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PDFWAC 51-11C-403292

Tables for Section C403.2.11.

Table C403.2.11.1(1)
Fan Power Limitation
 
Limit
Constant Volume
Variable Volume
Option 1: Fan system motor nameplate hp
Allowable nameplate motor hp
hp ≤ CFMS × 0.0011
hp ≤ CFMS × 
0.0015
Option 2: Fan system bhp
Allowable fan system bhp
bhp ≤ CFMS × 0.00094 + A
bhp ≤ CFMS× 0.0013 + A
For SI:
 
1 cfm = 0.471 L/s. 1 bhp = 735.5 W, 1 hp = 745.5 W.
Where:
 
 
CFMS
=
The maximum design supply airflow rate to conditioned spaces served by the system in cubic feet per minute.
hp
=
The maximum combined motor nameplate horsepower.
bhp
=
The maximum combined fan brake horsepower.
A
=
Sum of [PD × CFMD/4131]
Where:
 
 
PD
=
Each applicable pressure drop adjustment from Table C403.2.10.1(2) in. w.c.
CFMD
=
The design airflow through each applicable device from Table C403.2.10.1(2) in cubic feet per minute.
Table C403.2.11.1(2)
Fan Power Limitation Pressure Drop Adjustment
Device
Adjustment
Credits
Fully ducted return and/or exhaust air systems
0.5 inch w.c. (2.15 inches w.c. for laboratory and vivarium systems)
Return and/or exhaust air flow control devices
0.5 inch w.c.
Exhaust filters, scrubbers, or other exhaust treatment
The pressure drop of device calculated at fan system design condition
Particulate filtration credit: MERV 9 - 12
0.5 inch w.c.
Particulate filtration credit: MERV 13 - 15
0.9 inch w.c.
Particulate filtration credit: MERV 16 and greater and electronically enhanced filters
Pressure drop calculated at 2x clean filter pressure drop at fan system design condition
Carbon and other gas-phase air cleaners
Clean filter pressure drop at fan system design condition
Biosafety cabinet
Pressure drop of device at fan system design condition
Energy recovery device, other than coil runaround loop
(2.2 × energy recovery effectiveness) – 0.5 inch w.c. for each airstream
Coil runaround loop
0.6 inch w.c. for each airstream
Evaporative humidifier/cooler in series with another cooling coil
Pressure drop of device at fan system design conditions
Sound attenuation section (fans serving spaces with design background noise goals below NC35)
0.15 inch w.c.
Exhaust system serving fume hoods
0.35 inch w.c.
Laboratory and vivarium exhaust systems in high-rise buildings
0.25 inch w.c./100 feet of vertical duct exceeding 75 feet
Deductions
Systems without central cooling device
-0.6 inch w.c
Systems without central heating device
-0.3 inch w.c.
Systems with central electric resistance heat
-0.2 inch w.c.
 
For SI: 1 inch w.c.= 249 Pa, 1 inch = 25.4 mm.
 
w.c. = water column.
Table C403.2.11.4
Mechanical Ventilation System Fan Efficacy
Fan Location
Air Flow Rate Minimum (cfm)
Minimum Efficacy (cfm/watt)
Air Flow Rate Maximum (cfm)
Exhaust fan: Bathroom, utility room, whole house
10
1.4 cfm/watt
< 90
Exhaust fan: Bathroom, utility room, whole house
90
2.8 cfm/watt
Any
Table C403.2.11.5
Fan Control
Cooling System Type
Fan Motor Size
Mechanical Cooling Capacity
DX cooling
Any
≥ 65,000 Btu/h
Chilled water and evaporative cooling
≥ 5 hp
Any
≥ 1/4 hp
Any
[Statutory Authority: RCW 19.27A.025, 19.27A.160, and 19.27.074. WSR 16-03-072, § 51-11C-403292, filed 1/19/16, effective 7/1/16. Statutory Authority: RCW 19.27A.020, 19.27A.025 and chapters 19.27 and 34.05 RCW. WSR 13-04-056, § 51-11C-403292, filed 2/1/13, effective 7/1/13.]
Reviser's note: The brackets and enclosed material in the text of the above section occurred in the copy filed by the agency.
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