Table 9 - Outdoor unit heating capacity calculation 
Outdoor Unit Capacity x 1000 BTU  Outdoor Unit Capacity (HP) D 
72  8 
96  10 
120  12 
144  14 
QHo: Outdoor Unit Heating Capacity 
QHo = QHi x D/∑D(Round number) 
T2A correction factor E 
 
T = 102⁰F (default) 
QHr: Outdoor Unit Real Heating Capacity 
QHr = QHo + E 
For example: 
Outdoor Unit 72 + 96,Heating Indoor Unit (12K x 6) + (18K x 6),T1 = 63⁰F,TS = 70⁰F,T4 = 45⁰F,T2A (average) = 93⁰F 
T1 – TS = 63 – 70 = -7,so B = 2 
T4 = 45,so C = 100% 
T2A (average) = 93⁰F,so E = 6 
QHi = ∑(AxB) x C =(1.2 x 2 x 6 + 2.0 x 2 x 6)x 100% = 38.4,Round number:39 
72 outdoor unit capacity:QHo = QHix D / ∑D = 39 x 8 /(8 + 10)= 17.3,Round number:18 
96 outdoor unit capacity:QHo = QHix D / ∑D = 39 x 10 /(8 + 10)= 21.6,Round number:22 
72 outdoor unit actual capacity:QHr = QHo + E =18 + 6 = 24,From the frequency table:70Hz 
96 outdoor unit actual capacity:QHr = QHo + E = 22 + 6 = 28,From the frequency table:78Hz 
NOTES: 
TS:    Indoor unit setting temperature 
T1:    Room temperature 
T2A:  Temperature of evaporator inlet 
T2B:  Temperature of evaporator outlet 
T4:    Ambient temperature 
 
 
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