrementalVariable Costs (per unit) Incremental Fixed Costs (perunit) Total Product Incremental Design Material Labor Overhead Total Capital Design Total MfgCost Plastic Tank $5.25 $0.80 $3.20 $9.25 l $15.00 $3.00 $18.00 $27.25 Design Option Retail Prices 

### For purposes ofthisanalysis, the retail price is considered to be the cost to the consumer ofonlythe waterheating equipment. The cost to the consumer ofinstalling the water heater (i.e., the installation cost) isnot considered tobe part ofthe retail price and is discussed later. Theretail price for abaseline 50-gallon (190 liter) electric storage waterheater (with HCFC-141b foam insulation) was determined by contacting various plumbing contractors and large retail chains. Sincethe price ofawater heater is a function ofthelength ofthe manufacturer's warranty, only water heaterswarrantied for 5years were considered as baseline models. The 5year warranty isthe shortest warranty period offered bywater heater manufacturers (although a 1year warrantyis offered in special cases) and is typically reserved for those models which are produced in large volumes (i.e., baseline models). A longer warranty time period, in addition toraising the price, mayindicate the presence ofdesign feature not normally found in baseline models. Table 22provides the listofretail prices used to develope the retailprice ofthe baseline model. For each price listed, the source is also provided. All datapresented inTable 22 are fromtheLBNL Water Heater Database33



### . Table 22. 50-Gallon (190 liter) Electric Storage Water Heater Retail Prices Source Manufacturer Brand Model Retail Denver, CO State Industries Reliance 5-52-20RT $128.00 Dale City, VA American Water Heaters Craftsman $128.00 Atlanta, GA American Water Heaters PROLine E52-50R-045DV $129.00 Atlanta, GA American Water Heaters PROLine E52-50R-045DV $135.00 Stockbridge, GA American Water Heaters Envirotemp E52-50R-045DV $138.00 Marieeta, GA American Water Heaters Envirotemp E52-50R-045DV $138.00 Charlotte, NC American Water Heaters More-Flo E52-50R-045DV $141.00 Dallas, TX State Industries Reliance 5-52-20RT $146.00 WestAllis, WI American Water Heaters American $147.00 Chicago, IL American WaterHeaters More-Flo E52-50R-045DV $148.00 Minneapolis, MN American Water Heaters More-Flo E52-50R-045DV $148.00 SW Jackson, MS American Water Heaters American E52-50R-045DV $149.00 Lexington, KY American Water Heaters American E52-50R-045DV $149.00 New Orleans, LA American Water Heaters American E52-50R-045DV $149.00 Jacksonville, FL A.O. Smith Energy Saver EES-52 $152.00 Nashville, TN American Water Heaters American E52-50R-045DV $157.0040 Source Manufacturer Brand Model Retail St. Louis, MO American Water Heaters American E52-50R-045DV $160.00 Kilgore, TX A.O. Smith Energy Saver FSG-50 $163.00 Salt Lake City, UT American Water Heaters American E52-50R-045DV $168.00 Denver, CO State Industries Reliance 5-52-20RT $168.00 Reno, NV American Water Heaters American E52-50R-045DV $168.00 Harrisonburg, VA State Industries SCD-552-2ORT $170.00 Richmond, CA Sears/State Industries Kenmore 31256 $170.00 Charlotte, NC American Water Heaters $171.00 Sacramento, CA American Water Heaters American E52-50R-045DV $172.00 Seattle, WA State Industries Reliance 5-52-20RT $175.00 Nashville, TN American Water Heaters American E52-50R-045DV $177.00 Winchester, VA Rheem Rheem 81V52D $178.00 Phoenix, AZ State Industries Reliance 5-52-20RT $179.00 Las Vegas, NV State Industries Reliance 5-52-WORT $179.00 Fredericksburg, VA State Industries CD5-52-2ORT $180.00 Corpus Christy, TX Rheem Standard 81V52D $180.00 Boise, ID State Industries Reliance 5-52-2KRT $183.00 Boise, ID State Industries Reliance 5-52-20RT $184.00 Oklahoma City, OK State Industries Reliance 5-52-20RT $187.00 St. Louis, MO American Water Heaters American E52-50R-045DV $189.00 Boston, MA State Industries Powermiser 5 31256 $190.00 Indianapolis, IN State Industries CD6-52-20RT $197.00 Salt Lake City, UT American Water Heaters American E52-50R-045DV $198.00 Boston, MA State Industries Powermiser 5 31256 $200.00 Livermore, CA Sears/State Industries Kenmore $200.00 Charlottesville, VA Rheem Ruud PE52 $208.00 Boise, ID State Industries Reliance 5-52-2KRT $208.00 Berkeley, CA Rheem Rheem 81V52D $227.00 Anchorage, AK Bradford White $231.00 Tampa, FL Rheem Standard 81V50D $234.00 Berkeley, CA Rheem Rheem 81SV52D $239.00 Boston, MA State Industries Anniv. Series 10 $250.00 Bristow, VA Rheem Rheem 81V52D $282.00 Boise, ID State Industries Reliance 5-52-2KRT $297.00 Average Retail Cost $178.88 As listed in Table 22, the average retail price for a baseline 50 gallon (190 liter) electric storage water heater was $178.88 (without taxes). As presented earlier, the manufacturer cost ofany existing baseline water heater is $125.56. Using the average national value for taxes of5.20% (developed by A.D.L, 1998), yields aretail price of$188.18. Dividing the retail price ($188.18) by the manufacturer cost ($125.56) it yields a manufacturer cost-to-retail price markup of 1.50 (an exact value of 1.49874 is used as a multiplier).41 The baseline manufacturer cost-to-retail price markup was assumed constant for all design options considered for this analysis. Thus, the retail price for any modified design was simply determined bymultiplying the manufacturer cost by the derived markup of 1.50. Installation and Maintenance Costs The installation cost is the cost to the consumer ofinstalling the water heater and is not considered part oftheretail price. The costofinstallation covers all labor and material costs associated with the simple replacement ofan existing water heater. Delivery, removal, and permit fees are also included. LBNL collected datato establish the installation cost ofa 50 gallon (190 liter) baseline electric storage waterheater from the same sources that the retail price data was obtained. Table 23 lists the installation costsfor the water heater models. The average installation cost was $160.73. None ofthe design options considered forthis analysis increased the installation cost ofa baseline electric storage water heater. All datapresented in Table 23 are from the LBNL Water Heater Database34

. Table 23. 50-Gallon (190 liter) Electric Storage Water Heater Installation Costs
Source Manufacturer Brand Model Installation Berkeley, CA Rheem Rheem 81SV52D $65.00 Berkeley, CA Rheem Rheem 81V52D $65.00 Boise, ID State Industries Reliance 5-52-2KRT $114.00 Boise, ID State Industries Reliance 5-52-2KRT $114.00 Boise, ID State Industries Reliance 5-52-2KRT $114.00 Boise, ID State Industries Reliance 5-52-2KRT $114.00 Stockbridge, GA American Water Heaters Envirotemp E52-50R-045DV $119.00 Salt Lake City, UT American Water Heaters American E52-50R-045DV $125.00 Salt Lake City, UT American Water Heaters American E52-50R-045DV $125.00 Denver, CO State Industries Reliance 5-52-20RT $130.00 Denver, CO State Industries Reliance 5-52-20RT $130.00 SW Jackson, MS American Water Heaters American E52-50R-045DV $135.00 Phoenix, AZ State Industries Reliance 5-52-20RT $136.00 Atlanta, GA American Water Heaters PROLine E52-50R-045DV $142.00 Nashville, TN American Water Heaters American E52-50R-045DV $145.00 Nashville, TN American Water Heaters American E52-50R-045DV $145.00 Charlotte, NC American Water Heaters More-Flo E52-50R-045DV $145.00 Marieeta, GA American Water Heaters Envirotemp E52-50R-045DV $149.00 Reno, NV American Water Heaters American E52-50R-045DV $154.00 Charlotte,NC American Water Heaters $155.00 Dallas, TX State Industries Reliance 5-52-20RT $155.00 West Allis, WI American Water Heaters American $159.00 St. Louis, MO American Water Heaters American E52-50R-045DV $160.00 St. Louis, MO American Water Heaters American E52-50R-045DV $160.00 Dale City, VA American Water Heaters Craftsman $169.0042 Source Manufacturer Brand Model Installation Springfield, VA Rheem Rheem 81V52D $170.00 Springfield, VA A.O. Smith A.O. Smith EES52 $170.00 Las Vegas, NV State Industries Reliance 5-52-20RT $170.00 Richmond, CA Sears/State Industries Kenmore 31256 $174.00 Tampa, FL Rheem Standard 81V50D $175.00 Oklahoma City, OK State Industries Reliance 5-52-20RT $180.00 Lexington, KY American Water Heaters American E52-50R-045DV $200.00 Chicago, IL American Water Heaters More-Flo E52-50R-045DV $209.00 Sacramento, CA American Water Heaters American E52-50R-045DV $210.00 Boston, MA State Industries Anniv. Series 10 $220.00 Boston, MA State Industries Powermiser 5 31256 $220.00 Boston, MA State Industries Powermiser 5 31256 $220.00 New Orleans, LA American Water Heaters American E52-50R-045DV $225.00 Seattle, WA State Industries Reliance 5-52-20RT $231.00 Atlanta, GA American Water Heaters PROLine E52-50R-045DV $234.00 Minneapolis, MN American Water Heaters More-Flo E52-50R-045DV $258.00 Average Installation Cost $160.73 Information gathered to date suggests thatthere is virtually no maintenance of residential electric water heaters, although manufacturers recommend they be drained and flushed annually to minimize deposition ofsediment, maintain operating efficiency and prolong equipment life. Thus, maintenance costs were not developed for the baseline model. The design options considered forthis analysis were assumed not to increase the maintenance cost ofelectric water heaters. Cost-Efficiency Data The results ofthe design option analysis for 50 gallon (190 liter) electric storage water heaters are presented in Table 24. Included in the cost-efficiency table are the following: disaggregated manufacturer costs, retail prices, installation costs, maintenance costs, energy factor, energy use, and payback periods. Design options were added incrementally to the baseline model in order ofshortest payback period. The payback period for each setofdesign options was calculated relative to the baseline design according to the following relationship: 

### ACC ARC+ AIC PAYBA CK=
- = 

### AOC AEC+AMC where; PAYBACK = payback period (years), ACC = change in consumer cost relative to baseline, ($), AOC = change in operating cost relative to baseline, ($/year), ARC = change inretail cost relative to baseline, ($), AIC = change in installation cost relative to baseline, ($), AEC = change in energy cost relative to baseline, and ($/year),43 AMC =change in annualized maintenance cost relative to baseline, 

### ($/year). The existing baseline design with HCFC-141b foam insulation is presented in Table 24 to show the manufacturer cost and retail price differences between the baseline designs with HCFC-141b and HFC-245fa. For purposes ofthis analysis, the cost effectiveness ofall design options were evaluated relative to the analytic baseline design with HFC-245fa. Energy costs were from national average energy prices fortheyear 2003 from the 1998AnnualEnergy Outlook35. Metal heat traps are not included in the cost/efficiency table because plastic heat traps are more cost effective. The highest EF attainable is 0.908 which can be achieved through the use ofplastic heat traps, 2'/2 in. (6.4 cm) of jacket insulation, and aplastic tank. The payback period ofthis design isjust over 4 years and there are 238 kWh/yr energy savings. Electric water heaters incorporating plastic heat traps, 2.5 in. ofinsulation and tankbottom insulation have a payback of4.6 years. This design saves 233 kWh/yr in electricity. As described earlier in thisreport, theEF and other parameters ofthe water heater, such as the RE, were determined from output generated bythe WATSIM simulation model and the DOE test procedure equations. It is interesting to note that therecovery efficiencies calculated in thismanner for the baseline model and design options and reported in Table 24 are less than the 98% RE default permitted bythe DOE test procedure. Figure 1graphically depicts the relationship between both increased consumer cost and increased operating cost versus EF.44 Table 24. Cost-Efficiency Table for 50 gallon (190 liter) Electric Storage Water Heaters

Incremental Variable Costs '2 Incremental Fixed Costs Total Energy Use Payback Design Total Product Total Mfg Retail Install. Maint. Energy Recov. UA Daily Yearly Period4

No. Design Options Mat'l Labor Overhd Var. Capita Design Fixed Cost Price' Cost' Cost' Factor Eff. kWh/day kWh/yr years

0 Existing Baseline (l4b)- 1.5"(3.8 $62.16 $12.41 $50.99 $125.56 $0.00 $0.00 $. $125.56 $188.18 $160.73 $0.00 0.858 96.69% 3.64 13.60 4965 NA cm)' Oa Analytic Baseline (245fa)-1.5 $0.00 $0.00 $2.14 $0.00 $0.00 $0.00 $127.70$191.39 $160.73 $0.00 0.858 96.69% 3.64 13.60 4965 NA (3.8 cm) I Oa +Heat Traps (plastic) $2.59 $0.20 $0.83 $3.62 $0.00 $0.39 $0.39 $131.71 $197.40 $160.73 $0.00 0.876 97.02% 3.06 13.36 4875 0.85 2 +Incr. Insulation to 2"(5.1 cm) $8.59 $0.51 $3.66 $12.76 $0.00 $0.73 $0.73 $145.20 $217.62 $160.73 $0.00 0.890 97.17% 2.62 13.17 4805 2.08 3 I+Incr. Insulation to 2.5" (6.4 cm) $14.41 $1.02 $7.32 $22.75 $0.0 $1.02 $1.02 $155.48 $233.02 $160.73 $0.00 0.901 97.27% 2.29 13.03 4755 2.52 4 3+Plastic Tank4 $5.25 $0.80 $3.20 $9.25 $15.00 $3.00 $18.00 $182.73 $273.86 $160.73 $0.00 0.908 97.03% 2.06 12.95 4727 4.40 5 3+Insulate Bottom $0.00 $0.00 $0.00 $26.98 $0.00 $0.00 $3.39 $185.85 $278.54 $160.73 $0.00 0.908 97.27% 2.13 12.97 4732 4.76 All costs and prices in 1998$. 2 Incremental variable and fixed costs are perunit costs. 'For the Baseline Model with HCFC-141b, the TOTAL variable costs are provided. 4Annual operating cost for Payback Period calculation established with an electricity price of0.0787 $/kWh in 1998$.

Retail Prices are calculated based on theManufacturer to Retail Markup of 1.49874.45

$450 $395
w-----Consumer Cost 5 a $425 ! ...... Operating Cost $390
( $400 $385

_ 

### E * 

### 3 / 

### c; $375 $380
C $350 -a $375 0 E. 4 5 $325
- -$370 0.85 0.86 0.87 0.88 0.89 0.90 0.91 0.92 Energy Factor Figure 1. 50 gallon (190 liter) Electric Storage Water Heaters: Total Consumer Cost and Operating Cost vs. Energy Factor GAS-FIRED WATER HEATERS The Engineering Analysis models the design options forgas-fired water heaters using TANK, a computer simulation model for water heaters developed byBattelle for GRI. A 40 gallon (150 liter) nominal volume gas-fired water heaterwas used as the baseline model forthis analysis. Existing Typical Baseline model In using TANK to establish the baseline model, the goal was to establish the characteristics ofa40 gallon (150 liter) baseline gas-fired water heater with HCFC-141b foam insulation which would yield a 0.54 EF (the minimum EF allowed byNAECA) and a RE close to 76%. From information in GAMA's directory ofcertified water heaters and product literature from various manufacturers, it was determined thatmodels of40 gallon (150 liter) gas-fired water heaters achieved 0.54 EFs through the use of 1in. (2.5 cm) foam insulation only (heat traps were not necessary). The input rating varied between 34,000 and 40,000 Btu/hr (10,000 to 11,700 W). As a result ofpreliminary simulation work, it was determined that EFs close to 0.54 could only be achieved with input ratings of40,000 Btu/hr (11,700 W) and flue diameters of4 in.46 (10 cm). Thus, the baseline model was established with the following "general" characteristics: input rating of40,000 Btu/hr (11,700 W), flue diameter of4 in. (10.2 cm), 1in. (2.5 cm) offoam insulation, and no heat traps. In developing the baseline model, Battelle was consulted because ithad conducted simulations to characterize baseline gas-fired water heaters. Battelle's initial results were presented to a meeting ofGRI's Water Heater Technical Advisory Group (TAG) in November, 1997 and are depicted in Table 25. OfBattelle's baseline characteristics, the input rating (39,630 Btu/hr (11614 W)), insulation thickness (0.981 in. (2.492 cm)), flue diameter (4 in. (10.2 cm)), and heat traps (none) are virtually identical to the "general" baseline characteristics stated above. With regard to the insulation thickness, Battelle measurements revealed that insulation thicknesses in gas-fired water heaters are actually slightly less than the nominal values (e.g., a "1 in." nominal thickness is actually 0.981 in. (2.492 cm)). Table 25. Battelle Baseline Model Characteristics as presented at November 1997 GRI TAG meeting Parameter Value Input Rating 39630 Btu/hr (11614 W) Pilot Input 400 Btu/hr (117 W)

- Excess Combustion Air (%) 39.0 Pressurized Tank Dimensions Inside Diameter 15.84 in. (40.23 cm) Steel Wall Thickness 0.08 in. (0.20 cm) Height 47.6 in. (120.9 cm) Volume 38.0 gallons (143.8 liter) Jacket Description Foam insulation thickness 0.981 in. (2.492 cm) Sheet metal thickness 0.019 in. (0.483 mm) Thermal conductivity offoamed assembly 0.0155 Btu/hr-ft °F (0.0268 W/m-K) Off-cycle pressure loss coefficient 13.0042 Flue baffle effectiveness multiplier 1.896 Flue diameter 4.0 in. (10.2 cm) Recovery efficiency (RE) (%) 75.0 Energy factor (EF) 0.5447 From discussions with Battelle3 6, it was learned that three input variables, the excess combustion air, the flue baffle effectiveness multiplier, and the off-cycle pressure loss coefficient, were varied in an attemptto achieve both a 0.54 EF and a 76% RE. Invarying the above three inputvariables, Battelle was ableto arrive at an EF of0.54 but a RE ofonly 75%. Because a 76% RE wasnot achieved with Battelle's baseline specifications, additional simulations were conducted to tryto develop a 0.54 EF and 76% RE baseline. Feed-through losseswere kept the same for electric and gas-fired water heaters. In addition, the same conductivities were specified for thejacket insulation forboth the existing baseline gas and electric water heaters. The excess combustion air, flue baffle effectiveness multiplier, and the off-cycle pressure loss coefficient are not independent ofeach other and cannot be varied independently to arrive at the desired EF and RE values. The off-cycle pressure loss coefficient can be expressed as a function ofboth the flue baffle effectiveness multiplier and excess combustion air. Inturn,the EF and RE can also be expressed as functions offlue baffle effectiveness multiplier and excess combustion air (for a given set ofinput characteristics). Figure 2 depicts the variation ofEF and RE with excess combustion air and flue baffle effectiveness multiplier. As Figure 2 demonstrates, 0.54 EFs and 76% REs occur at different sets ofexcess combustion air and flue baffle effectiveness multiplier values. 4.0 EF 3.5 ---- RE _-- EF=0.56

. 3

.0 RE=78-

- ~ = _ _ _EF=0.5 5
1.5 RE=78%-

- - / -5 25 RE=77O/o-

- W O W. EF=0.54

_ 20 w u RE=76%0 EF= 0.53 ff 1.5 RE=75%/05
E RE= 74% -/" 1 .0 EF=0.52
0.5
0.0
--

22.5% 25.0%/ 27.5% 30.0%0 32.5% 35.0% 37.5% 40.0°/0 425% 45.0%/ 47.5% Excess Combustion Air Figure 2. Energy Factor and Recovery Efficiency vs. Flue Baffle Effectiveness and Excess Combustion Air48 Based onthe above results, other TANK input variables were investigated as a means of increasing RE (without significantly impacting EF) or decreasing EF (without significantly impacting RE). Table 26 indicates the TANK input variables which were investigated. The acceptable range provided for the combustion chamber inner wall thickness, the flue wall thickness, the fluebaffle thickness, the thermostat R-value, the skirt insulation, and thetank, flue, and flue baffle emissivities were based on what seemed to be reasonable values forthese variables. The off-cycle pressure loss coefficient is notprovided in Table 26 as it is dependent on the flue baffle effectiveness and the excess combustion air and is calculated byTANK. Table 26. TANK Input Variables: Approximate Impact on EF and RE
TANK Acceptable InputVariable Default Range Impact on EFand RE Flue Baffle Effectiveness 1.896 1.2

- 2.0 Increase causes increased EF and RE Excess Combustion Air 32% 25%

-70% Increase causes decreased EF and RE Pressure Vessel Wall Thickness

- in (cm) 0.08 (0.20) > 0.05 (> 0.13) Decrease causes small RE incr., small EF decr Combustion Chamber Height

- in (cm) 8.5 (21.6) 7.5-9.5 (19.1-24.1) Decrease causes incr'd RE; low impact on EF Comb. Chamber Inner Wall Thick.

- in (cm) 0.04 (0.10) > 0.03 (>0.08) Decrease causesincr'd RE; low impact on EF Multiplier for Dome-Shaped Comb. Chamber 1.15 1.00

- 1.30 Increase causes incr'd EF and RE; larger RE incr Flue Wall Thickness

- in (cm) 0.08 (0.20) > 0.05 (>0.13) Increase causes small RE incr.; noimpacton,EF Flue Baffle Thickness

-in (cm) 0.063 (0.16) > 0.04 (>0.10) Increasecauses incr'd RE; low impact on EF R-value T'stat Fitting

-hrft2- F/Btu (K-m2/W) 0.10 (0.02) 0.05-0.10 (0.01-0.02) Decrease causes small EF decr; no impact on RE Skirt Insul. Conduct

-Btu/hr-ft- "F(W/m2-K) 0.03 (0.05) 0.02-0.04 (0.03-0.07) Increasecauses decr'd EF and RE; larger EF deer Emissivity for Tank, Flue, and Flue Baffle 0.95 < 0.97 Decrease causes decr'd EF &RE; larger RE decr Starting with a fluebaffle effectiveness (2.0) and excess combustion air (40%) that yielded an EF close to 0.54 and as high an RE aspossible, the above input variables were adjusted in an attempt to increase the RE to 76% without significantly increasing the EF. In order to realize an EF and RE within a halfa percentage point ofthe desired values, some ofthe input variables had to be set beyond their acceptable range. Table 27provides the values ofthe above input variables that were used to arrive at acceptable EF and RE values. Input values in Table 27 appearing in bold font,the combustion chamber height, the combustion chamber inner wall thickness, the flue baffle thickness, andthe skirt insulation conductivity, were the only variables set beyond their acceptable limits. Although their limits were exceeded, none went significantly beyond the acceptable range. This set parameters may not match the physical characteristics ofthe actual water heaters, but do allow the simulation model to predict the expected level ofenergy consumption, EF and RE.49 Table 27. TANK Input Values providing acceptable EF and RE values
Value Acceptable Input Variable Used Range Flue Baffle Effectiveness 2.0 1.2

- 2.0 Excess Combustion Air 42% 25%

- 70% Pressure Vessel Wall Thickness

- in. (cm) 0.054 (0.137) > 0.05 (> 0.13) Combustion Chamber Height

- in. (cm) 6.5 (16.5)' 7.5

-9.5 (19.1

- 24.1) Comb. Chamb. Inner Wall Thick.

- in. (cm) 0.01 (0.025)' > 0.03 (> 0.08) Multiplier forDome-Shaped Comb. Chamber 1.25 1.00

- 1.30 Flue Wall Thickness

- in. (cm) 0.05 (0.13) > 0.05 (> 0.13) Flue Baffle Thickness

- in. (cm) 0.03 (0.076)' > 0.04 (> 0.10) R-value forThermostat Fitting

-hrft 2 °F/Btu(K-m2/W) 0.05 (0.01) 0.05

-0.10 (0.01

- 0.02) Skirt Insulation Conductivity

- Btu/hrft- °F(W/m-K) 0.042 (0.073)' 0.02

- 0.04 (0.03

- 0.07) Emissivity for Tank, Flue, and Flue Baffle 0.95 <0.97 'Value used isoutside ofacceptable range. The above input variables yielded a 0.5446 EF and a75.5% RE. Table 28 summarizes the primary baseline characteristics. Note that the conductivity ofthejacket insulation was changed from the TANK default value to match that being used in the baseline electric water heater model. The values in Table 28 describe the water heater in engineering terms used by TANK. Table 28. Gas-Fired Water Heater Baseline Model Characteristics Descriptive parameter Value Input Rating 40000 Btu/hr (11723 W) Pilot Input 400 Btu/hr (117 W) On-cycle power consumption 0.0 W Off-cycle power consumption 0.0 W Excess Combustion Air 42.0 (%) Off-cycle pressure loss coefficient 12.4047 Flue baffle effectiveness multiplier 2.000 Natural Gas

- Higher Heating Value 1028 Btu/scf(38302 kJ/m3) Pressurized Tank Dimensions Inside Diameter 15.892 in. (40.366 cm) Steel Wall Thickness 0.054 in. (0.1372 cm) Height 47.6 in. (120.9 cm) Volume 38.0 gallons (143.8 liter) Jacket Description Foam insulation thickness 0.981 in. (2.492 cm) Sheet metal thickness 0.019 in. (0.0483 cm) Thermal conductivity offoamed assembly 0.0140 Btu/hr-ft °F (0.0242 W/m-K)50 Outer Jacket Emissivity 0.92 Flue Description Internal Diameter 4.00 in. (10.16 cm) Area Fraction for Upflow 0.066 Flue Wall Thickness 0.050 in. (0.127 cm) Flue Baffle Emissivity 0.95 Flue Baffle Thickness 0.030 in. (0.0762 cm) Combustion Chamber Description Skirt Insulation Thermal Conductivity 0.042 Btu/hr-ft °F (0.073 W/m-K) Chamber Height 6.5 in. (16.5 cm) Chamber Inner Wall Thickness 0.010 in. (0.0254 cm) Flame Radiation View Factorto Skirt 0.2 Distance between Burner and Fire Entrance 4.00 in. (10.16 cm) Dome Heat Transfer AreaMultiplier 1.25 Pipes and Fittings Heat Traps (0

- none, I - metal, -1 - plastic) 0 Supply and Draw Pipe Inside Diameter 0.785 in. (1.994 cm) Pressure Relief Valve Exposed Area 18.0 in 2 (116.1 cm2 ) Drain Valve Exposed Area 9.0 in2 (58.1 cm2) Thermostat Exposed Area 9.0 in2 (58.1 cm2) Anode Rod Fittings Exposed Area 0.0 in 2 (0.0 cm2 ) Volume to Thermostat 4.05 gallons (15.33 liter) Modeling Design Options Table 1shows the seven design options which are being considered to improve the efficiency ofgas-fired storage water heaters. Each design option is briefly discussed below along with the methodology ofhow itwas analyzed with TANK. TANK determines the pressure loss coefficient based on the water heater's characteristics. Although the pressure loss coefficient is primarily dependent on the excess combustion air and the flue baffle effectiveness multiplier, any water heater characteristic can effect the off-cycle pressure loss coefficient. Thus, before a TANK simulation run was conducted for a design option, the off-cycle pressure loss coefficient was determined with TANK based on the characteristics.of the water heater. After the off-cycle pressure loss coefficient was established, it was specified as one ofthe water heater's characteristics and TANK was used to model the water heater's performance. For some design options, such as heattraps and increasedjacket insulation, there was little impact on the off-cycle pressure loss coefficient but the improved flue baffle design option had a significant effect on the off-cycle pressure loss coefficient. The side-arm heater was the only design option not modeled with TANK. Because TANK is not able to model side-arm heaters, the WHAM energy calculation method was used to estimate efficiency improvement ofthis design option. Analytical Baseline Model. The existing baseline model's HCFC-141b foam insulation51

was replaced with HFC-245fa foam insulation due to the impending phase out ofHCFC-141b in the year 2003. According to theBayer report, HFC-245fa has a 3.0% higher conductivity than HCFC-141b

- see Table 4. Thus, the conductivity value ofthe foam insulation in the baseline model listed in Table 26 was increased by 3.0% to a value of0.0144 Btu/hr-ft-°F (0.0249 W/m-K). In addition, the thickness ofthe foam insulation surrounding the tankwas increased from 0.981 in. (2.492 cm) to 1.00 in. (2.54 cm) to compensate for the insulation's increased conductivity. This increase in insulation thickness also resulted in an increase of jacket material. Table 29 summarizes the changes that were made to the existing baseline model with HCFC141b in order to simulate its performance with HFC-245fa. Table 29. Gas-Fired Water Heater Modeling Differences: Existing Baseline Model vs. Analytic Baseline Model Descriptive parameter Existing Baseline Analytic Baseline Jacket Description Foam insulation thickness 0.981 in.(2.492 cm) 1.000 in. (2.540 cm) Thermal conductivity offoamed assembly 0.0140 Btu/hrft-°F (0.0242 W/m-K) 0.0144 Btu/hr-ft-°F (0.0249 W/m-K) Heat Traps. Metal and plastic heat traps were analyzed for gas-fired storage water heaters. Bothtypes ofheat traps prevent the losses associated with the circulation ofhot water into the plumbing. To simulate the performance ofheat traps using TANK, the input variable designating the presence ofheat traps simply needs tobe specified with avalue of 1formetal heattraps or -1 for plastic heattraps. Table 30 summarizes the changes made to the analytic baseline model in order to simulate the performance ofmetal and plastic heat traps. Table 30. Gas-Fired Water Heater Modeling Differences: Analytic Baseline Model vs. Models with Metal and Plastic Heat Traps Descriptive parameer Analytic Baseline with Metal Heat with Plastic Heat Descriptive parameterTrapsTraps Traps Traps Pipes and Fittings Heat Traps (0

- none, 1 - metal, -1 -plastic) 0 1 -1. Increased JacketInsulation. Most gas-fired water heaters on the market today have at least 1-in. (2.5 cm) thick polyurethane foam insulation, while some manufacturers provide 2- or 3-in. (5.1 or 7.6 cm) thick insulation, as well. Although increasing the insulation thickness reduces the standby loss, the increase in the overall diameter ofthe water heater may pose some52 installation problems. There will also be an increase in shipping costs because fewer heaters will fit in atruck. Because ofthesepotential installation problems, maximum insulation thicknesses were limited to 21 /2in. (6.4 cm) for this analysis. Table 31 summarizes the changes made to the analytic baseline model to simulate the performance ofa gas-fired water heater insulated with nominal thicknesses of "2-in." (1.981 in. (5.032 cm)) and "2/2-in." (2.481 in. (6.302 cm)) offoam insulation. Table 31. Gas-Fired Water Heater Modeling Differences: Analytic Baseline Model vs. Models w/ 2 & 2/2 nominal in. offoam insulation
with 2 in. offoam with 2/2 in. offoam

Descriptive parameter Analytic Baseline . insulation insulation Jacket Description Foam insulation thickness 1.000 in.(2.540 cm) 1.981 in.(5.032 cm) 2.481 in.(6.302 cm) Improved Flue Baffle. The standard flue baffle is a twisted strip ofmetal inserted into the flue. It increases the turbulence offlue gases and improves heat transfer to the walls ofthe flue. The geometry ofthe flue baffle can be modified to increase its effectiveness. A research project funded by GRI reviewed technical literature, manufacturers' literature, and patents to determine what new technologies are applicable to heat exchangers that involve flue gases from combustion ofnatural gas37

. The conclusion wasthat significant increases inthe convective heat transfer coefficient could be achieved with the use ofheattransfer enhancement devices. The study suggested that in some cases, an increase inheat transfer coefficient might be accompanied by an increase in the pressure drop (due to an increase in the friction factor). The study identified twisted-tape inserts as a potential heat transfer enhancement device forwater heaters.Burners in fuel-fired water heaters are placed below the storage tank, with the flue extending up through the center ofthe tank to a drafthood. The combustion products enter the flue tube at a very high temperature (approximately 2300°F (1260 C)) andtransfer heat by convection andradiation to the tube wall, andthen by conduction to the water. When a baffle, such as a flatplate, isinserted in the flue, increased heat transfer occurs from the hot combustion products to the flue wall. The increase in the heat transfer is even greater when a twisted baffle tape is inserted in the flueway ofa water heater. The twisted tape augments the convective heat transfer from the flue gases to the wall surfaces. In addition, the hottape transfers heat to the water-tube walls byradiation.53 Beckermann and Goldschmidt3 8 investigated experimentally and empirically the effects of velocity ofthe flue gases, the twist (i.e., number ofturns) ofthetape, and the surface emissivities onthe total heat transfer (convection and radiation) in afuel-fired waterheater. They reported that compared to an emptytube, the flue tube with twisted tape enhances the overall heat transfer performance by as much as 50%. An improved flue baffle can increase the RE to about 78-85%, depending on the specific geometry. At the upper end ofthe RE range, the water heater would require power venting or induced draft and corrosion resistant flues for safe operation. Inaddition to an increase in RE, improved flue baffles also reduce standby loss. The offcycle standby loss is reducedby the additional restrictions to airflow due to the increased baffling. Butbecause the enhanced or increased flue baffling increases pressure drop across the flue, the combustion products may have to be forced through the flue with afan or blower. Venting combustion products through ahorizontal venting system also requires a fan orblower. When the blower forces fresh air into the chamber, the configuration iscalled aforced draft system. By contrast, whenthe blower is located in the flue-gas exit, the configuration is called an induced draft system. In an induced draft system the blower is exposed to hot and potentially corrosive flue gases and,therefore, shouldbe made ofmaterials that can withstand these conditions. Using a fan to force the flue gases through the baffle with either an induced-draft blower (downstream ofthe waterheater) or a forced-draft blower (upstream ofthe water heater), can increase the RE and reduce the off-cycle flue losses. The increased RE resulting from this design optionmay necessitate relining or otherwise modifying some venting systems to prevent corrosion or damage from condensation. Several manufacturers currently make water heaters with induced-draft blowers. However, this feature is usually added to allow sidewall venting and may not be accompanied by any increase in flue baffling. 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 prior to venting. The additional air cools the flue gases lowering temperature enough so that standard PVC piping can be used for venting. This eliminates any problems with corrosion. Plastic piping isoften cheaper and easier to install than sheet metal or masonry chimneys. While this technique offlue gas dilution does not necessarily increase water heater efficiency by itself, when combined with an improved flue baffle that increases RE, itcan help avoid venting problems. As discussed earlier under venting issues, design options with REs greater than 80% were not considered in this analysis. At REsbeyond 80%, flue-loss efficiencies exceed 84% resulting in flue gas condensation within the water heater's flue, leading to corrosion and a shortened life. To ensure that condensation would not occur within the flue system, only flue baffle54 improvements with maximum REs of78% were included in design options selected forfurther analysis. By keeping recovery efficiencies this low, itwas assumed that forced- or induced-draft blowers would notbe needed to overcome increased pressure drops due to the improved baffle system.Table 32 summarizes the changes made to the analytic baseline model to simulate the performance ofa gas-fired water heater with an improved flue baffle. Inorder to model a water heater with a 78% RE, the excess combustion air was decreased andthe flue baffle heat exchanger multiplier was increased. Table 32. Gas-Fired Water Heater Modeling Differences Analytic Baseline Model vs. Model with Improved Flue Baffle

Descriptive parameter Analytic Baseline w/ Improved Flue Baffle (RE = 78%) Excess Combustion Air (%) 42.0 34.0 Flue baffle effectiveness multiplier 2.000 2.200 Electronic Ignition. The most commonly used ignition system in gas-fired storage water heaters is a standing pilot ignition system. The disadvantage ofa standing pilot is itbums gas continuously at a rate ofapproximately 400 Btu/h (117W), and only part ofthis heat is converted to useful energy. In addition to the standing pilot, three electronic ignition devices are commonly used in gas-fired appliancies: * an intermittent pilot ignition device that by generating a spark lights a pilot, which in turn lights the main burner * an intermittent direct ignition device thatlights the main burner directly by generating a spark, and * a hot surface ignition (HSI) device that lights the main burner directly by generating a hot surface. Unlike standing pilots that consume gas continuously, these devices operate only at the beginning ofeach on-cycle. Although there isno increase in the steady-state efficiency with use ofelectronic ignition devices, the overall fuel consumption may be reduced. Burner on-time may increase to make up forthe heat the standing pilot would have supplied during standby periods. Electronic ignition devices require an outside electricity source forignition, usually a 24 V or a 120 V system. The power draw ofthe electrically operated gas valve is between 5W and 12 W, and power is consumed only when there is a call for heat. Electronic ignition systems also require a control module, which houses the electronic control circuitry and consumes 6 W of power during a call for heat. These systems also need an electronic thermostat that draws 1.2 W ofpower during the heating period and 0.4 W ofpower during the standby period. The HSI is a resistive device that draws about 2.5 amps at 120 V (about 300 W ofpower) for approximately55 30 seconds during ignition. For this analysis, an intermittent pilot ignition system was the only type ofnon-standing pilot ignition system analyzed for gas-fired storage water heaters. The total on-cycle power consumption was assumed to be 15.7W while the total off-cycle power consumption was assumed to be 0.4 W. Table 33 summarizes the changes made to the analytic baseline model to simulate the performance ofan intermittentpilot ignition system. Table 33. Gas-Fired Water Heater Modeling Differences Analytic Baseline Model vs. Model with Electronic Ignition

Descriptive parameter Analytic Baseline with Electronic Ignition Pilot Input 400 Btu/hr(117 W) 0 Btu/hr (0 W) On-cycle power consumption 0.0 W 15.7 W Off-cycle power consumption 0.0 W 0.4 W Flue Damper (Electromechanical). Gas-fired storage water heaters are equipped with a draft hood connecting the flue to aventpipe or chimney. During off-cycle, the waterheater loses heat by natural convection up the flue. A damper can be installed either at the flue exit or in the vent pipe to minimize the off-cycle heat losses. Aflue damper is installed upstream ofthe draft diverter, while the vent damper isinstalled downstream ofthe draft diverter. Electric flue dampers are activated by an external source ofelectricity. The dampers open before combustion starts and close immediately after combustion stops. When the damper reaches the open position, an interlock switch energizes the solenoid and enables the gas ignition circuit. Therefore, the burner cannot be ignited when the damper is in the closed position. Because the dampers open and close immediately, no bypass isneeded. Forflue dampers installed onwater heaters using a standing pilot,a knockout in the flue damper isprovided to vent the pilot's flue gases. Ofcourse in this situation, off-cycle losses would be greater than those in water heating equipment using a non-standing pilot ignition system. The electric flue damper needs a 24-volt electric source and consumes about 5W when the gas supply is off. Flue dampers are assumed to have no effect on the RE ofthe water heater. Forthis analysis, electromechanical flue dampers were analyzed only in conjunction with electronic ignition systems. Since electricity isrequired for the operation ofthe flue damper, it was assumed that the standingpilot would be converted overto an electronic ignition system in order to take advantage ofthe electrical power that exists at the water heater. Flue dampers were modeled according to the procedure outlined in the user's manual for TANK39

. Typically, TANK calculates the off-cycle pressure loss coefficient based on the physical characteristics of the water heater. Inthe case ofa flue damper, the off-cycle pressure loss coefficient is manually 1 determined based on the following expression:
e (c.f) 256

where; ed = the effective pressure loss coefficient ofthe flue damper, c = discharge coefficient ofthe flue damper, and f = fraction ofcenter flue area remaining open after the flue damper has closed expressed by the following equation:



### Dfwhere; Df = the internal flue diameter, and Dd = the electromechanical flue damper diameter. Because flue dampers are usually not designed to completely seal the flue, the fraction ofthe center flue remaining open after the damper closes is approximately 10%. Discharge coefficients vary from avalue of0.6 for knife-edged damper plates to 1.0 for smooth-edged damper plates. For purposes ofthis analysis, avalue of0.8 was assumed forthe discharge coefficient while a value of 10% was assumed forthe fraction ofthe center flue remaining open in order to calculate the pressure loss coefficient for a water heater utilizing a flue damper. Table 34 summarizes the changes made to the analytic baseline model to simulate the performance ofan electromechanical flue damper. Table 34. Gas-Fired Water Heater Modeling Differences: Analytic Baseline Model vs. Model with Electromechanical Flue Damper

Descriptive parameter Analytic Baseline with Electromechanical Flue Damper Off-cycle pressure loss coefficient 12.4047 156 Off-cycle power consumption 0.0 W 5.0 W
Side-Arm Heater. The side-arm heater design avoids large flue lossesby removing the flue from the center ofthe tank. Water is withdrawn from the bottom ofthe tank and heated over a burner in a small, separate heat exchanger. Water isreturned to the top ofthe 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 the pilot light losses. Auxiliary power is supplied by a low-voltage plug-in transformer. A water heater using this design in combination with electronic ignition and a plastic tank was commercially available until 1998. The expected EF and RE for a gas-fired water heater with a side-arm heater were based57 on information provided by Mr. Minniear40

. Table 35 provides EF estimates for two types of40 gallon (150 liter) gas-fired storage waterheater with side-arm heaters and metal storage tanks. One design is based on a 76% RE while the other is based on a 78% RE. Both designs incorporate an intermittent pilot ignition device, 1.981 in. (5.032 cm) ofHFC-245fa foam insulation, and plastic heat traps. Table 35. Side-Arm 40 gallon (150 liter) Gas-Fired Water Heater: Energy Factor Estimates
WaterHeater Design Energy Factor 76% RE Side Ann Heater with intermittent pilotignition device, 1.981 in. 0.655 (5.032 cm) foam insulation, and plastic heattraps 78% RE Side Arm Heaterwith intermittent pilot ignition device, 1.981 in. 0.668 (5.032 cm) foam insulation, andplastic heattraps

Because TANK cannot simulate theperformance ofwater heaters equipped with side-arm heaters, the WHAM energy calculation method was used to estimate its energy performance. If both the EF and RE are known, WHAM can be used to determine the UA ofthe waterheater and, in turn, its energy consumption. Appendix Bprovides a detailed explanation ofhow the WHAM energy calculation method was used to determine the energy consumption ofside-arm heater designs. Since side-arm heaters require a small circulation pump to move water through theheat exchanger, a component ofthe total energy input is due to the consumption ofelectrical energy. For this analysis, itwas assumed thatthe circulation pump had an on-cycle power consumption of30 W. The daily electrical energy use was determined bymodeling the flue damper water heater with the TANK simulation model and specifying an on- and off-cycle power consumption equal to that assumed for a side-arm heater. Since side-arm heaters already need electricity to operate, an intermittent pilot ignition system was also included aspart ofthe side-arm heater. For modeling purposes, the on-cycle power consumption was assumed tobe 45.7 W (30 W for the circulation pump and 15.7 W for the intermittent ignition device) while the off-cycle power consumption was assumed to be 0.4 W (forthe intermittent ignition device). Using TANK, this results in a daily electrical energy consumption of80.3 watt-hours. Plastic Tank. The lower heat conductivity ofa plastic tank reduces the amount ofheat conducted through the tank wall to the insulation. Plastic tanks cannot be used with standard center-flue gas-fired water heaters because the plastic cannot withstand the high temperatures produced bythe flames. This option was considered only with indirect water heating techniques (e.g., the side-arm water heater) that avoid flame temperature problems. Because indirect water heating techniques cannot be modeled with TANK, the efficiency benefits due to plastic tanks were not estimated with TANK. Plastic tanks were only analyzed in the context ofa side-arm heater design. Based on estimates provided by Mr. Minniear, a sidearm heater coupled with a plastic tank insulated with 2 nominal in. offoam insulation, (1.981 in.58 (5.032 cm)) plastic tank, plastic heat traps, and an intermittent pilot ignition device yields only a slightly higher EF than comparable metal tank designs. Table 36 provides the EF estimates for two 40 gallon (150 liter) gas-fired side-arm storage water heater designs. One is based on a RE of76% while the other isbased ona 78% RE. Both designs utilize aplastic tank, intermittent pilot ignition device, 2 nominal in. (1.981 in. (5.032 cm) ofHFC-245fa foam insulation, and plastic heat traps. Table 36. Side-Arm 40 gallon (150 liter) Gas-Fired Water Heater, Plastic Tank: Energy Factor Estimates
WaterHeater Design Energy Factor 76% RE Side Arm Heater with intermittent pilot ignition device, 1.981 in. (5.032 cm) foam insulation, and plastic heat traps 78% RE Side Arm Heater with intermittent pilot ignition device, 1.981 in. 0675 (5.032 cm) foam insulation, and plastic heat traps
Design Option Manufacturer Costs As with electric water heaters, manufacturer costswere primarily based upon data provided by GAMA. The side-arm heater and plastic tank were the only design options, which was analyzed using manufacturing cost provided by Mr. Minniear. All manufacturing cost estimates were based upon theproduction ofa 40 gallon (150 liter) gas-fired water heater and were disaggregated into variable (material, labor, overhead, transportation) and fixed (capital, product design) costs. Design option variable and fixed costs were provided as aper unit cost and expressed as an incremental increase over the baseline design. Existing Baseline Model. GAMA developed existing baseline model cost estimates for a 40 gallon (150 liter) gas-fired storage water heater with 1in. (2.5 cm) offoamedjacket insulation blown with HCFC-141b. These baseline model costs were used forthis Engineering Analysis. Table 37 presents thebaseline model manufacturer costs. The overhead includes the transportation cost too. Note, no fixed costs were assumed forthe baseline model. Table 37. Gas-Fired Water Heater Existing Baseline Model: Manufacturer Costs
Variable Costs (per unit) Fixed Costs (per unit) Total Product Mfg Design Material Labor Overhead Total Capital Design Total Cost Existing Baseline $75.02 $12.49 $50.10 $137.61 $0.00 $0.00 $0.00 $137.61 Analytical Baseline Model. In order to convert the baseline manufacturer costs associated with foam insulation blown with HCFC-141b to that blown with HFC-245fa, the amount and cost ofmaterials associated with varying thicknesses ofHCFC- 141 b and HFC-245fa59 foam insulation were developed. Thus, the material costs associated with aparticular level of HFC-245fa insulation could easily be determined by adding to thebaseline costs associated with a comparable level ofHCFC-141b foam insulation. Tables 38 and 39 summarize the material costs associated with varying levels ofHCFC-141b and HFC-245fa foam insulation, respectively. Thematerial costs ofHCFC-141b ($1/lb or $2.2/kg) as well as sheet metal cost ($0.30/lb or $0.66/kg), were based on estimates by Mr. Minniear41

. The material costs ofHFC245fa foam insulation ($1.32/lb or $2.9/kg) were based on estimates by Allied Signal, see Table 15. Table 38. Gas-Fired Water Heater Material Costs Associated with varying thicknesses ofHCFC141b Foam Insulation Polyurethane Foam 141b Jacket Sheet Metal Misc Total thickness volume' weight2 cost 3 area thickness weight4 cost' cost' cost

in. (cm) ft 3 (m3 ) lb (k) fi 2 (m2) ft 3 (m 3 ) lb (kg) 0.98(2.49) 1.57(0.04) 3.15(1.43) $3.15 23.76(2.21) 0.038(0.001) 18.40(8.35) $5.52 $0.00 $8.66 1.48(3.76) 2.47(0.07) 4.93 (2.24) $4.93 25.43 (2.36) 0.040(0.001) 19.69(8.93) $5.91 $1.62 $12.46 1.98(5.03) 3.42(0.10) 6.83(3.10) $6.83 27.12(2.52) 0.043(0.001) 21.00(9.53) $6.30 $4.04 $17.17 2.48 (6.30) 4.43 (0.13) 8.86 (4.02) $8.86 28.85 (2.68) 0.046 (0.001) 22.34 (10.13) $6.70 $5.86 $21.43 2.98(7.57) 5.51(0.16) 11.02(5.00) $11.02 30.62(2.84) 0.048(0.001) 23.71 (10.75) $7.11 $8.59 $26.72 '40 gallon (150 liter) tank dimensions: dia. = 15.8 in (40.1 cm), length = 47.5 in(120.7 cm), combustion chamber height = 6.5 in(16.5 cm)
2 Foam density =2 Ib/ft' (32 kg/m') 3Foam cost = $1/lb ($2.2/kg) 4 Sheet metal density = 489 Ib/ft' (7833 kg/m3 ) 5 Sheet metal cost = $0.30/lb ($0.66/kg) 6Miscellaneous cost includes additional cost for foam dams tocontain foram insulation ina larger cavity.60 Table 39. Gas-Fired Water Heater Material Costs Associated with varying thicknesses ofHFC245fa Foam Insulation Polyurethane Foam 245fa Jacket Sheet Metal Misc Total thickness' volume2 weight3 cost4 area thickness' weight5 cost6 cost 7 cost

in. (cm) ft 3 (m 3 ) lb(kg) ft (m 2 ) ft (m) lb (kg) 1.00 (2.54) 1.61 (0.05) 3.21 (1.46) $4.24 23.82 (2.21) 0.038 (0.001) 18.44 (8.36) $5.53 i $0.00 $9.77 1.48 (3.76) 2.47 (0.07) 4.93 (2.24) $6.51 25.43 (2.36) 0.040 (0.001) 19.69 (8.93) $5.91 $1.62 $14.03 1.98(5.03) 3.42(0.10) 6.83(3.10) $9.02 27.12(2.52) 0.043(0.001) 21.00(9.53) $6.30 $4.04 $19.36 2.48(6.30) 4.43(0.13) 8.86(4.02) $11.70 128.85(2.68) 0.046(0.001) 22.34(10.13) $6.70 I $5.86 $24.26 2.98(7.57) 5.51(0.16) 11.02(5.00) $14.55 30.62(2.84) 0.089(0.001) 23.71 (10.75) $7.11 $8.59 $30.25 'Thickness increased due toincreased conductivity of245fa relative to 141b. 240gallon (150 liter)tank dimensions: dia. = 15.8 in (40.1 cm), length =47.5 in(120.7 cm), combustion chamberheight= 6.5 in (16.5 cm) 3 Foam density =2Ib/ft (32 kg/m') 4Foam cost= $1.32/lb ($2.9/kg) 5Sheet metal density = 489 Ib/ft (7833 kg/m') 6Sheet metal cost =$0.30/lb ($0.66/kg) 7 Miscellaneous cost includes additional cost forforam dams tocontain foam insulation in a larger cavity. As noted in Table 39, the actual thickness level for 1nominal in. ofHFC-245fa foam insulation was assumed to be slightly greater than thethickness for HCFC-141b foam insulation due to HFC-245fa's higher conductivity. Table 40 presents the manufacturer cost estimates for a 40 gallon (150 liter) gas-fired waterheater with 1nominal in. ofHCFC-141b foam insulation and the costs associated with the same baseline model with HFC-245fa foam insulation. The material costs for the HCFC-141b baseline model were adjusted upward by the difference in material costs ($ 1.11) calculated for the HCFC-141b and HFC-245fa models. Table 40. Gas-Fired Water Heater Baseline Model with HCFC-141b and HFC-245fa: Manufacturer Costs
Variable Costs (per unit) Fixed Costs (per unit) Total Product Mfg Design Material Labor Overhead Total Capital Design Total Cost Baselinew/141b-0.981 in(2.492cm) $75.02 $12.49 $50.10 $137.61 $0.00 $0.00 $0.00 $137.61 Baseline w/ 245fa- 1.0 in (2.5 cm) $76.13 $12.49 $50.10 $138.72 $0.00 $0.00 $0.00 $138.72 Analytical Baseline Model with Flammable Vapor Ignition Resistant Design. In order to prevent the ignition offlammable 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 assumed a placeholder value of$35 was added to the total manufacturing cost ($15 variable costs & $20 fixed cost) for product redesign42

. The design would not require electricity at the water heater or modifications to the vent system. In addition.61 DOE assumed thatwater hater efficiency would not change. Table 39 presents the manufacturer cost estimates for the baseline model with the flammable vapor ignition resistant design. Table 41. Gas-Fired Water Heater Analytic Baseline Model with Resistant Flammable Vapor Ignition Design: Manufacturer Costs
Variable Costs (per unit) Fixed Costs (per unit) Total Product Mfg Design !Material Labor Overhead Total Capital Design Total Cost Baselinewith 245fa andFlammable Vapor IgnitionResistant Design $91.13 $12.49 $50.10 $153.72 $20.00 $.0 0.00 1203.72 Heat Traps. Manufacturer costs for metal andplastic heat traps were based upon data provided by GAMA. GAMA's data did notprovide a separate cost data for metal and plastic heat traps. Data from the heattrap manufacturer Perfection, Inc. was used as areference. It was assumed thatheat trap material cost isbased on the following design configurations: Metal heat trap material costs for both the supply and draw lines werebased on a /4-in. (1.9 cm)by 3-in. (7.6 cm) pipe nipple assembly design. Plastic heat trap material costs for the supply line were based on aplastic drop-intube design while those for the draw line were based on aplastic cartridge heat trap design within a combined outlet and and anode rod assembly. Table 42 summarizes the incremental manufacturer costs for incorporating metal and plastic heattraps into a gas-fired water heater. The costs reflect the addition ofheat traps to both the supply and draw lines. Table 42. Heat Traps for Gas-Fired Water Heaters: Incremental Manufacturer Costs
Incremental Variable Costs (per unit) Incremental Fixed Costs (perunit) Total |>i~~ !iT~ ~ Product Incremental Design 'Material Labor Overhead Total I Capital Design Total Mfg Cost Heat Traps (metal) $2.75 $0.16 $0.21 $3.12 I $0.07 $0.13 $0.20 $3.32 HeatTraps (plastic) i $2.75 $0.16 $0.21 $3.12 $0.07 $0.13 $0.20 $3.32 1)Perfection Inc.'s datawas almost identical for both types ($3.00 for plasticand $2.95 for metal heat traps); 2)GAMA's heat trapvariable costs are different forelectric water heaters andgas-fired waterheaters. Increased JacketInsulation. Since the current insulation blowing agent, HCFC-141b will be phased out by 2003, manufacturer costestimates forincreases in thejacket insulation were adjusted to account for insulation blown with HFC-245fa. Foam cost datawere based on information provided byAllied Signal. As presented earlier, Table 39 depicted the material costs for varying levels ofHFC-245fa foam insulation. GAMA provided variable and fixed cost data forjacket insulation increases from abaseline level of 1.0 in. (2.54 cm) to a thickness of2.0 in. (5.1 cm) only. In order to generate variable and fixed cost data for the next level ofinsulation, from a baseline level of 1.0 in. (2.54 cm) to a thickness of2.5 in. (6.4 cm), the data provided by M. Minniear was used to calculate ratios ofvariable and fixed cost for 2" insulation to 2.5" insulation. GAMA's cost for 2.0 in. (5.1 cm) ofinsulation was multiplied by those ratios to approximate the variable and fixed costs for 2.5 in. (6.4 cm) ofinsulation. Table 43 summarizes62 the incremental manufacturer costs forjacket insulation increases from abaseline level of 1.0 in. (2.54 cm) to athicknesses of 1.981 in. (5.032 cm) and2.481 in. (6.302 cm) (asprovided in Table 39). As stated earlier, insulation thicknesses were limited to 2/2 in. (6.4 cm) due to installation and shipping concerns. Table 43. Increased Jacket Insulation for Gas-Fired Water Heaters: Incremental Manufacturer Costs |Incr.Variable Cost (per unit) Incr.Fixed Costs (per unit) Total Product Incremental Design_ _____Material Labor Overhead Tot CapitTotal CapiTotal Mfg Cost Incr. Insulation- 1.981 in (5.032 cm) $9.59 $0.60 $4.93 $15.12 $0.85 $0.59 $1.44 $16.56 Incr. Insulation- 2.481 in(6.302 cm) $14.49 $1.20 $9.86 $25.55 $1.28 $1.18 $2.46 $28.01 Improved Flue Baffle. Manufacturer costs forthe improved flue baffle design were based on data from GAMA. Table 44 summarizes the incremental manufacturing costs for an improved flue baffle. The costs were based on a design that increased the RE to 78%. It is interesting to note that largest component ofthe manufacturing cost increase is the product design. Table 44. Improved Flue Baffle for Gas-Fired Water Heaters: Incremental Manufacturer Costs
Incr. Variable Cost (perunit) lIncr. Fixed Costs (per unit) Total Product Incremental Design Material Labor Overhead Total Capital Design Total l Mfg Cost Improved Flue Baffle l $0.97 $1.29 $1.32 $3.58 $1.17 $1.72 $2.89 $6.47 Electronic Ignition. Manufacturer costs for electronic ignition were based onthe replacement ofa standing pilot with an intermittent pilot ignition device. The cost ofthe electronic ignition system was based on data from GAMA. Table 45 summarizes the incremental manufacturing costs for switching from a standing pilot to an intermittent pilot ignition device. Table 45. Electronic Ignition for Gas-Fired Water Heaters: Incremental Manufacturer Costs
Incr. Variable Cost (per unit) ! Incr. Fixed Costs (per unit) Total Product Incremental Design Material Labor Overhead Total Capital Design Total Mfg Cost Electronic Ignition $43.78 $3.28 $11.72 $58.78 $2.09 $1.47 $3.56 $62.34

Flue Damper (Electromechanical). Manufacturer costs for including an electromechanical flue damper with a gas-fired water heater were based on data from GAMA. Table 46 summarizes the incremental manufacturing costs ofputting a flue damper on a gas-fired63 water heater. Because electromechanical flue dampers were analyzed only in conjunction with electronic ignition systems, the incremental manufacturer costs associated with both design options are also summarized inTable 46. As stated previously, because electricity is required for the operation ofthe flue damper, it was assumed that the standing pilot would be converted to an electronic ignition system in order to take advantage ofthe electrical power at the water heater. Table 46. Flue Damper w/Electronic Ignition for Gas-Fired Water Heaters: Incremental Manufacturer Costs
Incr. VariableCost (per unit) iIncr. Fixed Costs (per unit) Total Product Incremental Design Material Labor Overhead Total Capital Design Total Mfg Cost Flue Damper $85.05 $4.12 $15.87 $105.04 $3.45 $2.03 $5.48 i $110.52 FlueDamper+Electr. Ignition $128.83 $7.40 $27.59 $163.82 $5.54 $3.50 $9.04 $172.86 Side-Arm Heaterand Plastic Tank. Manufacturer costs forthe side-arm heater for a gas-fired water heater design were based on datafrom Mr. Minniear. Table 47 summarizes the costs for four types ofside-arm heater designs; 76% and 78 % RE designs that use a metal tank and electronic ignition and 76% and 78% RE designs with a plastic tank and electronic ignition. Forthis analysis itwas assumed that the cost difference between the 76% and 78% RE designs was equal to the cost ofthe improved flue baffle design. This assumption means that heat exchanger costs for a78% RE design would be higher than those for a76% RE design. Because side-arm heaters were analyzed only in conjunction with electronic ignition systems, the incremental manufacturer costs associated with both design options are also summarized in Table 47. As discussed previously, plastic tanks cannot be considered asa stand-alone design option for standard center-flue gas-fired water heaters due to the high temperature ofcombustion. Thus, plastic tanks can only be considered with indirect heating designs, such as a side-arm heater. Table 47. Side-Arm Heaters for Gas-Fired Water Heaters: Incremental Manufacturer Costs

> Incr.Variable Cost (perunit) Incr. Fixed Costs (perunit) Total I A Product Incremental Design Material Labor Overhead Total Capital Design Total MfgCost 76% RE Side-Arm Heaterw/Metal Tank: $24.50 $2.10 $7.20 $33.80 $4.00 $10.00 $14.00 $47.80 78%RE Side-Arm Heaterw/MetalTank $25.47 $3.39 $8.52 $37.38 $5.17 $12.72 $16.89 $54.27 76% RE Side-Arm Heater w/ Plastic Tank. $29.75 $2.90 $9.25 $41.90 $8.00 $16.00 $24.00 $65.90 78% RE Side-Arm Heater w/ Plastic Tank: $30.72 $4.19 $10.57 $45.48 $9.17 $17.72 $26.89 $72.37 76% RE Side-Arm Heater w/Metal Tank$6. 76%RESide-Arn Heaterw/Me 6828 $5.38 $26.02 $99.68 $6.34 $3.49 $9.83 $109.51 including IID 78% RE Side-Arm Heater w/ Metal Tank including IID $69.25 $6.67 $27.34 $103.26 $7.51 $5.21 $12.72 $115.98 76% RE Side-Arm Heater w/ Plastic Tank including lID $73.53 $6.18 $30.22 $109.93 $9.34 $4.09 $13.43 $123.36 78% RE Side-Arm Heater w/ Plastic Tank including lID $74.50 $7.47 $31.54 $113.51 $10.51 $5.81 $16.32 $129.8364 Design Option Retail Prices The retail price is considered to be the cost to the consumer ofonly the water heating equipment. The retail price foran existing baseline 40 gallon (150 liter) gas-fired storage water heater (with HCFC-141b foam insulation) was determined by contacting various plumbing contractors and large retail chains. Since the price ofa water heater depends onthe length ofthe manufacturer's warranty, only water heaters warrantied for 5years were considered to be baseline models. As with electric water heaters, the 5year warranty was accepted as the shortest warranty period offered by water heater manufacturers (although 1year warranties have been offered in special cases) and istypically reserved for those models which are produced in large quantities (i.e., baseline models). A longer warranty period, in additionto raising the price, may also indicate the presence ofsome design feature which would not normally be found inbaseline models. Table 48 provides the list ofretail prices which went into developing theretail price of the baseline model. For each price listed, the source forthat price is also provided. All information presented in Table 48 are from the LBNL Water Heater Database 43 As shown in Table 48, the average retail price for abaseline 40 gallon (150 liter) gasfired storage water heater is $149.94 (without taxes). As presented earlier, the baseline manufacturer cost ofa HCFC-141b-based water heater is $137.61. Using the average national value fortaxes of5.20% (developed by A.D.L, 1998), yields a retail price of$157.74. Dividing the retail price ($157.74) bythe manufacturer cost ($137.61.) yields a manufacturer cost-to-retail price markup of 1.15 (an exact value of 1.14626 is used as a multiplier). The baseline manufacturer cost-to-retail price markup was assumed constant forthe design options considered for this analysis. Thus, the retail price forany modified design was simply determined bymultiplying its manufacturer cost bythe derived markup of 1.15.65 Table 48. 40-Gallon (150 liter) Gas-Fired Storage Water Heater Retail Prices Source Manufacturer Brand Model Retail Little Rock, AR American Water Heaters Amerimore G51-40T34-3NV $115.00 Little Rock, AR American Water Heaters Amerimore G51-40S33-3NV $116.00 Salt Lake City, UT American Water Heaters American Water Heaters G51-40T34-3NV $118.00 West Allis, WI American Water Heaters American Water Heaters Add in later $126.00 Chicago, IL American Water Heaters More-Flo G51-40T34-3NV $126.00 Minneapolis, MN American Water Heaters More-Flo G51-40T34-3NV $126.00 Nashville, TN American Water Heaters American Water Heaters DVG52-40S38-NV $127.00 Portland, OR State Industries Reliance 5-40-NORT $128.00 Reno, NV American Water Heaters American Water Heaters G51-40T34-3NV $128.00 Stockbridge, GA American Water Heaters Envirotemp G51-40T34-3NV $129.00 Atlanta, GA American Water Heaters PROLine G51-40S33-3NV $129.00 Atlanta, GA American Water Heaters PROLine G51-40S33-3NV $129.00 Marieeta, GA American Water Heaters Envirotemp G51-40T34-3NV $129.00 Las Vegas, NV State Industries Reliance 5-40-NORT $129.00 Sacramento, CA American Water Heaters American Water Heaters G5140T34-3NV $129.00 Atlanta, GA American Water Heaters PROLine G5140S33-3NV $129.00 Atlanta, GA American Water Heaters PROLine G51-40T34-3NV $129.00 Chicago, IL American Water Heaters More-Flo PVG52-40T50-3NV $130.00 Denver, CO State Industries Reliance 5-40-NORT $131.00 Phoenix, AZ State Industries Reliance 5-40-NORT $131.00 St. Louis, MO American Water Heaters American Water Heaters G5140T34-3NV $131.00 Oklahoma City, OK State Industries Reliance 5-40-NORT $131.00 New Orleans, LA American Water Heaters American Water Heaters G5140T34-3NV $131.00 Dallas, TX State Industries Reliance 5-40-NORT $132.00 Emeryville, CA American Water Heaters American Water Heaters G5140T34-3NV $133.00 Falls Church, VA American Water Heaters PROLine G5140T34-3NV $134.00 Orange, CA State Industries Reliance 5-40-NORT $134.00 West Allis, WI American Water Heaters Craftsman $134.00 Seattle, WA State Industries Reliance 5-40-NORT $134.00 Nashville, TN American Water Heaters American Water Heaters G51-40T34-3NV $135.00 Lexington, KY American Water Heaters American Water Heaters G51-40T34-3NV $135.00 Livermore, CA Sears/State Industries Kenmore $139.99 Bensalem, PA American Water Heaters Moreflow G51-40t34-NV $144.00 Charlotte, NC American Water Heaters $147.00 Charlotte, NC American Water Heaters More-Flo G5140T34-3NV $147.00 Richmond, CA Sears/State Industries Kenmore 33246 $160.00 Emeryville, CA American Water Heaters American Water Heaters G51-40S33-3NV $161.00 Parkersburg, WV A.O. Smith FSG40 $162.88 Livermore, CA Sears/State Industries Kenmore $164.99 Berkeley, CA Rheem Rheem 21V40-7N $167.00 Indianapolis, IN State Industries PRV40 $170.00 Berkeley, CA Rheem Rheem 21V40S-2 $177.00 Berkeley, CA Rheem Rheem 21VR40-7 $177.00 Bethpage, NY Rheem RH21V40 $178.50 Winchester, VA Rheem Rheem 21V407 $184.00 Marion, IN A.O. Smith FSG40 $187.3866 Source Manufacturer Brand Model Retail Boston, MA State Industires POWERMISER 5 33246 $190.00 Boston, MA State Industires POWERMISER 5 33246 $200.00 Orange, CA State Industries Reliance 5-40-NBRT $209.00 Berkeley, CA Rheem Rheem 21V40T $222.00 Boston, MA State Industires ANNIV. SERIES 10 $250.00 Boston, MA State Industires POWERMISER 5 33246 $260.00 Average Retail Cost $149.94 Installation and Maintenance Costs The installation cost is the cost to the consumer ofinstalling the water heater and is not considered part ofthe retail price. The cost ofinstallation covers alllabor and material costs associated with the replacement ofan existing water heater. Delivery, removal, and permit fees are also included. Forthe baseline water heatermodels, data was collected from the same sources as those used to gather retail prices, toestablish the installation cost ofa 40 gallon (150 liter) baseline gas-fired storage water heater. Table 49 lists the installation costs. The average installation cost was determined to be $159.52. All information presented in Table 49 are from the LBNL Water Heater Database 44

. Table 49. 40-Gallon (150 liter) Gas-Fired Storage Water Heater Installation Costs
Source Manufacturer Brand Model Installation Berkeley, CA Rheem Rheem 21V40-7N $65.00 Berkeley, CA Rheem Rheem 21V40S-2 $65.00 Berkeley, CA Rheem Rheem 21VR40-7 $65.00 Berkeley, CA Rheem Rheem 21V40T $65.00 Falls Church, VA American Water Heaters PROLine G51-40T34-3NV $75.00 Anchorage, AK Bradford White $90.00 Anchorage, AK Bradford White $90.00 Stockbridge, GA American Water Heaters Envirotemp G51-40T34-3NV $119.00 Salt Lake City, UT American Water Heaters American Water Heaters G51-40T34-3NV $125.00 Denver, CO State Industries Reliance 540-NORT $130.00 Little Rock, AR American Water Heaters Amerimore G51-40S33-3NV $130.00 Little Rock, AR American Water Heaters Amerimore G51-40T34-3NV $130.00 Little Rock, AR American Water Heaters Amerimore DVG52-40S38-NV $130.00 Phoenix, AZ State Industries Reliance 5-40-NORT $136.00 Atlanta, GA American Water Heaters PROLine G51-40S33-3NV $142.00 Atlanta, GA American Water Heaters PROLine G51-40S33-3NV $142.00 Nashville, TN American Water Heaters American Water Heaters G51-40T34-3NV $145.00 Nashville, TN American Water Heaters American Water Heaters DVG52-40S38-NV $145.00 Marieeta, GA American Water Heaters Envirotemp G51-40T34-3NV $149.00 Livermore, CA Sears/State Industries Kenmore $153.99 Livermore, CA Sears/State Industries Kenmore $153.9967 Source Manufacturer Brand Model Installation Reno, NV American Water Heaters American Water Heaters G51-40T34-3NV $154.00 Dallas, TX State Industries Reliance 5-40-NORT $155.00 Charlotte, NC American WaterHeaters $155.00 Orange, CA State Industries Reliance 5-40-NORT $159.00 Orange, CA State Industries Reliance 5-40-NBRT $159.00 West Allis, WI American Standard American Standard $159.00 St. Louis, MO American Water Heaters American Water Heaters G51-40T34-3NV $160.00 Dale City, VA American Water Heaters Craftsman $169.00 Las Vegas, NV State Industries Reliance 5-40-NORT $170.00 Richmond, CA Sears/State Industries Kenmore 33246 $174.00 Charlotte, NC American Water Heaters More-Flo G51-40T34-3NV $175.00 Emeryville, CA American Water Heaters American Water Heaters G51-40T34-3NV $176.00 Emeryville, CA American Water Heaters American Water Heaters G51-40S33-3NV $176.00 Oklahoma City, OK State Industries Reliance 5-40-NORT $180.00 Lexington, KY American Water Heaters American Water Heaters G51-40T34-3NV $200.00 Chicago, IL American WaterHeaters More-Flo PVG52-40T50-3NV $209.00 Chicago, IL American Water Heaters More-Flo G51-40T34-3NV $209.00 Sacramento, CA American Water Heaters American Water Heaters G51-40T34-3NV $210.00 Boston, MA State Industires ANNIV. SERIES 10 $220.00 Boston, MA State Industires POWERMISER 5 33246 $220.00 Boston, MA State Industires POWERMISER 5 33246 $220.00 Boston, MA State Industires POWERMISER 5 33246 $220.00 Bew Orleans, LA American Water Heaters American Water Heaters G51-40T34-3NV $225.00 Seattle, WA State Industries Reliance 5-40-NORT $231.00 Atlanta, GA American Water Heaters PROLine G51-40S33-3NV $234.00 Atlanta, GA American Water Heaters PROLine G51-40T34-3NV $234.00 Minneapolis, MN American Water Heaters More-Flo G51-40T34-3NV $258.00 Average Installation Cost $159.52 Four design options were assumed to increase the cost ofinstalling a gas-fired water heater: the improved flue baffle, electronic ignition, the electromechanical flue damper, and the side-arm heater. For several designs, TANK reported flue efficiency close to 80%. For those designs it was assumed a Type B vent connector is required to ensure that condensation would not occur within the vent system. The additional installation cost associated with this vent connector was based on an analysis by GRI and independently verified byPNNL (see Appendix C). As established by GRI, the cost forreplacing a single-wall vent connector with a Type B double-wall vent connector is $85 in 1990 dollars 45 or$105.29 in 1998 dollarsa (conversions from 1990 dollars to 1998 dollars were adjusted by the consumer price index (CPI) fromthe Bureau of

a Values in 1990 dollars are converted to 1998 dollars by multiplying the 1990 value by theratio ofthe 1998 and 1990 CPI. The 1990 CPIfor all urban consumers is 130.7. The 1998 CPI isbased onthe average CPI during the first three months ofthe year (161.9).68 Labor Statistics 4 6). It was determined that 51.3% ofhouseholdsa required a Type B vent connector 4 7

. Thus, the average additional installation cost was determined by multiplying the $105.29 cost by 51.3%. This yields a value of$54.01 in 1998 dollars as the representative average installation cost for the improved flue baffle design, or other design options within RE=78%. 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 to bring electricity to the gas-fired water heater for these design options. This installation cost estimate was also based on data from GRI48

. Ofthe added installation cost, $6.20 in 1990 dollars, or $7.68 in 1998 dollars, isrequired for labor and wiring ofevery water heater with any ofthese three design options. Thirty-two percent ofhouseholds will also require an electrical outlet at the water heater. GRI estimated this cost at $66.15 in 1990 dollars4 9;this is equivalent to $81.94 in 1998 dollars. Thus, the average cost for installing an outlet was determined bymultiplying the $81.94 cost by 32%. This yields an average cost of$26.22 in 1998 dollars forthe installation ofan outlet. This value plus the wiring and labor cost of$7.68 yields a total representative added installation cost of$33.90 in 1998 dollars for the three design options which require electricity to operate. The electromechanical flue damper was the only design option that was assumed to increase a gas-fired water heater's maintenance cost. The maintenance cost ofthe flue damper was based on a prior DOE analysis50, in which the national average flue damper maintenance cost was estimated as $63.64 in 1990 dollars or $78.84 in 1998 dollars. For this analysis, the flue damper was assumed to fail in the tenth year ofoperation. Using a 6% discount rate, this yields a present value of$44.02 in 1998 dollars or an annualized maintenance cost over the ten year period of$5.98. With the exception ofthe electromechanical flue damper, information gathered to date suggests that there is virtually no maintenance ofresidential gas-fired water heaters. Side-arm heater designs may incur increased maintenance costs dueto fouling ofthe heat exchanger from hard water, but data has not been identified or provided to confirm this. It should be noted that manufacturers recommend that water heaters be drained and flushed annually to minimize deposition ofsediment, maintain operating efficiency and prolong equipment life. Cost-Efficiency Data

aThe 51.3% value was determined by multiplying the total number ofwater heater installations with either Type B vertical vents (42%) or masonry chimneys (48%) by the fraction ofhouseholds requiring a Type B vent connector (75%) and the fraction ofhouseholds not already utilizing Type B vent connectors (76%). Thus, the total number ofhousehold requiring a Type B vent connector isrepresented by the following equation: (42% + 48%) · 75% 76% = 51.3%.69 The results ofthe design option analysis for 40 gallon (150 liter) gas-fired storage water heaters are presented in Tables 50 and 51. Included in the cost and efficiency tables are disaggregated manufacturer costs, retail prices, installation costs, maintenance costs, energyefficiency and energy use data, and payback periods. Design options were added to the baseline model in order ofshortest payback period. The payback period for each set ofdesign options was calculated relative to thebaseline design according to the following relationship: 

### ACC ARC+AIC PAYBA CK - AA OC AEC+AMC where; PAYBACK = payback period (years), ACC = change in consumer cost relative to baseline, ($), AOC = change inoperating cost relative to baseline, ($/year), ARC = change inretail cost relative to baseline, ($), AIC = change in installation cost relative to baseline, ($), AEC = change in energy cost relative to baseline, and ($/year), AMC = change in annualized maintenance cost relative to baseline, ($/year).

The existing baseline design with HCFC-141b foam insulation ispresented in Table 50 to show the manufacturer cost and retail price differences between the baseline designs with HCFC141b and HFC-245fa. Also presented in Table 50 are the costsfor incorporating a design to resist igniting flammable vapors. Forpurposes ofthis analysis, the cost effectiveness ofall design options were evaluated in reference to the analytic baseline design with HFC-245fa and the flammable vapor ignition resistant design. Energy costs were from national average energy prices for 2003 from the 1998AnnualEnergy Outlook". The costs for allthe design option combinations are shown in Table 50 and the efficiency data is shown in Table 51. A design option selection process is presented as a flowchart in Figure 3. The first selected design option.combination is "Analytical Baseline" plus "Heat Traps", which has the shortest payback period

- 2.2 years. This combination is called selection 1. Selection 2 and selection 3 are branches from selection 1and include "2 in. Jacket Insulation" and "2.5 in. Jacket Insulation" design options. Based onthe next shortest payback period, selection 4 is chosen. It includes the "Side Arm Heater" design option and isbuilt on selection 3. The last is selection 5

- "Efficient Flue Baffle", which isbased on selection 2. Table 50a and 5la contain cost data and efficiency data forthe selected design combinations respectively. These selected design combinations are used in the Life Cycle Cost Analysis. Metal heattraps are not included in the cost-efficiency table because plastic heat traps are more cost effective. The highest EFs are obtained withthe side-arm heater designs. No designs pay back in lessthan 2 years. The gas-fired water heater withheat traps, 2/2 in. ofinsulation, electronic ignition and a mechanical flue damper has a .638 EF, energy savings of3.96 million70 Btu ofnatural gasper year and a payback of 18.96 years. The side-arm gas-fired water heater with efficient flue baffle, 2/2 in. ofinsulation and electronic ignition has a .675 EF, energy savings of6.45 million Btu ofnatural gas and a payback of7.05 years. Figure 4 graphically depicts the relationship between both increased consumer cost and increased operating cost versus EF.

Gas Fired Water Heaters Design Option Selection Process

Analytic Baseline 

### Opt. Oa

Opt. 0 + Heat Traps (Opt. 1) Opt. 1 + 2" ' insulation (Opt. 2) pt 2 &

i nsulation \(Opt. 3a) Opt. 3d Heater * Inreaeed RE

Opt. ___________________N Opt. 4b 2.5Ba

I Opt. 2 + Efficient | /< 9\ , o f | opt 4Baffle Opt. 3a + Side- Ar Arm Heater w/

Standard RE (Opt. -_ in---' ' ^ '~~sula / ^ ~~Opt. 3ae n1d & Electromechanical Flue St 40 -'''- ^v Damper

Opt. 2 5 Effici Opt. 4 + Efficient Flue Flue Baffle t(Opt. 3o

Figure 3. Gas Fired Water Heaters Design Option Selection Process7172 Table 50. Cost Table for 40gallon (150 liter) Gas-Fired Storage WaterHeater

IncrementalVariable Costs (per unit) '" Incr. Fixed Costs (perunit) *' Total Design Total Product Total Mfg Retail Install. Maint.

No. Design Options Material Labor Overhead Variable Capital Design Fixed Cost Price"' Cost' Cost' 0 Existing Baseline $75.02 $12.49 $50.10 $137.61 $0.00 $0.00 $0.00 $137.61 S157.74 $159.52 $0.00 Oa Analytic Baseline +Resistant Flammable Vapor $16.11 $0.00 $0.00 $16.11 $20.00 $0.00 $20.00 $173.72 $199.13 $159.52 $0.00 I Oa +Heat Trap $2.75 $0.16 $0.21 $3.12 $0.07 $0.13 $0.20 $177.04 $202.93 $159.52 $0.00 2 I +2"Jacket Insulation $9.59 $0.60 $4.93 $15.12 $0.85 $0.59 $1.44 $193.60 $221.92 $159.52 $0.00 3a +2.5" Jacket Insulation $14.49 $1.20 $9.86 $25.55 $1.28 $1.18 $2.46 $205.05 $235.04 $159.52 $0.00 3b 2 +Improved Flue Baffle $0.97 $1.29 $1.32 $3.58 $1.17 $1.72 $2.89 $200.07 $229.33 $213.54 $0.00 3c 2 +Electronic Ignition &Flue Damper 3 $128.83 $7.40 $27.59 $163.82 $5.54 $3.50 $9.04 $366.46 $320.06 $193.42 $5.98 3d 2 +Side-Arm Heater w/ Increased RE6 $69.25 $6.67 $27.34 $103.26 $7.51 $5.21 $12.72 $309.58 $354.86 $193.42 $0.00 4a 3a +Side-Arm leater w/Standard RE 7 $68.28 $5.38 $26.02 $99.68 $6.34 $3.49 $9.83 $314.56 $360.57 $193.42 $0.00 4b 3a+Improved Flue BaffleR $0.97 $1.29 $1.32 $3.58 $1.17 $1.72 $2.89 $211.52 $242.46 $213.54 $0.00 4c 3a +Electronic Ignition &Flue Damper 9 $128.83 $7.40 $27.59 $163.82 $5.54 $3.50 $9.04 $377.91 $433.18 $193.42 $5.98 5 4a +Improved Flue Baffle'" $0.97 $1.29 $1.32 $3.58 $1.17 $1.72 $2.89 $321.03 $367.98 $247.44 $0.00 All costs and prices in 1998$. 2Incremental variable and fixed costs are per unit costs. ' For the Existing Baseline Model with HCFC-141b, theTOTAL variable costs are provided.

Retail Prices are calculated based on the manufacturer cost-to-retail price markup of 1.14626. Design option 3c: The incremental cost covers Electronic Ignition &Flue Damper. The total cost includes Heat Trap and 2" Jacket Insulation Design option 3d: The incremental costcovers 78% RE Side-Arm heater w/Metal tank and Electronic Ignition

The total cost includes Heat Trap and 2" Jacket Insulation 7Design option 4a: Theincremental cost covers 76% RE Side-Arm heater w/Metal tank and Electronic Ignition

The total cost includes Heat Trap and 2.5" Jacket Insulation Design option 4b: Theincremental cost covers Improved Flue Baffle. The total cost includes Heat Trap and 2.5" Jacket Insulation Design option 4c: The incremental cost covers Electronic Ignition &Flue Damper.

The total cost includes Heat Trap and 2.5" Jacket Insulation '"Design option 5: The incremental cost covers Improved Flue Baffle.

Ihetotal cost includes Heat Trap, 2.5" Jacket Insulation, 78% RE Side-Arm heater w/ Metal tank and Electronic Ignition.73
Table 50a. Cost Table for 40 gallon (150 liter) Gas-Fired Storage Water Heater

- Selected Design Option Combinations Incremental Variable Costs (per unit) ''. Incr. Fixed Costs (per unit) '1 Total Selection Design Total Product Total Mfg Retail Install. Maint.

No. No. Design Options Material Labor Overhead Variable Capital Design Fixed Cost Price" Cost' Cost'

0 0 Existing Baseline' $75.02 $12.49 $50.10 $137.61 $0.00 $0.00 $0.00 $137.61 $157.74 $159.52 $0.00 Oa Oa Analytic Baseline +Resistant Flam. $16.11 $0.00 $0.00 $16.11 $20.00 $0.00 $20.00 $173.72 $199.13 $159.52 $0.00 I I Oa+ Heat Trap $2.75 $0.16 $0.21 $3.12 $0.07 $0.13 $0.20 $177.04 $202.93 $159.52 $0.00 2 2 1+2" Jacket Insulation $9.59 $0.60 $4.93 $15.12 $0.85 $0.59 $1.44 $193.60 $221.92 $159.52 $0.00 3 3a 1+2.5" Jacket Insulation $14.49 $1.20 $9.86 $25.55 $1.28 $1.18 $2.46 $205.05 $235.04 $159.52 $0.00 4 4a 3a +Side-Arm Heater' $68.28 $5.38 $26.02 $99.68 $6.34 $3.49 $9.83 $314.55 $360.57 $193.42 $0.00 5 3b 2+Improved Flue Baffle $0.97 $1.29 $1.32 $3.58 $1.17 $1.72 $2.89 $200.07 $229.33 $213.54 $0.00 All costs and prices in 1998$. 2Incremental variable and fixed costs are per unit costs. 'For the Existing Baseline Model with HCFC-141b, the TOTAL variable costs are provided. 4Retail Prices are calculated based on the Manufacturer to Retail Markup of 1.0896. 'Side-arm heaterwith metal tank includes electronic ignition, 2.5"insulation, heat traps.74
Table 51. Efficiency Table for 40 gallon (150 liter) Gas-Fired Storage Water Heater
Fuel Energy Use Electrical Energy Use Payback

Design Energy Recovery UA Thermal Daily Yearly Daily Yearly Period2

No. Design Options Factor Efficiency Efficiency Btuday MMBu/ear kWh/day kWh/year years 0 Existing Baseline 0.545 75.48% 13.82 77.90% 78289 28.58 0.00 0.00 NA Oa Analytic Baseline +Resistant Flammable Vapor 0.544 75.56% 13.86 77.90% 78298 28.58 0.00 0.00 NA I Oa +Heat Trap 0.554 75.57% 12.96 77.90% 77523 28.30 0.00 0.00 2.31 2 I +2"Jacket Insulation 0.580 76.21% 11.04 77.85% 75159 27.43 0.00 0.00 3.42 3a I +2.5" Jacket Insulation 0.587 76.38% 10.64 77.74% 74647 27.25 0.00 0.00 4.63 3b 2 +Improved Flue Baffle 0.595 78.01% 10.69 79.75% 72784 26.57 0.00 0.00 7.19 3c 2 +Electronic Ignition &Flue Damper 0.638 76.52% 5.95 77.85% 67465 24.62 0.14 52.77 19.81 3d 2+Side-Arm Heater w/ Improved Flue Baffle 0.655 76.00% 5.68

- 62483 22.81 0.08 29.32 5.82 4a 3a +Side-Arm Heater 0.662 76.00% 5.24
- 61819 22.56 0.08 29.32 5.97 4b 3a +Improved Flue Baffle 0.600 78.03% 10.37 79.57% 72530 26.47 0.00 0.00 7.19 4c 3a +Electronic Ignition &Flue Damper 0.645 76.71% 5.52 77.84% 66792 24.38 0145 52.77 18.75 5 4a +Improved Flue Baffle 0.675 78.00% 5.36

- 60618 22.13 0.08 29.32 7.28 'Annual operating cost for Payback Period calculation established with a gas price of$5.82 /MMBtu and an electricity price of$0.0787 /kWh in 1998$. Thermal Efficiency isused todetermine the risk ofventing system corrosion...75
Table 51a. Efficiency Table for 40 gallon (150 liter) Gas-Fired Storage Water Heater

- Selected Design Option Combinations
Fuel Energy Use Electrical Energy Use Payback Selection Design Energy Recovery UA Thermal Daily Yearly Daily Yearly Period'

No. No. Design Options Factor Efficiency Efficiency 2 Btu/day MMBtu/year kWh/day kWh/year years 0 0 Existing Baseline 0.545 75.48% 13.82 77.90% 78289 28.58 0.00 0.00 NA Oa Oa Analytic Baseline +Resistant Flam. 0.544 75.56% 13.86 77.90% 78298 28.58 0.00 0.00 NA I I Oa +Heat Trap (plastic) 0.554 75.57% 12.96 77.90% 77523 28.30 0.00 0.00 2.31 2 2 1+2"Jacket Insulation 0.580 76.21% 11.04 77.85% 75159 27.43 0.00 0.00 3.42 3 3a I +2.5" Jacket Insulation 0.587 76.38% 10.64 77.74% 74647 27.25 0.00 0.00 4.63 4 4a 3a + Side-Arm Heater 0.662 76.00% 5.23
- 61819 22.56 0.08 29.32 5.97 5 3b 2 +Improved Flue Baffle 0.595 78.01% 10.69
- 72784 26.57 0.08 0.00 7.19 Annual operating cost for Payback Period calculation established with agas price of$5.82 /MMBtu and an electricity price of$0.0787 /kWh in 1998$. 2Thermal Efficiency is used to determine therisk ofventing system corrosion.76

540 4 180 i-- ConsumerCost I X 500 1-------

- - Operating Cost

__ 170

a 460

- _ - - - . _____ 160 S I s ;J I a

340 2 130 0.52 0.54 0.56 0.58 0.60 0.62 0.64 0.66 0.68 

### Energy Factor Figure 4. 40 gallon (150 liter) Gas-Fired Storage Water Heaters: Total Consumer Cost and

Oil-fired water heaters are typically constructed using aglass-lined metal storage tank 

### located above an insulated combustion chamber. There are two basic design types, center flue andrear flue (also referred to as floating tank design). Both designs utilize anoil-burner consisting ofoil pump, blower, ignition device, and controls. The two basic designs are differentiated by flue location. Inacenter flue design, the combustion products are vented through acenter flue that goes up the middle ofthe storage tank. By contrast, rear-flue designs provide forthe combustion gases totravel around the outside ofthe storage tank. The rear-flue designprovides significantly more heat exchange areabetween the storage tank and flue gases. Thus, these designstypically have higherRE and input ratings compared to centerflue designs of similar storage volumes. However, becausethe hot exhaust gases travel near the outside ofthe water heater, there is also more heat transfer area for off-cycle losses to the flue. Because centerflue designs are much more common in residential use, the DOE analysis foroil-fired water 

### heaters only considers center-flue designs. heaters only considers center-flue designs.77 The pump and blower ofthe water heater are powered by a single motor. The blower provides for proper mixing ofoil and combustion air. The oil and airmixture is electrically ignited with ahigh voltage spark. Inmostburners, this spark operates continuously as long as the burner is firing. Since the spark does not operate when the burner is off, this is referred to as an intermittent ignition system. Oil-fired water heaters have higher input ratings than similar sized gas-fired storage water heaters, resulting in higher recovery rates. Because ofthe relatively high recovery rates, the industry uses storage tank volumes slightly smaller than those used with gas-fired or electric storage water heaters. The oil-fired water heater industry uses twocommon tank volumes, each witha corresponding input rating. These are either 32 gallon (120 liter) water heaters with an input rating between 85,000 to 95,000 Btu/hr (24,905 to 27,835 watts) or, 50 gallon (189 liter) water heaters with an input rating between 100,000 to 110,000 Btu/hr (29,300 to 32,230 watts). Discussions with installers andmanufacturers indicate that the 32 gallon water heater size represents thebulk oftheresidential market and this is the size used as abaseline model in the engineering analysis. Existing Baseline Model The first step in the design options analysis is to characterize the energy usage ofthe existing model. As stated previously, the existing oil-fired water heater used in this analysis has an EF of0.529, an RE of75% and an energy consumption of90,962 Btu/hr (90,000 Btu/hr of fuel oil and 282 W [962 Btu/hr] for the pump and blower motor) during firing. Table 52 summarizes theprimary baseline characteristics. Thejacket insulation was assumed to be 1in. ofHCFC-141b foam, characteristic ofwater heater models known to closely match DOE's baseline performance criteria. Many existing oil-fired water heater models use fiberglass insulation, however these models typically use more than 1in. ofinsulation and have better performance. Note thatthe analysis did not address the modeling ofthe combustion chamber and hence no detailed description ofthe combustion chamber was needed. The values in Table 50 describe the water heater in engineering terms for use in the heattransfer calculations. Table 52. Oil-Fired WaterHeater Baseline Model Characteristics Descriptive parameter Value Input Rating (oil) 90000 Btu/hr (26377 W) On-cycle power consumption 282 W Off-cycle power consumption 0.0 W Tank Dimensions Inside Diameter 17.892 in. (40.366 cm) Steel Wall Thickness 0.054 in. (0.1372 cm) Height 32.7 in. (83.1 cm) Volume 32.0 gallons (120 liter)78 Jacket Description Foam insulation thickness 0.981 in. (2.492 cm) Sheet metal thickness 0.019 in. (0.0483 cm) Thermal conductivity offoamed 0.0140 Btu/hr-ft °F (0.0242 Outer Jacket Emissivity 0.87 Flue Description Internal Diameter 6.00 in. (15.24 cm) In order to determine the daily energy consumption, the first step isto determine the hours ofoperation. This is done with the following equation.
Qdr,, 

### BOH= draw (A) 

### EF. Po where; BOH = burner operating hours, the number ofhours per daythe burner is on (hrs/day), Qdraw = the amount ofheat added to the water in the daily draw underthe DOE testprocedure, (41,094 Btu/day [43,346 kJ/day]), 

### Pon = thetotal energy consumption rate (both electrical and fuel oil) when the burner is firing (Btu/hr) For the existing model, this results in 0.854 burner operating hours per day. Using the DOE testprocedure as a guideline, the daily energy consumption is calculated from the electrical and oil inputrates multiplied by the number ofoperating.hours per day. This results in an oil consumption of76,860 Btu/day (81,072 kJ/day) and an electrical energy consumption of241 Wh/day. The UA from the DOE test procedure was estimated using the following equation: 1 1 

### EF P,, ((ta-- t-n b 24 1 RE ( Qdra.w i R Pon Plugging in the appropriate existing model values ofEF, RE, and Pon results in a UA of 14.494 Btu/hr-°F (7.64 W/°C) for the existing model. By definition, this UA consists ofstandby heat losses through the tank shell, through fittings, and from the flue during the off-cycle. Table 53 summarizes the results for the energy characteristics ofthe existing baseline model. Table 53. Performance Characteristics for Existing Baseline Oil-Fired Water Heater79 Description UA RE EF Oil Use Electrical Use Btu/hr °F (W/°C) Btu/day (kJ/day) Wh/day Existing Baseline 14.494 (7.64) 75% 0.529 76,860 (81,072) 241 The continuous losses, on-cycle flue losses, and off-cycle flue losses are determined from two equations. The first equation sets two definitions oftotal dailyheat loss equal. It states that the sum ofthe rates ofloss multiplied bythe hours ofeach type ofloss equals thetotal consumption minus delivered energy. The second equation isbased on the definition ofRE, i.e., thetotal on-cycle lossesequal the energy input minus the hot water energyremoved from atank during the recovery portion ofthe DOE test procedure. The two equations can be written as follows: 24-Losscontinuous+ (24-BOH)Loss_Flue_off + BOH Lossflue_on =Qda /EF

- Qd (C) Losscontinuous+Lossjlue_on =Input (1

-RE) (D) where; Loss_continuous = continuous losses through thejacket insulation and outthe fittings, (Btu/hr) or (Watts), Lossflue_on = on-cycle losses up the flue, (Btu/hr) or (Watts), Lossflue_off = off-cycle losses up the flue as well as other off-cycle noncontinuous losses, (Btu/hr) or (Watts), These losses are not used for calculating annual energy consumption, rather they are used as the basis fordifferences in heat loss rates for other design options. Analytic Model. Similarly to gas water heaters, the existing model's HCFC-141 b foam insulation was replaced with HFC-245fa foam insulation due to the impending phase out of HCFC-141b in 2003. HFC-245fa has a 3.0% higher conductivity than HCFC-141b and for this design option, the conductivity value ofthe foam insulation inthe existing model was increased by 3.0% to a value of0.0144 Btu/hr-ft-°F (0.0249 W/m *K). Tomaintain the same R-value of the insulation (and thus maintain constant UA and REvalues for the water heater) the thickness ofthe nominal 1-in. offoam insulation surrounding the tank was increased from 0.981 in. (2.492 cm) actual thickness to 1.01 in. (2.57 cm). This increase in insulation thickness also resulted in an increase of jacketmaterial. Table 54 summarizes the changes thatwere made to the existing model with HCFC-141b to provide the same performance with HFC-245fa (see Table 53). All further design options assume the use ofHFC-245fa for the tank insulation. Table 54 summarizes the results for the energy characteristics ofthe analytic baseline model.80 Table 54. Oil-Fired Water Heater Modeling Differences: Existing Model with HCFC-141b vs. Analytic Model with HFC

Descriptive Parameter Existing Model Analytic Model Jacket Description Foam insulation thickness 0.981 in. (2.492 cm) 1.01 in. (2.57 cm) Thermal conductivity of 0.0140 Btu/hr-ft-F (0.0242 0.0144 Btu/hr-ft-°F (0.0249 foamed assembly W/m-K) W/m-K) Table 55. Performance Characteristics for Analytic Oil-Fired Water Heater Description UA RE EF Oil Use Electrical Use Btu/hr °F (W/°C) Btu/day (kJ/day) Wh/day Analytic Baseline 14.494 (7.64) 75% 0.529 76,860 (81,072) 241 Heat Traps. Two types ofheat traps were analyzed for oil-fired water heaters: metal and plastic. Both types ofheat traps prevent the losses associated with the circulation ofhot water into the piping distribution system. An estimate for thereduction offittingheat losses due to heat traps added to the analytic model was based on the analysis ofthe same design option applied to gas-fired water heaters. Results from TANK simulations (see analysis ofgas-fired water heaters) suggests that metal heat traps reduce the UA ofa water heater tank by 0.318 Btu/hr-°F (0.168 W/°C) during the DOE test. The TANK analysis suggested plastic heat trapsreduced the UA ofthe tank by 0.899 Btu/hr-°F (0.474 W/°C). There is no impact on the RE ofthe analytic model. Subtracting these UA reductions from the UA ofthe analytic oil-fired model andplugging the new UA into equation (B) without changing the values for the other parameters from the analytic models yields a new estimate forEF. The results ofthis analysis are shown in Table 56. Table 56. Analysis Results for Design Option #1(Heat Traps) Design Option#1 UA RE EF Oil Use Electrical Use Btu/hr °F (W/C) Btu/day (kJ/day) W-h/day Metal Heat Trap 14.176 (7.476) 75% 0.532 76,363 (80,547) 239 Plastic Heat Trap 13.595 (7.17) 75% 0.539 75,456 (79,590) 236 For this analysis, plastic heat traps will be the chosen design option. Manufacturing costs appear to be roughly comparable between metal and plastic traps and plastic heat traps are considerably more effective in reducing the water heater standby losses. Note, using the results from TANK in this manner is slightly conservative. Since oilfired water heaters have larger recovery rates, they spend more ofthe "Standby" portion ofthe81 DOE test not firing. Thus, they will have longer periods for which heat traps are useful and consequently heat traps should have slightly higher benefits on oil-fired water heaters compared with gas-fired water heaters. This hasnot been accounted forin this analysis. Increased JacketInsulation. This design option replaces the nominal 1-in. (2.54cm) of 

### foam insulation surrounding the storage tank in theexisting tankdesign with 2in. (5.08 cm) of polyurethane foam insulation around the sides and top ofthe tank. The diameter ofthe tank increases to 22 in. (56 cm) and the total height ofthe water heater (including the combustion chamber) increases to 51 (130 cm) in.. It isassumed that there are no changes to thethickness of insulation surrounding the combustion chamber and no benefit has been calculated forthis. No other changes tothe tank design are assumed in this analysis except to enlarge the entire water heaterjacket to accommodate the increased thickness ofinsulation. A waterheater designer will either increase the fiberglass insulation thickness around the combustion chamber, or increase the internal dimensions ofthe combustion chamber to maintain a smooth cylindricaljacket on the water heater. These will add additional costs to the design. The addition ofinsulation may require awayto recess the burner orto increase the length ofthe 

### burner blast tube tomaintain properplacement ofthe nozzle in thecombustion chamber. This analysis does not account for anymodifications to the heat loss fromthe combustion chamber. Jacket heat losses are calculated as conductive losses through theinsulation to thejacket in series with convective and radiative heat transfer from thejacket to the surrounding air and environment. The side insulation is modeled asahollow cylinder with the inner diameter equal to the tank diameter (18 in. [45.7 cm]) and the same height as the tank (32.7 in. [83.1 cm]). The top insulation is modeled as a disk(18 in. diameter [45.7 cm]) with a hole forthe flue in the center (6 in. diameter [15.2 cm])). The details ofthe calculation ofthetotal conductive heat loss from the top and sides ofthe storage are provided in Appendix E. Both RE and UA are changed bythisreduction intotaljacket heat loss as itoccurs continuously during water heater use. Sincejacket losses are continuous losses, they are related to the RE through equation (D): Loss_continuous +Losslue_on =Po, (1

- RE) (D) Thus, RE = - (Losscontinuous+Loss_flue_on)/ Po (E) And subtracting the RE for two different levels of jacket loss when all other losses are held constant gives RE 2 -RE, = (Loss_continuous,

- Loss continuous)/Po, (F)

or82 RE 2 - RE, = (Jacket_loss,

- Jacketloss)/Po, (G) In the DOEtest procedure, the UA represents the average rate oftank energy input needed to maintain the tank at a constant temperature during standby. The standby heat loss rate is calculated as: Standby heatlossrate = UA (Tan

- Tam (H) This "standby heat loss rate" isthe average rate ofheat input needed to maintain a tank at a constanttemperature during standby. It includes continuous losses, flue losses when firing, and flue losses and piping losses during the off-cycle. An overall energy balance on the standby period yields:

UA-(Tta,

- Tb)-(24

-BOH&a) = (Loss_continuous+LossJlue_off.(24

- BOH) + BOH,-,Pan(1

- RE) (I) where; BOHda =Burner operating time to make up for hot water drawn from the tank (hr), BOHs, =Burner operating time to make up for standby losses (hr). BOHs,can be calculated from the total energy required during the standby period divided bythe energy input during firing. The energy required to make up for losses during the standby period is equal to the energy input forthe whole DOE test minus the energy that is actually used to heat water removed from thetank. In equation form, BOH,,is: BOHs, = I/Po, Qdr, (I/EF-1/RE) (J) And by default BOHdrw =BOH-BOHs, (K) Inserting equation (J) in equation (K) and solving for the loss components gives

UA (Tin-Tamb) (24 BOH+BOHs,,)- Q. (I- RE)- (F- (L) Losscontinuos+Lossflu rff = 2- 24

- BOH Plugging in the known parameters forthe analytic model water heater, and water heater with plastic heat traps gives combined Loss_continuous +LossJlue_offvalues of742 Btu/hr (217 W), and 695 Btu/hr (204 W) respectively. With the addition ofmore insulation, the continuous losses from the plastic heat trap design option are reduced by the difference in thejacket losses between the design with 2 in. (5.183 cm) ofinsulation (design option 2) and the same design with 1in. (2.5 cm) ofinsulation (design option 1

- heat traps). By solving the equations (A), (B), (J) and (L), the UA value and EF value can be found that provides the new combined Loss_continuous +Loss_flue_offvalue for the water heater with 2 in. (5.1 cm) insulation. Table 57 shows the results ofthisprocedure. Table 57. Analysis Results for Design Options 2

- 2" Jacket Insulation

Design Option Actual Calculated UA, RE EF Oil Use Electrical Insulation Shell Loss, Btu/hr- Btu/day Use Thickness "F (kJ/day)

in. (cm) Btu/hr (W) ( /°C) (W-h/day) 2" Jacket 1.981 89.2 12.241 75.1% 0.555 73,285 230 Insulation + (4.82) (26.1) (6.46) (77,301) Heat Traps ImprovedFlue Baffle. Asdescribed forgas-fired storage water heaters, improvedfluebaffle designs allowthe extraction ofmore heatfromthe exhaust gases andincrease the flue-loss (and hence recovery) efficiency ofthe water heater. The oil-fired water heater analysis assumes thatthe improved fluebaffle isadded afterheattraps and 2" jacket insulation. The energy savings for this design option are calculated by assuming that modification ofthe flue baffle will provide more efficient heat transfer to the storage tank. This design option will allow the water heater to achieve a RE of 0.78 by impacting reduction of Flue_loss_ononly. No modifications to Flue loss_offor Loss_continuous are assumed with this design option. There donot appear tobe significant concerns with condensing flueproducts at aREof0.78. The references regarding the existing rear-flue oil-fired water heaters report REs in this range. Additionally, thepremium water heater products soldbyBockWater Heaters allexceed this level of RE 5 2 , 5 3

.Improving the RE alone, from 0.75 to 0.78, while maintaining the sum of Flue_loss_off and Loss_continuous at 626 Btu/hr (183 W) as in the previous design option (2" jacket insulation) provides an EF of0.576 as shown in Table 58. Table 58. Analysis Results forDesign Option 3

- Improved Flue Baffle Design Option UA RE EF Oil Use Electrical Btu/hr- "F Btu/day Use

(W/°"C) (kJ/day) (W-h/day) Improved Flue 11.786 (6.216) 78% 0.576 70,562 (74,429) 221 Baffle + 2" Jacket84 Insulation + Heat Traps IncreasedHeatExchangerSurfaceArea. Thisisabroad areaofdesignoptions, generically referred to as Increased Heat Exchange Surface Area. The suggested design option makes use of small projections from the inner flue surface to: 1) increase the heat transfer area and 2) increase turbulence along the inner flue wall. One manufacturer presently builds water heaters that use aflue withmany smallrectangular fins attached in ahelical pattern onthe inside flue surface. Variations ofthis model have the highest efficiency rating listed in the GAMA directory for oil-fired water heaters.This design option is used here to describe a number ofpossible design modifications that would increase the surface area for heat exchange between the flue gases and water. These could include increased flue diameter with improved baffling, multiple flues, or internally finned flues. Presently,the only design feature on the U.S. market representative ofthis design option istheBock Turboflue system. The Turboflue designuses many smallrectangular finswelded in a helical pattern onthe insideofthe flue. The finsprovideincreased surfacearea forheat exchangewiththe flue gases and they create turbulence in the flue. The use ofthis type ofinternally finned flue is assumed to preclude the useofimproved fluebaffles, andhence theincreased heatexchanger surface areadesign option isreally an alternative to the improved flue baffle design option. The energyperformance of theincreased heat exchanger surface areadesign optionismodeled byincreasing theRE ofthe 2"jacket insulation (design option 2) to 0.82. Several ofthe water heater models that include the Turboflue in their design have a listed RE of0.82. As was done when considering the improved flue baffle design, no modifications to Flue_loss_oforLosscontinuous are assumed with this design option. Improving the RE alone, from 0.75 to 0.82 whilemaintaining the sum ofFlue_loss_off and Loss_continuousat 626 Btu/hr(183 watts) (as indesign option 2) provides an energy factorof0.606. Table 59 shows theresulting performance for Design Option 4

- Increased Heat Exchanger Area.85 Table 59. Analysis Results for Design Option 4

- Increased Heat Exchanger Area Design Option UA RE EF Oil Use Electrical Btu/hr- °F Btu/day (kJ/day) Use



### (W/°C) (W-h/day)
Increased Heat 11.216 (5.915) 82% 0.606 67,149 (70,829) 210 Exchanger Area + 2" Jacket Insulation + Heat Traps It should be noted thatthe energy factor estimate arrived at above maybe conservative. An examination oftheenergyperformance parameters ofseveral ofthe water heater models that usethe Turboflue design suggested much better energy performance can be achieved. For example, a 32 gallon (121 liter) waterheater model 32PP (Bock) utilizesthe internallyfinned Turbofluedesign and has 1"jacket insulation. However, this model reports an energy factor of0.66 and an RE of0.82. Bock's standard design model 32E, also incorporating the Turboflue design, has areported energy factor of0.63 and an RE of0.82. To illustrate this example, the energy losses forthe model 32PP design were partitioned as wasdone for the analytic model, but using the EF, RE andrated input ofthe 32PP model. Inserting an EFof0.66,RE of0.82, andrated inputof 104,000 Btu/hr(30,472 W) from the GAMA directory into equation (B) results in aUAvalue of7.652 Btu/hr(4.036 W/°C). Note however, that it should actually be easierto achieve theRE of0.82 ona waterheater when the rated input isthe same asthe analytic modelunit. Ifthepartitioning oflossesis doneusing the EF of0.66, RE of0.82, and rated input of90,962 Btu/hr (26,652W),the resultantUAis 7.676Btu/hr- F(4.052 W/°C). Bothofthese examples suggest a considerable reduction in UA above what has been assumed for the increased heat exchanger surface area design option. Standby losses for the Bock 32PP model are reduced significantly from that estimated for the increased heat exchanger surface area design option. It is not clear how much ofthis reduction in standby loss can be attributed to the Turboflue design (possiblybyrestricting air movement duringthe off-cycle) andhow muchisachieved through other means. InterruptedIgnition. Interrupted ignition devices allowfor the ignition sparkto be turned offafter a flame has been established. Interrupted ignition devices will provide electrical energy savings since thetime the spark is operating is shorter thanwith the intermittent ignition systems in use on present water heaterdesigns. Intermittent ignition systems provide spark continually while the burner is operating. Note, interrupted ignition systems may also increase the life ofthe spark electrodes somewhat and may reduce maintenance costs.86 Interrupted ignition provides electrical energy savings by shutting offthetransformer used to make the sparks. A typical intermittent ignition system utilizing an iron-core transformer may drawapproximately 1.7Ampsat 110V during operation61

. Itdoesthis forallburneroperation hours, so thedaily electrical energyuse for theignition system forthe increasedheatexchanger surface area design option (the most efficient case ofthe previous design options) would be calculated as: Intermittentlgnition_Energy=(1. 7Amps) (110 0V)BOH (S) Forthe designoption 3

- increased heat exchanger surface area, BOHis 0.746 hrs/day from equation (A). Equation (S) ignores anypower factorrelationshipsinthetransformerorelectronic circuitry. The Intermittent_Ignition_Energy forthe increased heatexchanger surfaceareadesign optionisthen calculated to be 140 wh/day. Foran interrupted ignition system, the system fires for approximately 20 seconds each time theburner is ignited. The duration ofeach water-heater on-cycle isa function oftheusage pattern, but the DOE test procedure, with six 10.3-gallon draws per day, will serve as the basis for this analysis. For most water heater designs, there will be a single recovery for each draw, with the length ofeach recovery period given by 1/6' ofBOHw (see equation Q). Forthe increased heat exchanger surface area design option waterheater, BOHdw equals 0.551 hrsand therecovery period after each draw is thus 0.092 hrs. Additionally, during the standby period there will be one ormore occasions for the burner to fireto make up forstandby losses. The working assumption isthat the average tanktemperature drops 20°F below the set point before firing is initiated, as dictated by the typical water-heater thermostat deadband. The energyrequired for each recovery isthentheproductofthe actual storage volume ofthe water heater (estimated at 95% ofthe ratedvolume), the density andheat capacity of the water, andthe watertemperature rise duringfiring. Thetimefor each individual recovery during standby can then be estimated as BOHrecoverysandby= ( Vol, dens C,) (Trise)/ (Po RE) (M) where; BOHrecoverystandby = the average time for each recovery during standby (hr) Volnk = 0.95 * rated tank volume (gal) Trse = the difference betweenthe average tanktemperature before and afterrecovery (°F) Solving the above equation yields an average BOHrecovey,stan equal to 0.0676 hr/day. The number ofdraws during standby equals BOHst/ BOH recoverystandby Using designoption 3

- increased heat exchanger surface area as abase, this isequal to2.125 draws during the standby period. Thus, on average, the DOE test procedure would require the burner to fire an average of

4'
-

### 87 8.125 times per day. At 20 seconds ofigniter operation per firing, this requires 0.045 hours of ignition operation per day. The difference between intermittent ignition and interrupted ignition operating time isthus 0.701 hrsperday (0.746hr

- 0.045 hr), saving 131 wh/day ofelectrical energy. This represents 447 Btu/day reduction inthe Loss_burner_on losses. Ifthis energy savings is averaged over the total burneroperating hoursof0.749 hrs/day for theincreased heatexchanger surface areadesign option, this represents an average reduction inelectrical power draw of 176 W (602 Btu/hr). Since the Pon is reduced by 602 Btu/hr (176 W) and the output ofthe water heater is unaffected,thedefinition ofRE canbeusedtoconstruct an equation for thenewREwhenthedesign goes to interrupted ignition. RE_interrupted= (RE_intermittent Polintermittent) / (Pointerrupted) (N) 

### For the water heater described by the increased heat exchanger surface area design option, thechange from an intermittant to an interrupted ignitionresults inanincrease inRE from 0.820 to 0.825. The UA is also affected, since there is some burner operation during the standby period. Again, sincethe energy inputtothe tankduring the standby period (represented byUA) is changed while the heat energy to the water during standby does not change, the ratio ofthe UA of the intermittent ignition system totheUA ofthe interrupted ignition systemis equal totheratio ofthe input (Pon) for the intermittent system to the input ofthe interrupted ignition system. Hence, UAinterrupted= UA_intermittent

.(Pointerrupted /Pointermittent) (0) 

### And solving,UA_interrupted = 11.142 Btu/hr-°F (5.88 W/°C). This UA,incombination witha calculated RE of0.825 results in aEFof0.610 fromequation (B). The same interrupted ignitionanalysiscanbeperformed on the improvedflue baffledesign option. Theresulting performance parameters are an RE of0.785, UA of11.708 Btu/hr- F (6.17 W/°C), and EF of 0.580. Table 60 shows the resulting performance for Design Option 5

- Interrupted Ignition.88 Table 60. Analysis Results forDesign Option 5

- Interrupted Ignition Design Description UA RE EF Oil Use Electrical Option Btu/hr- °F Btu/day Use (W/"C) (kJ/day) (W-h/day) 5a Interrupted 11.708 (6.175) 78.5% 0.580 70,562 83 Ignition + (70,829) Improved Flue Baffle 5b Interrupted 11.142 (5.876) 82.5% 0.610 67,151 79 Ignition + (70,829) Increased Heat Exchanger Area NOTE: The savings indicated fromthe interrupted ignition design option arebased on the use of a conventional magnetic transformer to provide high voltages in the ignition system. Electronic highvoltage generators used in electronic igniter circuitrytypically use about 0.5Amps, orless than a thirdthe current draw ofmagnetic igniter circuitry6',62. Assuming the same hours of burner operation as from design option 3

- increased heat exchange, the transition to electronic ignitioncircuitry from magnetic ignitioncircuitry in anintermittent ignition system would save 90 Wh/day. This is70% ofthe energy saved from going to aninterrupted ignition system. However, the adoption ofan interrupted ignition system in a water heater with electronic igniter circuitry would result in net energy savings ofonly 51 Wh/day (176 Btu/day) ascompared with intermittent electronic-ignition circuitry. Discussions with oil-fired water heater manufacturers indicates that electronic ignition circuitry is not commonly used in residential water heater burners, but is an available technology. Design OptionManufacturerCosts Manufacturing cost estimates for the oil-fired water heater design options are broken down into variable and fixed costs for each design option. These cost estimates are shown in Table 59 and the assumptions and sources behind the estimates are discussed below. Note that all fixed conversion costs have been amortized over a fiveyear period unless otherwise noted, and also amortized over an assumed shipment volume of5,000 units annually. Existing Baseline. Baseline cost forthe oil-fired water heat tank (without burner) was estimated based on data provided by Mr. Minniear under contract to LBNL63. It was recognized that manufacturers ofoil-fired water heaters use both fiberglass and foam in theirbaseline models. For the purposes ofthis analysis however, the cost for the baseline model, whether foam or fiberglass insulated, are assumed to be equivalent. A calculation ofthe volume offoam and shell material forthe baseline model was made independently ofthe data supplied by Mr.89 Minniear. For a 32 gal baseline model the total mass ofthe insulation was estimated at2.77 lbs ofHCFC141b foam. The unit price for the HCFC141b based insulation was estimated at $1.00/lb, yielding a total cost ofthe insulation for the 32 gallon water heater of$2.77/unit. Total shell material is 16.87 lbs ofsteel at $0.30/lb resulting in a manufacturer cost of$5.06. Total material cost for insulation and shell is $7.83. This cost information was used in determining the cost impact ofincreasing the insulation thickness on oil fired waterheaters. Analytic design option. The analytic model assumed 1.01 in. ofHFC245fa based insulation on top and sides oftank. For 32 gal tank, total mass ofthe insulation was estimated at2.86 lbs. At $1.32/lb estimated cost forHFC245fa based insulation, total insulation cost was estimated at $3.77. Total shell material was estimated to be 16.93 lbs ofsteel at $0.30/lb for a total shell cost $5.08. Total material cost for foam and shell is $8.85, an addition of$1.02 for materials over the baseline model. Sincethe phase out ofHCFC141b as a foaming agent is unrelated to the DOE's energy efficiency mandate and willbe borne by themanufacturers regardless ofmandated efficiency improvements, fixed costs for the analytic design option have not beenestimated. Heat Traps.Variable cost estimates for heat traps are based on data gathered by Mr. Minniear. Variable costs forheat traps were also estimated bya second consultant, Mr. Eugene West. Both estimates were very comparable. Mr. Minniear's estimates are used here as they provided the higher cost (more conservative) estimate and werebroken out into variable material, labor, and overhead costs. Fixed conversion costs to incorporate heat traps were developed from product design cost estimates provided byMr. West 4 65. For a small manufacturer, capital cost impact to incorporate heattraps was deemed negligible. 2" Jacket Insulation. Variable costs to increase insulation from 1to 2nominal in. of(1.01 to 1.981 in. actual thickness) ofHFC-245fa based insulation were estimated based on a nominal 1in. increase in foam on both thetop and side walls ofthe tank. Total foam mass for2 in. of insulation was estimated at 6.01 Ibs. At $1.32/lb foran HFC-245fa based foam, thetotal foam cost is estimated at $7.93. The corresponding increase in tankjacket size increased the total mass of jacket steel to 19.16 Ibs. Assuming an estimated $0.30/lb forjacket metal provided a jacket cost estimated at $5.75. Total material cost forfoam and shell is $13.68. An additional cost of$0.76 for miscellaneous costs such as foam stop blocks and larger shipping cartons was incorporated into the material costs based on data provided byMr. West 65

. Additional labor cost of$0.29/unit and additional overhead burdens of0.99/unit, provided bythe same source, were also incorporated into the variable cost. Finally, the addition ofinsulation can affect the shipping cost for the water heaters. No data for the increased shipping cost for an oil-fired water heater was provided to LBNL or PNNL; however, an estimate for this impact on shipping cost was made based on GAMA's estimated increase in shipping costs of$2.56 for an increase of 190 in ofinsulation on gas-fired water heaters66

. This value was added to the variable cost overhead, resulting in anet cost increase to $9.43 in variable cost over that calculated forthe analytic model. Fixed conversion costs forthis design option werebased on data provided by Mr. West67, who estimated that a small manufacturer, using spin forming to shape the top andbottom pans for the waterheater, would incur an estimated $18,000 in engineering costsfor this design option, and a further $20,000 in capital expenses to modify the production line65

. It is noted here that amanufacturer who used a die stamping method to produce the top and bottom pans could expect approximately $100,000 in new die costs alone. However, it wasbelieved that for alarge manufacturer, cost fordies to cut and form the top and bottom pans would likely have most ofthat cost amortized over an existing, similar diameter, gas product line. Inaddition to the above costs, discussions with manufacturers and installers ofoil-fired waterheaters have indicated that at least one-halfofall installations ofoil-fired water heaters are retrofits ofanew water heater to an existing oil burner. The oil burner life is typically at least twicethat ofthe typical water heater tank, however in some cases ifanew model or brand ofwater-heater is installed itmay be impossible or costly to fitto an existing burner and a complete installation oftank and new burner will beundertaken. Since the cost ofa new burner is a significant fraction ofthe cost ofthe water heater tank on most models, it is desirable to be able to attach an existing burner onto a new water heater. This isa significant problem since the extra insulation thickness would affect the burner placement and hence the combustion characteristics ofthe water heater. The solution, suggested by several industry members; was for the manufacturer to provide a kit that allowed replacement ofthe nozzle and blast tube on the existing burner with a nozzle and blast tube that was suitable for a new, heavily insulated, model. The estimated cost formanufacturing and stocking this kit wasbetween $20 and $40 based on input from Mr. West68

. The midpoint ofthat range, plus a labor charge of$6.50 (20 minutes ofservice at $19.50/hour) is used as an additional cost when tanks utilizing this design option are retrofit to existing burners. Improved Flue Baffles. Variable costs forimproved flue baffles were estimated as $3.75 for material, $0.55 for labor, and $1.00 perunit foroverhead costs based on estimates providedby Max Minniear. Fixed costs forimproving the fluebaffle design are estimated at $300,000 for production improvements and $500,000 for product design cost based on estimates provided by Mr. Minniear. Increased Heat Exchanger Surface. Variable costs forproviding increased heat exchanger surface area were estimated at $17.25/unit for material costs, $1.75/unit for labor costs and $4.25/unit in overhead. Fixed conversion costs for this design option were estimated at $1,500,000 for production improvements and $500,000 for product design costs. The fixed cost estimates are based on Bock's Turboflue model.91 InterruptedIgnition. Variable coststo incorporate interrupted ignition circuitry in oil burners was estimated at $16.50 material costs based on data provided byMr. Minniear. Discussions with aburner manufacturer69 indicated thatthe burner manufacturers cost differential for interrupted versusintermittent controls was presently between $10 and $15 and that typically these controls are installed onthe burner bythe burner manufacturer. The burner units withcontrols are then sent to the waterheater manufacturer who subsequently ships the burnerto the distributer or equipment dealer. There were not anticipated to be any additional overhead or labor costs for interrupted ignition controls over intermittent ignition controls. It was also the opinion ofthe person consulted that in the near future, interrupted controls would likely be the primary control option offered on all burners. However, no attemptwas made to indicate the effect ofthis onthe interrupted ignition control cost. No fixed capital costs are anticipated for interrupted ignition. Design costs for the water heatermanufacturer are predominantly related to testing and certification ofthe water heater. These costs are estimated at$25,000 based on similar product testing costs for increased insulation and heat traps submitted byMr. West. It is assumed that these costs are amortized over a 5 yearperiod. DOE hopes that GAMA willgather cost data for these design options from GAMA members who produce oil-fired water heaters. IfGAMA supply manufacturer cost data, DOE will revise the analysis with the GAMA data and use the consultants data as an independent check onthe GAMA data. As ofthiswriting, GAMA has been unsuccessful ingathering this cost data for oil-fired water heaters. The cost for all the considered design option combinations are shown in Table 61 and the cost for the selected design options is presented in Table 61a. The first selected design option combination is "Analytical Baseline" plus "Heat Traps", which has the shortestpayback period

- 3.8 years. This combination is called design option 1.Selection 2 "2 in. ofJacket Insulation" is based on design option 1. Based on the next shortest payback period, design option 3 is chosen. It includes "Improved Flue Baffle" design option and is built on selection 2. The last is selection 5

- "Interrupted Ignition", which is also based ondesign option 3. Table 62 and Table 62a presents accordingly the relative first cost, performance and annual energy use predicted for the considered design options and forthe selected design options used in this analysis. Those selected design combinations are furtherused in the Life Cycle Cost Analysis.92

Table 61. Cost Table for 32 gallon Oil-Fired Storage Water Heater Design Options

Incremental Variable Costs (per unit) '12 Incr. Fixed Costs (per unit) '12 Total Mfg to Design Total Product Total Mfg Retail Retail Install. Maint. No. Design Options Material Labor Overhead Variable Capital Design Fixed Cost Markup Price' Cost' Cost'

0 Baseline (HCFC14 b)

- I" foam3 $85.00 $18.25 $36.00 $139.25 $0.00 $0.00 $0.00 $139.25 3.20 $445.60 $491.00 $97.14 Oa Analytic (HFC245fa)- I" foam $1.02 $0.00 $0.00 $0.00 $0.00 $0.00 $10.00 $140.27 3.20 $448.86 $491.00 $97.14 I Oa +Heat Trap (plastic) $2.95 $0.05 $0.15 $3.15 $0.00 $1.52 $1.52 $144.94 3.20 $463.81 $491.00 $97.14 2 I +Increased Insulation to 1.981" (5.032 cm)4 $5.59 $0.29 $3.55 $9.43 $0.80 $0.72 $1.52 $155.89 3.20 $498.85 $509.25' $97.14 3 2 +Improved Flue Baffle (78% RE) 4 $3.75 $0.55 $1.00 $5.30 $12.00 $20.00 $32.00 $193.19 3.20 $618.21 $509.25' $97.14 4 2 +Increased Heat Exchanger Surface4 $17.25 $1.75 $4.25 $23.25 $60.00 $20.00 $80.00 $259.14 3.20 $829.25 $509.25' $97.14 5a 3+Interrupted Ignition4 $16.50 $0.00 $0.00 $16.50 $0.00 $1.00 $1.00 $210.69 3.20 $674.21 $509.254 $97.14 5b 4 +interrupted Ignition4 $16.50 $0.00 $0.00 $16.50 $0.00 $1.0 1.00 .00 $ 276.64 3.20 $885.25 $509.25' $97.14 All costs and prices in 1998$. 2Incremental variable and fixed costs are per unit costs.

For the Baseline Model with HCFC-141b, the TOTAL variable costs areprovided. ' Includes additional installation cost for burner conversion kit for 50% ofexisting market93 

### Consumer Cost, Installation, andMaintenance Costs foroil fired waterheaters. Sales and installation ofresidential oil-fired water heaters are typically done by alocal residential heating oil dealer. Hence, in most cases, the purchase and installation ofthe water heater is as apackage, making it somewhat difficult tobreak out installation cost from purchase price. A phone survey of29 companies dealing in oil-fired water heating equipment was made, with 13 companies providing some form ofconsumer price data to PNNL. Based on that survey as well as discussion with water heater and burner manufacturers and two oil-heating associations, the following costs were established. Typical consumer cost for abase performance oil-fired water heater without burner: $446 Typical consumer cost for an oilburner foran oil-fired water heater: $285 Typical installation cost for new oil-fired water heater $300-$700 The estimated installation cost for atypical oil-fired water heater was estimated at $491 based on data provided by seven dealers in the northeastern U.S.70

. In addition, it was established that at least 50% ofoil-fired water heater installations involve fitting anew water heater tank to an existing burner. For thepurpose ofthis analysis, it isassumed that 50% ofall oil-fired water heaters sold are for retrofit to an existing burner. Therefore, 50% ofthe installations ofwater heaters with 2" ofinsulation would require an oil burner modification kit. On average, the installation cost would rise to $509.25. Atypical manufacturer to consumer markup of320% was used across all design options based on the $446 figure forthe existing baseline oil-fired water heater cost (without burner), and the estimated manufacturing cost of$139.25 is shown on Table 59. A typical maintenance contract cost of$97.14/yr was included in Table 59. It is based on data provided by aphone survey discussed previously. This charge is highly variable, depending on thepresence ofother oil-fired equipment in the residence. Since none ofthe design options is anticipated to impact maintenance significantly, this charge has no bearing on the final engineering analysis ofthe design options. It mayhowever impact the final economic analysis when evaluating possible fuel switching. Relative Cost vs. Efficiency for Oil-fired WaterHeaterDesign Options Table 62presents the relative first cost,performance and annual energy use predicted for the design options considered in this analysis. Table 62apresents the relative first cost, performance and annual energy usepredicted for the design options selected from this analysis. It also shows the annual energy cost and estimated simple payback for each design option. Annual energy costs were based on residential energy rates of$7.522/MMBtu ofoil and $0.0787/kWh of electricity. Design options were selected based on the payback andthe energy factor. Those design options well beyond the average life ofan oil-fired water heaterwere not selected.9495 Table 62. Energy Impact and Simple Payback ofOil-Fired Water Heater Design Options
Recover Fuel Energy Use Electrical Energy Annual Design Factory Retail Install. Energy Efficienc UA Daily Yearly Daily Yearly Energy Simple

No. Design Options Cost Price Cost Factor (%) Btu/hr- Btu/day MMBtu/ Wh/day kWh/yr Cost' Payback

0 Existing $139.25 $445.60 $491.00 0.529 0.750 14.494 76860 28.05 241 87.9 $217.94

-- Oa Analytic model w/HFC-245fa $140.27 $448.86 $491.00 0.529 0.750 14.494 76860 28.05 241 87.9 $217.94

--- I Oa +Heat Traps $144.94 $463.81 $491.00 0.539 0.750 13.595 75456 27.54 236 86.3 $213.96 3.8 2 1+2in. foam insulation $155.89 $498.85 $509.25 0.555 0.751 12.241 73285 26.75 230 83.8 $207.80 8.7 3 2+Improved Flue Baffles $193.19 $618.21 $509.25 0.576 0.780 11.786 70562 25.76 221 80.7 $200.08 13.1 4 2+Increased Heat Exchanger $259.14 $829.25 $509.25 0.606 0.820 11.216 67149 24.51 210 76.8 $190.40 17.9 5a 3+Interrupted Ignition $210.69 $674.21 $509.25 0.580 0.785 11.708 70562 25.76 83 30.3 $196.11 14.1 5b 4 + Interrupted Ignition $276.64 $885.25 $509.25 0.610 0.825 11.142 67151 24.51 79 29.0 $186.64 14.1 'Annual energy costs are based on residential energy rates of$7.522/MMBtu ofoil and $0.0787/kWh ofelectricity.
Table 62a. Energy Impact and Simple Payback ofSelected Oil-Fired Water Heater Design Options
Recover Fuel Energy Use Electrical Energy Annual Design Factory Retail Install. Energy Efficienc UA Daily Yearly Daily Yearly Energy Simple

No. Design Options Cost Price Cost Factor (%) Btu/hr- Btu/day MMBtu/ Wh/day kh/yr Cost' Payback

0 Existing $139.25 $445.60 $491.00 0.529 0.750 14.494 76860 28.05 241 87.9 $217.94

--- Oa Analytic model w/HFC-245fa $140.27 $448.86 $491.00 0.529 0.750 14.494 76860 28.05 241 87.9 $217.94

--- I Oa+ Heat Traps $144.94 $463.81 $491.00 0.539 0.750 13.595 75456 27.54 236 86.3 $213.96 3.8 2 1+2 in. foam insulation $155.89 $498.85 $509.25 0.555 0.751 12.241 73285 26.75 230 83.8 $207.80 8.7 3 2+Improved Flue Baffles $193.19 $618.21 $509.25 0.576 0.780 11.786 70562 25.76 221 80.7 $200.08 13.1 5a 3+ Interrupted Ignition $210.69 $674.21 $509.25 0.580 0.785 11.708 70.562 25.76 83 30.3 $196.11 14.1 Annual energy costs are based on residential energy rates of$7.522/MMBtu ofoil and $0.0787/kWh ofelectricity.96 REFERENCES 1. Department ofEnergy, Energy Information Administration, AnnualEnergy Outlook 1998 (AE098), http://www.eia.doe.gov/oiaf/aeo98/earlyrel.html, December 18, 1997. 2. 10 Code ofFederal Regulations, Part 430- EnergyConservationProgramforConsumer Products Energy Conservation Program forConsumerProducts, AppendixEtoSubpartB

- Uniform TestMethodforMeasuringtheEnergy ConsumptionofWaterHeaters. 3. Department ofEnergy, Energy Information Administration,AnnualEnergy Outlook1998 (AE098), http://www.eia.doe.gov/oiaf/aeo98/earlyrel.html, December 18, 1997. 4. GasAppliance Manufacturers Association, October 1997, Consumers'Directory of Certified Efficiency Ratings forResidentialHeating andWaterHeating Equipment,Arlington, VA 5. U.S. Census Bureau; Current Industrial ReportforMajorHousehold Appliances(MA36F), 1995;published 18 September 1996; <ftp://ftp.census.gov/pub/industry/ma36f95.wkl> 6. Paul, D. D., Sheppard, W. J., Whitacre, G. R., Fischer, R.D., Rutz, A. L., Locklin, D. W., Crisafulli, J. J., Stickford, G. H., Murray, J. G., Landstrom, D. K., Talbert, S. G., Buhr, A. R., DeWerth, D. W., Farnsworth, C. A.,Loria, A. R., & Pietsch, J. A. (1991).Assessmentof TechnologyforImprovingtheEfficiency of ResidentialGasWaterHeaters,Topical Report No. GRI-92/0298). Battelle. 7. Barbour, Edward C., Dieckman, John T., and Nowicki, Brian J., Market Dispositionof High-Efficiency Water Heating Equipment,Final Report,ArthurD.Little,Inc., reference no. 46230, Washington, DC, prepared for Office ofBuilding Equipment, Office ofBuilding Technologies, State and Government Programs, U.S. Department ofEnergy, November 1996, 8. Water Heater Rulemaking Framework (June 11, 1997) http://www.eren.doe.gov/buildings/codes_standards/posted/whbb8O8.pdf 9. National Appliance Energy Conservation Act (NAECA). 1987. Public Law 100-12. 10. Federal Technology Alert. Sep. 1995. "Residential HeatPump WaterHeaters",prepared by Pacific Northwest National Laboratory forthe Federal Energy Management Program, U.S. Department ofEnergy, Washington, D.C. 11. Arthur D. Little, Inc., "MarketDispositionof High-Efficiency WaterHeating Equipment", 1996. 12. 10 Code ofFederal Regulations, Part 430, op. cit. 13. Hiller, Carl C., Lowenstein, Andrew I., Merriam, Richard L.,.WATSIM User'sManual, Version1.0:EPRIDetailedWaterHeating SimulationModelUser 'sManual,Electric Power Research Institute, Palo Alto, CA, TR-101702, October 1992,

### 97 14. Paul, D.D.; Whitacre, G.R.; Crisafulli, J.J.; Fischer, R.D.; Rutz, A.L.; Murray, J.G.; Holderbaum, G.S., TANK Computer ProgramUser's Manual withDiskettes:AnInteractive PersonalComputerProgramto Aid in the DesignandAnalysis ofStorage-Type Water Heaters.prepared for Gas Research Institute GRI-93/0186, Battelle Memorial Institute, Columbus, OH, July 1993 15. DOE, GRI, LBNL and PNNL, conferencecall,July 23, 1998. 16. Lutz, J.D., C.D.Whitehead, A.Lekov, D.Winiarski, G.J.Rosenquist, WHAM: A Simplified Energy Consumption Equation for Water Heaters, Proceedings of the ACEEE 1998 SummerStudy on EnergyEfficiency inBuildings,American Council foran Energy Efficient Economy (ACEEE), Washington, DC, 1998 17. U.S. Office of the Federal Register. 1993. Code ofFederalRegulations, Title 40, Environment. Part82:Protectionof StratosphericOzone; FinalRule. Washington, DC. Vol. 58, No. 236, December 10, 1993. 18. McGee, I.E., Dobransky, M. A.,and Ingold, K.A., HFC-245faasaBlowingAgentfor Water Heater FoamInsulation,Bayer Corporation, Pittsburgh, PApp 170-173 in Proceedings of thePolyurethanes EXPO' 96, sponsored bythePolyurethane DivisionofThe Society ofthe Plastics Industry, Inc., Las Vegas, NV October 20-23, 1996. 19. Ghadiali N.D., presentation to GRI's GasWater HeaterTechnical Advisory Group, Battelle, Columbus, OH, p.5, December 1997 20. Topping, R.F., and Benedek, K.R., Flammable Vapor TestMethodologyDevelopment for Gas-Fired WaterHeaters,Arthur D. Little, Inc., Cambridge, MA,April 1996, prepared for Gas Research Institute, GRI-96/0102. 21. Crisafulli, JJ.; Pate, A. D.; Philips, D. B.; Talbert, S. G.; and Rutz, A. L. Gas WaterHeater VentingIssuesandAlternatives.,GRI-96/0443, Battelle Memorial Institute, Columbus, OH, December 1996. prepared for Gas Research Institute. 22. Philips, D.B., Talbert, S.G., Whitacre, G.R., Crisafulli, J.J., and Rutz, A.L., Categorization Criteria forResidentialDraft-Hood-Equipped Gas WaterHeaters,GRI-95/0198, Battelle, Columbus, OH, October 1995, prepared for Gas Research Institute. 23. National Fuel GasCode

-AnAmerican National Standard, ANSIZ223.1 -1996,National Fire Protection Association, Quincy, Massachusetts, 1996, pp.51-53 24. Carl Hiller,personalcommunication,conversation with Greg Rosenquist, November 1997 25. Gas Research Institute, TANK ComputerProgramUser'sManual, report GRI-93/0186, prepared by Battele, Columbus, OH, 199398 26. Nisson,J.D. Ned, ed. 1994. "Simple Heat Trapfor WaterHeaters," EnergyDesign Update, Vol. 14, No. 10,New York, p 14. 27. Harvey, J.A. "Making Your Water Heater More Efficient." HomeMechanix,March, 1994, p.14. 28. Hiller, 1992, p. C-7. Op. cit. 29. Rheem Manufacturing Company, Water Heater Division, "Marathon High Performance, High Efficiency, Lifetime Gas Water Heater," Form No. 101-41, 10-93 BP, Montgomery, AL, 1993 30. Max Minniear,personalcommunication,e-mail to Jim Lutz, LBNL, Feb. 25, 1998 31. Dave Williams, Allied Signal,personalcommunication,telephone conversation with Jim Lutz, LBNL, March 17, 1998 32. lain Gilchrist, Perfection, Inc., Madison, OH, personal communication, fax to Judy Roberson, LBNL, March, 13, 1998 33. LBNL Water Heater Database, under continuous development, 1998. 34. Ibid. 35. Department ofEnergy,AnnualEnergy Outlook1998(AE098), 1997, Op. cit. 36. Ghadiali N.D., 1997, p.2, Op. cit. 37. Bergles, A.E., M.K. Jensen, E.F.C. Sommerscales, and R.M. Manglik. 1991. "Literature Review of Heat Transfer Enhancement Technology for Heat Exchangers in Gas-Fired Applications." GRI-91/0146, Gas Research Institute, Chicago, Illinois. 38. Beckermann, C. and V.W. Goldschmidt. 1986. "Heat Transfer in the Flueway ofWater Heaters." ASHRAE Transactions 92(2): 485-495. 39. Gas Research Institute, 1993, pp.45-47, Op.cit. 40. Max Minniear, "Initial Estimates ofManufacturing Costs and Energy Consumption", Task 1ofsubcontract 6466797, p.3, Minniear Corporation, Panama City, Florida, Nov 1997 41. Max Minniear, Feb. 25, 1998, Op. cit. 42. Jack Langmead, Water Heater Flammable Vapor Ignition Prevention Consortium, DOE, April 2, 1998, Op.Cit. 43. LBNL Water Heater Database, 1998, Op. cit.99 

### 44. LBNL Water Heater Database, 1998, Op. cit. 45. Paul, D.D., ShepardW.J., Whitacre, G.R.,FischerR.D., RutzA.L., LocklinD.W., Crisafulli J.J., Stckford G.H., Murray J.G., Landstrom D.K., Talbert S.G., Buhr A.R., Assessmentof TechnologyforImprovingtheEfficiencyofResidentialGasWater Heaters.prepared forGas Research Institute GRI-91/0298, Battelle Memorial Institute, Columbus, OH, December 1991, Table 8.1, page 96. 46. U.S. Census Bureau; "Consumer Price Index-All Urban Consumers ;" April 1998, <http://www.census.gov/146.142.4.24/cgi-bin/survymoct> 47. Paul, D.D., etal,.,GRI-91/0298, Appendix C, Op. cit. 48. Paul, D.D., etal., GRI-91/0298, Table B.10, Op. cit. 49. Paul, D.D., et al., GRI-91/0298, Appendix D., Op. cit. 50. Technical Support Document: EnergyEfficiency Standards forConsumerProducts: Volume 1, Appendix D, page D-2, DOE, November 1993 51. Department ofEnergy,AnnualEnergy Outlook 1998(AE098), 1997, Op. cit.
52 Product literature from JohnWood (GSW) Water Heaters, received from John Wood on 4/27/1998 and Bock Water Heaters product catalog. 53. Bock Water Heaters product catalog, 1998. 61. John Grahm at R.W. Beckett Corporation,personalconversation,May 16, 1998. 62. Dave Nelsen, Education Chairmen ofNAOHSM (National Association of Oil Heating Service Managers),personalconversation,April 16, 1998. 63. Max Minniear, "Initial Estimates ofManufacturing Costs and Energy Consumption", Task 1ofsubcontract 6466797, p.3, Minniear Corporation, Panama City, Florida, Nov 1997

65. Eugene West, "Oil Fired Water Heaters, Improvement tothe Energy UseAttribute",received by PNNL on August 14, 1998. 66. GAMA Cost Data,recieved by LBNL onJuly 17, 1998 67. Eugene West, "Oil Fired WaterHeaters Increased Insulation Thickness

- Analysis ofFixed Cost to Implement". received by PNNL on September 9. 1998100

68. Eugene West, "Oil Fired Water Heaters, Improvement to the Energy Use Attribute". Op. cit. 69. John Grahm at R. W. Beckett Corporation,personalconversation,September 25, 1998. 70. Survey ofresidential oil-fired equipment dealers conducted byPNNL during April, 1998.APPENDIX A: "WATSIM-DOE TEST.XLS"

- SPREADSHEET TOOL TO DETERMINE THEENERGY PERFORMANCE CHARACTERISTICS OF ELECTRICSTORAGE WATER HEATERS BASED ON OUTPUT FILESFROM THE WATSIM COMPUTER SIMULATION MODEL

This Appendix describes the spreadsheet tool "WATSIM-DOE Test.xls", which was developed to calculate the energy efficiency characteristics according to the specifications of the DOE test procedure from a standard WATSIM output file. This tool can be found onDOE's Office ofCodes and Standards' web-site (www.eren.doe.gov/buildings/codes_standards/index.htm). Background The WATSIM electric water heating simulation program contains two simulation algorithms: one for the detailed simulation of the energy performance of water heater tanks and a second for controlling water draw profiles for use with the tank model. The output ofWATSIM does not however include EF, RE, and UA values, which are specific to the DOE testprocedure. Since the simulation analysismustbe performed according tothe requirements ofthe DOE test procedure', the water drawprofile is specified to 64.3 gallon (243.4 liter) level. The specified draw profile is provided in a standard WATSIM draw file (machine.643). WATSIM provides detailed temperature profiles for the water inthe water heatertank during the simulation run. The temperature profiles are specified in theWATSIM input file (baseline.dat). The drawfile and input file are available in the same DOE's Office ofCodes and Standards' web-site. The temperature profile is provided in a standard WATSIM output file called tw_vs_tl.out. These temperature readings are used by the "WATSIM-DOE Test.xls" to determine EF, RE, and UA. "WATSIM-DOE Test.xls" was developed using Microsoft Excel and is a workbook file consisting ofthree individual worksheets: 1)results,2) tw_vs_tl, and3) EF calc.(Note that atthe bottom ofthe screen view arethe names ofall three individual Worksheets.) This is a customized analysis tool, developed specifically for this analysis and, as such it has certain limitations, descriptions ofwhich are provided in the detailed explanation oftheprocedure. Program Description Introduction. The followingrequirements must be satisfied before performing the procedure: 1)"WATSIM-DOE Test.xls" works in conjunction withthe standard WATSIM output file twvstl.out. The two files need to be in the same directory. 2) The tool is customized to work with a set ofparameters required by the DOE test procedure. Itisnecessary to supplyvaluesforthefollowing variables used forthe actual simulation:

A-I* water heater rated input, V,, * average inlet watertemperature, Ti,,n, average ambient temperature during the total standby period, Tstb,,, * average ambient temperature afterthe last draw to the end ofthe 24-hour test, Ts,stb.
The input cells for those variables are located in the twvstl worksheet. "Results"Worksheet. The purpose ofthe "results"worksheet isto load WATSIM's tw vs tl.out file into the spreadsheet tool. The user simply needs to "click" on the Load Data File button to activate a macro, which loads the tw_vs_tl.outfile into the spreadsheet tool. Figure A. shows an

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A-2 )"tw vstl" Worksheet. After the tw_vs_tl.out file is loaded into the spreadsheet tool, the user is automatically transferred over to the twvs_t] worksheet. The twvstl worksheet is where the tw_vs_tl.out file is actually loaded. Because the twvstl worksheet will contain a previously loaded twvstl.outfile, the userwill need to edit the worksheet after the current twvstl.outfile isloaded. Editing consistsofclearing outthedata from theprevious file. FigureA.2 shows apartial Excel screen view ofthe spreadsheet tool's tw_vs_tl worksheet. It showsthe datathat is provided in WATSIM's twvstl.out file. * Column Aprovides the DAYon whichdata isbeingrecorded. Sincethe DOE simulated use test lasts 24 hours, avalue of 1is always recorded. * Column B provides the TIME (in minutes) when data isbeing recorded. Sincethe DOE simulated use test lasts 24 hours, the last value inwhich data will be recorded is at the 1440thminute. Obviously, all the data up the 1440th minute cannot be shown in Figure A.2 as hundreds ofdata records are contained in any single tw_vstl.out file. * Column Cprovides the water DRAW (in gallonsper minute) atthetimethe data isbeing recorded. Sincethe drawpattern isconducted pertherequirements of theDOE simulated usetest, the value recorded will eitherbe 3gpm or0 gpm. It shouldbe noted thatduring the water draw period, WATSIM records data into the tw_vstl.out file approximately every 5seconds. Thus, duringthe six drawperiods lastingapproximately 3Vz minutes as prescribed by the DOE simulated usetest, a wealth ofdata will be recorded. * Column D provides the rate ofelectrical HEATER consumption (in Btu/hr) at the time in whichdataisbeingrecorded. InFigureA.2, resultsare provided for a50-gal (190-liter) electric storagewater heaterwithtwo4.5 kWelectrical heater elements. Thus, in the case shown in Figure A.2, the rate ofelectrical heater consumption will always be 15,370 Btu/hr (4.5 kW) when the heater element is required to come on to maintain the temperature setpoint. It should be noted that during anon-water draw period while the heaterelement ison,WATSIMrecords datainto thetw_vstl.outfileapproximately every 33 seconds. At conditions where there is no water draw and the heater element is off, WATSIM records data into the tw_vs_tl.out file approximately every 5minutes. * Columns E through AB contain the HOT WATER TEMPERATURE profile data. For example, Temperature #1 corresponds to the temperature measurement taken closest to the bottom ofthe tank while Temperature #24 corresponds to the measurement taken closestto the top of the tank. Temperature #24 isassumed toequal the temperature ofthe hot water drawn from water heater. Temperature #24 is also referred to as the DRAWTEMP. The 24 temperatures are measured at evenly spaced intervals throughout the tank.

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A-5Figure A.3 shows the remaining variables in the tw_vs_tl worksheet. The remaining variables are NOTrecorded byWATSIM intothetw_vstl.outfile. Rather, theyare variables which are automatically calculated in orderto determine quantities necessary for establishing the EF, RE, and UAofthewaterheaterbeing analyzed according tothe DOEtestprocedure. FigureA.3 presents a partial Excel screen view ofthe spreadsheet tool's twvs_tl worksheet showing the calculated variables. * MEANTEMP islocated incolumn AC. Itrepresents themean hot water tanktemperature and is based on 12 ofthe 24 temperatures recorded in Columns E through AB. The following equation shows how MEANTEMP is calculated. 

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### 2 6 Sincethe DOE testprocedure requires that six temperature readings be used to establish themean tanktemperature, thosetemperatures recorded intw_vs_tl. outthatbest represent the six temperatures (the average ofthe two temperatures representing the six evenly spaced regions ofthe tank) are used to calculate MEANTEMP. * DCA islocated in column AD. DCA returns avalue of1onlyiftherowDRAWchanges from a value of0to 1. * DCB is located in column AE. DCB is 1whenever DRAW changes value (either going from avalue of0to 1or 1to 0). Thus, avalue of 1will be calculated forDCB only at the beginning and end ofeach water draw period. * DCC is located in column AF. DCC sums up the values in column AE (variable DCB) ifand only ifDCB equals avalue of1andDRAW changes value. Thus, avalue of 1or greater will be calculated for DCC only at the beginning and end ofeach water draw period. For example, during the first draw period, DCC will equal a value of 1 at the beginning ofthe draw and a value of2 at the end ofthe draw. During the second draw period, DCC will equal a value of3at the beginning ofthe draw and a value of4 at the end ofthe draw. DCC gets incremented by avalue of 1for each subsequent draw. * DCD is located in column AG. DCD changes to an incrementally larger value for the length ofeachofthe six drawperiods. Forexample, DCD is avalue of1during thelength ofthe firstdraw period, a value of2 during the length ofthe second draw period, a value of3 during the length ofthird draw period, and so on for each subsequent draw period.

* HCA islocated incolumn AH. HCA is comparable to variableDCA exceptthat itsvalue is based onthe status ofHEATER rather thanDRAW. HCA changes to a value of 1only
A-6when HEATER changes from a value of0 to 1. * HCB islocated in columnAI. HCB iscomparable to variable DCB except that itsvalue is based on the status ofHEATER rather than DRAW. HCB switches to a value of 1 whenever HEATER changes value (either going from a value of0to 1or 1to 0). Thus, avalue of1will becalculated for HCBonly atthe beginning and endofeach timeperiod in which the heater element is on. * HCC islocated in column AJ. HCC iscomparable to variable DCC exceptthat its value isbased on the status ofHEATER rather than DRAW. * HCD is located incolumn AK. HCC iscomparable tovariable DCC exceptthat its value isbased on the status ofHEATERrather than DRAW. HCD changesto an incrementally larger value forthe length ofeach time period thattheheater element ison. It shouldbe noted that, unlike the water draw periods, there may be more than six time periods in which the heater element comes on. The heater element comes on to maintain temperature setpoint, thus, it cycles during standby operation after all six water draws have been completed. For example, a typical baseline 50-gal (190-liter) electric water heater will have its heater element cycle 9to 10 times inthe course ofthe 24-hour DOE simulated use test. * HCF is located in column AL. HCF switches to a value of 1and remains a value of 1 after the heater element has cycled for sixth time. * TIMEDIFFislocated in columnAM. TIMEDIFFtracksthetimedifference between each set ofrecorded data. * TDIFF_TEMP is located in columnAN and isused tocalculate "time-weighted average" mean tank temperatures. Because the time difference between data records varies depending on the status ofthe water DRAW andthe HEATER elements, the mean tank temperature for a time period spanning multiple water draws cannot be determined directly from the values calculated for MEANTEMP. TDIFF_TEMP allows for the determination of accurate mean tank temperatures. TDIFF_TEMP is calculated by multiplying TIMEDIFF by MEANTEMP. Thus, for any desired time period, the mean tank temperature is determined by summing the values for TDIFF_TEMP and dividing by the elapsed time forthe time period.

A-7"EF calc"Worksheet. Thisworksheet showsthe results oftheprocedure. After all ofthe datahas been loaded and intermediate values generated inthe tw_vstl worksheet, the user must manually switch to theEFcalcworksheet to see the results ofthe energy performance calculations. All the energyperformance calculations inthe EF calcworksheet, includingthose forEF, RE, andUA,.are done automatically. Figure A.4 shows the energy performance values as they are presented in the EFcalc worksheet. All the variables in the EFcalc worksheet are required by the DOE test procedure equations in orderto determine RE, UA, andEF. TheEFcalcworksheet uses the same nomenclature as in the DOE testprocedure in order to maintain consistency and to enable the user to easily identify and define all the variables. All shaded areas in the EFcalcworksheet represent variables that are determined directly from the data in the twvstl worksheet. All other variables are determined from DOE test procedure equations orare equal todefault valuesprovided inthe test procedure. A listofvariables in the EFcalcworksheet determined from the data in twvstl worksheet is provided below. * M,, mass ofwater withdrawn during the firstdraw (lbm): Determined bymultiplying the DRAW rate (3 gpm) during the first drawbythe elapsed timeofthe firstdraw. Once the total draw is determined in gallons, it isconverted to lbm using conversion factors. The calculation is based on the use ofvariable DCC inthe twvstl worksheet. The TIME when DCC equals 1(the beginning ofthe first draw) is subtracted from the TIME when DCC equals 2 (the end ofthe first draw) in order to calculate the elapsed time. * Tde,1, average delivery temperature forthe first draw(°F): Determined by calculating the average draw temperature during the first draw. The calculation is based on the use of variable DCD in the twvstl worksheet. First, all the DRAWTEMPs (hot water temperature #24) for the period when DCD equals 1 (the length ofthe first draw) are summed. Then, the summed DRAWTEMP value is divided by the number oftimes in which DCD equals 1to arrive at the average delivery temperature during the first draw. * Tmax, maximum mean tank temperature recorded after cutout following the first draw (°F): The key to to determining Tm.,, is selecting the maximum temperature after the HEATER element first cycles off. This determination is based on the use ofvariable HCC in the twvstl worksheet. Since the maximum temperature occurs immediately after the HEATER element cycles off,the valuefor the maximum MEANTEMP is when HCC equals 2 (the end ofthe first HEATER cycle). * To, maximum mean tanktemperature recorded priortothe first draw(°F): This is simply the first value for MEANTEMP recorded in the twvs_1 worksheet. * Qr, total energy used by the water heater between cutout following the first draw, including auxiliary energy such as pilot lights, pumps, fans, etc. (Btu): Determined by multiplying the HEATER's rate ofconsumption (15,370 Btu) during its first cycle by the elapsed time ofthe HEATER's first cycle. Key to determining Qr is the calculation of the elapsed time of the first HEATER cycle. The calculation is based on the use of
A-8variable HCC in the tw_vs_tl worksheet. The TIME when HCC equals 1(the beginning ofthe first cycle, i.e., when the HEATER element first turns on) is subtracted from the TIMEwhen HCC equals2 (theendofthe firstcycle, i.e., when theHEATER element first turns off) in order to calculate the elapsed time.
Qsby, total energy consumed bythe water heaterbetween thetime at which themaximum mean tank temperature is observed after the sixth draw and the end ofthe 24-hour test period (Btu): Determined by calculating the total HEATER energy consumption during the standby period ofthe water heater. The standby period, withrespect to calculating Qtbystarts immediately afterthe sixth cycleofthe HEATERelement. Thisis becausethe maximum meantanktemperature occurs immediately afterthe HEATERelement cycles offfor the sixth time. Keyto determining Qtby is the calculation ofthe elapsed time of eachHEATER cycle after the HEATER element's sixth cycle. The calculation is based ontheuse ofvariable HCC inthe twvstl worksheet. Atthe TIME whenthe HEATER cycles offfor the sixth time, HCC equals 12. Thus, the elapsed time ofthe seventh HEATER cycle is determined by subtracting the TIME when HCC equals 13 (the beginning ofthe seventh cycle) from the TIME when HCC equals 14 (the end of the seventh cycle). The elapsed times ofall subsequent cycles are determined in the same manner with the beginning and ending HCC values for each cycle incremented by 1. Once allthe elapsed times are determined, they are summed and thenmultiplied bythe HEATER's rate ofconsumption to come up the total HEATER energy consumption during the standby period. T24,mean tanktemperature atthe end ofthe 24-hour test period (°F): This is simply the value for MEANTEMP corresponding to the last record in the tw_vs_l worksheet (i.e., when TIME equals 1440). * T,,, maximum mean tank temperature observed after the sixth draw (°F): Key to determining T,,is selecting the maximum temperature after theHEATER element cycles offfor the sixth time. This determination is based on the use ofvariable HCC in the tw_vstl worksheet. Since the maximum temperature occurs immediately after the HEATER element cycles off,the value for the maximum MEANTEMP is when HCC equals 12 (the end ofthe sixth HEATER cycle). * tstby,, elapsed time between the time at which the maximum mean tank temperature is observed afterthe sixth draw andthe end ofthe 24-hourtest period (hours): Very similar to determining Ts. Key to determining tstby, is selecting the maximum temperature after the HEATERelement cycles offfor the sixth time. Thisdetermination isbased on the use ofvariable HCC in the tw_vs_tl worksheet. Since the maximum temperature occurs immediately after the HEATER element cycles off, the value for the maximum MEANTEMP iswhen HCC equals 12 (theend ofthe sixth HEATER cycle). The TIME corresponding to when HCC equals 12 is subtracted from 1440 (the TIME at the end of the test period) to arrive at the elapsed time.

A-9* Tstby, average storage tank temperature between the time at which the maximum mean tank temperature is observed after the sixth draw and the end ofthe 24-hour test period (°F): Keyto determining Tstby is selecting themaximum temperature afterthe HEATER element cycles offfor the sixth time. This determination is based on the use ofvariable HCF in the twvstl worksheet. Since the maximum temperature occurs immediately afterthe HEATER element cycles off, the value for themaximum MEANTEMP iswhen HCF equals 1(the end ofthe sixth HEATER cycle). HCF remains a value of 1 for the remainder ofthe 24-hourtest period. Fortime period when HCF equals 1,the sum ofthe TDIFF_TEMP values and the sum ofthe TIMEDIFF values are calculated. The average storage tank temperature isdetermined by dividing the sum ofthe above TDIFF_TEMP values bythe sum ofthe above TIMEDIFF values. * M2, mass ofwater withdrawn during the second draw (Ibm): Determined bymultiplying theDRAW rate (3 gpm) during the second drawbythe elapsed time ofthe second draw. Once the total draw is determined in gallons, it is converted to lbm using conversion factors. The calculation isbased on the use ofvariable DCC in the twvstl worksheet. The TIME when DCC equals 3 (the beginning ofthe second draw) is subtracted from the TIME whenDCC equals4 (the end ofthe second draw) in order to calculate the elapsed time. * Tde, 2, average delivery temperature forthe second draw (°F): Determined by calculating the average draw temperature during the second draw. Thecalculation isbased on the use of variable DCD in the twvstl worksheet. First, all the DRAWTEMPs (hot water temperature #24) forthe period when DCD equals 2 (the length ofthe second draw) are summed. Then, the summed DRAWTEMP value is divided by the number oftimes in which DCDequals 2to arriveatthe average deliverytemperature during thesecond draw. * M3, mass ofwater withdrawn during the third draw(Ibm): Determined bymultiplying the DRAW rate (3 gpm) during the third draw by the elapsed time ofthe third draw. Once the total draw is determined in gallons, it is converted to lbm using conversion factors. The calculation is based on the use ofvariable DCC in the twvs_t] worksheet. The TIME when DCC equals 5(the beginning ofthe thirddraw) is subtracted from the TIME when DCC equals 6 (the end ofthe third draw) in orderto calculate the elapsed time. Tde,3,average deliverytemperature forthethird draw (°F): Determined by calculatingthe average draw temperature during the third draw. The calculation isbased on the use of variable DCD in the twvstl worksheet. First, all the DRAWTEMPs (hot water temperature #24) for the period when DCD equals 3 (the length ofthe third draw) are summed. Then, the summed DRAWTEMP value is divided bythe number oftimes in which DCD equals 3to arrive at the average delivery temperature during the third draw. M4, mass ofwater withdrawn during thefourth draw (Ibm): Determined bymultiplying the DRAW rate (3gpm) during the fourth drawby theelapsed time ofthe fourth draw. Once the total draw is determined in gallons, it is converted to Ibm using conversion factors.
A-10The calculation is based on the use ofvariable DCC in the twvstl worksheet. The TIMEwhen DCC equals 7 (thebeginning of the fourth draw)is subtracted fromtheTIME when DCC equals 8 (the end ofthe fourth draw) in orderto calculate the elapsed time. Tde,4, average delivery temperature forthe fourth draw (°F): Determined by calculating the average drawtemperature during the fourth draw. The calculation isbased ontheuse ofvariable DCD in the twvstl worksheet. First, all the DRAWTEMPs (hot water temperature #24) for the period when DCD equals 4 (the length ofthe fourth draw) are summed. Then, the summed DRAWTEMP value is divided by the number oftimes in which DCD equals 4to arrive atthe average deliverytemperature duringthe fourth draw. * Ms, mass ofwater withdrawn during the fifth draw (lbm): Determined bymultiplying the DRAW rate (3 gpm) during the fifth drawbytheelapsed time ofthe fifth draw. Once the total draw is determined in gallons, itis converted to Ibmusing conversion factors. The calculation isbased on the use ofvariable DCC inthe twvstl worksheet. The TIME when DCC equals 9 (the beginning ofthe fifth draw) is subtracted fromthe TIME when DCC equals 10 (the end ofthe fifth draw) in order to calculate the elapsed time.
* Tdel5, average delivery temperature forthe fifth draw (°F): Determined by calculating the average drawtemperature during the fifth draw. The calculation is based on the use of variable DCD in the twvs tl worksheet. First, all the DRAWTEMPs (hot water temperature #24) for the period when DCD equals 5 (the length ofthe fifth draw) are summed. Then, the summed DRAWTEMP value is divided bythe number oftimes in which DCD equals 5to arrive at the average delivery temperature during the fifth draw. * M6, massofwater withdrawn during the sixthdraw (lbm): Determined bymultiplying the DRAW rate (3 gpm) during the sixth draw bythe elapsed time ofthe sixth draw. Once the total draw is determined in gallons, it is converted to lbm using conversion factors. The calculation is based on the use ofvariable DCC in the twvstl worksheet. The TIME whenDCC equals 11 (the beginningofthe sixth draw) is subtracted from theTIME when DCC equals 12 (the end ofthe sixth draw) in order to calculate the elapsed time.
* Tde,6, average delivery temperature forthe sixthdraw ( F):Determined bycalculating the average draw temperature during the sixthdraw. The calculation is based onthe use of variable DCD in the twvstl worksheet. First, all the DRAWTEMPs (hot water temperature #24) for the period when DCD equals 6 (the length ofthe sixth draw) are summed. Then, the summed DRAWTEMP value is divided by the number oftimes in whichDCD equals 6to arrive at the average delivery temperature during the sixth draw. * Q, total energy used bythe water heater during the 24-hour simulated use test including auxiliary energy such aspumps, fans, etc. (Btu): Determined ina very similar manner to Qstby. Key todetermining Q isthe calculation of the elapsed time ofeach HEATER cycle in the 24-hour test period. The calculation is based on the use ofvariable HCC in the twvstl worksheet. The variable HCC increments by a value of 1 each time the
A- IHEATER turns onand off. Thus, forthe first HEATER cycle, HCC equals 1when the HEATER turns onand increments to a value of2 when the HEATER turns off. Foreach subsequent HEATER cycle,the value ofHCC increments by 1. Thus, the elapsed TIME of any given cycle is determined by subtracting the TIME corresponding to the "beginning" HCC value forthatcycle from the TIMEcorresponding tothe "ending" HCC value for the same cycle. The "beginning" HCC value for any cycle will have an odd numerical value while the "ending" HCC value willhave aneven numerical value. Thus, ifthe HEATER cycles ten times in a 24-hour period, the "beginning" HCC value will equal 19 and the "ending" HCC value will equal 20. Once the elapsed times ofall HEATER cycles aredetermined, theyare summed andthen multiplied by theHEATER's rate ofconsumption to come up the total HEATER energy consumption during the 24- hour test period. * Tby, mean tank temperature during the total standby portion ofthe 24-hour test (°F): Determined by calculating the average mean tank temperature whenever aDRAW isnot occurring. This determination is based on the use ofvariable DCD in the tw_vs_tl worksheet. Whenever DCD equals 0 (i.e., when a DRAW is not occurring), the sum of the TDIFFTEMP values and the sum ofthe TIMEDIFF values are calculated. The average mean tank temperature is determined by dividing the sum of the above TDIFF_TEMP values by the sum ofthe above TIMEDIFF values.

* tby2, the number ofhours during the 24-hour simulated test when water was not being withdrawn from the water heater (hours): Determined by calculating the elapsed times between DRAWS and the elapsed timebetween the end ofthe last(sixth) DRAW andthe 24-hour time period. This determination is based on the use ofvariable DCC in the tw_vs_tl worksheet. The TIME when DCC equals 3 (thebeginning ofthe second draw) is subtracted from the TIME when DCC equals 2 (the end ofthe first draw) in order to calculatethe elapsedtimebetween the first andsecond draw periods. Foreachsubsequent time periodbetween draws,the elapsed timeiscalculated inthe same manner. The TIME when DCC equals 12 (the end ofthe sixth draw) is substracted from the TIME atthe end ofthe 24-hour testperiod inorderto calculate the elapsed time between the end ofthe 24 test period andthe last draw. After all the elapsed times when water isnot being drawn are determined, they are summed to arrive at the value for ttby,2.

A-12RECOVERY EFFICIENCY (n,) CALCULATIONS M Td

U ^, ,., (TdL+Tb,)/2 C T

. T.Io 0-, l+To)/2 C2 -p Qt |i n, lb, F F F Bht/lb, F F F F Bhi/lb,-F gal lb,/gal Btuj 88.00 135.00 58.00 96.50 0.99 131.42 131.42 131.42 1.00 45.00 8.23 6936.99 0.966 UA CALCULATIONS Q.,b T -4 T. - (Tz2+T.)/2 t,,t Cp p M Qh T, T- T,- UA Bnt F F F hours Bh/lb, -F lh/gal lb,, Btu/hr F Bu/hr-F 458.19 132.28 1 31.41- 131.4 18.54 I.OU 8.23 370.13 230.12 130.82 7.0 3.5-3- PRELIMINARY CALCULATIONS

- T I

It] Co M, | 1d2 | L-M^ | Cp |1 Ib,,, F Biv/lb,.-F Ib, F Bhu/lb,-F Ib, F Btu/lb -F M.W 135.W 1.00 8- 0. 134.60-99 V.7.5U0 34.6 U9.YY
rKtLIMIINAKY LALLULA IIJNS M I I dL I CPS M I U' M -- CP6 lb," F Bhtulb-F 1b, F Bhu/lb,-F lb,, F Bnu/lb -F | X7.50 u 134.60 | .99 | X.W

- 134.60 --- - O -. YY | K8.Z4 | 134.60 -|1O.Y ENEKGY USED ''O HEAI WAI'ER (Qw)- CALCULATIONS | djl-Tm)/n,l MCp2(TdKr2-T.)1n, MplC3(TrT)n, MC*(I-bn, MnSicpsn(TLkS-nbiln M AC(ln F

/UU7.U6 \ 69U.3 I 6863.15 6862.72 -- o 0.38 I 6Y1.15 I 4, .X | S.M ENERGY USED '10 HEAI WA'IER IF DELIVERED IEMPERAIURE EQUALS 135'F (QHW. 7 ) - CALCULATIO.NS M,C,,(135-58)/n, M,C,,(135-58)/n, M,C,,(135-58n,7 M ^(4 5-58)/n, MC,^(35-58n, M 6C, 6(35-5)/n, [| Q 

# h | 7007.50 | 6Y37.42 689Y.536 689.36 | 0937.4Z 6956.XS | 4163.31 6 6 MODIFIED DAILY WATER HEATING ENERGY CONSUMPI'ION (Qd) CALCULATIIONS | Q | T b | T*Y ta,2 | b | t Q Qdm Bht Bht F I F Bt B h u B 4640 .27 46311.7 1 13U.11 67.0 | 3.64 | 46731.63 | 179.47 4011.1u ENERGY FACTOR (Er) CALCULATIONS M,C,,(135-58)/Qd= I MCp,,(135-58)/Qd I M,Cp(135-58YQd= M4Cp(135-58)/Qma MCp(I-58)/Qd MC(- E 0.1i444 0.1430 , 0.142
- 0.142. 0.1143430 4 " -J- S Figure A.4 Energy Performance Values aspresented in the EFcalcWorksheet

A-13References

1. 10 Code ofFederal Regulations, Part 430- Energy ConservationProgram for Consumer ProductsEnergyConservation Program for ConsumerProducts, AppendixEtoSubpart B

- Uniform TestMethodforMeasuringtheEnergy ConsumptionofWaterHeaters.

A-14APPENDIX B: WATER HEATER ANALYSIS MODEL (WHAM)

- METHOD FOR DETERMINING WATER HEATERENERGY CONSUMPTION Introduction The Water Heater Analysis Model (WHAM) is a simple energy equation that accounts for a variety ofoperating conditions and water heater characteristics when calculating energy consumption. The WHAM energy calculation is based on assumptions that account for a variety offield conditions and water heater types. The results ofWHAM calculations have been compared tothe results ofdetailed water heater simulation programs and show ahigh level of accuracy in estimating energy consumption. WHAM Algorithm Fundamentals WHAM, which isbased onthe DOE water heater testprocedure, permits the user to minimally describe both the waterheater and the water heater operating conditions (10CFR430, Subpart B). The operating conditions are characterized byfour variables: * dailydraw volume, * thermostat setpoint temperature, * inlet water temperature, and * ambient air temperature. The waterheater is described by: * rated input (Pon), * stand-by heat loss coefficient (UA), and * recovery efficiency (RE). The DOE waterheater test procedure includes a method forcalculating the Energy Factor (EF), a measure ofefficiency. During the standard test procedure, a 24-hour trial isperformed in which 6 equal draws are made during the first 6 hours ofthe test for a total of64.3 gallons (243.4L). For the remaining 18 hours, the water heater is in stand-by mode and associated energy losses are measured. The energy consumption during the test istotalled and the mass ofwater drawn is summed over the six draws. The temperature ofthe water entering, leaving, and inside the water heater tank isrecorded. The temperature ofthe air around the water heater is also noted. Additional equations appear in the test procedure to correct forany deviation from the standard testing specifications to guarantee uniformity in testing results in different laboratories. The test is based on the conditions shown in Table 1.

B-lTABLE 1.DOE Test Procedure Operating Conditions Daily Draw, Thermostat Setpoint Temperature, Inlet Water Temperature, Ambient Air gallon (liter) °F (°C) °F (°C) Temperature, °F (°C) 64.3 (243.4) 135 (57) 58 (14) 67.5 (49.7) Stated in general terms, EF isthe ratio ofthe energy output ofthe water heater to the total amount ofenergy delivered to the water heater. EF is the added energy content ofthe water drawn from the waterheater divided bythe energy required to heat and maintain the water atthe waterheater's setpointtemperature:
,EF MCp-(tank

- Tinier) EF = (1) Qdm
where:

EF = energy factor M = mass ofwater drawn (Ibs) (kg) C, = specific heat ofwater, (Btu / lb

- °F) (kJ/kg

- °C) Ttank = water heater thermostat setpoint temperature (°F) (°C) 7 Tniet = the inlet water temperature (°F) (°C) Qdm = water heater's daily energy consumption (Btu) (kJ) This equation establishes the EF forwater heaters. Manufacturers are required by federal law to determine EF and to label all products with EF. UA and RE are determined in the course ofthe testprocedure and are used in the test procedure equations to calculate EF. WHAM isbased on a number ofassumptions. It assumes that the values for Pon, UA, and RE do not change significantly when conditions differ fromtestprocedure conditions. Other assumptions also help to simplify the equation: * Water temperature in the tank is always at the thermostat setpoint Water and air temperatures are constant * Water density is constant Specific heat ofwater is constant WHAM only calculates average energy use. Other tools should be used for calculating water heaters' response to peak use and for sizing systems.

WHAM Development

B-2WHAM relies on the following variables, which are defined in the DOE test procedure: Qn = total water heater energy consumption (Btu/day) (kJ/day) Qrov = 

### energy consumed toheat the water drawn from thewater heater (Btu/day) (kJ/day)
Qstdby = 

### energy consumed tomake up for standby heat loss from the waterheater (Btu/day) (kWh/day) Qot = heat content ofthe water drawn from the water heater (Btu/day) (kJ/day) 

### Hby = hours ofstandby for storage waterheaters (hr/day) RE = recovery efficiency EF = energy factor Pon = rated input power (Btu/hr) (kJ/day) UA = standbyheat loss coefficient (Btu/hr

- °F) (kJ / hr

- °C) Tak = tank thermostat setpoint temperature (°F) (°C) Tin = inlet watertemperature (°F) (°C) Tmb = temperature ofambient air surrounding the water heater (°F) (°C) vol = volume ofwater drawn in 24 hours (gal/day) (liter/day) den = density ofwater (Ib/gal) (kg/L) Cp= specific heat ofwater (Btu/lb

- °F) (kJ/(kg °C) The amount ofenergy consumed bythe water heater (Qn) includes not only the amount of energy needed toheat the water (Qcov) but also the amount ofenergy to replace that which is lostto the surroundings when no water is being drawn from the tank (Qwby).


### Qi Q +Qstdby (2)
Bydefinition, energy consumed to heat the water drawn from the water heater (without standby losses) is equal to the heat content in the water divided by the RE. 

### 0 = Q

### ou (3 u) Qrecov n R(3)
Energy consumption to compensate for standby energy loss from a storage tank water heater is equal to the difference in the water heater thermostat setpoint and the average ambient airtemperature around the water heater multiplied by the standby heat loss coefficient and the hours ofstandby. Note thatthe standby heat loss coefficient is expressed in terms ofenergy losses to the environment. The hours ofstandby are equal to the number ofhours the burner is not firing, plus the number ofhours the burner is firing (or elements are energized) to make up for standby heat losses.

B-3Qstdby = UA '(Tank

- Tmb) Hstdby (4)

The hours ofstandby equals the time the water heater is not recovering from a draw. This is equal to 24 hours minus the ratio ofthe amount ofenergy used to heat the water drawn from the waterheater divided by the rated input power ofthe water heater. Qrecov Hstdby = 24- (5) Pon

Heat content ofthehot water drawn from the water heater is equal to the volume ofwater drawn multiplied bythe water's density, specific heat, and the temperature difference between the waterheater setpoint and the inletwater temperature. Qot = vol-den Cp(Ttank

- Tin) (6)

The energy factor is equal to the heat content ofthe water drawn from the water heater divided bythe total energy consumption. Q out EF = (7) Qin
Q i, can be represented bythe parameters from the DOE testprocedure by substituting for Qrecov and Qtdby 

### in equation (2): 

### 24.'^ ^-^ -^)-^ -^^ (8) Qin = QREt + UA (Ttank Tb) 

### 24 RE 

### QPont 

### (8) RE RE.Pon

WHAM can now be expressed by expanding Qu,,, rearranging the terms, and simplifying. This is the equation to calculate average dailyenergy consumption. Q vol den-CP (Tnk

- Tn) 

## ( l UA (Ttank

- Tamb) 24 UA(T -T ) (9) voldenC'(Tt k- T) Pon an m

The WHAM equation is a function ofreadily available information that can be grouped
B-4into three categories: * Physical characteristics ofwater represented by density and specific heat (Cp) * Water heater operating conditions represented by draw volume and temperatures * Water heater parameters represented byUA, RE, and Pon


### WHAM: Calculation ofStandby HeatLoss Coefficient UA UA is anecessary input inthe WHAM equation,yetit is not always available. The same DOE testprocedure that established a basis forthe WHAM equation canbe used for determining avalue for UA. Since energy consumption to make up for standby losses isequal to the total energy consumption minusthe energy content ofwater withdrawn fromthe waterheater, it is possible to rearrange equation (2) as follows:

Qstdby = Qin-Qrecov (10)


### Substituting for Qn and Qcov from equations (3)and (6), equation (10) becomes: Qtdby 

### Qit EF RE(11)
The energy consumption to make up for standby losses can also be defined by combining equations (3), (4), and (5):
Qsdby = UA (Tk- Tb) 24 Pon(12)
Equating the twoterms for Qtdbyfrom equations (11) and (12) and solving for UA produces equation (13):
EF RE 

### U (TAnkTamb) ( RE___ (13) (Tk - T.)- -24
- I 

### Qout RE-Pon Inserting the temperatures and conditions specified inthe test procedure, the equation becomes:
B-5

### UA EF RE] UA= = 24 1 (14)

41094 RE-Pon
This equation allows the userto determine a value for UA, ifit is unavailable from other sources.
WHAM Sample Calculation A sample application oftheWHAM equation to calculate the energy consumption and the standby heat loss coefficient (UA) is presented in Table 1and Table 2. The available data is organized into three sections representing: 1)the inputs for the energy parameters from DOE test procedure, 2) the operating conditions parameters, and 3) the physical characteristics ofwater. The average daily energy input (energy consumption) and the standby heat loss coefficient are calculated directly from the input data. Detailed definitions ofall theparameters can be found in the DOE test procedure document (see reference 2 ofthe main report).

C:\DATA\WATERHTR\whtsd\Appd_B.wpd B-6Table 1 WHAM Sample Calculation with Specified Inputs



### WHAMSanme Calculation Ipus: 10CRpo t430TesmgP IwedRaads UA 3.319(1.751) Blahr-&egF(W/degQ SlaxLbyHe LsCoefficiet RE 0.98 [-] Rc yEfficiency Pbn 15,354(4500) Btuhr(W) Raed ltpt o Total Voduma ofrPe Rumed Vl 55(208) gl/day(/day) DIiigte24hrTest bmak 140(60) degF(deg) Tlmmostat SetRint Tn 56(13) degF(degC) InletaWTaerT Tanb 65(18) degF(degC) Arriae Tmwatre ftad Chmceis csf Wter F des 8.293752(995.25) Wb/galW(kgcubic mer) DityoftheWaer M 4562(206.9) Ib(kg) Ns ofVtrWdirtnDingtTe24hrTest Qp 1.000743(4.187) Btu/lxfegF(k/(g-degC SpecificI atof W Results: Qin 44468(13033) Btu/day(Wday) AvSrge Dily ey Inp

vol dens Cp(Ttank Tin) [ UADOE(Ttnk- Tamb) Qm- -- 1-------DOE + 24 UADOE,(Ttank- Tamb) OC :\DAT ER E OEA\WA TR\whtsd

C :\DATA\WATERHTR\whtsd\Appd_B.wpd B-7Table 2 UA Sample Calculation with Specified Inputs 

## Standby Heat LossCoefficent (UA) Sample Calculation Inputs: 10 CFRpart430 Testing Procedure Results EF 0.700 Energy Factor RE 0.78 Recovery Efficiency Pon 40000 (11.72) Btu/hr (kW) Rated Input Power Operating Conditions Removed During the 24 hr vol 64.3 (243) gal/day (Lday) Test Ttank 135 (57) deg F(deg C) Thermostat Set Point

Tin 58 (14.5) deg F(deg C) Inlet Water Temperature Energy Content ofWater Withdrawn During 24 hr Qout =M*Cp*(Ttank-Tin) Btu/day (W-h/day) Test Physical Characteristiscs ofthe Wateratmean ofTin & Toutat testconditions dens 8.2938 (995.25) Ib/gal (kg/cubic meter) Density ofthe Water Mass ofWater Withdrawn M 456.2 (206.9) lb (kg) During the 24 hrTest Cp 1.0007 (4.187) Btu/lb-deg F(kJ/kg
- K: Specific Heat ofWater Results: StandbyHeatLoss Coefficient UA 3.655 (1.928) Btu/hr-deg F(W/deg C) where, 1 1 UA= EF RE BTU 67.5-

# ( 24

_ 1 deg-hr 2(Qou-t -RE Ponjd

C:\DATA\WATERHTR\whtsd\Appd_B.wpd B-8APPENDIX C: VENTING ISSUES IN GAS-FIRED WATER HEATERS This Appendix summarizes the available data on the impacts ofhigh-efficiency water heaters on water heater vent system corrosion.
Introduction Use ofhigh flue-loss efficiency gas-fired water heaters (flue-loss efficiency generally greater than 80.0%) with existing venting systems that are not designed for lowertemperature flue gases can potentially lead to excessive corrosion and failure ofthe vent system in certain situations. DOEhas recognized this potential problem and will incorporate into the efficiency standards analysis necessary costs for venting modifications inthe total installation costs forgasfiredwater heaters. Venting problems are not unique to gas-fired water heaters; other gas-fired appliances have similar problems. The gas industry, through research sponsored by the Gas Research Institute (GRI), has identified and established new venting guidelines for high efficiency gas furnaces'. Although there are no such guidelines forgas-fired water heaters, a few research studies were conducted bythe gas industry to evaluate the upper limits offlue-loss efficiency. This appendix summarizes the findings ofthe previous studies on the impacts ofhighefficiency waterheaters on vent system corrosion. The results from two surveys conducted by PNNL to estimate the cost ofrelining exterior masonry chimneys with corrosion-resistant material and the cost ofreplacing a single-wall vent connector with a double-wall vent connector are summarised. Background Information Relationship between Flue-Loss EfficiencyandRecovery Efficiency Flue-loss efficiency (alsoreferred to asthermal efficiency in the older literature; the proposed ASHRAE Standard 90.1-1989R correctlyuses thermal efficiency to refer to recovery efficiency) is defined as the ratio ofthe input energy minus the energy lost through the flue in the exhausted combustion products to the input energy. The recovery efficiency isthe percentage ofenergy transferred to the hot water compared to the input energy. Ittakes into account the amount ofthe energy that is lost out ofthe flue and other parts ofthe water heater, such asjacket andfitting losses. Therefore, recovery efficiency is always less than the flue-loss efficiency for a given water heater. Flue-loss efficiency is the key parameter used to estimate the amount ofcondensation that can occur in a vent system because higher flue-loss efficiencies mean lower flue gas
c-itemperatures. The DOE testprocedure for rating residential-sized water heaters does not measure this key parameter, it instead measures the recovery efficiency. Therefore, a relationship between the flue-loss efficiency and recovery efficiency is needed to estimate the flue-loss efficiency from the DOE testprocedure results. In the past, the water heater industry suggested that most waterheaters have arecovery efficiency that is about 3% less thanthe flue-loss efficiency2 The same study also noted that this number is a guideline and individual appliance efficiencies can vary widely. The TANK water heater simulation program developed by GRI to evaluate the design options for gas-fired storage water heaters alsopredicts the difference between the two efficiencies tobe ator less than 3%.3 Although the gas industry has been using the 3% difference as a rule-of-thumb for a long time (at least since 1990), in the past year the gas industry October 23, 1998 informed DOE that the difference between thetwo efficiencies may be greater than 3%. 4 Thebasis ofthis claim is six tests ofwater heaters that GRIrecently reviewed that showed the difference between the two efficiencies tobe between 3% and 6%. In these sixtests, the flue-loss efficiency was measured in the laboratory and therecovery efficiency was inferred from the GAMA catalog for the models tested. When DOE requested the test data forreview, GAMA denied the request, stating thatthe tests were incomplete and, therefore, inconclusive. The gas industry hasrecommended additional tests to verifythe new data. DOE hasnoted these concerns and will monitorthem as part ofthe ongoing rulemaking process. However, because ofa lack ofsufficient datathat conclusively shows the difference to be higher than 3%, DOE has decided, for now, to rely onthe TANK predictions and the industryestablished guideline. Categorization ofGas Appliances Although not formally adopted for water heaters, the gas industry uses the same gas appliance venting system categories developed for gas furnaces. This categorization helps installers to match the proper vent system withthe appliance (Paul 1991). A Category Iappliance is defined as an appliance thathas a flue-loss efficiency ofless than 83%, and operates under negative pressure inthe vent. Most water heaters sold today are classified as Category I appliances. 5 Most Category I appliances rely on the natural draft ofthe hot combustion products forventing, however some rely on fans or blowersto push or pull the combustion products through the appliance to overcome the flow resistance (with the vent still under negative pressure). Appliances that have a flue-loss efficiency ofgreater than 83% and operate under negative pressure are classified as Category II appliances. Category III appliances have flue-loss efficiencies ofless than 83% but operate under positive pressure in the vent system. Similarly, Category IV appliances operate under positive pressure but have flue-loss efficiencies greater than 83%.

C-2All Category II, III, and IV appliances have special venting requirements that are specified by the manufacturers. These units, in general, cannot be vented into existing vent systems without major modifications. The modifications for Category II units include a condensate drain and corrosion-resistant vent material (usually PVC, because the vent temperatures are low). Category III units are permitted to vent side-ways, butneed pressure-tight vent systems. Category IV units require a condensate drain, corrosion-resistant vent material, and pressure-tight vents. Most gas-fired water heaters soldtoday are classified as Category I appliances because the flue-loss efficiency forthose units is less than 83% and they operate under negative pressure in the vent system. The maximum flue-loss efficiency corresponding to theproposed design options being considered is less than 83%, and will not require forced venting; therefore, Category I water heaters will still dominate the market even ifthe optionwith the maximum proposed flue-loss efficiency is accepted asthe new manufacturing standard for residential-sized waterheaters. Summary ofPrevious Studies This section summarizes the previous studies bythe gas industry that deal with specific issues related to masonry chimneys, vent connectors, and various scenarios ofinstallation ofhigh flue-loss efficiency (>80.0%) waterheaters and modifications thatmay be required to avoid excessive wet-times in the vent systems. Masonry chimneys have to be wet for a significant period oftime (over 1000 hours) for any damage to occur. 6 GRI estimated that 53% ofU.S. residences have common vent systems for water heaters and furnaces. With increased minimum furnace efficiency requirements (since 1992), mostreplacement furnaces now have higher efficiencies than the units they are replacing. Although masonry chimneys are quite resilient to corrosion, relining may be necessary in some cases when the existing low flue-loss efficiency furnace isreplaced with ahigh flue-loss efficiency furnace. Because furnace on-times are significantly higher than water heater on-times, masonry chimneys rely on the furnace to dry the condensate deposited by the water heater. In high flue-loss efficiency furnaces, the flue gas temperatures are lower, thereby increasing the potential ofexcessive wet-times in the chimney. The various situations arising from the replacement ofgas-fired water heaters and furnaces are discussed in the following sections. Replacement Installations Most water heaters sold today are for the replacement market. Therefore, in some cases, replacement ofa low flue-loss efficiency (< 80%) water heater with a high flue-loss efficiency water heater (> 80%) into an unmodified existing vent system may lead to excessive wet-times and thereby corrode the vent system. In almost all replacement situations, there are vent systems and reliners on the market to meetthe venting requirements for installing high flue-loss
C-3efficiency water heaters

- there are no technological barriers to using high flue-loss efficiency water heaters in a replacement situation. Base Case-Two-Appliance Configuration In the following section, a base case installation for atwo-appliance configuration is defined and the effect on the vent system when the base case unit is replaced with a high flue-loss efficiency unitwith varying characteristics and under various conditions is discussed. All the information is extracted from the GRI, 1991 report and the findings are summarized in Table C.2. A base case configuration is assumed to have two natural draft appliances, a furnace and a water heater venting into acommon vent system. The flue-loss efficiency ofeach ofthese units is assumed to be less than 80%. The vent connectors are assumed to be single wall metallic connectors and the vent tobe an exterior masonry chimney that isproperly sized. Replace Existing Water Heater with a Water HeaterEquipped withDraftHoodandaFlueLoss Efficiency of80.0% Since the water heater is equipped with a draft hood and also because the flue-loss efficiency is not greater than 80.0%, the newwater heater can continue to vent into the existing vent system. Replace Existing Water Heaterwith aHigh Flue-LossEfficiency Model Ifthe flue-loss efficiency ofthe water heater exceeds 83%, the exterior masonry chimney needs relining in all DOE defined regions ofthe United States. DOE regions are listed in Table C.1. Ifthe flue-loss efficiency ofthe replacement unit exceeds 80.0% but is less than 83%, relining may be necessary only in some regions. Table C.1 DOE Regions

Climate Zone Location Cooling Degree Heating Degree Days Days Region I Minneapolis, MN 750 8070 Region II Chicago, IL 998 6194 Region III Washington, D.C. 1425 4236 Region IV Pasadena, CA 1053 1670 Region V Charleston. NC 2047 2193

C-4

### Replace ExistingFurnacewith aHighFlue-LossEfficiency Fan-AssistedModel
Whenthe new high flue-loss efficiency (83%) furnace (fan-assisted combustion) vents into the existing chimney, relining the chimney is recommended in all DOE regions, except for DOE region I (Phillips 1994). Ifthe flue-loss efficiency ofthe furnace is 80.0%, thenrelining is required inregions II and IV under somecircumstances but is always required in DOE region V. 

### Replace Both Existing WaterHeaterandFurnacewith aHigh Flue-LossEfficiency Models

The exterior masonry chimney has tobe relined in all DOE regions ifthe flue-loss efficiency ofeither ofthe two appliances exceeds 83%, and in some regions ifthe flue-loss efficiency exceeds 80.0% (but is lessthan 83%). 

### A Caseof an "Orphaned"water heater When an existing commonly vented furnace is replaced with a high flue-loss efficiency furnace requiring its own vent system, it "orphans" the water heater (i.e., the water heater is left alone to vent into the exterior masonry chimney). Depending on theregion and the efficiency of the waterheater, the existing chimney may have to be relined. Table C.2 Summary ofRecommendations for Relining Exterior Masonry Chimneys for Residential Installations in a Two-Appliance Configuration Option Comment Base case: both furnace and water heaterw/ flue-loss efficiency less than 80% Norelining is necessary Replace base case waterheater with 80.0% efficient (flue-loss) unit No relining is necessary Replace base case water heater with 83% Relining may beneeded in most DOE efficient (flue-loss) unit regions Replace base case furnace with 83% Relining ofthe chimney is recommended in efficient (flue-loss) unit (fan-assisted) allregions except DOE region I Ifthe flue-loss efficiency isbetween 80.0% and 83%, chimneys in some DOE regions Replace base case water heater and furnace may need relining. Ifthe flue-loss efficiency with high flue-loss efficient units is above 83%, relining is recommended in all regions except region I. "Orphaned" water heater Relining is recommended in all DOE regions

C-5Base Case

- One-Appliance Configuration Inthe following section, abase case installation with onlya water heater venting into a vent system isdefined, and the effect on the vent system when the base case unit isreplaced with a high flue-loss efficiency unit with various characteristics is discussed. At the end ofthe section, the findings are summarized in Table C.3. A base case configuration is assumed to have a natural draft water heater venting into a exterior masonry chimney. The flue-loss efficiency ofthe unit is assumed to be lessthan 80%. The vent connectors are assumed to be single wall metallic connectors and the vent is assumed to be properly sized. Replace Existing Water Heater with a Water HeaterEquipped withDraftHoodandaFlueLoss Efficiency of80.0% Since the water heater is equipped with a draft hood and also because the flue-loss efficiency is not greater than 80.0%, the new water heater can continue to vent into the existing vent system. Replace Existing Water Heater with aHigh Flue-LossEfficiency Model

Ifthe flue-loss efficiency ofthe water heater exceeds 83%, the exterior masonry chimney needs relining in all DOE regions. Ifthe flue-loss efficiency ofthe replacement unitexceeds 80.0% but is less than 83%, relining may be necessary in most regions, except forDOE region I. Table C.3

- Summary ofGeneral Recommendations for Relining Exterior Masonry Chimneys for Residential Installations in a One-Appliance Configuration Option Comment Base case: flue-loss efficiency ofthe water heater is less than 80% No relining is necessary Replace base case water heaterwith 80.0% efficient (flue-loss) unit No relining is necessary Replace base case water heater with 83% Relining may beneeded in most DOE efficient (flue-loss) unit regions, except DOE region I New Construction
Most water heaters with efficiencies greater than 80.0% require manufacturer-specified vent systems. Therefore, in new construction with a proper vent system, there isno upper limit on the flue-loss efficiency. Some issues related to new construction installations are: Use ofhigh flue-loss efficiency (greater than 80.0%) water heaters do not constitute venting
C:\DATA\WATERHTR\whtsd\Appd_C.wpd C-6problems, because there are vent systems currently on the market that will handle low temperature flue gases and anypotential corrosion from the condensate. *There are no general guidelines similar to the National Fuel Gas Code (NFGC) for Category I

appliances for installing vents for high flue-loss efficiency water heaters. Manufacturers ofhigh flue-loss efficiency water heaters are required to provide the vent installation instructions. Installers are generally not aware ofpotential venting problems and availability ofalternate vent systems. Ifproper venting systems are used and installed according to manufacturers' recommendations, there is no upper limit for flue-loss efficiency.

Vent Connectors The portion ofthe vent system connecting the gas appliance flue collar or draft hood to the vent is called a vent connector. A single wall vent connector limits the flue-loss efficiency of gas appliances to 80.0% in a worst case installation (Talbert, 1995). According to GRI, use ofsingle-wall vent connectors isrestricted to appliances with flue-loss efficiency ofup to 80.0%, because efficiencies above 80.0% increase the wet-times in the connectors significantly. Higher flue-loss efficiency units can be allowed ifthe draft-hood diameters are increased slightly, for example, from 3" to 4". Use ofType-B metal vent connectors with Type-B metal vents will allow for higher minimum flue-loss efficiency (upto 84% from 80%). Ifa water heater has a flue-loss efficiency of84% or higher, a condensate drain may also be needed. Type-B metal vent connectors and Type-B metal vents are also recommended forwater heaters installed in unheated spaces (such as in a garage, basements, outdoors). GRI estimates an upper limit of83.5% to 84% flue-loss efficiency in a typical house. (A typical installation uses a single wall metal vent connector and a Type-B metal vent and has a capacity of35,000 Btu/hr. A worst case installation has a flue-loss efficiency upper limit of 80.0%).

C :\DATA\WATERHTR\whtsd\Appd C.wpd C-7Vent Modification Cost Summary
Since there are a significant number ofmasonry venting system in the U.S., DOE recognizes that there could be apotential problem ifenergy efficiency standards resulted in gas-fired water heaters with high flue-loss efficiencies (>80.0%). Therefore, DOE will incorporate into the analysis for standards, where necessary, the costs ofventing modifications in waterheater installation costs. Relining the vent system and installation ofdouble -wall vent connectors may be necessary when some existing gas appliances (water heaters and furnaces) attached to exterior masonry chimneys are retrofitted with higher flue-loss efficiency units (flue-loss efficiency greater than 83%). In this section, the cost estimates obtained by DOE for relining exterior masonry chimneys are presented and compared with the costs published inthe 1991 GRIreport. The primary reason for the comparison is to verify that the costs reported in the 1991 report are still valid (after adjusting for inflation). Two consultants to PNNL (one fromPortland, OR and the other from Grand Rapids, MI) collected two separate sets ofdata (herein called Data Set 1and Data Set 2) to estimate the cost ofrelining the vent system andthe cost ofType-B vent connectors. DataSet 1Results.The Portland contractor conducted a quick nationwide survey ofchimney sweeps who actively reline chimneys for gas appliances. All ofthese sweeps operate successful and relatively large businesses; several ofthem serve on the Board ofDirectors ofthe National Chimney Sweep Guild. Nine responses to the request forinformation were received

- seven from the East, one from the Midwest, and onefrom the West. The sweeps were asked to provide materials and labor cost forrelining exterior masonry chimneys with the three most commonly used relining materials: Aluminum (flexible), Type-B metallic, and AL29-4C Stainless Steel. They were asked to provide separate estimates foroneand two-story houses having either a4" ora 5" diameter chimney flue. The height ofthe flue was not specified: the respondents were allowed to use their judgment for what is typical in their region for one- or two-story detached houses. The average costs ofrelining the exterior masonry chimneys are summarized in Table C.4. The left-hand side ofthe table provides average costs from all nine responses and the right-hand side ofthe table provides average costs with the highest and lowest estimates (outliers) dropped. The bottom line shows the cost estimates from the 1991 GRI report (converted $1998) for the same relining materials.

C:\DATA\WATERHTR\whtsd\Appd_C.wpd C-8Table C.4 Data Set 1

- Summary ofCost Estimates and Comparison with the GRI Vent Diameter/ Average with Outliers No. ofStories Average ofAll Responses Dropped Aluminum Type-B AL29-4C Aluminum Type-B AL29-4C 4"/one $689 $757 $1,040 $479 $603 $893 5"/one $769 $840 $1,174 $558 $711 $1,049 4"/two $833 $940 $1,288 $602 $788 $1,146 5"/two $912 $1,021 $1,434 $679 $888 $1,305 GRI Reported Cost Estimates 

### $505 $505 $1,285
The GRI cost estimates are based on a baseline vent system with a single wall vent connector (4" indiameter, 8' long with two elbows) attached to either a Type-B vertical vent (5" in diameter, 22' high) or amasonry chimney (also 22' high from the breaching to the top ofthe chimney outlet). Therelining cost estimates from Data Set 1are generally higher than those reported inthe GRI report. The discrepancy may be due to the factthat the flue height was not specified in the sweeps' survey and the respondents may have assumed aworst case scenario. The complete data are presented at the end ofthis appendix in Table C.6 (responses Ithru IX). DataSet 2Results. The Grand Rapids consultant was asked was asked to estimate the cost for abaseline vent system as specified by the GRI document. The consultant interviewed six installers in Grand Rapids, MI. None ofthe interviewees had experience with installing Type-B or AL29-4C reliners, and therefore, only provided cost estimates forrelining the vent systems with aluminum. The value of$309 represents the average from all sixresponses and includes materials and labor. This group also provided a costestimate forreplacing single-wall vent connector with Type-B vent connector. Table C.5 summarizes the costs collected from Data Set 2. The raw data is shown in Table C.6 (responses X thru XV).
Table C.5 Data Set 2

- Summary ofCost Estimates

Aluminum Type B Vent Connector 8" Length Elbow (each) Labor $309 $52 $31 $36

DataCollectionConclusion.The average costto reline the vent system in a one-story house with a 5" diameter chimney flue with aluminum forboth Data Sets 1& 2 is approximately $433. This compares with $505 ($1998) inthe GRI estimates. The GRI cost estimate for replacing a single-wall vent connector with a Type-B double wall vent connector was $105 ($1998) compared to the survey estimate of$114 (8" length. 2 C:\DATA\WATERHTR\whtsd\Appd_C.wpd C-9elbows). DOE has decided to use the estimates fromthe recent two data sets for replacing a single-wall vent connector with a Type-B double wall vent connector. The Department has not considered design options that would require chimney reining.

C:\DATA\WATERHTR\whtsd\AppdC.wpd C-10Table C.6 RawSurvey Data One-Story Two-Story 4" 5" 4" 5" Materials Labor Total Materials Labor Total Materials Labor Total Materials Labor Total Response I Aluminum $201.00 $345.00 $546.00 $283.00 $414.00 $697.00 $300.00 $525.00 $825.00 $378.00 $525.00 $903.00 AL29-4C $731.00 $345.00 $1,076.00 $831.00 $414.00 $1,245.00 $1,104.00 $525.00 $1,629.00 $1,240.00 $525.00 $1,765.00 Type B $221.00 $345.00 $566.00 $278.00 $414.00 $692.00 $318.00 $525.00 $843.00 $411.00 $525.00 $936.00 Response II Aluminum $213.20 $581.80 $795.00 $245.25 $604.75 $850.00 $213.20 $581.80 $795.00 $245.25 $604.75 $850.00 AL29-4C $751.85 $546.15 $1,298.00 $846.25 $551.75 $1,398.00 $842.11 $555.89 $1,398.00 $949.43 $548.57 $1,498.00 Type B $197.42 $600.00 $797.42 $223.32 $600.00 $823.32 $226.20 $600.00 $826.20 $256.56 $600.00 $856.56 Response Ill Aluminum AL29-4C $245.00 $225.00 $470.00 $285.00 $225.00 $510.00 $435.00 $350.00 $785.00 $443.00 $390.00 $833.00 Type B $90.00 $175.00 $265.00 $110.00 $180.00 $290.00 $146.00 $250.00 $396.00 $170.00 $275.00 $445.00 Response IV Aluminum $146.00 $300.00 $446.00 $161.00 $300.00 $461.00 $176.00 $400.00 $576.00 $198.00 $400.00 $598.00 AL29-4C $491.00 $450.00 $941.00 $539.00 $450.00 $989.00 $680.00 $450.00 $1,130.00 $755.00 $450.00 $1,205.00 Type B Response V Aluminum $351.72 $1,600.00 $1,951.72 $4.6 1,600.00 2,034.64 $387.40 ,600.00 $1,987.40 $477.06 $1,600.00 $2,077.06 AL29-4C $876.72 $1,600.00 $2,476.72 $950.94 $1,600.00 $2,550.94 $1,246.86 $1,600.00 $2,846.86 $1,364.20 $1,600.00 $2,964.20 Type B $264.84 $1,600.00 $1,864.84 $307.46 $1,600.00 $1,907.46 $337.60 $1,600.00 $1,937.60 $394.06 $1,600.00 $1,994.06

(C:\I)AITA\WA'TIIRlIITR\whlsd\AppdC.wpd C-l C-I IResponse VI Aluminum AL294C Type B $104.44 $55.00 $159.44 $180.00 $80.00 $260.00 $260.00 $125.00 Response Vll Aluminum $150.00 $160.00 $310.00 $170.00 $175.00 $345.00 AL294C $325.00 $160.00 $485.00 $370.00 $175.00 $545.00 $410.00 $170.00 $580.00 $490.00 $190.00 Type B $300.00 $160.00 $460.00 $370.00 $200.00 $570.00 Response VIII Aluminum $248.31 $150.00 $398.31 $328.70 $200.00 $528.70 $283.00 $150.00 $433.00 $380.00 $200.00 AL294C $661.85 $225.00 $886.85 $772.00 $300.00 $1,072.00 $826.44 $225.00 $1,051.44 $932.00 $300.00 Type B $315.00 $275.00 $590.00 $460.00 $300.00 $760.00 $420.00 $275.00 $695.00 $572.00 $300.00 Response IX Aluminum $228.92 $150.00 $378.92 $264.16 $200.00 $464.16 $228.92 $150.00 $378.92 $264.16 $200.00 AL294C $423.85 $260.00 $683.85 $839.11 $240.00 $1,079.11 $623.31 $260.00 $883.31 $1,037.03 $260.00 Type B Response X Aluminum $150.00. $225.00 $375.00 Response XI Aluminum $200.00 $125.00 $325.00 Response XII Aluminum $225.00 $125.00 $350.00 Response Xlll Aluminum $200.00 $100.00 $300.00 Response XIV Aluminum $210.00 $90.00 $300.00 Response XV Aluminum $125.00 $80.00 $205.00

C':\l)A IA\WA'I'RI IfR\whtsd\Appd_C.wpd C-12References 1. GAMA. 1990. Venting Tables forCategoryI Central Furnaces", Supplementary Installation InstructionsDistributed with Furnaces ShippedSince September1990, Arlington, VA. 2. Paul, D.D. W.J. Sheppard, G.R. Whitacre, R.D. Fischer, A.L. Rutz, D.W. Locklin, J.J Crisafulli, G.H. Stickford, A.L. Murray, D.K. Landstrom, S.G. Talbert, A.R. Buhr, D.W. DeWerth, C.A. Farnsworth, R.L. Loria, and J.A. Pietsch. 1991.Assessment ofTechnology forImprovingtheEfficiency of Residential Gas-firedWaterHeaters.GRI-91/0298, Gas Appliance Technology Center, Gas Research Institute, Chicago, IL. 3. Paul, D.D, G.R. Whitacre, R. D. Fischer, J. J. Crisafulli, A.L. Rutz, J. G. Murray, and G. S. Holdebaum. 1993. TANK ComputerProgramandUser'sManualwithDiskettes. GRI-93/0186, Gas Appliance Technology Center, Gas Research Institute, Chicago, IL. 4. Conference calls, GAMA and DOE, March 1998 and July 1998, 5. Talbert S.G., D.B. Philips, G.R. Whitacre, J.J. Crisafulli, and A.L. Rutz. 1995. "Categorization ofCriteria for Residential Draft-Hood-Equipped Gas Water Heaters." GRI-95/0198, Gas Appliance Technology Center, Gas Research Institute, Chicago, IL. 6. Phillips D.B, A.L. Rutz, G.R. Whitacre, S.G. Talbert. 1994. Venting GasAppliancesinto Exterior MasonryChimneys: Analysis andRecommendations.GRI-94/0193, Gas Appliance Technology Center, Gas Research Institute, Chicago, IL.

C:\DATA\WATERHTR\whtsd\Appd_C.wpd C-13APPENDIX D: MANUFACTURER COST DATA FOR RESIDENTIAL ELECTRICAND GAS-FIRED WATER HEATERS This Appendix presents the manufacturer cost data forresidential electric and gas-fired water heaters provided to the U.S. Department ofEnergy bythe Gas Appliance Manufacturer Association Inc. (GAMA), on July 17, 1998, for use in the rulemaking process to amend the federal efficiency standards for such products. Introduction The cost data supplied by GAMA are a primary input to theEngineering and theLifeCycle Cost analyses. GAMA collected cost data directly from the major manufacturers of electric and gas-fired water heaters. No data was supplied foroil-fired or LPG waterheaters, which are also covered in this analysis. The GAMA data consisted ofestimates ofthe manufacturer cost for a defined baseline model and for design options to increase the efficiency ofthismodel. Before providing the data to DOE, it was aggregated toprotect the confidentiality ofthe individual manufacturers submissions. Note that datawere provided fortypical 50-gallon electric and 40-gallon gas-fired water heaters only. DataFormat The cost data were provided in a format developed bythe Arthur D.Little Company to reflect the order ofthe design options used inthe analysis. GAMA usedthe term "level" to indicate the ordering sequence ofthe design options. The following table shows the GAMA "levels" as they were provided with the data.

GAMA Electric Water Heaters Gas-fired Water Heaters

Level I Baseline Baseline 2 Heat Traps Heat Traps 3 2" Improved Insulation 2" Improved Insulation 4 2.5" Improved Insulation* Flue Damper (electro-mechanical) 5 Plastic Tank* Improved Flue Baffle 6 Insulated Bottom Tank Electric Ignition (IID) 7 Side Arm Heater* 8 _Improved Combustion Chamber *Because ofinsufficient data, GAMA did notprovide data forthree ofthe design options being considered: 2.5" improved insulation, plastic tank, and side arm heater. Forthe baseline unit and the design options, separate data were provided for variable manufacturing cost, fixed manufacturing cost, and the total manufacturing cost. The variable cost represents materials, labor, overhead, and transportation; fixed cost isthe capital and product design cost on a per unit basis; and the total cost is the sum ofthe variable and the fixed manufacturing cost.

D-lThe GAMA data are presented in Tables D.1through D.6. For example in terms of cumulative frequencies distribution functions for each design option cost. Each table contains a set ofcost values below which a given percentage ofmanufacturers said that they could produce a given technology option. The tables were generated by sampling from the aggregate distributions ofmanufacturing cost provided to GAMA bythe water heater manufacturers. The values are theresult of 10,000 random samples from these aggregate distributions. Table D. 1

- Electric Water Heaters Cumulative Variable Cost Table D.2

- Electric Water Heaters Cumulative Fixed Cost Table D.3

- Electric Water Heaters Cumulative Total Cost Table D.4

- Gas-fired Water Heaters Cumulative Variable Cost Table D.5

- Gas-fired Water Heaters Cumulative Fixed Cost Table D.6

- Gas-fired Water Heaters Cumulative Total Cost In addition GAMA provided average values for the design option components ofthe variable and the fixed costs. This data are shown in Table D.7 and D.8.

D-2

### GAMA Manufacturing Cost
- ElectricWater Heaters (50-gal) Table D.1 Cumulative Variable Cost Lvl Design Options Variable Costs Percentiles 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% 1 Baseline 84.96 93.00 97.74 98.38 98.38 101.54 139.21 145.80 154.46 159.70 171.82 2 HeatTraps 105.02 105.02 105.02 110.91 110.91 110.91 140.58 147.43 156.85 162.31 174.54 3 2" Improved Insulation 93.34 102.26 107.01 130.15 133.71 140.63 155.11 158.92 161.92 165.93 175.97 4 2.5" Improved Insulation 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 5 PlasticTank 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 8 Insulated BottomTank 131.88 134.81 136.53 138.61 141.31 146.40 162.57 165.34 168.11 171.88 181.08



### GAMA Manufacturing Cost
- ElectricWater Heaters (50-gal) Table D. 2 Cumulative Fixed Cost Lvl Design Options FixedCost Percentiles 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% 1 Baseline 0.99 0.99 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.01 1.01 2 Heat Traps 0.12 0.12 0.12 0.23 0.24 0.27 0.47 0.50 0.68 0.72 0.78 3 2" Improved Insulation 0.39 0.47 0.52 0.62 0.65 0.72 2.39 2.42 19.28 20.28 22.01 4 2.5" Improved Insulation 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 5 Plastic Tank 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 8 Insulated Bottom Tank 2.53 2.66 2.73 2.81 2.92 3.12 3.90 3.95 4.01 4.09 4.27

D-3GAMA Manufacturing Cost - Electric Water Heaters (50-gal) Table D.3 Cumulative Total Cost Lvl Design Options Total Cost Percentiles 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% 1 Baseline 85.96 93.99 98.74 99.38 99.38 102.54 140.21 146.81 155.47 160.70 172.82 2 Heat Traps 105.45 105.49 105.52 111.14 111.15 111.18 141.30 148.12 157.01 162.43 174.66 3 2" Improved Insulation 93.80 102.73 107.50 130.80 134.36 141.33 162.99 168.27 173.58 179.74 194.83 4 2.5" Improved Insulation 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 5 PlasticTank 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 8 Insulated Bottom Tank 134.62 137.61 139.33 141.41 144.13 149.16 166.57 169.36 172.10 175.89 185.22
GAMA Manufacturing Cost - Gas-fired Water Heaters (40-gal) Table D.4 Cumulative Variable Cost Lvl Design Options Variable Costs Percentiles 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% 1 Baseline 104.31 114.33 119.90 129.57 133.05 137.49 144.18 149.55 154.93 160.83 174.40 2 HeatTraps 107.84 118.37 124.01 133.12 136.47 140.78 145.99 151.80 157.69 163.63 178.26 3 2" Improved Insulation 111.68 122.16 128.09 150.61 153.42 156.10 158.96 162.44 166.92 173.07 187.92 4 Flue Damper (electro-mechanical) 193.55 200.11 206.99 225.16 234.01 239.94 246.05 254.29 293.25 307.78 334.75 5 Improved Flue Baffle 112.42 123.03 128.70 131.41 134.38 140.15 148.66 154.89 161.49 168.76 183.51 6 Electric Ignition (lID) 138.48 152.27 159.29 169.62 174.30 182.94 199.36 209.02 242.97 254.90 276.93 7 Side Arm Heater 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 8 Improved Combustion Chamber 172.07 196.94 206.17 212.02 217.39 224.26 238.52 278.89 284.10 290.94 307.51

D-4

### GAMA Manufacturing Cost - Gas-fired Water Heaters (40-gal) Table D.5 Cumulative Fixed Cost Lvl Design Options FixedCost Percentiles 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% 1 Baseline 0.99 0.99 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.01 1.01 2 HeatTraps 0.01 0.01 0.01 0.12 0.13 0.14 0.28 0.29 0.36 0.38 0.42 3 2"Improved Insulation 0.01 0.01 0.01 0.26 0.29 0.32 0.34 0.36 4.99 5.23 5.69 4 Flue Damper (electro-mechanical) 0.19 0.20 0.22 0.51 0.54 0.60 5.53 5.80 15.05 15.78 17.13 5 Improved Flue Baffle 0.14 0.21 0.22 0.24 0.29 0.39 0.95 1.01 9.70 10.19 11.07 6 Electric Ignition (IID) 0.12 0.13 0.14 0.16 0.16 0.76 0.81 0.87 12.60 13.25 14.39 7 Side Arm Heater 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 8 Improved Combustion Chamber 1.40 1.49 1.56 1.66 2.04 2.12 2.20 3.51 4.63 5.43 7.23


### GAMA Manufacturing Cost - Gas-fired Water Heaters (40-gal) Table D.6 Cumulative Total Cost Lvl Design Options Total Cost Percentiles 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% 1 Baseline 105.32 115.33 120.90 130.57 134.05 138.49 145.18 150.55 155.94 161.83 175.40 2 Heat Traps 108.12 118.66 124.28 133.24 136.64 141.02 146.35 152.07 157.88 163.64 178.27 3 2"Improved Insulation 111.94 122.45 128.38 151.88 154.98 158.31 161.60 164.88 169.05 174.04 187.93 4 Flue Damper (electro-mechanical) 193.75 200.31 207.21 226.40 235.95 242.96 250.03 259.04 308.84 323.53 351.40 5 Improved Flue Baffle 112.75 123.29 128.95 131.65 134.64 141.42 157.51 161.92 166.12 170.84 184.47 6 Electric Ignition (IID) 138.64 152.43 159.45 170.45 175.12 183.71 199.49 209.15 255.95 267.98 289.85 7 SideArm Heater 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 8 Improved Combustion Chamber 175.88 200.84 209.09 214.97 220.13 227.41 243.38 280.49 285.66 292.51 309.12

D-5Table D.7 Average Design Option Component Costs - Electric Water Heaters Variable Costs Fixed Costs Material Labor Transportation Overhead Total Capital Product Design DOE Design Options $/Unit $/Unit $/Unit $/Unit $/Unit $mln $min I Baseline 62.16 12.41 10.11 40.88 125.56

-- 2 Heat Traps 64.75 12.61 10.11 41.71 129.18 3 2" Improved Insulation 70.39 12.92 11.55 43.1 137.96 4 2.5" Improved Insulation -- -- -- -- 5 Plastic Tank 6 Insulated Tank Bottom -- -- -- -- --

Table D.8 Average Design Option Component Costs - Gas-fired Water Heaters Variable Costs Fixed Costs Material Labor Transportation Overhead Total Capital Product Design DOE Design Options $/Unit $/Unit $/Unit $/Unit $/Unit $mln $ min 1 Baseline 75.02 12.49 9.67 40.43 137.61 -- -- 2 Heat Traps 77.77 12.65 9.67 40.64 140.73 0.07 0.13 3 2" Improved Insulation 83.53 13.09 12.23 42.8 151.65 0.85 0.59 4 2.5" Improved Insulation -- -- -- -- -- -- -- 5 Plastic Tank -- -- -- -- -- 6 Improved Flue Baffle 75.99 13.78 9.67 41.75 141.19 1.17 1.72 7 Multiple Flues -- -- -- -- -- 8 Improved Combustion Chamber 134.24 21.68 10.82 62.03 228.77 1.42 1.4 9 Submerged Combustion Chamber -- -- -- -- -- -- -- 10 Flue Damper (electro-mechancial) 160.07 16.61 16.84 49.13 242.65 3.45 2.03 11 Side Arm Heater -- -- -- 12 Two Phase Thermosiphon -- -- --- . 13 lID 118.8 15.77 14.51 47.31 196.39 2.09 1.47

D-6D-7APPENDIX E: OIL-FIRED WATER HEATERS CONDUCTIVE HEAT LOSS CALCULATION This Appendix presents the detailed approach taken in this analysis to calculate the heat lossthrough the top and sides ofoil-fired waters. Heat Loss Calculation Water heaterjacketheat losses were calculated as conductive heat losses from the water through the insulation to thejacket in series with convective and radiative heat transfers from the jacket to the surrounding airand environment. Conductive heat losses are calculated using standard conductive heattransfer equations. The equations for conductive heat transfer through the top and sides are': Qondtop = (k *areaso /th,) 

### *(Tank- Tjiked 

### (1) and Qcondde=[(k-2-nheight) / (144-In (diamcke,/ diam,a))] (Ta

- Tae,) (2) where k =equivalent conductivity ofinsulation (Btu-in/hr-ft2-0F) or (W/m2-°C), area, = area oftop oftank (ft 2) or (cm2), thnsl =thickness ofinsulation (in) or(cm), height =height oftank (in) or (cm), diamiacke, = diameter of jacket (in) or (cm), diam,an = diameter oftank (in) or(cm), Tank = temperature oftank (°F) or (°C), Tjace, = temperature of jacket (°F) or (°C,), 144 = conversion factor (ft/in 2) (non-SI units only),

The foam insulation isHFC-245fa, with a conductivity (k) of0.0144 Btu/hr-ft-°F (0.0249 W/m-°C) 2.

Convective heat loss fromthejacket to the surrounding air is calculated as: Q_conv =J, hconv,

.area, (Tacke,
- Tm,) (3) where hconv, =convective heat transfer coefficient for surface i (Btu/hr-ft2-°F) or (W/m 2-°C), area, = area ofsurface ioftank (ft2) or(cm 2), Tmb = temperature ofambient air (°F) or (°C).

E-lThe convective heat transfer coefficient varies depending on surface orientation, so the total convective heat loss is a summation ofall oftheheat losses from the tank surfaces exposed to the surroundings (the top and sides ofthe tank). The relationships used for the convective heat transfer coefficients are3: for horizontal heat flow: hconv =0.19 (Tjacket-Tamb) 33 (Btu/h-ft2-oF) for vertical upwards heat flow: hconv = 0.22 (TjacketTamb)0 33 (Btu/h-ft2-oF) or forhorizontal heat flow: hconv = 1.31 (Tjaket-Tab)0 33 (W/m-°C) for vertical upwards heatflow: hconv = 1.52 (Tjack,e-Tab) 0 33 (W/m-°C) The radiative heat loss from thejacket to the surroundings was calculated as:
Qrad = , hrad area, (Tacke,
- Tam (4) where area, is define as forequation 3, and where the radiative heat transfer coefficient is defined as: 

### hd = e * 

### a* [(Tjcke + (Tamb2 ]. ( Tacke,_R + Tamb_R) (5) where a =the Stephan-Boltzman constant, 0.1714 * 10'8} Btu/hr-ft2-°R 4 (5.6697 x 10-8 W/m2-K4), E = emissivity ofwater heater surface, or white painted surfaces, 0.87, Tjacke_R = the absolute temperature ofthe waterheaterjacket (°R) or (K), Tmb R =the absolute temperature ofthe environment around the water heater (°R) or(K). Equation (5) is based onthe simplifying assumption that thejacket is completely surrounded by ablack body enclosure at the ambient temperature'. Since in most cases the space thetank is located in is significantly larger than the tank itself, this is a good working assumption. At steady-state conditions, the heat flow from the tank through the insulation must equal the heat leaving thejacket by convective and radiative cooling: Qcond = Qcn, + Qrad (6) All three terms are dependent on the unknownjacket temperature, with the radiative and convective heat losses non-linear with temperature. To solve equation (6), thejacket temperature is chosen iteratively until the conductive heat loss matches the sum ofthe convective and radiative losses. Thisjacket temperature can then be used to solve for the total conductive heat loss from the top and sides ofthe tank.

E-2Both RE and UA are changed by areduction in totaljacket heat loss, as it occurs continuously. Sincejacket losses are continuous losses, they are related to the RE through equation (7) below. Loss_continuous + Lossflue_on =Po, (1

-RE) (7) Thus, RE =1- (Loss continuous + Lossflue_on)/Po (8) And subtracting the RE for two different levels of jacket loss when all other losses are held constant gives: RE 2 -RE, = (Losscontinuous,

-Loss_continuous) /Pon (9)
or, since the differences in continuous losses is equivalent to the difference injacket losses, RE 2 - RE, =(Jacket_loss,

-Jacketloss)/Pon (10)

The standby heat lossrate is: Standbyheatlossrate = UA (Tank
- Tam) (11) This "standby heat loss rate" is the average rate ofheat input needed to maintain a tank at a constant temperature during standby. It includes continuous losses, flue losses when firing, and flue losses and piping losses during the off-cycle. Ifan assumption ismade that the time to reach the nominal water temperature after a draw is short compared to the length ofthe test, an overall balance on losses during thetest period can be developed as: UA (T,ak

- Tamd(24

- BOHdr,) =(Loss_continuous+ Loss_flue_off (24

- BOH,,- BOHdaJ+ BOH,,Po,,(1

- RE) (12) where BOHd,, = Burner operating time to make up for hot water drawn from the tank (hr), BOH,, =Burner operating time to make up for standby losses (hr). BOH,,can be calculated from the total energy required during the standby period divided bythe energy input during firing. The energy required to make up for losses during the standby period is equal to the energy input forthe whole DOE test minus the energy that is actually used to heat water removed from the tank. The procedure to develop the equation for BOH,,is:

E-3Q.sby = Qn - Qrecov (13a)
Qin = Qdrw/EF (13b)
Qrecov = Qdr/w RE (13c)
Qs,by =BOH5, *Pon = Qdr, / EF

- Qdr, / RE (13d) and BOHs, = /P,, Qdr w (1/EF-1/RE) (13) Where Qby =the input energy to make up for standby losses during the test Qn = the input energy used during the test Qrecov =the input energy needed to make up for the hot water drawn from the tank Qdrw =the heat content ofwater drawn from the tank during the test

And bydefault BOHdw =BOH-BOH,, (14) BOH is calculated as shown in equation (A) ofthe oil-fired section ofthe report as BOH= Qdra / (EF-P,) (A) Inserting equation (12) in equation (13) and solving forthe loss components gives:

UA (T..,n Tmb).(24 BOH+BOH,,)

- Qdw (1-RE) (- (15) Lossconinous +Lossflue_off = F R (15) 24- BOH By substituting in equation (15) the known parameters from the analytic baseline water heater, and using equation 13 for BOH,,and equation (A) for BOH, it ispossible to calculate the combined Loss_continuous +LossJlue_offvalues for any ofthe design options.

E-4References

1. Incropera, F.P, De Witt, D.P., Fundamentals of HeatandMass Transfer, 2nd ed., John Wiley & Sons, New York, 1985. 2. McGee, I.E., Dobransky, M. A., and Ingold, K.A., HFC-245faasaBlowingAgent for WaterHeaterFoamInsulation,Bayer Corporation, Pittsburgh, PA, pp. 170-173 in Proceedings ofthe Polyurethanes EXPO' 96, sponsored by the Polyurethane Division of The Society ofthe Plastics Industry, Inc., Las Vegas, NV, October 20-23, 1996. 3. American Society ofHeating, Refrigeration, and Air-Conditioning Engineers (ASHRAE), 1997Fundamentals Handbook,p.3.12. Atlanta, GA, 1997.

E-5APPENDIX F: ESTIMATES OF MANUFACTURING COSTS AND ENERGY CHARACTERISTICS FORELECTRICAND GAS-FIRED STORAGE WATER HEATERS

- DATA FROM MAX MINNIEAR

This Appendix documents the manufacturer cost data for residential electric and gas-fired water heaters provided to the U.S. Department ofEnergy byMax Minniear, consultant to Lawrence Berkeley National Laboratory (LBNL), on May 7, 1998. The data are used in the Engineering and the Life-Cycle Cost analyses to develop the federal efficiency standards for such products. Introduction The primary source ofbothmanufacturer cost and efficiency data forthis analysis wasthe Gas Appliance Manufacturers Association (GAMA), which collected datafrom waterheater manufacturers. GAMA did notprovide data for three ofthe design options being considered (2.5 in.jacket insulation, plastic tank and side arm heater). The missing data were obtained from Max E. Minniear, former Vice President ofEngineering at A. O. Smith Water Products Company who was recommended by the Gas Appliance Manufacturers Association (GAMA). Mr. Minniear was contracted by LBNL to provide disaggregated cost and efficiency data forbaseline designs and various design options. Mr. Minniear's datawas usedprimarily for two purposes: 1)to supply the manufacturing data for the missing design options, and, 2)to confirm the reasonableness ofthe computer models' estimates used in the analysis.

Data Mr. Minniear provided manufacturer cost and efficiency data forboth electric and gasfired water heaters. The data was provided in the format developed byA.D.Little Company to reflect the basic design options used in the analysis. ElectricWaterHeaters:Forthe typical existing baseline 50-gal electric water heater, Mr. Minniear provided total manufacturing cost data. Plus incremental manufacturing costs for each design option. Table F. 1contains the manufacturing costs andthe associated uncertainty ranges for electric waterheaters and Table F.2 containsthe energy characteristics values and the associated uncertainty ranges. Gas-firedWaterHeaters:For the typical existing baseline 40-gal gas-fired water heater, Mr. Minniear provided total manufacturing cost data. Plus incremental manufacturing costs for each design option.

F-ITable F.3 contains the manufacturing costs and the associated uncertainty ranges for gasfired water heaters and Table F.4 contains the energy characteristics values and the associated uncertainty ranges.

F-2Table F.I Manufacturing Costs

- Electric Water Heaters (50-gal) Cost Uncertainty Cost Uncertainty Design Options Variable Costs' Range Fixed Costs 2 '3 Range Variable Costs Fixed Costs Material Labor Overhead Total (+/- percentage) Capital Product Design Total (+/- percentage) $/unit $/unit $/unit $/unit Maximum Minimum min. $ min. $ min. $ Maximum Minimum 1 Baseline 58.43 5.77 18.11 82.31 1% 1% 0.00 0.00 0.00

- - 2 Heat Traps4 2.00 0.05 0.15 2.20 1% 1% 0.01 0.01 0.02 1% 1% 3 Increased Insulation (R24 Foam)5 8.50 0.15 0.45 9.10 5% 2% 0.02 0.04 0.06 3% 2% 4 Increased Insulation (R32 Vacuum) 6 20.00 0.50 1.50 22.00 15% 5% 0.16 0.16 0.32 20% 20% 5 Plastic Tank 7 5.25 0.80 3.20 9.25 5% 5% 0.60 0.12 0.72 10% 5% The total variable cost includes material, labor and overhead cost. The overhead cost is only the factory overhead 2Conversion cost - millon $/40,000 units 3There isno fixed costassociated with the existing baseline model 4 The Heat Trap design option cost is assumed to be the same for plasticand metal heat traps 5R24which isequivalent to 3inches of polyurethane foam 6R32which isequivalent to avacuum insulation 7Cost for plastictank design option reflectsthe "steel shell/plastic interior"tank method used inthe analysis Table F.2 Energy Characteristics

- Electric Water Heaters (50-gal) DOE Design Options Energy Data Uncertainty Range EF RE UA On-Cycle Off-Cycle EF Elec Elec (+/- percentage) (t) -W W Maximum Minimum 1 Baseline 0.900 0.98 5.50 4400 0 89.5% 87.5% 2 Heat Traps 0.905 0.98 5.25 4400 0 90.7% 89.0% 3 Increased Insulation (R24 Foam) 0.935 0.98 4.00 4400 0 93.7% 90.0% 4 Increased Insulation (R32 Vacuum) 0.955 0.98 3.30 4400 0 96.0% 90.0% 5 PlasticTank 0.910 0.98 5.00 4400 0 92.0% 90.0%

F-3Table F.3 Manufacturing Costs

- Gas-fired Water Heaters (40-gal) Cost Uncertainty Cost Uncertainty DOE Design Options Variable Costs 1 Range Fixed Costs 2.3 Range Variable Costs Fixed Costs Material Labor Overhead Total (+/- percentage) Capital Product Design Total (+/- percentage)

$/unit $/unit $/unit $/unit Maximu Minimum min. $ min. $ min. $ Maximum Minimum m 1 Baseline 64.53 6.50 16.72 87.75 1% 1% 0.00 0.00 0.00
- - 2 Heat Traps 4 2.00 0.05 0.15 2.20 2% 2% 0.01 0.01 0.02 2% 2% 3 Increased Insulation (R16 Foam)5 6.00 0.05 0.15 6.20 5% 5% 0.02 0.02 0.04 4% 2% 4 Increased Insulation (R24 Foam)5 14.50 0.15 0.45 15.10 10% 5% 0.04 0.06 0.10 5% 2% 5 Plastic Tank 7 29.75 2.90 9.25 41.90 10% 5% 0.80 0.40 1.20 10% 5% 6 Improved Flue Baffle 1.25 0.15 0.45 1.85 5% 5% 0.07 0.15 0.22 5% 2% 7 Multiple Flues 13.25 0.65 2.25 16.15 5% 5% 0.75 0.15 0.90 5% 2% 8 Improved Combustion Chamber 0.00 0.00 9 Submerged Combustion Chamber 17.25 1.75 5.75 24.75 5% 5% 0.20 1.00 1.20 8% 4% 10 Flue Damper (electro-mechanical) 6.25 0.70 2.25 9.20 10% 5% 0.03 0.15 0.18 10% 3% 11 Side Arm Heater 24.50 2.10

. 7.20 33.80 20% 10% 0.20 0.50 0.70 20% 10% 12 Two Phase Thermosiphon 12.25 1.15 3.20 16.60 20% 10% 0.04 0.12 0.16 10% 10% 13 IID 14.50 1.25 4.50 20.25 10% 5% 0.07 0.10 0.17 5% 5% ' The total variable cost includes material, laborand overhead cost. The overhead cost isonly the factory overhead 2Fixed costs - min $/50,000 units 3There isno fixed cost associatedwith the existing baseline model 4The Heat Trap design option cost isassumed to be the same for plastic and metal heat traps 5R16which isequivalent to 2inches of polyurethane foam 6R2which isequivalent to 3inches of polyurethanefoam 7

Cost for plastictank design option assumes that the design has asidearm combustion system with the plastictank as astorage media.

F-4Table F.4 Energy Characteristics

- Gas-fired Water Heaters (40-gal) DOE Design Options Energy Data Uncertainty Range EF RE UA On-Cycle Off-Cycle EF Gas Elec Gas Elec (+/- percentage) Btu/hr W Btu/hr W Maximum Minimum 1 Baseline 0.560 0.75 12.0 40,400 0 400 0 56.5% 54.5% 2 Heat Traps 0.565 0.75 11.5 40,400 0 400 0 57.5% 56.0% 3 Increased Insulation (R16 Foam) 0.576 0.75 10.5 40,400 0 400 0 58.0% 56.0% 4 Increased Insulation (R24 Foam) 0.581 0.75 10.0 40,400 0 400 0 58.5% 56.5% 5 Plastic Tank 0.644 0.80 7.5 40,400 0 400 0 67.0% 63.0% 6 Improved Flue Baffle 0.595 0.79 11.0 40,400 0 400 0 60.0% 58.0% 7 Multiple Flues 0.568 0.80 14.0 40,400 0 400 0 57.5% 55.5% 8 Improved Combustion Chamber 9 Submerged Combustion Chamber 0.583 0.77 11.0 40,400 0 400 0 59.0% 57.5% 10 Flue Damper (electro-mechanical) 0.604 0.75 8.0 40,400 30 400 0 60.6% 58.5% 11 Side Arm Heater 0.637 0.80 8.0 40,400 0 400 0 64.5% 62.0% 12 Two Phase Thermosiphon 0.560 0.75 12.0 40,400 0 400 0 56.5% 54.5% 13 IID 0.565 0.75 11.5 40,000 15 0 5 56.5% 56.0%

F-5

### APPENDIX G: DESIGN OPTION COMBINATIONS
This Appendix contains alist ofall design option combinations forresidential electric and gas-fired water heaters considered inorder to develop the final set ofdesigns used in the analysis to develop federal efficiency standards for suchproducts. A total of 18 alternative combinations were considered to develop a set of 5electric water heaterdesign option combinations. Table G.1 provides a list ofall ofthe alternative combinations explored for the electric waterheaters. Atotal of41 alternative combinations were explored to develop a set of5gas water heater design options.Table G.2provides a listofall ofthe alternative combinations explored for the gas-fired water heaters.

G-ITable G.1 Corn lete List ofAlternative Design Option Combinations

- Electric Water Heaters Design Index Design Option 0 Existing Baseline (14 lb) I Analytic Baseline (245fa) 2 Heat Traps (metal) 2a Heat Traps (plastic) 3 Increased Insulation (2" foam) 3a Increased Insulation (2" foam) + Heat Traps (metal) 3b Increased Insulation (2" foam) + Heat Traps (plastic) 4 Increased Insulation (2.5" foam) 4a Increased Insulation (2.5" foam) + Heat Traps (metal) 4b Increased Insulation (2.5" foam) +Heat Traps (plastic) 5 Insulted Tank Bottom 5a Insulted Bottom +Heat Traps(metal) + Increased Insulation (2" foam) 5b Insulted Bottom +Heat Traps (plastic) + Increased Insulation (2" foam) 5c Insulted Bottom +Heat Traps (metal) +Increased Insulation (2.5" foam) 5d Insulted Bottom + Heat Traps (plastic) +Increased Insulation (2.5" foam) 6 Plastic Tank 6a Plastic Tank +Heat Traps (metal) + Increased Insulation (2" foam) 6b Plastic Tank +Heat Traps (plastic) + Increased Insulation (2" foam) 6c Plastic Tank +Heat Traps (metal) +Increased Insulation (2.5" foam) 6d Plastic Tank +Heat Traps (plastic) +Increased Insulation (2.5" foam)

Table G.2 Complete List ofAlternative Design Option Combinations

- Gas Water Heaters Design Index Design Option 0 Existing Baseline 141a 1 Analytic Baseline 245fa la Analytic Baseline 245fa (Resistance to Flammable Vapors Ignition) 2 Heat Trap (plastic) 2a Heat Trap (metal) 3 Increased Insulation (2" foam) 3a Increased Insulation (2" foam) +Heat Traps (plastic) 3b Increased Insulation (2" foam) +Heat Traps (metal) 4 Increased Insulation (2.5" foam) 4a Increased Insulation (2.5" foam) +Heat Trap (plastic) 4b Increased Insulation (2.5" foam) +Heat Trap (metal) 5 · 78% RE (Improved Flue Baffle) 5a 78% RE (Improved FlueBaffle) +Increased Insulation (2" foam) 5b 78% RE (Improved Flue Baffle) +Increased Insulation (2" foam) +Heat Trap (metal) 5c 78% RE (Improved Flue Baffle) +Increased Insulation (2" foam) +Heat Trap (plastic) 5d 78% RE (Improved Flue Baffle) + Increased Insulation (2.5" foam) 5e 78% RE (Improved Flue Baffle) +Increased Insulation (2.5" foam) + Heat Trap (metal)

G-2Table G.2 (cont.) Design Index Design Option 5f 78% RE (Improved Flue Baffle) +Increased Insulation (2.5" foam) + Heat Trap (plastic) 6 Electronic Ignition &Electromech. Flue Damper 6a Electronic Ignition &Electromech. Flue Damper + Increased Insulation (2" foam) 6b Electronic Ignition &Electromech. Flue Damper +Increased Insulation (2" foam) + Heat Trap (metal) 6c Electronic Ignition &Electromech. Flue Damper + Increased Insulation (2" foam) +Heat Trap (plastic) 6d Electronic Ignition & Electromech. Flue Damper + Increased Insulation (2" foam) +Heat Trap (metal) +78% RE 6e Electronic Ignition & Electromech. Flue Damper +Increased Insulation (2" foam) +Heat Trap (plastic) + 78% RE 6f Electronic Ignition &Electromech. Flue Damper + Increased Insulation (2.5" foam) 6g Electronic Ignition &Electromech. Flue Damper +Increased Insulation (2.5" foam) +Heat Trap (metal) 6h Electronic Ignition &Electromech. Flue Damper +Increased Insulation (2.5" foam) +Heat Trap (plastic) 6i Electronic Ignition & Electromech. Flue Damper +Increased Insulation (2.5" foam) +Heat Trap (metal) + 78% RE 6j Electronic Ignition & Electromech. Flue Damper+ Increased Insulation (2.5" foam) +Heat Trap (plastic) +78% RE 7a Side-Arm Design (Indirect Heating +IID +Metal Tank+ Insulation I") 7b Side-Arm Design (Indirect Heating +IID +Metal Tank +Insulation 1" + HT(plastic)) 7c Side-Arm Design (Indirect Heating + IID+ Metal Tank +Insulation 2") 7d Side-Arm Design (Indirect Heating + IID +Metal Tank +Insulation 2" + HT(plastic)) 7e Side-Arm Design (Indirect Heating +IID +Metal Tank + Insulation 2.5") 7f Side-Arm Design (Indirect Heating +IID +Metal Tank + Insulation 2.5" + HT(plastic)) 7g Side-Arm Design (Indirect Heating +IID +Plastic Tank + Insulation 1") 7h Side-Arm Design (Indirect Heating +IID +Plastic Tank +Insulation 1" + HT(plastic)) 7i Side-Arm Design (Indirect Heating + IID +Plastic Tank + Insulation 2") 7j Side-Arm Design (Indirect Heating +IID +Plastic Tank + Insulation 2" + HT(plastic)) 7k Side-Arm Design (Indirect Heating +IID +Plastic Tank + Insulation 2.5") 71 Side-Arm Design (Indirect Heating + IID +Plastic Tank +Insulation 2.5" + HT(plastic)) 7m Side-Arm Design (Indirect Heating + Metal Tank +76% RE) 7n Side-Arm Design (Indirect Heating +Plastic Tank + 76% RE)

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