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31
HE
gpm x 500
Reference Calculations
Heating Calculations:
Cooling Calculations:
LWT = EWT +
LAT (DB) = EAT (DB) -
LC = TC - SC
S/T =
HR
gpm x 500
SC
cfm x 1.08
SC
TC
LWT = EWT -
LAT = EAT +
TH = HC + HW
HC
cfm x 1.08
Legend
Abbreviations and Definitions
cfm
= airflow, cubic feet/minute
EWT = entering water temperature, Fahrenheit
gpm = water flow in gallons/minute
WPD = water pressure drop, psi and feet of water
EAT = entering air temperature, Fahrenheit (dry bulb/wet bulb)
HC
= air heating capacity, MBtu/h
TC
= total cooling capacity, MBtu/h
SC
= sensible cooling capacity, MBtu/h
kW
= total power unit input, kilowatts
HR
= total heat of rejection, MBtu/h
HE
= total heat of extraction, MBtu/h
HWC = hot water generator capacity, MBtu/h
EER = Energy Efficient Ratio
= Btu output/Watt input
COP = Coefficient of Performance
= Btu output/Btu input
LWT = leaving water temperature, °F
LAT
= leaving air temperature, °F
TH
= total heating capacity, MBtu/h
LC
= latent cooling capacity, MBtu/h
S/T
= sensible to total cooling ratio
Operating Limits
Operating Limits
Cooling
Heating
(°F)
(°C)
(°F)
(°C)
Air Limits
Min. Ambient Air
-10
-23.3
-10
-23.3
Rated Ambient Air
80
26.7
70
21.1
Max. Ambient Air
100
37.8
85
29.4
Min. Entering Air
50
10.0
40
4.4
Rated Entering Air db/wb
80.6/66.2
27/19
68
20.0
Max. Entering Air db/wb
110/83
43/28.3
80
26.7
Water Limits
Min. Entering Water
30
-1.1
30
-1.1
Normal Entering Water
50-110
10-43.3
30-70
-1.1
Max. Entering Water
120
48.9
90
32.2
Nominal Water Flow
1.5 to 3.0 gpm per ton
(1.6 to 3.2 l/m per kW)
Notes:
Minimum/maximum limits are only for start-up conditions, and are meant for bringing the space
up to occupancy temperature. Units are not designed to operate at the minimum/maximum
conditions on a regular basis. The operating limits are dependent upon three primary factors:
1) water temperature, 2) return air temperature, and 3) ambient temperature. When any of the
factors are at the minimum or maximum levels, the other two factors must be at the normal level
for proper and reliable unit operation.
AFFINITY SERIES
OUTDOOR PACKAGED HEAT PUMP INSTALLATION MANUAL