6.1-i

APPENDIX 6.1. TECHNICAL DESCRIPTION OF THE REVERSE ENGINEERING

COST ESTIMATION METHODOLOGY

TABLE OF CONTENTS

6.1.1 INTRODUCTION .................................................. 6.1-1

6.1.2 TEAR-DOWNS .................................................... 6.1-1

6.1.2.1 General Tear-Down Practice ..................................... 6.1-1

6.1.2.2 Specific Product Class Features ................................... 6.1-2

6.1.2.3 Weight Confirmation of Tear-down Results ......................... 6.1-2

6.1.2.4 Final Confirmation of Tear-down Results .......................... 6.1-2

6.1.2.5 General Tear-down Practice of “Hypothetical” Units .................. 6.1-3

6.1.3 CREATING THE TEAR-DOWN BILL OF MATERIALS ................... 6.1-4

6.1.4 ADDITIONAL PRODUCTION COST DATA ............................. 6.1-5

6.1.4.1 Labor and Factory Overhead ..................................... 6.1-5

6.1.4.2 Depreciation .................................................. 6.1-5

6.1.4.3 Parts and Materials ............................................ 6.1-6

6.1.5 STRUCTURE OF THE COST MODELS ................................. 6.1-8

6.1.5.1 Main Cost Model ............................................. 6.1-8

6.1.6 SENSITIVITY ANALYSIS RESULTS ................................. 6.1-12

LIST OF TABLES

Table 6.1.2.1 Specific Features for Each Product Class ........................... 6.1-2

LIST OF FIGURES

Figure 6.1.3.1 Bill of Materials Sample ........................................ 6.6-5

Figure 6.1.5.1 Cost Model Structure ........................................... 6.6-8

Figure 6.1.5.2 Sample of Global Controls Sheet .................................. 6.6-9

Figure 6.1.5.3 Subassembly Breakdown ........................................ 6.6-9

Figure 6.1.5.4 Site Table Spreadsheet ......................................... 6.6-10

Figure 6.1.5.5 Components Sheet ............................................ 6.6-10

Figure 6.1.5.6 In-house Fabrication Process .................................... 6.6-11

Figure 6.1.5.7 Raw Materials Sheet .......................................... 6.6-11

Figure 6.1.6.1 Standard Deviations of Manufacturing Costs ....................... 6.6-13
6.1-1

APPENDIX 6.1. TECHNICAL DESCRIPTION OF THE REVERSE ENGINEERING

COST ESTIMATION METHODOLOGY

6.1.1 INTRODUCTION 

The manufacturing cost estimation methodology—"reverse engineering"—is a detailed,

component-focused, activity-based technique for rigorously estimating the manufacturing cost of

a product. It considers direct materials, direct labor, and plant overhead costs. 

This appendix describes the technical aspects of the approach as applied to residential

furnaces and boilers. Refer to Chapter 6 of the Technical Support Document (TSD) for more

information on assumptions and context. 

6.1.2 TEAR-DOWNS 

The first step in the reverse engineering process was to perform tear-downs on equipment

samples that are typical of today's furnaces and boilers. A tear-down is a thorough disassembly

of the equipment followed by a detailed inspection of the parts and subassemblies. The level of

resources allocated to different product classes and the unit selection process are described in

Chapter 6.

6.1.2.1 General Tear-Down Practice

Representative minimum, medium, and high-efficiency units were disassembled for

many product classes, as discussed in Chapter 6. The Department made every attempt to

perform the disassembly in reverse of the actual assembly process; the bill of materials (BOM)

reflects the order of these operations. From observations of industry practices, DOE assumed

that major sub-assemblies arrive pre-assembled at the final assembly line.

There were a few cases where individual manufacturer practices differed from industrywide practices, but the cost impact of these differences is within the tolerances of the analysis. 

First, sub-assembly allocation practices varies between manufacturers—for example, some stage

sub-assemblies elsewhere and then add them to the final assembly line, while others build all

assemblies directly on the final assembly line. A reasonable middle ground was taken, and the

extremes assessed; assembly times varied on the order of minutes, well within the tolerances of

the analysis. Second, manufacturing out-sourcing practices vary between manufacturers. A

similar middle ground was taken, and extreme points evaluated; these variations again fell within

the tolerances of the analysis.
6.1-2

6.1.2.2 Specific Product Class Features

Each product class presented some specific features that differ from the general teardown practice that the Department performed. Specific features for each product class are

indicated in Table 6.1.2.1.

Table 6.1.2.1 Specific Features for Each Product Class

Product Class Variation

Gas Furnace Clamshell and tubular constructions evaluated separately

and averaged.

Gas Boiler Cast iron heat exchangers are in-sourced at a sister plant

for one major manufacturer. The Department assumed the

transfer price would be equivalent to the open market

value, and a high level of automation is applicable.

Oil Furnace None

Oil Boiler Based on bills of materials of gas boilers and oil furnaces.

Mobile Home Furnaces None

Weatherized (Packaged)

Furnaces

A/C coil model used rather than furnace/boiler model.

This is fully described in the Technical Support Document

for the Residential Air-Conditioning Rulemaking.1

6.1.2.3 Weight Confirmation of Tear-down Results 

The Department confirmed the cost and weight predictions using a number of methods. 

Initially, DOE compared shipping weight predictions with published shipping weights. Since

cost and weight tend to be highly correlated in manufactured goods, the ability to accurately

predict weight is usually an important indication of the accuracy of the cost model. However,

DOE discovered that at least one equipment manufacturer had published erroneous weight data. 

Since it could not verify all the published weights, DOE could not place confidence in the weight

verification. 

6.1.2.4 Final Confirmation of Tear-down Results 

For further confirmation of tear-down results, DOE solicited feedback and comments on

the cost analysis directly from the manufacturers of units that were torn down. As a disinterested

third party, DOE modeled their factory conditions and assumed production volumes, and

calibrated the model assumptions and results for their particular units. Final results, as discussed

in Chapter 6 of this TSD, were generated using a set of industry-wide aggregate assumptions to

avoid disclosure of company-specific sensitive cost data. 
6.1-3

6.1.2.5 General Tear-down Practice of “Hypothetical” Units

Although DOE had detailed information on a number of units physically torn down, it

needed many more samples to span a broad range of efficiency levels in each of the product

classes. To cost these samples, DOE created “hypothetical” units. For these units, DOE started

from a calibrated tear-down BOM, and then modified the BOM to obtain the desired efficiency

level. Typically, for any change in efficiency level, there are numerous paths to take and a

variety of hardware changes that can be made to obtain a particular efficiency level. According

to existing literature, three options appear to be the most promising for gas furnaces—increased

heat exchanger area, improved heat transfer coefficient, and derating (see discussion in Chapter

6).

Aside from the two design options selected for non-weatherized gas furnaces, a few

others were considered for other product classes. These include:

1. Electronic ignition for boilers.

2. Two-stage Modulation. Efficiency gains ascribed to modulation varied from 0 percent to

2.5 percent, dependent on unit and operating conditions. A conservative 1 percent gain

was applied.

3. Insulation. For weatherized furnaces only, additional insulation can improve AFUE

ratings.

In addition, design options that affect fuel and electricity consumption were costed. 

These include:

1. Two-stage Modulation—Uses a two-speed combustion air fan, a dual flow rate gas valve,

a multi-speed blower, and associated electronic controls.

2. Continuous Modulation—Uses a continuously variable combustion air fan and gas valve,

a multi-speed blower, and associated sensors and controls.

3. Interrupted Ignition (Oil-Fired equipment only)—Uses interrupted firing of the burner

rather than continuous, and associated controls.

4. Fan Atomized Burner (Oil-Fired equipment only) with modulation—Uses a fan and ECM

motor to atomize the oil. Prototypes exist; conservative costs have been used to reflect

the relatively undeveloped nature of this technology.

For each hypothetical tear-down, DOE modified the BOM hardware to reflect applicable

design options from the list above, costed each design option path, and averaged the results.
6.1-4

6.1.3 CREATING THE TEAR-DOWN BILL OF MATERIALS

The Department used the tear-down process to create a complete and structured BOM for

each torn-down and hypothetical unit. In the process of completely dismantling each piece of

the unit, DOE characterized every part according to weight, dimensions, material, quantity, and

the manufacturing processes used to fabricate and assemble it. 

The BOMs incorporate all materials, components, and fasteners with estimates of raw

materials and purchased parts and sub-assemblies. The Department based its sourcing

assumptions on previous industry experience, recent information in trade publications, and

discussions with high- and low-volume original equipment manufacturers (OEMs). To augment

its understanding of the industry's manufacturing practices, DOE also visited several

manufacturing plants. These visits focused on observing and characterizing current

manufacturing practices. 

Figure 6.1.3.1 illustrates a small section of a structured bill of materials. It shows:

C Serial Number: Assigned during disassembly.

C Part Number: Assigned during disassembly.

C Description: A description of the part. Subassemblies are grouped. 

C Quantity: Number of parts assembled in a given step for a given subassembly.

C Extended Quantity: Flat bill-of-materials.

C V: This entry denotes whether a part is a purchased component or fabricated in-house.

C Material: Material type or component number

C OD, Length, Width, Depth, Thickness: Physical parameters that describe the finished

part. 

C Extended Weight: Final weight of the part, in grams.

C Extended Material Cost: Final material cost of the part (calculated), accounting for

scrap losses but excluding required assembly, painting, fabrication, or joining costs. 

C Extended Assembly Time: The manual labor (in seconds) required to handle all parts

and assemble them into the unit.
6.1-5

Figure 6.1.3.1 Bill of Materials Sample

6.1.4 ADDITIONAL PRODUCTION COST DATA

The tear-down process and the development of the structured BOMs provided the starting

points for estimating production costs, but DOE still needed information on manufacturing

operations, part and material prices, wages, plant equipment amortization, and plant overhead.

Chapter 6 describes the assumptions and data sources. This section briefly describes the

processes DOE used to gather the data and how it used them. 

6.1.4.1 Labor and Factory Overhead

The Department obtained information on equipment and tooling costs, typical process

cycle times, and materials used for fabrication from the proprietary TIAX manufacturing

databases. Plant equipment suppliers provided details concerning equipment capabilities and

processing parameters (cycle times, scrap rates, etc.). Fabrication cycle rates are directly entered

into the cost model and depend on part complexity and processes used. 

6.1.4.2 Depreciation

Depreciation, or amortization, is the accounting process by which capital costs are

allocated to production volume. Amortization occurs over the whole period of time that it takes

to produce a product, so that at the end of that time, all capital costs are accounted for in the full

cost of producing the product. For example, if a manufacturer produces one million furnaces

over ten years and amortizes a $10 million investment over the same ten years, each furnace

produced during that time would include $10 in amortization charges. 

The methodology DOE used to allocate depreciation depended on whether it is assumed

that the plant machinery is dedicated or non-dedicated to the production of the sample product. 

Dedicated machinery is tied solely to the production of the sample product. During times when a

piece of dedicated machinery is not needed for that product, it sits idle. The entire capital cost of
6.1-6

a piece of dedicated machinery is amortized across the annual volume of the sample product. 

Conversely, non-dedicated machinery may be used to produce another product when it is not

needed for the sample product. Only a fraction of the capital cost of non-dedicated machinery is

allocated to the sample product, based on the time the machinery was used to produce the sample

product. For example, a non-dedicated press that was used 55 percent of the time to produce the

sample product would allocate 55 percent of its depreciation charges to the sample product and

45 percent to the other products with which it is associated. A dedicated press, on the other

hand, would allocate 100 percent of its depreciation to the sample product, even if its utilization

was 55 percent, since the press is not used for any other production. 

The Department assumed that all fabrication machinery is non-dedicated, unless it is part

of an assembly line (welding, or bending, directly on the line). Due to the seasonal nature of the

furnace and boiler business, some manufacturers have off-season uses for their fabrication

machinery (e.g., to make air conditioners).

The Department also allocated labor to operate a piece of machinery based on whether

the machinery is dedicated or non-dedicated. 

As equipment utilization rates approach 100 percent, the costs associated with dedicated

versus non-dedicated equipment costs become equal. However, few dedicated pieces of

equipment ever achieve 100 percent utilization due to lack of demand, capacity mismatches

between process steps, scheduled downtime, etc. Thus, non-dedicated equipment results in

lower overall costs per part, as depreciation, maintenance, and other costs are only assessed on

the basis of how much time each part uses a piece of equipment. As equipment types vary, so do

the manufacturing equipment and labor requirements. Depreciation charges therefore also vary

across equipment types.

6.1.4.3 Parts and Materials 

Cost estimates for raw materials and purchased components were drawn from TIAX

manufacturing databases and supplemented with information obtained from manufacturer and

supplier sources. The Department adjusted the cost estimates as appropriate to include price

discounts typically seen in the industry as the result of high-volume purchases.

As purchased components make up much of the unit costs, DOE paid special attention to

establishing accurate OEM-level price data. Through manufacturer submissions, industry

literature, and active research, DOE was able to ascertain the exact specifications for the

majority of components used in the units under investigation. For the relatively few purchased

components DOE could not identify, it substituted parts from comparable equipment. For

example, a manufacturer's technical data sheet may report that a sample furnace uses a certain

type of motor supplied by a particular company, but may not state the precise size or part

number. In the cases when distributors could not positively identify the part, industry experts

would compare the known attributes of similar units (such as horse power, voltage, etc.) with
6.1-7

those of the sample equipment. The Department would then select a specific motor size and type

based on an interpolation of the available data. 

The Department then consulted with local distributors, wholesalers, parts suppliers, and

OEMs to determine high-volume pricing. The Department applied a discount to the prices

received from each of those sources based on their place in the distribution chain. These

discounts were based on markup data and DOE’s previous experience in the industry. The many

different data sources and the large purchased parts list also allowed DOE to do some crosschecking of price data and discounts. The Department selected those that, most likely reflected

actual prices to OEMs. The discounts on each component are a function of the total dollar

volume of a typical OEM's account with a typical supplier. Since DOE is modeled high volume

OEMs who deal with one supplier for each component, this resulted in substantial discounts

relative to retail or wholesale prices. In addition, OEM manufacturers commented on assumed

OEM pricing, as detailed in section 6.1.2.4 of this appendix.

6.1.5 STRUCTURE OF THE COST MODELS

Once the Department had collected all of the information required to estimate production

costs for each sample, DOE used Excel spreadsheet models to perform the required calculations. 

In addition, DOE used Boothroyd-Dewhurst, Inc. (BDI) Design for Assembly software to

calculate assembly times, and BDI’s Concurrent Costing software to estimate casting and

machining processes.2

 Figure 6.1.5.1 illustrates the structure and relationship of the spreadsheets

and software used to make the estimates.
6.1-8

Global Controls

Sheet

Materials

Sheet

Components

Sheet

Processes

Sheet

BOM Sheets

(1 per teardown)

BDI

Design For

Assembly

BDI

Concurrent

Costing

Part Data Assy Time

Cast, Machined

Part Cost Data

 Cost

Data

Global

Variables

Site Table

Sheet

Mfg Site Dependent

Variables (labor rate, etc.)

Purchased

Part Costs

Equipment Cost,

Cycle Times

Material

Costs

VBA Macros, Portability file data transfer

Figure 6.1.5.1 Cost Model Structure

6.1.5.1 Main Cost Model 

The main model serves to hold data and perform the calculations that determine the

production cost of the final assembled equipment. It contains a number of worksheets that

perform different functions.

Global Controls Sheet. This worksheet sets parameters such as production volume and

wages; it also displays the cost results by sub-assembly. The basic parameters (e.g., days

available per year) of the Global Controls sheet are linked to multiple BOM sheets, one for each

tear-down. A sample section of those controls is shown in Figure 6.1.5.2. Shaded fields are also

varied in the sensitivity analysis. 
6.1-9

Designed Fabrication Work Days per Year: 240

Designed Assembly Work Days per Year: 240

Runtime per Shift (hrs): 8

Equipment Uptime (%): 90%

Designed Assembly Worker Downtime (%): 20%

Auxiliary Equipment + Installation Cost: 60%

Building Depreciation Life (Years): 25

Tooling Depreciation (Years): 7

Ratio of Walkways to Fabrication + Storage: 20%

Yearly Maintenance Ratio (as % of Equipment Cost) 4%

Utility Cost (% of factory cost) 3.0%

Invest. Relativity Factor (%) 1

Avg Depreciation Life (%) 1

Freight Factor: 3%

Freight Cost($/cu ft): $1.66

Benefits 40%

Building Cost ($/sf) 120

Figure 6.1.5.2 Sample of Global Controls Sheet

The Global Controls sheet also shows costs broken down by sub-assembly and cost

category. The results are shown in tables 6.1.5.2 and 6.1.5.3. Figure 6.1.5.3 features costs by

major sub-assembly and cost type. Cost breakdowns to this fine level allowed DOE to zero in on

the differences between equipment across efficiency levels and facilitated the calibration and

industry review processes.

XX% AFUE Material Labor Overhead

Blower

Casing

Circulator

Electrical/Controls

Exterior Components

Fuel Control

Heat Exchanger

Inducer

Packaging

Total

Grand Total

YY Class

Figure 6.1.5.3 Subassembly Breakdown

Site Table Sheet. Variables that vary from manufacturing site to manufacturing site

were isolated on the Site Table sheet. These include labor rates, purchasing power (effective

production volumes for components shared across many product families), and a number of other

variables. (see Figure 6.1.5.4). After individual manufacturer data was gathered, an industry

average were generated, along with two sub-group averages—large and small manufacturers. To

avoid disclosure of manufacturing site-specific information, the industry average column was
6.1-10

Industry Avg Small Mfg. Large Mfg. Mfg A Mfg B Mfg C ...

Assembly Factor

assy shifts / day

Design vs. Actual Capacity Ratio

Direct Labor Rate

fab shifts / day

Ind:Dir Labor Ratio

Management Span (people/manager)

Pay Difference Manager to Line worker

Production Volume

Purchasing Power

rework rate (all repaired)

Lot size (days of inventory)

JIT ratio

Figure 6.1.5.4 Site Table Spreadsheet

Component 

ID

Comp Class 

Name

Comp 

SubClass 

Name Name

Manufacturer 

Part Number

Cost

Model ID 

Number Q1 Q1000 Q10000 Q100000 Q1000000 TotQty1 CompCost1

1 0 0 Dummy

2 Electronic PCB Control Board, Damper

3 Electronic PCB Control Board, Mfg A

4 Electronic PCB Control Board, Mfg B

5 Mechanical Motor Blower Motor

6 Mechanical Motor Blower Motor

7 Mechanical Motor Blower Motor

8 Mechanical Fan Blower Wheel

9 Mechanical Fan Blower Wheel

10 Mechanical Fan Blower Wheel

11 Mechanical Pump Circulator with gaskets

12 Mechanical Motor Blower Motor

13 Mechanical Motor Blower Motor

14 Electronic Switch Dual Pressure Switch SubAssy

15 Mechanical Fan Blower Wheel

16 Mechanical Fan Blower Wheel

17 Fuel System Valve Gas valve

18 Fuel System Valve Gas Valve Assy

19 Fuel System Valve Gas Valve Assy

20 ... ... ...

Figure 6.1.5.5 Components Sheet

used to generate all numbers in this TSD. The ranges found from individual manufacturers were

used in the sensitivity analysis.

Components Sheet. The Components sheet contains two types of data: major purchased

components unique to each model; and minor, common purchased components used by every

model.

Major Purchased Components. The Components sheet represents the output of the TIAX

manufacturing component database, which logs multiple quotations at a variety of production

volumes to build a production volume versus cost curve. These outputs are shown in the Q1 to

Q1000000 columns in Figure 6.1.5.5. Depending on quantity per model and production

volumes, the component cost is fed to the BOM sheet through the CompCostX column, which

queries the result by unit number. These tables determine at least 45 percent of total cost. 

Minor, Common Purchased Components. These include items such as connectors, wire,

fasteners, board transformers, and other smaller parts that OEMs are likely to purchase from

outside suppliers. From the TIAX manufacturing component database, DOE gathered price

quotations from multiple sources (suppliers, distributors, prior experience) in quantities
6.1-11

Process 

ID Class Name

SubClass 

Name Machine Name Capacity

Capacity 

Units

Capacity 

Rate

Capacity 

Rate Units

Cycle Time 

(minutes)

Depreciation 

Life (Years) Q1

Capital 

Cost ($)

1 None None Dummy Process

2 Material Handling Convey Conveyor

3 Material Removal Tube Tube Cut

4 Deformation Forming Tube Tube Bend

5 Deformation Forming Tube Roll Form

6 Deformation Forming Tube Tube Coil

7 Sheet Metal Stamp Large Press

8 Sheet Metal Stamp Med Press

9 Sheet Metal Stamp Sm Press

10 Sheet Metal Bend Press Brake

11 Sheet Metal Blank Blanking

12 Sheet Metal Stamp Turret Punch

13 Material Removal Machine Machining Center

14 Casting Plastic Injection Mold

15 Casting Metal Sand Cast

16 Casting Metal Investment Cast

17 Finishing Powder Coat Paint

18 Material Removal Stamp Plasma

19 Assembly Adhesive Adhesive Bonding

20 Assembly Weld Seam Welding

21 ... ... ...

Figure 6.1.5.6 In-house Fabrication Process

Class Name SubClass Name Material Full Name

Physical 

Form Name Density (g/cc) Q1 Q1000 Q10000 Q100000 Q1000000

TotWt1 

(g)

MatCost1 

($/g)

Polymer Thermoplastic ABS Pellet 1.06

Metal Commodity Metal Aluminum Sheet 2.70

Metal Commodity Metal Alumized Steel Sheet 7.87

Metal Commodity Metal Aluminum Tube Tube 2.70

Polymer Commodity Metal Strap Band N/A N/A

... ... ... ......

Figure 6.1.5.7 Raw Materials Sheet

throughout the price versus volume curve. In the same fashion as for major purchased

components, minor component costs are passed to the BOM sheets.

Figure 6.1.5.6 shows modeled fabrication processes; material cost in these cases is

determined by the part weight times a cost per gram as detailed on the Raw Materials sheet,

Figure 6.1.5.7. For out-sourced parts, DOE applied a vendor profit markup of 1.2. The

Department assumed that even in cases of a sister company manufacturing sub-components, this

markup will capture the transfer price and the profit of the sister unit.

Bill-of-Materials Sheet. The Bill-of-Materials sheet (as illustrated in Figure 6.1.3.1 and

discussed in section 6.1.3) serves as a structured assembly tree, summarizes fabrication and

assembly tool data, and calculates production costs based on the price of the part or material and

the labor and machinery required to fabricate or assemble it. The BOM sheet also adjusts many

other costs in response to changes in physical parameters. For example, the model adjusts

baseline sheet metal sizes to incorporate different enclosure sizes. Also, the size of the fiberglass

insulation is a function of the sheet metal it has to cover and the efficiency level of the unit

(insulation is thicker at higher efficiencies). Many fastener quantities and labor costs are also a

function of the sheet metal walls they have to secure. The result is that every unit cost estimate

is unique, using the initial BOM as a starting point. 
6.1-12

Labor, parts, materials, and depreciation costs are aggregated by sub-assembly and linked

back to the Global Controls page. 

Processes Sheet. This sheet, from the TIAX manufacturing database, is a list of process

costs for all the plant machinery involved in the production of furnaces and boilers. An implicit

assumption is that the plant equipment required to produce lower-efficiency samples is also able

to produce higher-efficiency samples without any modification. The process data show installed

equipment costs, equipment capacity, depreciation life, whether equipment is dedicated, cycle

times, labor requirements per station, consumables costs, etc. The installed costs include price

quotations for the equipment plus markups to account for installation labor and auxiliary

equipment (e.g., electrical service to the equipment).

6.1.6 SENSITIVITY ANALYSIS RESULTS

Chapter 6 of the TSD described the Monte Carlo analysis process. The results are

presented in Figure 6.1.6.1 in the form of standard deviation values. These results are used as an

input for the LCC analysis. Confidence intervals are easily calculated using standard deviation

values.
6.1-13

Material Labor Overhead Shipping Total

Non-weatherized Gas-fired Furnaces

Baseline $5 $3 $2 $1 $6

80% AFUE $4 $2 $1 $1 $5

81% - 83% AFUE $5 $3 $2 $1 $6

Non-condensing Furnaces with Modulation $8 $3 $2 $1 $9

90% AFUE $3 $3 $4 $1 $6

92% AFUE $10 $3 $6 $1 $12

92% with Modulation $15 $3 $6 $1 $16

96% AFUE $35 $3 $6 $1 $36

Weatherized Gas-fired Furnaces

Mobile Home Furnaces

75% AFUE $5 $2 $1 $1 $5

80% AFUE $6 $2 $1 $1 $6

90% AFUE $30 $10 $3 $1 $32

Oil-fired Furnaces

Baseline $6 $10 $6 $1 $14

Other Options $10 $10 $6 $1 $15

Gas Boilers

Baseline $4 $4 $3 $1 $7

81% - 84% AFUE $4 $4 $3 $1 $6

Gas Boiler with Modulation $10 $4 $3 $1 $11

88% AFUE $30 $10 $3 $1 $32

91% AFUE $75 $15 $5 $1 $77

99% AFUE $100 $20 $10 $1 $102

Oil-fired Boilers

Baseline $10 $4 $3 $1 $11

81%-86% AFUE $10 $4 $3 $1 $11

Oil Boiler with Other Options $10 $10 $6 $1 $15

90% AFUE $75 $15 $5 $1 $77

95% AFUE $100 $20 $10 $1 $102

Same as Non-weatherized

Figure 6.1.6.1 Standard Deviations of Manufacturing Costs
6.1-14

REFERENCES

1. U.S. Department of Energy-Office of Building Research and Standards, Technical

Support Document: Energy Efficiency Standards for Consumer Products: Residential

Central Air Conditioners and Heat Pumps, 2000, U.S. Department of Energy. 

Washington, DC.

<http://www.eere.energy.gov/buildings/appliance_standards/residential/ac_central.html>

2. Boothroyd Dewhurst, Design for Manufacture and Assembly ( DFMA), (Last accessed

December 17, 2000, <http://www.dfma.com/software/dfaben.html>