6.3-i

APPENDIX 6.3. DETERMINATION OF FURNACE AND BOILER ENERGY USE

TABLE OF CONTENTS

6.3.1 INTRODUCTION ..................................................... 6-1

6.3.2 CALCULATIONS ..................................................... 6-1

6.3.2.1 Determination of Average Annual Fuel Energy Consumption (EF) ............. 6-1

6.3.2.2 Determination of Average Annual Electrical Energy Consumption (EAE) ......... 6-2

6.3.2.3 Determination of National Average Number of Burner Operating 

Hours (BOHSS) .................................................. 6-3

6.3.2.4 Determination of National Average Number of Burner Operating Hours for 

Two-Stage and Step Modulating Furnaces and Boilers ..................... 6-4

6.3.2.5 Determination of Heating Seasonal Efficiency (EffySS) ...................... 6-5

6.3.3 PARAMETERS TO DETERMINE THE ENERGY USE OF 

MODULATING FURNACES ............................................ 6-5

6.3.3.1 Parameters to Determine Average Annual Fuel Energy Consumption ........... 6-6

6.3.3.2 Parameters to Determine Annual Fuel Utilization Efficiency .................. 6-7

6.3.3.3 Conclusions ..................................................... 6-8

6.3.4 SUMMARY TABLES .................................................. 6-8

LIST OF TABLES

Table 6.3.3.1 AFUE for Similar Single-Stage and Two-Stage Furnace Models Series ......... 6-8

Table 6.3.4.1 Single-Stage Non-Weatherized Gas Furnaces ............................ 6-9

Table 6.3.4.2 Single-Stage Weatherized Gas Furnaces ............................... 6-10

Table 6.3.4.3 Single-Stage Mobile Home Furnaces ................................. 6-11

Table 6.3.4.4 Single-Stage Oil-Fired Furnaces ..................................... 6-11

Table 6.3.4.5 Single-Stage Hot-Water Gas Boilers ................................. 6-12

Table 6.3.4.6 Single-Stage Hot-Water Oil Boilers ............................... 6-12

Table 6.3.4.7 Two-Stage Non-Weatherized Gas Furnaces ............................ 6-13

Table 6.3.4.8 Two-Stage Mobile Home Furnaces .................................. 6-13

Table 6.3.4.9 Two-Stage Hot-Water Oil Furnaces .................................. 6-14

Table 6.3.4.10 Two-Stage Hot-Water Gas Boilers .................................. 6-14

Table 6.3.4.11 Two-Stage Hot-Water Oil Boilers ................................... 6-14
6.3-1

APPENDIX 6.3. DETERMINATION OF FURNACE AND BOILER ENERGY USE

6.3.1 INTRODUCTION

The DOE test procedure for measuring the energy consumption of furnaces and boilers

provides a calculation approach for determining the energy use of furnaces and boilers under test

conditions.1 This approach requires the calculation of the average annual fuel energy consumption (EF),

the average annual electrical energy consumption (EAE), and the national average number of burner

operating hours (BOHSS) of furnaces and boilers.

The following calculations and summary tables describe the determination of EF, EAE, and

BOHSS for gas- and oil-fired furnaces and boilers.

6.3.2 CALCULATIONS

6.3.2.1 Determination of Average Annual Fuel Energy Consumption (EF)

The average annual fuel consumption is calculated in sections 10.2.2 and 10.2.2.1 of the DOE

test procedure:1

EF = BOHss * (QIN - QP) + 8,760 * QP , for single-stage furnaces and boilers Eq. 1

and

EF = EM + 4,600 * QP, for two-stage and step modulating furnaces and boilers Eq. 2

where:

BOHss = National average number of burner operating hours (see section 6.3.2.3 of this

appendix for derivation),

QIN = Steady-state nameplate input rate in Btu/h for single-stage furnaces and boilers or

steady-state nameplate maximum input rate in Btu/h for two-stage and step

modulating furnaces and boilers,

QP = Pilot flame fuel input rate in Btu/h, and

EM = Average annual energy used during the heating season for two-stage and

modulating furnaces.

QIN is based on the baseline value for each product class. QP is zero for all product classes,

except for the baseline mobile home gas furnace and gas boiler. 
6.3-2

6.3.2.2 Determination of Average Annual Electrical Energy Consumption (EAE)

Using the DOE test procedure,1 the average annual electrical energy consumption is calculated

in sections 10.2.3, 10.2.3.1, and 10.2.3.2:

EAE = BOHSS (yP * PE + yIG * PEIG + y * BE), for single-stage furnaces and boilers Eq. 3

and

EAE = BOHR (yP*PER + yIG*PEIG + y*BER) + BOHHorM (yP*PEH + yIG*PEIG + y*BEH), for

two-stage and step modulating furnaces and boilers Eq. 4

where:

BOHss = See section 6.3.2.3 of this appendix,

BOHH = National average number of burner operating hours at the maximum operating

mode (see section 6.3.2.4 of this appendix),

BOHM = National average number of burner operating hours at the modulating operating

mode (see section 6.3.2.4 of this appendix),

BOHR = National average number of burner operating hours at the reduced operating mode

(see section 6.3.2.4 of this appendix),

yP = Ratio of induced or forced draft blower on-time to average burner on-time,

PE = Burner electrical power input at full-load steady-state operation in kW,

PER = Burner electrical power input at full-load steady-state operation in kW, measured at

the reduced fuel input rate,

PEH = Burner electrical power input at full-load steady-state operation in kW, measured at

the maximum fuel input rate,

yIG = Ratio of burner interrupted-ignition device on-time to average burner on-time,

PEIG = Electrical input rate to the interrupted ignition device on the burner,

y = Ratio of blower or pump on-time to burner on-time,

BE = Circulating-air fan or water pump electrical energy input rate in kW,

BER = Circulating-air fan or water pump electrical energy input rate in kW, measured at

the reduced fuel input rate, and

BEH = Circulating-air fan or water pump electrical energy input rate in kW, measured at

the maximum fuel input rate.

The value yP is calculated using tP (post-purge time in minutes). For this calculation, the

Department took tP to be less than or equal to 30 seconds and set it equal to 0 seconds, according to

sections 8.2 and 8.4. The Department calculated the value yIG using tIG (on-time of the burner

interrupted ignition device in minutes). The Department calculated the value y using t+ (blower or pump

on-delay in minutes) and t

-

 (blower or pump off-delay in minutes). For furnaces, t

+

 = 2 min and t

-

 =
6.3-3

1.5 min. t

+

 = 0 and t

-

 = 0 for gas and oil boilers. PE, tIG, PEIG, and BE values are corrected for

different design options. For design options which include modulation, the Department set PER and

PEH to have the same values as PE, since it assumed no inducer modulation. The Department set BEH

equal to BE, and set BER to be 80 percent of BE for furnaces.

6.3.2.3 Determination of National Average Number of Burner Operating Hours (BOHSS) 

From the test procedure, the national average number of burner operating hours is

calculated in section 10.2.1:

BOHSS = 2080 * 0.77 * A * DHR - 2080 * B Eq. 5

where:

A = As defined in sections 10.2.1 and 10.2.1.1, 

B = As defined in sections 10.2.1, and

DHR = Typical design heating requirements as listed in Table 8,2 using the proper value of

QOUT.

To calculate factors A and B, the Department calculated yP, PE, yIG, PEIG, y, BE, QIN, and

QP as described in section 6.3.2.2 of this appendix. To calculate A, the Department assumed the

burner motor efficiency Effmotor = 0.5 (as defined in section 10.2.11), except for oil furnaces and boilers

with fan-atomized burners—where Effmotor = 0.8. The Department calculated EffyHS, heating seasonal

efficiency, as defined in section 10.2.1. For QP = 0, EffyHS is equal to the annual fuel utilization

efficiency (AFUE). The factor R, used in calculating A, is defined in section 10.2.1.1. For factor B, if

QP = 0, then B = 0, which is true for all cases except for the baseline mobile home gas furnace and

baseline gas boiler. To calculate factor A for weatherized furnaces, the Department used the equation

for induced-draft unit isolated combustion systems (ICS), because the intention is to account for the

heat from the motor, which always goes into the air distribution system.

QOUT (heating capacity for single-stage furnaces and boilers, or maximum heat capacity for

two-stage and step modulating furnaces and boilers) is used to calculate design heating rate (DHR) for

the considered efficiency levels and design options. Furthermore, to calculate QOUT (see eqn. 8 defined

in section 6.3.2.5 of this appendix), DOE used QIN (defined in section 6.3.2.1 of this appendix), EffySS

(defined in section 6.3.2.5 of this appendix), K (factor that adjusts the jacket losses, where K = 1.7 for

non-weatherized furnaces, 3.3 for weatherized furnaces, and 1 for boilers), and Lj (jacket loss, where

Lj = 1 is the default value).

In the current test procedure DHR is a step function of furnace output capacity ranges

(Table 82). It was observed that small changes in QOUT may assign an efficiency level to a different

DHR range, which could cause significant variations of BOHSS (in some cases up to 20-30 percent). 
6.3-4

For example, the non-weatherized gas furnace at 81 percent AFUE and at 75 kBtu/h capacity has a

QOUT which calls for a DHR value of 30, while the same capacity furnace at 82 percent AFUE require a

DHR value of 40. As a result, an AFUE change of 1 percent (from 81 percent to 82 percent AFUE)

represents a 24 percent increase in energy consumption for the 82 percent AFUE furnace as compared

to the 81 percent AFUE furnace. It results in higher energy consumption for a more efficient furnace

(82 percent AFUE vs 81 percent AFUE) and as a result the payback for 82 percent AFUE becomes

negative. This test procedure feature impacts several efficiency levels in the engineering analysis for

non-weatherized gas furnaces, mobile home furnaces and gas and oil-fired boilers.

Note: The ASHRAE committee in charge of the furnace/boiler test procedure (SPC 103)

is taking steps to correct this anomaly in the current test procedure. The approach by ASHRAE SPC

103 is to eliminate the DHR parameter from the formula for calculating BOHSS and replace it with a

parameter containing QOUT and an oversized factor, which has a constant value of 0.7. ASHRAE SPC

103 plans to present this furnace/boiler test procedure update for public comment in the near future.

6.3.2.4 Determination of National Average Number of Burner Operating Hours for

Two-Stage and Step Modulating Furnaces and Boilers

From the test procedure, the national average number of burner operating hours are

calculated in sections 10.2.1.2, 10.2.1.3, and 10.2.1.41:

BOHR = XR*EM / QIN,R, at the reduced operating mode, Eq. 6

BOHH = XH*EM / QIN, at the maximum operating mode, and Eq. 7

BOHM = XH*EM / QIN,M, at the modulating operating mode Eq. 8

where:

XR = Fraction of heating load at the reduced fuel input operating mode, Table 10,2

XH = Fraction of heating load at the reduced fuel input operating mode, Table 10,2

EM = Average annual energy used during the heating season for two-stage and

modulating furnaces,

QIN = As defined in section 6.3.2.1 of this appendix,

QIN,R = Steady-state reduced-fuel input rate, and

QIN,M = Steady-state modulating fuel input rate. 

The Department calculated XR and XH using TC (balance-point temparature), " (the

oversize factor), QOUT,R (reduced fuel input rate heating capacity), EffySS,M (steady-state efficiency at

the modulating fuel input rate), EffySS,R (steady-state efficiency at the reduced fuel input rate), TOA,H

(average outdoor temperature at the modulating or maximum fuel input operating mode), and QOUT,M
6.3-5

(modulating fuel input rate heating capacity), which are defined in section 11.4.2 The Department

determined QOUT, as defined in section 6.3.2.3 of this appendix. To calculate EM, the Department used

BOHSS, QIN, and QP as defined in section 6.3.2.1 of this appendix. The Department set QIN,R to be 68

percent of QIN, where this value represents the average ratio QIN/QIN,R as derived using manufacturer

product literature and Gas Appliance Manufacturers Association (GAMA) April 2002 Directory data

for all listed two-stage furnace models.3 From section 11.4.8.6 or 11.5.8.6,2 QIN,M is calculated using

QOUT and EffySS,M (as defined in section 11.4.8.8 or 11.5.8.8)2.

6.3.2.5 Determination of Heating Seasonal Efficiency (EffySS)

EffySS is required to calculate QOUT, the heating capacity and is also used to determine

AFUE, the annual fuel utilization efficiency for heating equipment with pilot lights. The approach DOE

chose was to determine the average (EffySS - AFUE) difference for each product class.

From Section 11.2.8.1 of ANSI/ASHRAE 103-19932:

QOUT = QIN*[EffySS - (K)(Lj)]/100 Eq. 9

The (EffySS -AFUE) values were calculated by solving Eqn.8 for EffySS and subtracting

AFUE from both sides:

EffySS -AFUE = 100*[(QOUT /QIN) + (K)(Lj)] - AFUE Eq. 10

The Department used the available model information (QIN, QOUT, and AFUE) from the

GAMA directory to determine average (EffySS -AFUE) values for each product class.4 The average

(EffySS -AFUE) values are listed in the look-up table which is a part of the engineering spreadsheet

(see "SSE Analysis.xls" spreadsheet).

6.3.3 PARAMETERS TO DETERMINE THE ENERGY USE OF MODULATING

FURNACES

The furnace energy use calculations are based on the current DOE test procedure for

determining the AFUE of residential furnaces and boilers,1 which for the most part references the

industry test standard ANSI/ASHRAE 103/1993 of the American Society of Heating, Refrigerating,

and Air Conditioning (ASHRAE).2 In the case of single stage and two-stage furnaces rated at one and

the same AFUE level, the analysis points to a significant difference in the energy use between both

designs, which result in very different national energy savings (0.4 quads for single-stage furnaces vs 1.0

quads for two-stage furnaces, as determined by the analysis reported in Ch.10 of this document). This

introduces an inconsistency, because with a ratio of reduced to maximum input of about 70 percent the

test procedure shows that the furnace would supply almost 95 percent of the annual heating load at the
6.3-6

reduced input. Therefore a two stage furnace operates almost all of the time as a single-stage furnace

at a reduced input rate. However, as pointed out above, the calculations based on the current test

procedure indicate much more efficient operation.

This section outlines the parameters involved in the calculations and provides an additional

basis upon which the stakeholders can comment on this part of the analysis.

6.3.3.1 Parameters to Determine Average Annual Fuel Energy Consumption

The average annual fuel energy consumption for both single-stage and two-stage furnaces

(as calculated using CFR Appendix N, Subpart B of Part 430, Uniform Test Method for Measuring

the Energy Consumption of Furnaces and Boilers, sections 10.2.2 and 10.2.2.11) is:

EF = BOHSS * (QIN - QP) + 8,760 * QP Eq. 11

EF (for single and two-stage furnaces) differs due to the different approach used to calculate

the national average number of burner operating hours - BOHSS:

BOHSS = 2080 * 0.77 * A * DHR - 2080 * B Eq. 12

where for single-stage furnaces 

A = 100,000 / [341,300 * (yIG * PEIG + y * BE) + (QIN - QP) * EffyHS], Eq. 13

and for two-stage and step modulating furnaces 

A = 100,000 / [341,300 * (yIG * PEIG + y * BE)*R + (QIN - QP) * EffyHS] Eq. 14

where the term (yIG * PEIG + y * BE) in the formula for two-stage furnaces is increased by the factor

R=2.3.

The derivation of R-values for single and two-stage furnaces is described in Kweller5 as

follows: Burner on-time for single-stage furnace is assigned values in the DOE test procedure of 3.8

minutes on and 13.3 minutes off. The corresponding values for two-stage modulating furnaces are 10

minutes and 10 minutes. The ratio of percent time-on for a single-stage furnace is 3.8/(3.8+13.3)=0.22

and for a two-stage furnace is 10/(10+10)=0.50. Using these on-time fractions, the ratio “R” of ontime for the two-stage furnace vs the single-stage furnace is 0.50/0.22=2.27. In other words the

amount of electrical energy required for the two stage furnaces is 227 percent (or R=2.3) of the singlestage furnace.

The different value of R is the cause for the reduced energy consumption for modulating

furnaces compared to single-stage at the same efficiency level. In this case, the increased electrical

energy use for two-stage furnaces is credited in reducing the house heating load.
6.3-7

6.3.3.2 Parameters to Determine Annual Fuel Utilization Efficiency

The AFUE equals the heating seasonal efficiency (EffyHS) when no pilot light is present. 

The detailed test procedure approach to determine EffyHS requires specific information on heat-up and

cool down temperatures as measured during an actual test. When test results are not available, the

general approach is to make an assumption for the value of the AFUE. 

From Section 11.2.12 and 11.4.12 of ANSI/ASHRAE 103-19932 (DOE furnace/boiler

test procedure refers to this standard):

AFUE = EffyHS (when no pilot light is present) Eq. 15

EffyHS for two-stage furnaces is a function of XH and XR = 1 - XH, ratios representing the

fraction of heating load at maximum and reduced input rate.

XH is a function of the steady-state efficiency at maximum (EffySS) and reduced (EffySS,R)

fuel input rate capacities. From several actual modulating furnace tests described in Liu6 DOE found

that the values for EffySS,R are sometimes higher and sometimes lower than the EffySS values. 

Therefore, based on these tests it is possible to assume that EffySS,R = EffySS. This assumption is

confirmed in the above cited reference,5 where the furnace steady-state efficiency at maximum (EffySS)

and reduced (EffySS,R) fuel input rate capacities are assumed the same. Once this assumption is

confirmed, then it is straightforward to calculate the reduced fuel input heating capacity QOUT,R = QOUT *

QIN,R / QIN and the balance-point temperature TC. Knowing TC allows one to determine XH and XR

from Table 10.2

DOE did not use the above approach to determine EffyHS . The Department examined 8

families of furnace models at 80 percent AFUE from six manufacturers, and compared pairs of models

which are essentially identical with the exception of the modulating component. (See Table 6.3.3.1) 

The comparison showed that the reported AFUE for each pair is identical. This finding indicates that

EffyHS is the same for single-stage and two-stage furnaces, which are otherwise identical and therefore

AFUE value may be used as proxy for EffyHS in the equation 13 and 14.
a

 Some models in this series have AFUE of 80% or 81%. 

6.3-8

Table 6.3.3.1 AFUE for Similar Single-Stage and Two-Stage Furnace Models Series

Manufacturer Single-Stage Series Two-Stage Series AFUE

Amana GUIC GUIS 80%

Carrier 58DLA 58CTA 80%

Lennox G50 (UH/DF) G60 (UH/DF) 80%

Rheema RGLJ/RGPH RGLK/RGPK 80%

Trane TDD-C/TUD-C TDD-R/TUD-R 80%

York PDN/PHU PDD/PDU 80%

6.3.3.3 Conclusions

The fuel consumption difference between single-stage and modulating furnaces is determined

by:

1) the value of the parameter R, and

2) the value of XR and XH, (ratios representing the fraction of heating load at maximum and reduced

input rate), where they are functions of the steady-state efficiency at maximum and reduced fuel input

rate capacities as determined by test procedure measured quantities.

To bring the energy use of single-stage and two-stage furnaces in line with the actually observed

field performance it may be necessary to correct at least the above parameters. This may require

assuming different values for the furnace time on/off and also changing the oversizing factor. There may

be other factors in the test procedure which should be examined.

6.3.4 SUMMARY TABLES

The summary tables below include single-stage and two-stage modulation tables referenced in

Chapter 6 (section 6.7.2) of the TSD. Tables 6.3.3.1 and Tables 6.3.4.1 through 6.3.4.6 in this

appendix contain data about the furnaces with single-stage controls, and Tables 6.3.4.7 through

6.3.4.11 present data about two-stage modulation furnace designs.
6.3-9

Table 6.3.4.1 Single-Stage Non-Weatherized Gas Furnaces

Description QIN QOUT QP EFFyHS PE BE PEIG TIG RDHR BOHss EAE EF

Gas Furnace, 78% w/time delays, w/o pilot 75,000 57,809 0 78 0.076 0.50 0.4 0.62 30 792 558 59.42

Gas Furnace, 80%(A) w/time delays, w/o pilot 75,000 58,704 0 80 0.076 0.50 0.4 0.62 30 773 545 57.99

80%(A1) - ImprovedCircBlowerMotor (PSC) 75,000 59,742 0 80 0.076 0.48 0.4 0.62 30 774 532 58.04

80%(A2) - ImprovedCircBlowerMotor(ECM) 75,000 59,135 0 80 0.076 0.40 0.4 0.62 30 778 459 58.36

80%(A3) - ImprovedCircBlowerMotor(SR) 75,000 59,264 0 80 0.076 0.43 0.4 0.62 30 776 487 58.23

80%(A4) - ImprovedCircBlowerImpeller w/ PSC 75,000 59,482 0 80 0.076 0.42 0.4 0.62 30 777 480 58.26

80%(A5) - ImprovedCompactCircBlowerImpeller + ECM 75,000 58,725 0 80 0.076 0.34 0.4 0.62 30 781 407 58.58

Gas Furnace, 81% w/time delays, w/o pilot 75,000 59,475 0 81 0.076 0.50 0.4 0.62 30 764 538 57.29

81%(A1) - ImprovedCircBlowerMotor (PSC) 75,000 59,475 0 81 0.076 0.48 0.4 0.62 30 765 525 57.35

81%(A2) - ImprovedCircBlowerMotor(ECM) 75,000 59,475 0 81 0.076 0.40 0.4 0.62 30 769 453 57.65

81%(A3) - ImprovedCircBlowerMotor(SR) 75,000 59,475 0 81 0.076 0.43 0.4 0.62 30 767 481 57.54

81%(A4) - ImprovedCircBlowerImpeller w/ PSC 75,000 59,475 0 81 0.076 0.42 0.4 0.62 30 768 475 57.56

81%(A5) - ImprovedCompactCircBlowerImpeller + ECM 75,000 59,475 0 81 0.076 0.34 0.4 0.62 30 772 402 57.87

Gas Furnace, 82% w/time delays, w/o pilot 75,000 60,225 0 82 0.076 0.50 0.4 0.62 40 1007 709 75.49

82%(A1) - ImprovedCircBlowerMotor (PSC) 75,000 60,225 0 82 0.076 0.48 0.4 0.62 40 1008 692 75.56

82%(A2) - ImprovedCircBlowerMotor(ECM) 75,000 60,225 0 82 0.076 0.40 0.4 0.62 40 1013 597 75.96

82%(A3) - ImprovedCircBlowerMotor(SR) 75,000 60,225 0 82 0.076 0.43 0.4 0.62 40 1011 634 75.81

82%(A4) - ImprovedCircBlowerImpeller w/ PSC 75,000 60,225 0 82 0.076 0.42 0.4 0.62 40 1011 625 75.84

82%(A5) - ImprovedCompactCircBlowerImpeller + ECM 75,000 60,225 0 82 0.076 0.34 0.4 0.62 40 1017 529 76.24

Gas Furnace, 83% w/time delays, w/o pilot 75,000 60,975 0 83 0.076 0.50 0.4 0.62 40 995 701 74.61

Gas Furnace, 90% w/time delays, w/o pilot 75,000 66,225 0 90 0.076 0.50 0.4 0.62 40 920 648 68.99

90%(A1) - ImprovedCircBlowerMotor (PSC) 75,000 66,225 0 90 0.076 0.48 0.4 0.62 40 921 633 69.05

90%(A2) - ImprovedCircBlowerMotor(ECM) 75,000 66,225 0 90 0.076 0.40 0.4 0.62 40 925 545 69.38

90%(A3) - ImprovedCircBlowerMotor(SR) 75,000 66,225 0 90 0.076 0.43 0.4 0.62 40 923 579 69.25

90%(A4) - ImprovedCircBlowerImpeller w/ PSC 75,000 66,225 0 90 0.076 0.42 0.4 0.62 40 924 571 69.28

90%(A5) - ImprovedCompactCircBlowerImpeller + ECM 75,000 66,225 0 90 0.076 0.34 0.4 0.62 40 928 483 69.62

Gas Furnace, 92% w/time delays, w/o pilot 75,000 67,725 0 92 0.076 0.50 0.4 0.62 40 900 635 67.53

92%(A1) - ImprovedCircBlowerMotor (PSC) 75,000 67,725 0 92 0.076 0.48 0.4 0.62 40 901 619 67.59

92%(A2) - ImprovedCircBlowerMotor(ECM) 75,000 67,725 0 92 0.076 0.40 0.4 0.62 40 905 534 67.91

92%(A3) - ImprovedCircBlowerMotor(SR) 75,000 67,725 0 92 0.076 0.43 0.4 0.62 40 904 567 67.79

92%(A4) - ImprovedCircBlowerImpeller w/ PSC 75,000 67,725 0 92 0.076 0.42 0.4 0.62 40 904 559 67.82

92%(A5) - ImprovedCompactCircBlowerImpeller + ECM 75,000 67,725 0 92 0.076 0.34 0.4 0.62 40 908 473 68.14
6.3-10

Table 6.3.4.2 Single-Stage Weatherized Gas Furnaces

Description QIN QOUT QP EFFyHS PE BE PEIG TIG RDHR BOHss EAE EF

Gas Furnace, 78% w/time delays, w/o pilot 75,000 56,004 0 78 0.076 0.50 0.4 0.62 30 792 558 59.42

Gas Furnace, 80% w/time delays, w/o pilot 75,000 57,504 0 80 0.076 0.50 0.4 0.62 30 773 545 57.99

80%AFUE - Improved Insulation 75,000 57,616 0 80 0.076 0.50 0.4 0.62 30 772 544 57.88

80%AFUE - ImprovedCircBlowerMotor (PSC) 75,000 57,504 0 80 0.076 0.48 0.4 0.62 30 774 532 58.04

80%AFUE - ImprovedSupplyFanMotor (ECM) 75,000 57,504 0 80 0.076 0.40 0.4 0.62 30 778 459 58.36

Gas Furnace, 81% w/time delays, w/o pilot 75,000 58,254 0 81 0.076 0.50 0.4 0.62 30 764 538 57.29

81%AFUE - Improved Insulation 75,000 58,366 0 81 0.076 0.50 0.4 0.62 30 763 537 57.19

81%AFUE - ImprovedCircBlowerMotor (PSC) 75,000 58,254 0 81 0.076 0.48 0.4 0.62 30 765 525 57.35

81%AFUE - ImprovedSupplyFanMotor (ECM) 75,000 58,254 0 81 0.076 0.40 0.4 0.62 30 769 453 57.65

Gas Furnace, 82% w/time delays, w/o pilot 75,000 59,004 0 82 0.076 0.50 0.4 0.62 30 755 532 56.62

82%AFUE - Improved Insulation 75,000 59,116 0 82 0.076 0.50 0.4 0.62 30 754 531 56.52

82%AFUE - ImprovedCircBlowerMotor (PSC) 75,000 59,004 0 82 0.076 0.48 0.4 0.62 30 756 519 56.67

82%AFUE - ImprovedSupplyFanMotor (ECM) 75,000 59,004 0 82 0.076 0.40 0.4 0.62 30 760 448 56.97

Gas Furnace, 82.5% w/time delays, w/o pilot 75,000 59,379 0 83 0.076 0.50 0.4 0.62 30 751 529 56.29

82.5%AFUE - Improved Insulation 75,000 59,866 0 83 0.076 0.50 0.4 0.62 30 745 525 55.86

82.5%AFUE - ImprovedCircBlowerMotor (PSC) 75,000 59,379 0 83 0.076 0.48 0.4 0.62 30 751 516 56.34

82.5%AFUE - ImprovedSupplyFanMotor (ECM) 75,000 59,379 0 83 0.076 0.40 0.4 0.62 30 755 445 56.64
6.3-11

Table 6.3.4.3 Single-Stage Mobile Home Furnaces

Description QIN QOUT QP EFFyHS PE BE PEIG TIG RDHR BOHss EAE EF

MH Gas Furnace, 75% w/time delays, w/ pilot 75,000 55,992 500 77 0.076 0.50 0 0.00 30 781 500 62.96

MH Gas Furnace, 80% w/time delays, w/o pilot 75,000 59,742 0 80 0.076 0.50 0.4 0.62 30 773 545 62.37

80% AFUE ImprovedSupplyFanMotor (ECM) 75,000 59,742 0 80 0.076 0.40 0.4 0.62 30 778 459 62.74

MH Gas Furnace, 81% w/time delays, w/o pilot 75,000 60,492 0 81 0.076 0.50 0.4 0.62 40 1019 718 80.77

81% AFUE ImprovedSupplyFanMotor (ECM) 75,000 60,492 0 81 0.076 0.40 0.4 0.62 40 1025 604 81.25

MH Gas Furnace, 82% w/time delays, w/o pilot 75,000 61,242 0 82 0.076 0.50 0.4 0.62 40 1007 709 79.87

82% AFUE ImprovedSupplyFanMotor (ECM) 75,000 61,242 0 82 0.076 0.40 0.4 0.62 40 1013 597 80.34

MH Gas Furnace, 90% w/time delays, w/o pilot 75,000 67,242 0 90 0.076 0.50 0.4 0.62 40 920 648 73.37

Table 6.3.4.4 Single-Stage Oil-Fired Furnaces

Description QIN QOUT QP EFFyHS PE BE PEIG TIG RDHR BOHss EAE EF

Oil Furnace, 78% w/time delays, w/o pilot 105,000 80,689 0 78 0.16 0.50 0.045 26.00 50 944 969 99.09

Oil Furnace, 80% w/time delays, w/o pilot 105,000 82,789 0 80 0.16 0.50 0.045 26.00 50 921 946 96.69

Oil Furnace, 81% w/time delays, w/o pilot 105,000 83,839 0 81 0.16 0.50 0.045 26.00 50 910 934 95.54

81%AFUE Interrupted Ignition 105,000 83,839 0 81 0.16 0.50 0.025 0.75 50 921 671 96.66

81%AFUE ImprovedSupplyFanMotor (ECM) 105,000 83,839 0 81 0.16 0.40 0.045 26.00 50 914 833 95.97

Oil Furnace, 82% w/time delays, w/o pilot 105,000 84,889 0 82 0.16 0.50 0.045 26.00 50 899 923 94.41

82%AFUE Interrupted Ignition 105,000 84,889 0 82 0.16 0.50 0.025 0.75 50 910 663 95.50

82%AFUE ImprovedSupplyFanMotor (ECM) 105,000 84,889 0 82 0.16 0.40 0.045 26.00 50 903 824 94.83

Oil Furnace, 83% w/time delays, w/o pilot 105,000 85,939 0 83 0.16 0.50 0.045 26.00 50 889 913 93.31

83%AFUE Interrupted Ignition 105,000 85,939 0 83 0.16 0.50 0.025 0.75 50 899 656 94.38

83%AFUE ImprovedSupplyFanMotor (ECM) 105,000 85,939 0 83 0.16 0.40 0.045 26.00 50 893 814 93.72

Oil Furnace, 84% w/time delays, w/o pilot 105,000 86,989 0 84 0.16 0.50 0.045 26.00 50 878 902 92.24

84%AFUE Interrupted Ignition 105,000 86,989 0 84 0.16 0.50 0.025 0.75 50 888 648 93.28

84%AFUE ImprovedSupplyFanMotor (ECM) 105,000 86,989 0 84 0.16 0.40 0.045 26.00 50 882 804 92.64

Oil Furnace, 85% w/time delays, w/o pilot 105,000 88,039 0 85 0.16 0.50 0.045 26.00 50 868 892 91.19

85%AFUE Interrupted Ignition 105,000 88,039 0 85 0.16 0.50 0.025 0.75 50 878 641 92.20

85%AFUE ImprovedSupplyFanMotor (ECM) 105,000 88,039 0 85 0.16 0.40 0.045 26.00 50 872 795 91.58
6.3-12

Table 6.3.4.5 Single-Stage Hot-Water Gas Boilers

Description QIN QOUT QP EFFyHS PE BE PEIG TIG RDHR BOHss EAE EF

Gas Boiler, 80% w/time delays, w/ pilot 105,000 84,754 500 81 0.13 0.07 0 0.00 50 914 183 95.93

Gas Boiler, 81% w/time delays, w/o pilot 105,000 85,804 0 81 0.13 0.07 0.4 0.62 50 936 211 98.23

81%AFUE Improved Circulating Pump 105,000 85,804 0 81 0.13 0.05 0.4 0.62 50 936 189 98.32

Gas Boiler, 82% w/time delays, w/o pilot 105,000 86,854 0 82 0.13 0.07 0.4 0.62 50 924 209 97.04

82%AFUE Improved Circulating Pump 105,000 86,854 0 82 0.13 0.05 0.4 0.62 50 925 187 97.13

Gas Boiler, 83% w/time delays, w/o pilot 105,000 87,904 0 83 0.13 0.07 0.4 0.62 50 913 206 95.88

83%AFUE Improved Circulating Pump 105,000 87,904 0 83 0.13 0.05 0.4 0.62 50 914 185 95.97

Gas Boiler, 84% w/time delays, w/o pilot 105,000 88,954 0 84 0.13 0.07 0.4 0.62 50 902 204 94.74

84%AFUE Improved Circulating Pump 105,000 88,954 0 84 0.13 0.05 0.4 0.62 50 903 183 94.83

Gas Boiler, 88% w/time delays, w/o pilot 105,000 93,154 0 88 0.13 0.07 0.4 0.62 50 862 194 90.46

Gas Boiler, 91% w/time delays, w/o pilot 105,000 96,304 0 91 0.13 0.07 0.4 0.62 60 1000 226 105.00

Gas Boiler, 99% w/time delays, w/o pilot 105,000 104,704 0 99 0.13 0.07 0.4 0.62 60 920 207 96.56

Table 6.3.4.6 Single-Stage Hot-Water Oil Boilers

Description QIN QOUT QP EFFyHS PE BE PEIG TIG RDHR BOHss EAE EF

Oil Boiler, 80% w/time delays 140,000 113,413 0 80 0.16 0.07 0.045 26.00 70 993 348 138.99

Oil Boiler, 81% w/time delays 140,000 114,813 0 81 0.16 0.07 0.045 26.00 70 981 344 137.29

81%AFUE Interrupted Ignition 140,000 114,813 0 81 0.16 0.07 0.025 0.75 70 984 228 137.78

81%AFUE Improved Circulating Pump 140,000 114,813 0 81 0.16 0.05 0.045 26.00 70 981 321 137.39

Oil Boiler, 82% w/time delays 140,000 116,213 0 82 0.16 0.07 0.045 26.00 70 969 340 135.63

82%AFUE Interrupted Ignition 140,000 116,213 0 82 0.16 0.07 0.025 0.75 70 972 225 136.11

82%AFUE Improved Circulating Pump 140,000 116,213 0 82 0.16 0.05 0.045 26.00 70 969 318 135.72

Oil Boiler, 83% w/time delays 140,000 117,613 0 83 0.16 0.07 0.045 26.00 70 957 336 134.01

83%AFUE Interrupted Ignition 140,000 117,613 0 83 0.16 0.07 0.025 0.75 70 961 223 134.47

83%AFUE Improved Circulating Pump 140,000 117,613 0 83 0.16 0.05 0.045 26.00 70 958 314 134.10

Oil Boiler, 84% w/time delays 140,000 119,013 0 84 0.16 0.07 0.045 26.00 70 946 332 132.43

84%AFUE Interrupted Ignition 140,000 119,013 0 84 0.16 0.07 0.025 0.75 70 949 220 132.88

84%AFUE Improved Circulating Pump 140,000 119,013 0 84 0.16 0.05 0.045 26.00 70 947 310 132.51

Oil Boiler, 86% w/time delays 140,000 121,813 0 86 0.16 0.07 0.045 26.00 70 924 324 129.37

85%AFUE Interrupted Ignition 140,000 121,813 0 86 0.16 0.07 0.025 0.75 70 927 215 129.80

85%AFUE Improved Circulating Pump 140,000 121,813 0 86 0.16 0.05 0.045 26.00 70 925 303 129.45

Oil Boiler, 90% w/time delays 140,000 127,413 0 90 0.16 0.07 0.045 26.00 70 883 310 123.66

Oil Boiler, 95% w/time delays 140,000 134,413 0 95 0.16 0.07 0.045 26.00 80 957 336 133.94
6.3-13

Table 6.3.4.7 Two-Stage Non-Weatherized Gas Furnaces

Description QIN QOUT QP EFFyHS BE, BEH PEIG TIG RDHR BOHss EAE EF

Gas Furnace, 80% - 2-stage 75,000 59,309 0 80 0.500 0.4 0.62 30 747 572 56.03

80%(C1) - ImprovedCircBlowerMotor (PSC) 75,000 59,309 0 80 0.484 0.4 0.62 30 749 559 56.14

80%(C2) - ImprovedCircBlowerMotor(ECM) 75,000 59,309 0 80 0.398 0.4 0.62 30 757 484 56.77

80%(C3) - ImprovedCircBlowerImpeller w/ PSC 75,000 59,309 0 80 0.424 0.4 0.62 30 754 507 56.58

80%(C4) - ImprovedCompactCircBlowerImpeller + ECM 75,000 59,309 0 80 0.337 0.4 0.62 30 763 431 57.22

Gas Furnace, 81% - 2-stage 75,000 60,059 0 81 0.500 0.4 0.62 40 985 754 73.85

81%(C1) - ImprovedCircBlowerMotor (PSC) 75,000 60,059 0 81 0.484 0.4 0.62 40 987 737 73.99

81%(C2) - ImprovedCircBlowerMotor(ECM) 75,000 60,059 0 81 0.398 0.4 0.62 40 997 638 74.81

81%(C3) - ImprovedCircBlowerImpeller w/ PSC 75,000 60,059 0 81 0.424 0.4 0.62 40 994 668 74.57

81%(C4) - ImprovedCompactCircBlowerImpeller + ECM 75,000 60,059 0 81 0.337 0.4 0.62 40 1005 568 75.40

Gas Furnace, 82% - 2-stage 75,000 60,809 0 82 0.500 0.4 0.62 40 973 745 73.00

82%(C1) - ImprovedCircBlowerMotor (PSC) 75,000 60,809 0 82 0.484 0.4 0.62 40 975 728 73.15

82%(C2) - ImprovedCircBlowerMotor(ECM) 75,000 60,809 0 82 0.398 0.4 0.62 40 986 631 73.95

82%(C3) - ImprovedCircBlowerImpeller w/ PSC 75,000 60,809 0 82 0.424 0.4 0.62 40 983 660 73.71

82%(C4) - ImprovedCompactCircBlowerImpeller + ECM 75,000 60,809 0 82 0.337 0.4 0.62 40 994 561 74.52

Gas Furnace, 90% - 2-stage, w/ ECM 75,000 66,809 0 90 0.398 0.4 0.62 40 903 578 67.70

90%(C4) - ImprovedCompactCircBlowerImpeller + ECM 75,000 66,809 0 90 0.337 0.4 0.62 40 909 513 68.18

Gas Furnace, 92% - 2-stage w/ ECM 75,000 68,309 0 92 0.398 0.4 0.62 40 884 566 66.30

92%(C4) - ImprovedCompactCircBlowerImpeller + ECM 75,000 68,309 0 92 0.337 0.4 0.62 40 890 503 66.76

Table 6.3.4.8 Two-Stage Mobile Home Furnaces

Description QIN QOUT QP EFFyHS BE, BEH PEIG TIG RDHR BOHss EAE EF

80% AFUE w/ Two-stage Modulation + ECM 75,000 59,742 0 80 0.398 0.4 0.62 30 757 484 61.15

81% AFUE w/ Two-stage Modulation + ECM 75,000 60,492 0 81 0.398 0.4 0.62 40 997 638 79.19

82% AFUE w/ Two-stage Modulation + ECM 75,000 61,242 0 82 0.398 0.4 0.62 40 986 631 78.33
6.3-14

Table 6.3.4.9 Two-Stage Hot-Water Oil Furnaces

Description QIN QOUT QP EFFyHS BE, BEH PEIG TIG RDHR BOHss EAE EF

81%AFUE Fan Atomized Burner w/ Two-stage Modulation 105,000 83,839 0 81 0.398 0.045 26.00 50 897 759 94.21

 82%AFUE Fan Atomized Burner w/ Two-stage Modulation 105,000 84,889 0 82 0.398 0.045 26.00 50 887 750 93.12

83%AFUE Fan Atomized Burner w/ Two-stage Modulation 105,000 85,939 0 83 0.398 0.045 26.00 50 877 742 92.05

84%AFUE Fan Atomized Burner w/ Two-stage Modulation 105,000 86,989 0 84 0.398 0.045 26.00 50 867 733 91.00

85%AFUE Fan Atomized Burner w/ Two-stage Modulation 105,000 88,039 0 85 0.398 0.045 26.00 50 857 726 89.98

Table 6.3.4.10 Two-Stage Hot-Water Gas Boilers

Description QIN QOUT QP EFFyHS BE, BEH PEIG TIG RDHR BOHss EAE EF

Gas Boiler, 81% w/ Two-stage Modulation 105,000 85,804 0 81 0.070 0.4 0.62 50 929 241 97.50

Gas Boiler, 82% w/ Two-stage Modulation 105,000 86,854 0 82 0.070 0.4 0.62 50 917 238 96.33

Gas Boiler, 83% w/ Two-stage Modulation 105,000 87,904 0 83 0.070 0.4 0.62 50 907 235 95.18

Gas Boiler, 84% w/ Two-stage Modulation 105,000 88,954 0 84 0.070 0.4 0.62 50 896 233 94.06

Table 6.3.4.11 Two-Stage Hot-Water Oil Boilers

Description QIN QOUT QP EFFyHS BE, BEH PEIG TIG RDHR BOHss EAE EF

Oil Boiler, 82% Fan Atomized Burner w/ Two-stage Modulation 140,000 116,213 0 82 0.070 0.045 26.00 70 965 329 135.10

Oil Boiler, 83% Fan Atomized Burner w/ Two-stage Modulation 140,000 117,613 0 83 0.070 0.045 26.00 70 954 325 133.49

Oil Boiler, 84% Fan Atomized Burner w/ Two-stage Modulation 140,000 119,013 0 84 0.070 0.045 26.00 70 942 321 131.92

Oil Boiler, 85% Fan Atomized Burner w/ Two-stage Modulation 140,000 120,413 0 85 0.070 0.045 26.00 70 931 318 130.39
6-15

REFERENCES

1. Title 10, Code of Federal Regulations, Chapter II Part 430 Appendix N, Subpart BUniform Test Method for Measuring the Energy Consumption of Furnaces, January 1,

2001. 

2. American Society for Heating Refrigeration and Air-Conditioning Engineers, Method of

Testing for Annual Fuel Ultilization Efficiency of Residential Central Furnaces and

Boilers, 1993, ANSI/ASHRAE. Atlanta, GA. Report No. Standard 103-1993. 

3. Gas Appliance Manufacturers Association, Consumers' Directory of Certified Efficiency

Ratings for Heating and Water Heating Equipment Database, April 2002.

<http://www.gamanet.org/consumer/certification/wd042002/install/Gama_web.EXE>

4. Gas Appliance Manufacturers Association, Consumers' Directory of Certified Efficiency

Ratings for Heating and Water Heating Equipment Database, October 2002.

<http://www.gamanet.org/consumer/certification/wd102002/install/Gama_web.EXE>

5. Kweller, E., A Study of Three Measures for Energy Efficiency of Fossil Fueled Furnaces

and Boilers, October, 1987, National Bureau of Standards. Report No. NBSIR87-3645. 

6. Liu, S. T., Proposed Revisions of Part of the Test Procedures for Furnaces and Boilers in

ASHRAE Standard 103-1993, September, 2002, U.S. Department of Commerce, National

Institute of Standard and Technology. Gaithersburg, MD. Report No. NISTIR 6913.