7

- G

- i APPENDIX 7

- G. DETERMINATION OF FUR NACE ENERGY USE IN T HE LCC

ANALYSIS

TABLE OF CO NTENTS

7

- G.1 INTRODUCTION

................................ ................................ ................................ . 7

- G

- 2

7

- G.2 DETERMINATION OF AVE RAGE ANNUAL FUEL ENE RGY CONSUMPTION (E F )

................................ ................................ ........................... 7

- G

- 2

7

- G.3 Determination of Average Annual Electrical Energy Consumption (E AE )

............ 7

- G

- 3

7

- G.4 Determination of National Average Number of Burner Operating Hours (BOH SS )

................................ ................................ ................................ ................. 7

- G

- 47

- G

- 2 APPENDIX 7

- G. DETERMINATION OF FUR NACE ENERGY USE IN T HE LCC

ANALYSIS

7

- G.1 0 INTRODUCTION

The energy consumption in the LCC analysis is determined using the 2007 ASHRAE SPC 103R “Method of Testing for Annual Fuel Efficiency of Residential Central Furnaces an d

Boilers”. 1 This approach requires the calculation of the average annual fuel energy consumption ( E

F

), the average annual electrical energy consumption ( E

AE ), and the national average number of burner operating hours ( BOH ) of furnaces.

The following calculations and summary tables describe the determination of E F , E AE , and BOH for gas

- and oil

- fired furnaces.

7

- G.2 0 DETERMINATION OF AVE RAGE ANNUAL FUEL ENE RGY CONSUMPTION (E F )

The average annual fuel consumption is calculated in Appendix C secti on 2 of the ASHRAE

103/2007 test procedure: 1

E

F = BOH SS * ( Q IN - Q P ) + 8,760 * Q P , for single

- stage furnaces, Eq. 1

E

F = ( BOH H * Q IN

) + ( BOH R * Q IN,R ) + [8,760

- ( BOH H + BOH R )]* Q P , for two

- stage furnaces

and Eq. 2

E

F = ( BOH M * Q IN,M ) + ( BOH R * Q IN,R )+ [8,760

- ( BOH M + BOH R )]* Q P , for continuous modulating 1 furnaces Eq. 3

where,

BOH SS = national average number of burner operating ho urs (see derivation in section 7

- G .2.3),

BOH H = national average number of burner operating hours at the maximum operating

mode for two

- stage furna ces (see derivation in section 7

- G .2.3),

BOH R = national average number of burner operating hours at the reduced operating mode

for two

- stage or continuous modulating furna ces (see derivation in section 7

- G .2.3),

BOH M = national average number of bur ner operating hours at the modulating operating mode for continuous modulating furna ces (see derivation in section 7

- G .2.3), Q

IN = steady

- state nameplate input rate in Btu/h for single

- stage furnaces or steady

- state nameplate maximum input rate in Btu/h fo r two

- stage and continuous modulating furnaces,

1 In this Technical Support Documentation, “continuous modulating” term is used instead of “step

- modulating”. Both terms are interchangeable used in the literature.7

- G

- 3 Q

IN,R = steady

- state reduced fuel input rate, Q

IN,M = steady

- state modulating fuel input rate, and Q

P = pilot flame fuel input rate in Btu/h.

Q IN is based on the baseline value for each product class. We set Q IN,R to be 69% of Q IN for non

- condensing two

- stage equipment, 67% for condensing two

- stage equipment, and 40% for continuous modulation equipment, where this value represents the average rati o Q IN /Q IN,R as derived using manufacturer product literature and AHRI March 2010 Directory data for all listed

two

- stage furnace models. 2

From the test procedure

, 1 Q IN,M is calculated using Q OUT,M a nd Effy SS,M (as defined in section 11.4.8.10 or 11.5.8.8). 1 Q P is zero for all product classes, except for the baseline

manufactured

- home gas furnace and gas boiler.

7

- G.3 0 Determination of Average Annual Electrical Energy Consumption (E AE )

Us ing the ASHRAE SPC 103/2007 test procedure, 1 the average annual auxiliary electrical energy consumption is calculated in Appendix C section 3:

E

AE = BOH SS (y P * PE + y IG *PE IG + y * BE) , for single

- stage furnaces, Eq. 4

and

E AE = BOH R (y P,R *PE R + y IG,R *PE IG,R + y R *BE R ) + BOH H or M (y P *PE H + y IG *PE IG,H + y*BE H

) 2 , for two

- stage and continuous modulating furnaces, Eq. 5

where

BOHss = as defined in section 7

- G .2.3,

BOH H = as defined in section 7

- G .2.3,

BOH M = as defined in section 7

- G .2.3,

BOH R = as defined in section 7

- G .2.3,

y

P = ratio of induced or forced draft blower on

- time to average burner on

- time,

y

P,R = ratio of induced or forced draft blower on

- time to average burner on

- time, measured at the reduced fuel input rate,

PE = burner (or draft inducer) electrical pow er input at full

- load steady

- state operation in kW,

PE R = burner (or draft inducer) electrical power input at full

- load steady

- state operation

in kW

, measured at the reduced fuel input rate,

PE H = burner (or draft inducer) electrical power input at f ull

- load steady

- state operation in kW, measured at the maximum fuel input rate,

2 The ASHRAE test procedure does not deal with ignitor energ y consumption. The ratio of ignitor on

- time to burner on

- time and the ignitor power consumption variables come from the DOE test procedure. 37

- G

- 4 y

IG = ratio of burner interrupted

- ignition device on

- time to average burner on

- time,

y

IG,R = ratio of burner interrupted

- ignition device on

- time to average burner on

- time, measured at the reduced fuel input rate,

PE IG = electrical input rate to the interrupted ignition device on the burner,

PE IG,R = electrical input rate to the interrupted ignition device on the burner, measured at the reduced fuel input rate,

PE IG,H = electrical input rate to the interrupted ignition device on the burner, measured at the maximum fuel input rate,

y = ratio of blower or pump on

- time to burner on

- time,

y

R = ratio of blower or pump on

- time to burner on

- time, measured at the reduced fuel input rate,

BE = circulating

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

BE R = circulating

- air fan or water pump electrical energy input rate in kW, measured at the reduced fuel input rate, and

BE H = circulating

- air fan or wate r pump electrical energy input rate in kW

, measured at the maximum fuel input rate.

The values y P and y P,R are calculated using t P (post

- purge time). For this calculation,

DOE took t P to be 5 seconds for furnaces, which is less than or 30 seconds and is therefore set equal to 0 seconds, according to Appendix C section 1 of the ASHRAE SPC 103/ 2007 DOE calculated the values y and y P,R using t + (blower or pump on

- delay) and t - (blower or pump off

delay). For furnaces, t + = 2 min and t - = 0.5 min, which are values obtained for the generic furnace models. For gas furnaces, PE is equal to 75 W for non

- condensing furnaces and 90 W for condensing furnaces. For oil furnaces, PE is set to 220 W. 6 For design options which include modulating controls, we set PE R and PE H to have the same values as PE, since it is assumed that there is no inducer modulation. For gas furnaces, PE IG , PE IG,R , and PE IG,H are set equal to 400 W. 7 For oil furnaces, PE IG is equal to 45 watts for oil equipment without interrupted ignition and 25 watts with oil equipment with interrupted ignition. 8 For design options which include modul ating controls, we set PE IG,R and PE IG,H to have the same values as

PE IG , since it is assumed that there is no ignition modulation. For furnaces, BE and BE R values are calculated using equations in Appendix 7

- G for the different design options.

7

- G.4 0 Determination of National Average Number of Burner Operating Hours (BOH SS )

From th e ASHRAE SPC103/2007 test procedure, 1 the national average number of burner operating hours for furnaces and boilers is calculated in Appendix C section 1:

BOH SS = 2080 * 0.77 * A * ( Q OUT / (1 + α ))

- 2080 * B , for single

- stage furnaces,

BOH H = X H * (2080) * (0.77) * A H * ( Q OUT / (1 + α ))

- 2080 * B H , for two

- stage furnaces at the maximum operating mode, Eq. 7

BOH R = X R * (2080) * (0.77) * A R * ( Q OUT / (1 + α ))

- 2080 * B R , for two

- stage and continuous modulating furnaces operating at the reduced operating mode, Eq. 87

- G

- 5 and

BOH M = X H * (2080) * (0.77) * A M * ( Q OUT / (1 + α ))

- 2080 * B M

, for continuous modulating furnaces operating at the modulating operating mode, Eq. 9

where

2080 = national average heating load hours,

0.77 = adjustment factor to adjust the calculated design heating requirements and heating load hours to the actual heating load experienced by the heating system,

A = 100,000/ [341300(y P * PE + y IG,R *PE IG,R + y * BE) + (Q IN - Q P ) * Effy HS ] 3

A H = 100,000/ [341300(y P * PE H + y IG,R *PE IG,R + y * BE H ) + (Q IN - Q P ) * Effy U,H ] a

,

,

A R = 100,000/ [341300(y P,R * PE R + y IG,R *PE IG,R + y R * BE R ) + (Q IN,R - Q P ) * Effy U,R ] a

, A M = 100,000/ [341300(y P * PE H + y IG,R *PE IG,R + y * BE H ) + (Q IN,M - Q P ) * Effy U,M ] a

, B = 2 * (Q P ) * (Effy HS ) * (A) / 100,000,

B H = 2 * (Q P ) * (Effy U,H ) * (A H ) / 100,000,

B R = 2 * (Q P ) * (Effy U,R ) * (A R ) / 100,000,

B

M = 2 * (Q P ) * (Effy U,M ) * (A M ) / 100,000, Q OUT = maximum fuel input rate heating capacity,

α = oversize factor,

X

H = fraction of heating load at maximum fuel input rate operating mode,

X

R = fraction of heating load at reduced fuel input rate operating mode (1

- X H ), Q

IN = as defined in section 7

- G .2.1 of this ap pendix, Q

IN,R = as defined in section 7

- G .2.1 of this appendix, Q

IN,M = as defined in section 7

- G .2.1 of this appendix, Q

P = as defined in section 7

- G .2.1 of this appendix,

y

P = as defined in section 7

- G .2.2 of this appendix,

y

P,R = as defined in section 7

- G .2.2 of this appendix,

PE = as defined in section 7

- G .2.2 of this appendix,

PE R = as defined in section 7

- G .2.2 of this appendix,

PE H = as defined in section 7

- G .2.2 of this appendix,

y

IG = as defined in section 7

- G .2.2 of this appendix,

y

IG,R = as defined in section 7

- G .2.2 of this appendix,

PE IG = as defined in section 7

- G .2.2 of this appendix,

PE IG,R = as defined in section 7

- G .2.2 of this appendix,

PE IG,H = as defined in section 7

- G .2.2 of this appendix,

y = as defined in section 7

- G .2.2 of this appendix,

y

R = as defined in section 7

- G .2.2 of this appendix,

BE = as defined in section 7

- G .2.2 of this appendix,

3 The ASHRAE test procedure does not deal with ignitor energy consumption. The ratio of ignitor on

- time to burner on

- time and the ignitor power consumption variables come from the DOE test procedure. 37

- G

- 6 BE R = as defined in section 7

- G .2.2 of this appendix,

BE H = as defined in section 7

- G .2.2 of this appendix,

E

ffy HS = ratio of the average length of the heating season in hours to the average heating load hours, Effy U,H = average part load efficiency at the maximum fuel input rate, Effy U,R = average part load efficiency at the reduced fuel input rate, and Effy U ,M = average part load efficiency at the modulating fuel input rate.

Equations 6 through 9 are modified to account for the fact that we know the house heating load (HHL) for each RECS hous ehold (see Chapter 7 ). First we set HHL equal to the

factors in equations 6 through 9 used to approximate HHL:

HHL = 2080 * 0.77 * ( Q OUT / (1 + α )) Eq. 10

Therefore α is set equal to:

α = Q OUT * (2080) * (0.77) / ( HHL )

- 1 Eq. 11

instead of being equal to the constant value 0.7 as defined in the ASHRAE SPC103/2007 test procedure. 1

The modified equations used in the LCC spreadsheet are as follows (Note that the maximum value for BOH is set to 8760):

BOH SS = A * HHL

- 2080 * B , for single

- stage furnaces, Eq. 12

BOH H = X H * A H * HHL

- 2080 * B H , for two

- stage furnaces at the maximum operating mode, Eq. 13

BOH R = X R * A R * HHL

- 2080 * B R , for two

- stage and continuous modulating furnaces operating at the reduced operating mode, Eq. 14

and

BOH M = X H * A M * HHL

- 2080 * B M

, for continuous modulating furnaces operating at the modulating operating mode, Eq. 15

To calculate factors A

, A H , A R , A M , B

, B H , B R , and B M

, DOE calculated y P , y P,R , PE

, PE R , PE H

, y IG , y IG,R , PE IG , PE IG,R , PE IG,H , y , y R , BE

, BE R , BE H

, , PE

, y IG , PE IG , y , BE

, Q IN

, and Q P y P , as described in section 7

- G .2.2 of this appendix. For factor B , if Q P = 0, then B = 0, which is true for all cases except for the baseline manufactured

- home gas furnace and the baseline gas boiler.

We calculate d Effy HS , heating seasonal efficiency, as defined in sections 11.2.11, 11.3.11.3, 11.4.11.3, and 11.5.11.3. 1 For Q P = 0, Effy HS is equal to the annual fuel utilization efficiency ( AFUE ). For Q P > 0, Effy HS is calculated using Effy SS (as defined in section 11.2.8.1 1 ). Effy SS is calculated using Q OUT (as defined below), K (factor that adjusts the jacket losses, where K = 1.77

- G

- 7 for non

- weatherized furnaces and Lj (jacket loss, where Lj = 1 is the default value as described in

section 11.2.8.1 1 )

Q OUT for all product classes is calculated using the following equations based on AHRI Directory data for Non

- Weatherized Gas Furnaces 2 :

Q OUT = Q IN (0.72 47 * AFUE + 0.22346), for non

- condensing equipment, and Eq. 16

Q OUT = Q IN (0.8127 * AFUE + 0.17557), for condensing equipment. Eq. 17

DOE calculated X H by using T C (balance

- point temperature as defined in section 11.4.8.4

1 ), α (the oversize factor, as calculated in Equation 11), Q OUT , and Q OUT,R (reduced fuel input rate heating capacity). Q OUT,R is set equal to 69% Q OUT for non

- condensing equipment and 67% Q OUT for condensing equipment, as derived using manufacturer produc t literature and AHRI Directory

data for all listed two

- stage furnace models. 2 X R is set equal to 1

- X H

. Effy U,H = Effy U,R and therefore using the equation in section 11.5.11.3 1 is equal to Effy SS

. Effy U,M is calculated using the eq uation in section 11.4.9.2.3. 17

- G

- 8 REFERENCES

1. American Society of Heating Refrigerating and Air

- Conditioning Engineers Inc., Method of Testing for Annual Fuel Utilization Efficiency of Residential Central Fur naces and

B oilers, 2007. Atlanta, GA. Report No. ASHRAE Sta ndard 103

- 2007.

2. AHRI. AHRI Directory March 2010, 2010.

3. U.S. Department of Energy, Title 10, Code of Federal Regulations, Chapter II Part 430 Appendix N, Subpart B

- Uniform Test Method for Measuring the Energy Consumption of Furnaces and Boilers, January 1, 2007.

4. Honeywell Inc., Hot Surface Modules: S89C, D, G, H, J and S890C, D, G, H, J, 1989.

Form Number: 68

- 0079

- 1.

5. Carlin Combustion Technology Inc., Oil Burner Ignition Systems: Interrupted D uty vs. Intermittent Duty, 2002. (Last accessed October 29, 2002.) <http://www.carlincombustion.com/TechLib/tech_speaking1.html>

6. Brookhaven National Laboratory, Comparison of Burner Operating Options, 1994. Brookhaven National Laboratory.

7. Gable, G., Report to Lawrence Berkeley National Laboratory on Gas Furnace Ignition Systems, 2003.

8. Oswald, K., Report to Lawrence Berkeley National Laboratory on Pumps and Burners,

2002.

9. Taco Inc., 110

- 120 Red Baron Circulators, 2003.