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5-1-1. Cooling
Outdoor dry bulb temperature
Total cooling load
Room 1
Indoor dry bulb temperature
Indoor wet bulb temperature
Cooling load
Room 2
Indoor dry bulb temperature
Indoor wet bulb temperature
Cooling load
Other
Indoor/Outdoor piping equivalent length
Capacity of indoor unit
Model class of indoor unit
Model capacity (kBtu/h)
Model name
06
SVZ
-
SLZ-KF
-
SEZ-KD
-
MFZ-KJ
-
MLZ-KP
-
MSZ-FH
6.0
MSZ-FS
6.0
MSZ-GL
6.0
MSZ-EF
-
PEAD
-
PLA
-
■ Cooling calculation
• Tentative selection of indoor units
Room1: PEFY-P30
Room2: PEFY-P36
In this case, the total capacity is 66.0. (30.0 + 36.0 = 66.0)
• Tentative selection of outdoor unit
Proper outdoor unit in this case is SM72TAM as the total capacity of the indoor units is 66.0.
SM72TAM
• Calculation for the corrected capacity of the total indoor units (CTi)
Correction factor for indoor design wet bulb temperature: Room 1 (68.0°F) 1.02 (Refer to Figure 1 in 5-2-1.)
CTi = Σ (Rated capacity of indoor unit × Correction factor for indoor temperature)
= 30.0 × 1.02 + 36.0 × 0.95
= 64.8 kBtu/h
• Calculation for the corrected capacity of the outdoor unit (CTo)
Correction factor for outdoor temperature (95.0°F)
Correction factor for piping length (196 ft)
CTo = Rated capacity of outdoor unit × Correction factor for outdoor temperature × Correction factor for piping length ×
G(CTi)*1
= 72.0 × 1.00 × 0.93
= 66.96 kBtu/h
*1. G(CTi) is used only when greater than 100% indoor model size are connected in total. Refer to Standard capacity
diagram.
• Determination of maximum system capacity (CTx)
Comparison between CTi and CTo:
CTi = 64.8 < CTo = 66.96, thus, select CTi.
CTx = CTi = 64.8 kBtu/h
• Comparison with essential load
Against the essential load 60.6 kW, the maximum system capacity is 64.8 kW: A proper outdoor unit is selected.
• Calculation for the maximum indoor unit capacity of each room
When CTx = CTi, use the calculation formula below.
Room1: Rated capacity of indoor unit × Correction factor for indoor design temperature
= 30.0 × 1.02
= 30.6 kBtu/h
The capacity is enough for the cooling load of Room 1 (27.2 kBtu/h): A proper indoor unit is selected.
Room2: CTx × Indoor unit rating × Correction factor for indoor design temperature
= 36.0 × 0.95
OCH800A_15
Design condition
04
05
06
08
12
15
4.0
5.0
6.0
8.0
12.0 15.0 18.0 24.0 27.0 30.0 36.0 48.0 54.0 72.0 96.0
Capacity class
09
12
15
18
-
12.0
-
18.0
24.0
8.4
11.1
15.0
-
8.1
11.5
14.1
17.2
9.0
12.0
15.0
17.0
9.0
12.0
-
17.2
9.0
12.0
15.0
17.2
9.0
12.0
15.0
17.2
9.0
12.0
14.0
17.2
22.5
9.0
12.0
15.0
18.0
9.0
12.0
15.0
18.0
24.0
-
12.0
-
18.0
24.0
30.0 kBtu/h (Nominal)
36.0 kBtu/h (Nominal)
72.0 kBtu/h (Nominal)
98.6ºF (37.0ºC)
60.6 kBtu/h
80.6ºF (27.0ºC)
64.4ºF (20.0ºC)
27.2 kBtu/h
75.2ºF (24.0ºC)
64.4ºF (19.0ºC)
33.4 kBtu/h
196 ft
18
24
27
30
36
48
24
30
36
30.0
36.0
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
30.0
36.0
30.0
36.0
Room 2 (66.2°F) 0.95 (Refer to Figure 1 in 5-2-1.)
1.00 (Refer to Figure 2 in 5-2-1.)
0.93 (Refer to Figure 5 in 5-5-1.)
54
72
96
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