7

- B

- i A P PENDIX 7

- B

. SYSTEM CURVE DERIVAT ION FOR FURNACE FANS

TABLE OF CO NTENTS

7

- B.1 INTRODUCTION

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

- B

- 1

7

- B.2 FURNACE FANS REFEREN CE SYSTEM CURVES

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

- B

- 2

7

- B.3 FIELD STUDIES

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

- B

- 3

7

- B.4 DETERMINATION OF REF ERENCE SYSTEM CURVES FOR DOE
FURNACE FAN TEST PRO C EDURE

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

- B

- 4

7

- B.4.2 Other reference system curves

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

- B

- 6

7

- B.5 DISRIBUTION OF SYSTE M CURVES USED IN LCC ANALYSIS

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

- B

- 6

LIST OF TABLES

Table 7

- B.3.1 Single Family Field Data ESP at Cooling Airflow Setting

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

- B

- 3
Table 7

- B.3.2 Manufactured Home Field Data

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

- B

- 4
Table 7

- B.4.1 Evaporator Coil Pressure Data

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

- B

- 4
Table 7

- B.4.2 Filter Pressure Data

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

- B

- 4
Table 7

- B.4.3 Fraction of Installations with Evaporator Coil in ESP

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

- B

- 5
Table 7

- B.4.4 Summary of Weighted Average Reference System ESP Values

......... 7

- B

- 5
Table 7

- B.5.1 Reference System ESP Distribution Parameters Values by Product
Class

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

- B

- 6

LIST OF FIGURES

Figure 7

- B.1.1 Sample of System Curves with a Typical Fan Curve

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

- B

- 1 Figure 7

- B.5.1 External Static Pressure Distribution for Non

- Weatherized Gas Furnace Fan; Oil Furnace Fan; Electric Furnace / Modular Blower Fan; Hydronic Air H andler Fan (Heat/Cool) with Central Air Conditioning

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

- B

- 7 Figure 7

- B.5.2 External Static Pressure Distribution for Non

- Weatherized Gas Furnace Fan; Oil Furnace Fan; Electric Furnace / Modular Blower Fan; Hydronic Air Handler Fan (Heat/Cool) without Central Air Conditioning or Weatherized Gas Furnace Fan

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

- B

- 7 Figure 7

- B.5.3 External Static Pressure Distribution for Manufactured Home Non

Weatherized Gas Furnace Fans; Manufactured Home Electric Furnace / Modular Blower Fan with Central Air Conditioning

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

- B

- 8 Figure 7

- B.5.4 External Static Pressure Distribution for Manufactured Home Non

Weatherized Gas Furnace Fans; Manufactured Home Electric Furnace / Modular Blower Fan without Central Air Conditioning

...... 7

- B

- 87

- B

- 1 APPENDIX 7

- B. SYSTEM CURVE DERIVATION FOR FURNA CE FANS

7

- B.1 IN TRODUCTION

The system curve of the air

- distribution system is a graphical representation of the airflow through the supply and return ducts in a house for different static pressures. The airflow and pressure drop at which the furnace will operate can be determined by the intersection of the system curve of the house and the fan curve of the furnace fan. 1 Figure 7

- B.1.1 show s an

exam ple of a plot of system curves intersecting a furnace fan curve.

DOE modeled system curves as quadratic curves, which is standard in heating, ventilation, and air conditioning (HVAC) design and fan selection handbooks. 2 The curves are
based on Bernoulli’ s equations for fluid flow and are expressed as the following equation:

Q = � P

α

Where:

Q = airflow (cfm),

P = static pressure (in.w.g.), and

α = a constant coefficient.

0 400 800 1200 1600

0.00 0.25 0.50 0.75 1.00

External Static Pressure (in. w.g.) Airflow (CFM)

Highest 1%

median

Lowest 10%

1200 CFM Generic Single-Stage Furnace Model (Heating Tap)

Figure 7

- B.1.1 Sample of System Curves with a Typical Fan Curve7

- B

- 2 7

- B.2 FURNACE FANS REFEREN CE SYSTEM CURVES

In DOE’s propose d furnace fa n test procedure

, t he reference system curve is defined as

follows:

K ref = ES P ref Q max 2

where:

K

ref = a constant that characterizes the reference system;

ESP ref = Reference System External Static Pressure ( ESP ); and

Q max = a max ESP ref 2 + b max ESP ref + c max

The operating point in the maximum airflow

- control setting is defined by the reference system criteria: E SP ref and Q
max . External static pressure (ESP) is the portion of the fan total pressure that exists by virtue of degree of compression external to the HVAC product in which
the furnace fan is contained. ESP does not include the pressure drop across appurt enances internal to the HVAC product. In the field, ESP is measured as the difference in pressure between the HVAC product inlet and outlet points

, and includes the ductwork, inlet filter, and coil outside of the unit if applicable.

In the field there are four distinct reference system ESPs associated with specific equipment:

a) Units with Cooling Option (Coil Outside of Unit): This includes n on

- weatherized gas
furnaces and oil

- furnaces. Reference system is measured at the maximum default cooling airflow control setting. ESP includes a fraction of units in the field that include the evaporator coil.

b) Heating only units : This includes heating

- only hydronic air

- handlers

. a Reference system is
measured at the default heating airflow control setting. ESP does not include evaporator coil.

b) Units with Coil inside Unit: This includes weatherized gas and oil

- fired furnaces. Reference system is measured at the maximum default cooling airflow control setting. ESP does not include evaporator coil.

c) Manufact ured Home Units: This includes manufactured home gas or oil

- fired furnaces. Reference system is measured at the cooling airflow control setting for these units. ESP includes a fraction of units in the field that include the evaporator coil.

a Units like First Company’s FWA series: http://www.firstco.com/products/fwa_hw.asp

.7

- B

- 3 7

- B.3 FIELD STUDIES

DOE gathered field data from available studies and research reports to determine an appropriate ESP value to propose for the reference system. DOE compiled over 1300 field ESP
measurements from 27 studies that included furna ce fans in single family and man ufactured
homes in different regions of the country. Table 7

- B.3.1 summarizes the field data for single family homes at cooling airflow setting. Table 7

- B.3.2 summarizes the field data for manufactured homes at cooling airflow setting. The average measured ESP values are the actual values measured in each study. Some studies did not include the evaporator coil or filter in the ESP measurement. To account for this DOE added the filter pressure drop to all adjusted ESP values (“Adj. w/o Coil” and “Adj. w/ Coil”). In addition, DOE subtracted the pressure drop of the evaporator co il for “Adj. w/o Coil” and added the pressure drop of the evaporator coil for “Adj. w/ Coil” when appropriate. See next section for the determination of average filter and evaporator pressure drop values.

Table 7

- B.3.1 Single Family Field Data ESP at Cooling Airflow Setting Study Sample
Size Ave ra ge ESP (in. w.c.) Notes

Measured Adj. w/o Coil Adj. w/ Coil
Blasnik et al. 1995 3 40 0.41 0.41 0.61 1
Blasnik et al. 1996 4 28 0.48 0.48 0.68 1
Parker 1997 5 9 0.55 0.55 0.75 1
Proctor et al. 1995 6 40 0.53 0.53 0.73 1
Proctor et al. 1996 7 36 0.51 0.51 0.71 1
Proctor et al. 1998 8 15 0.45 0.45 0.65 1

Proctor 1998 9 36 0.42 0.42 0.62 1

Proctor 2005 10 78 0.48 0.48 0.68 1
Proctor et al. 200 7 11 4 1.01 0.81 1.01

Proctor 2000 1 2 5 0.50 0.50 0.70 1

Proctor 2001 1 3 69 0.54 0.54 0.74 1

Proctor 2003 1 4 69 0.53 0.53 0.73 1

Proctor 199 6a 1 5 8 0.45 0.45 0.65 1
Proctor 1996b 1 6 92 0.31 0.52 0.73 1,2
Wilcox et. al. 2006 1 7 51 0.77 0.57 0.77
Dickenhoff 1998 1 8 13 0.54 0.54 0.74 1 Baylon et al. 2005 1 9 148 0.36 0.57 0.78 1,2 Ueno 2010 (2008 Study) 20 4 0.90 0.70 0.90

Ueno 2010 ( 2009 Study) 20 1 1.12 0.92 1.12 Pigg 2008 (2007 Study) 21 76 0.73 0.53 0.73 Pigg 200 8 (2005 Study) 21 37 0.53 0.53 0.73 1 Pigg 2003 22 31 0.55 0.55 0.75 1 Weighted Average 890 0.50 0. 52 0. 73

1 ESP measurement i ncludes Coil

2 ESP measurement includes Filter7

- B

- 4 Table 7

- B.3.2 Manufactured Home Field Data Study Sample
Size Average ESP (in. w.c.) Notes

Measured Adj. w/o Coil Adj. w/
Coil Baylon et al. 1995 23 164 0.18 0.18 0.38 1
Davis et al. 2000 24 36 0.23 0.23 0.43 1
Davis et al. 2004 25 100 0.12 0.12 0.32 1 Ecotope 2006 26 69 0.23 0.23 0.43 1 Baylon et al. 2009 27 89 0.12 0.12 0.32 1 Weighted Average 458 0.17 0.17 0.37

1 ESP measurement does not include Coil

2 ESP measurement does not include Filter

7

- B.4 DETERMINATION OF REFERENCE SYSTEM CUR VES FOR DOE
FURNACE FAN TEST PRO CEDURE

Using field data from 3 studies, DOE estimated average filter and coil pressures in order to adjust field data that did not include the filter or coil. On average

, the pressure drop measured for the evaporator coil was 0.20 in w.c. (as shown in Table 7

- B.4.1 ) and the pressure drop for the filter was 0.21 in w.c. (as shown in Table 7

- B.4.2 ).

Table 7

- B.4.1 Evaporator Coil Pressure Data Study Sample Size Average Pressure Drop (in. w.c.) Pigg 2008 (2007 Study) 21 75 0.20 Pigg 200 8 (2005 Study) 21 19 0.19
Wilcox et. al. 2006 1 7 51 0.21 Weighted Average 145 0.20

Table 7

- B.4.2 Filter Pressure Data Study Sample Size Average Pressure Drop (in. w.c.)
Pigg 2008 (2007 Study) 21 76 0.25 Pigg 200 8 (2005 Study) 21 37 0.21
Wilcox et. al. 2006 1 7 46 0.16 Weighted Average 159 0.21

Using EIA’s RECS 2005 data, DOE estimate d the fraction of furnace installations with and without a coil in the ESP. For units with a cooling option (coil outside unit)

, DOE looked at all households with either a gas or oil

- fired furnace and determined that 72.9% of these7

- B

- 5 households had central air

- conditioners. b

Table 7

- B.4.3 For manufactured home units DOE looked at all manufactured home households with either a gas or oil

- fired fur nace and determined that 50.2%
of these households had central air

- conditioners. DOE estimated that these two fractions would represent the fraction of installations with evaporator coil in the ESP. data shows the results for each of the distinct reference systems. None of the heating only units or units with
coil inside are assumed to have a n evaporator coil in the ESP.

Table 7

- B.4.3 Fraction of Installations wit h Evaporator Coil in ESP Product Description Fraction of Installations with Evaporator Coil in ESP Units with Cooling Option (Coil Outside Unit) 72.9% Heating only units 0%
Units with Coil inside 0%
Manufacture Home 50.2%

Table 7

- B.4.4 presents the final results of this analysis for each distinct reference system

curve used in DOE’s NOPR furnace fan test procedure . The results take into account the fraction
of units with the coil included in the ESP.

Table 7

- B.4.4 Summary of Weighted Average Reference System ESP Values Product Description Airflow Control Setting Weighted Average ESP (in. w.c.) Units with Cooling Option (Coi l Outside Unit) Cooling 0.65 Heating only units Heating 0.50
Units with Coil inside Cooling 0.50
Manufacture Home c Cooling 0.30 (All Values Rounded)

The results are determined as follows: 1) f or units with cooling option (coil outside unit), 7 2 % of the furnace fans are installed with CAC (see Table 7

- B.4.3 ), so 72% * 0.73 in. w.c. + 28% * 0.52 in. w.c., which is

rounded to 0.65 in w.c. ; 2) f or manufactured homes furn ace fans, 50% of the furnaces are installed with CAC ( see Table 7

- B.4.3 ), so 50% * 0.17 in. w.c. + 50% * 0.37 in. w.c., which is rounded to

0.30 in w.c. ; 3) f or heati ng only units and units with coil inside the weighted average ESP is rounded

from 0.52 in. w.c. to 0.50 in w.c.

b For simplicity, electric furnaces are excluded since they are mostly associated with heat pumps. Also, RECS does not provide information to distinguish which households have hydronic air

- handlers. Adding electric furnaces and hydronic equipment will incr ease the fraction of households with central air

- conditioners, since this equipment tends
to be located in warmer climates.

c M anufactured home external static pressure is much smaller due to the fact there is no return air ductwork in
manufactured homes. Also HUD requirements stipulate that the ductwork for cooling should be set at 0.3 in. w.c.7

- B

- 6 7

- B.4.2 Other reference system curves

Manufacturers Rating for Cooling

– 0.5 in.w.c. at cooling airflow setting [manufacturer product literature]
DOE test procedure for Cooling

- 0.1 to 0.2 in.w.c. for conventional split systems [Subpart B Appendix M of Title 10 Part 430 of the Code of Federal Regulations (CFR)] DOE test procedure for Furnaces

– 0.12

– 0.58 in.w.c. minimum static pressure values depend on equipment type as follows [Subpart B Appendix N of Title 10 Part 430 of the Co de of Federal Regulations (CFR) , which references ANSI/ASHRAE 103, table 4 and 5]: a) Gas furnaces and Oil furnaces (w/ temp rise greater than 65 deg)

- 0.18 to 0.33 in. w.c. (de pending on input capacity) b) Oil furnace (w/ temp rise less than or equal to 65 deg)

– 0.38

- 0.58 in w.c. (depending on input capacity) c) Electric furnaces

- 0.12 to 0.25 in.w.c. (dependant on Standard Air Quantity (SCFM))

Canadian Furnace Fan Standard

– 0.3 inches WC (Recommended practice ) and 0.6 inches WC (Common Practice) at heating airflow setting [ CSA. C823

- 11 : Performance of air handlers
in residential space conditioning systems . May 2011. ] HUD for Manufactured Home with comfort cooling certifica te

– 0.3 inches WC at cooling airflow setting [Title 24 of the HUD code PART 3280

-- Manufactured Home Construction and Safety Standards, Part 3280.715 (a) (3) (ll)]

7

- B.5 DISRIBUTION OF SYSTE M CURVES USED IN LCC ANALYSIS

For the LCC analysis

, DOE used the field data above to generate normal distributions for the various eq uipment installation variations as shown in Table 7

- B.5.1

. Figure 7

- B.5.1 to Figure 7

- B.5.4 show the external static pressure distribution s used in the analysis.

Table 7

- B.5.1 Referenc e System ESP Distribution Parameters Values by Product Class

Product Classes Household
Has
Central AC Average
ESP (in. w.c.) Standard
Deviation

(in. w.c.)

Non

- W eatherized Gas Furnace Fan ; Oil Furnace Fan ; Electric Furnace / Modular Blower Fan ; Hydronic Air Handler Fan (Heat/Cool) Yes 0.7 3 0.12

No 0.52 0.12

Weatherized Gas Furnace Fan Yes 0.52 0.12
Manufactured Home Non

- W eatherized Gas Furnace

Fan s; Manufactured Home Electric Furnace / Modular
Blower Fan Yes 0.37 0.06

No 0.17 0.067

- B

- 7 Figure 7

- B.5.1 External Static Pressure Distribution for Non

W eatherized Gas Furnace Fan ; Oil Furnace Fan ; Electric Furnace / Modular Blower Fan ; Hydronic Air Handler Fan (Heat/Cool) with Central Air Conditioning

Figure 7

- B.5.2 External Static Pressure Distribution for Non

W eatherized Gas Furnace Fan ; Oil Furnace Fan ; Electric Furnace / Modular Blower Fan ; Hydronic Air Handler Fan (Heat/Cool) without Central Air Conditioning or Weatherized Gas Furnace Fan7

- B

- 8 Figure 7

- B.5.3 External Static Pressure Distribution for
Manufactured Home Non

- W eat herized Gas Furnace

Fan s; Manufactured Home Electric Furnace /

Modular Blower Fan with Central Air Conditioning

Figure 7

- B.5.4 External Static Pressure Distribution for
Manufactured Home Non

- W eatherized Gas Furnace

Fan s; Manufactured Home Electric Furnace /

Modular Blower Fan without Central Air Conditioning7

- B

- 9 REFERENCES

1. Michael R. Lindeburg, P., Fans and Ductwork . In Mechanical Engineering Reference Manual for the PE Exam , P. Michael R. Lindeburg, Editor. Tenth ed. 1997. Professional Publications, Inc.: Belmont, CA . p. 20

- 1, 20

- 26

2. American Society of Heating Refrigeration and Air

- Conditioning Engineers, ASHRAE
1997 Handbook

- Fundamentals . 1997. Atlanta, GA.p. 3.12.

3. Blasnik, M., J.P. Proctor, T.D. Downey, J. Sundal, and G. Peterson. 1995a. Assessment
of HVAC Install ations in New Homes in Nevada Power Company’s Service Territory. Research Project 3841

- 03, Final Report. Palo Alto, CA: Electric Power Research Institute, Inc. TR

- 105309

.

4. Blasnik, M., T.D. Downey, J.P. Proctor, and G. Peterson. 1996. Assessment of HVAC

Ins tallations in New Homes in APS Service Territory. Research Project Final Report. Phoenix, AZ: Arizona Public Service Company, Inc.

5. Parker, D.S. 1997. Measured Air Handler Fan Power and Flow. Memorandum to Armin Rudd. Cocoa, FL. Florida Solar Energy Center

6. Proctor, J.P., M. Blasnik and T.D. Downey. 1995. Southern California Edison Coachella Valley Duct and HVAC Retrofit Efficiency Improvements Pilot Project. San Dimas, CA: Southern California Edison Company.

7. Proctor, J.P., M. Blasnik, T.D. Downey, J . Sundal, and G. Peterson. 1996 . Assessment of HVAC Installations in New Homes in Nevada Power Company’s Service Territory. 1995 Update. Las Vegas, NV: Nevada Power Company.

8. Proctor, J.P. , M. Blasnik. 1998. New Jersey Testing.

9. Proctor, J.P. 1998. New Jersey Testing in Existing Housing.

10. Proctor, J.P. 2005. Proctor Engineering Group (PEG) analysis of data collected by Conservation Services Group (CSG) field personnel during the summer of 2005 on 76 air conditioner installations in New Jersey.

11. Proctor, J.P. 2007. Perf ormance of Furnace as an Air Handler (HDAC Testing in California).

12. Proctor, J.P. 2000. Cochella Valley CA.

13. Proctor, J.P. 2001. LIPA Baseline 2001. Long Island New York.

14. Proctor, J.P. 2003. A120 Long Island Participants and non

- Participants.7

- B

- 10 15. Proctor, J.P. 1 996 a . Eastern US testing.

16. Proctor, J.P. 1996 b . Southern Indiana Gas and Electric Co. Testing.

17. Wilcox, B. J. Proctor, R. Chitwood, and K. Nittler. 2006. Furnace Fan Watt Draw and Air Flow in Cooling and Air Distribution Modes. 2008 California Building Energ y Efficiency
Standards.

18. Dickenhoff, D. 1998 . California Fan Testing.

19. Baylon D., S. Strand, B. Davis, D. Robison, and E. Kruse. 2005. Analysis of Heat Pump Installation Practices and Performance: Market Research Report. Northwest Energy Efficiency Alliance

20. Ueno. May 2010. ECM Efficiency Better (and Worse) Than You Think. Home Energy. (Two Studies reported 2008 and 2009)

21. Piggs, S. 2008. Central Air Conditioning in Wisconsin: A Compilation of Recent Field Research. Energy Center of Wisconsin. (Two studies rep orted 2005 and 2007)

22. Piggs, S. 2003. Central Electricity Use by New Furnaces: A Wisconsin Field Study.

23. Baylon, D., B. Davis, L. Palmiter. 1995. Manufactured Home Acquisition Program: Analysis of Program Impacts. Prepared for Bonneville Power Administra tion under
Contract No. DE

- AM79

- 91BP13330, Task Order #71945.

24. Davis, B, A. Roberts, D. Baylon. 2000. Summary of SGC Manufactured Home Field Data (1997

- 98 Sittings in Idaho and Washington). Prepared for Idaho Department of

Water Resources

- Energy Division

.

25. Davis, B. and D. Baylon. February 2004. "Summary of SGC Manufactured Home Field Data (2001

- 02 Sitings)." Prepared for Northwest Energy Efficient Manufactured Homes (ODOE), Northwest Energy Efficiency Alliance, Idaho Department of Water Resources,

Ener gy Division.

26. Ecotope, Summary of Results of Field Testing on Newer NEEM Homes With Mastic Duct Systems,"" memorandum to Tom Hewes and Brady Peeks of Oregon Dept of Energy, 10 June 2006. "

27. Baylon, D. and B. Davis. January 2009. "Summary of NEEM Manufactured Home Field Data." Submitted to Oregon Department of Energy.