VII ARI/ISO
Performance standard ARI/ISO
The ARI/ISO Standard incorporates a consistent rating methodology for including fan and pump energy for calculating cooling capacity, heating capacity, and energy efficiency ratios (EER). This simplifies the use of rating data for heat pump per- formance modeling in seasonal energy analysis cal- culations, and allows for direct rating comparisons across applications.
a) ISO Capacity and Efficiency Equations
The following equations are used to calculate and correct cooling capacity, heating capacity, and respective EER:
ISO Cooling Capacity = (Cooling Capacity in Btuh) + (Fan Power Correction in Watts x 3.412)
ISO Cooling EER = (ISO Cooling Capacity in Btuh/3.412)/(Power Input in watts – fan power correction in watts + pump power correction in watts) = Watts/Watts
NOTE: Do not divide ISO Cooling Capacity by 3.412 to obtain Btuh/Watts.
ISO Heating Capacity = (Heating Capacity in Btuh) – (Fan Power Correction in Watts x 3.412)
ISO Heating EER = (ISO Heating Capacity in Btuh/3.412)/(Power Input in watts – fan power correction in watts + pump power correction in watts) = Watts/Watts
NOTE: Do not divide ISO Heating Capacity by 3.412 to obtain Btuh/Watts.
b)Identify the design conditions corrected for air and water conditions.
Airflow Cfm = 308 Cfm
Water Flow
(Based upon 10 F rise in temp) = 3.1 GPM
External Static Pressure = 0.0 in. wg
Water Pressure Drop = 3.7 ft of head Power input = 1,067 watts Cooling Capacity = 11,741 Btuh
c) Perform Fan Power Correction Adjustment
Use the following formula to calculate Fan Power Correction:
Fan Power
Correction = (Cfm x 0.472) x (External Static Pressure x 249)/300 = Watts
=(308 x 0.472) x (0 x 249)/300
=0 Watts
d)Perform Pump Power Correction Adjustment
Use the following formula to calculate Pump Power Correction:
Pump Power
Correction = (GPM x 0.0631) x (Pressure Drop
x 2,990)/300
=Watts
=(3.1 x 0.0631) x
(3.7 x 2,990)/300
=7.2 Watts
e)Perform capacity and EER calculations
Use the following formula to calculate capacity and EER:
ISO Cooling
Capacity = (Cooling Capacity) + (Fan Power Correction x 3.412)
=11,741 + (0 x 3.412)
=11,741 Btuh
f)Perform Corrections by using the ISO Equations
ISO EER = (ISO Cooling Capacity/3.412)/ (Power Input – Fan Power Correc- tion + Pump Power Correction)
= Watts/Watts
NOTE: Do not divide ISO Cooling Capacity by 3.412 to obtain Btuh/Watts.
=(11,741/3.412)/(1,067 – 0 + 7.2)
=3.20 Watts/Watt
=10.93 Btuh/Watt
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