Mitsubishi Electric MXZ-4C36NAHZ Technical & Service Manual page 16

<Cooling>
Outdoor Design Dry Bulb Temperature
Total Cooling Load
Room1
Indoor Design Dry Bulb Temperature
Indoor Design Wet Bulb Temperature
Cooling Load
Room2
Indoor Design Dry Bulb Temperature
Indoor Design Wet Bulb Temperature
Cooling Load
<Other>
Indoor/Outdoor Equivalent Piping Length
Capacity of indoor unit
1. Cooling Calculation
(1) Temporary Selection of Indoor Units
Room1
MSZ-FH15
Room2
MSZ-FH18
(2) Total Indoor Units Capacity
15 + 18 = 33
(3) Selection of Outdoor Unit
The P36 outdoor unit is selected as total indoor units capacity is P33
MXZ-4C36
(4) Total Indoor Units Capacity Correction Calculation
Room1
Indoor Design Wet Bulb Temperature Correction (68.0ºF)
Room2
Indoor Design Wet Bulb Temperature Correction (66.2ºF)
CT
(5) Outdoor Unit Correction Calculation
Outdoor Design Dry Bulb Temperature Correction (98.6ºF)
Piping Length Correction (250 ft)
CTo =
(6) Determination of Maximum System Capacity
CTi = 31.6 < CTo = 32.8, thus, select CTi.
CTx = CTi
(7) Comparison with Essential Load
Against the essential load 29.6 kBTU/h, the maximum system capacity is 31.6 kBTU/h: Proper outdoor units have been selected.
(8) Calculation of Maximum Indoor Unit Capacity of Each Room
CTx = CTi, thus, calculate by the calculation below
Room1
Indoor nit Rating Indoor Design Temperature Correction
Room2
Indoor nit Rating Indoor Design Temperature Correction
Go on to the heating trial calculation since the selected units fulfill the cooling loads of Room 1, 2.
OCH573E
Design Condition
98.6ºF (37.0ºC)
29.6 kBTU/h
80.6ºF (27.0ºC)
68.0ºF (20.0ºC)
13.6 kBTU/h
75.2ºF (24.0ºC)
66.2ºF (19.0ºC)
16.0 kBTU/h
OK: fulfills the load 13.6 kBTU/h
OK: fulfills the load 16.0 kBTU/h
250 ft
1.2
1.0
0.8
15.0 kBTU/h (Rated)
0.6
17.2 kBTU/h (Rated)
0.4
59 60.8
15 16
Figure 1 Indoor unit temperature correction
To be used to correct indoor unit only
1.4
1.3
1.2
36.0 kBTU/h
1.1
1.0
0.9
0.8
0.6
1.02 (Refer to Figure 1)
0.5
23
5 14
-15 -10 -5
Figure 2 Outdoor unit temperature correction
0.95 (Refer to Figure 1)
To be used to correct outdoor unit only
1.00
0.95
0.90
0.98 (Refer to Figure 2)
0.93 (Refer to Figure 3)
0.85
0.80
0 20 40
Figure 3 Correction of refrigerant piping length
62.6 64.4 66.2 68 69.8 [°F W.B.]
18 19 20 21 22 23 24 [°C W.B.]
Indoor Temperature
Indoor
Temperature
(19.4°C) W.B
32 41 50 59 68 86 95 104 113 [°F W.B.]
[°C D.B.]
0 5 10 15 20 25 30 35 40 45
Outdoor Temperature
Total capacity of indoor unit
60 80 100 120 140 160 180 200 220 240 260
Piping equivalent length (ft)