Mitsubishi Electric MXZ-4C36NAHZ Technical & Service Manual page 17

<Heating>
Outdoor Design Wet Bulb Temperature
Total Heating Load
Room1
Indoor Design Dry Bulb Temperature
Heating Load
Room2
Indoor Design Dry Bulb Temperature
Heating Load
<Other> Indoor/Outdoor Equivalent Piping Length
Capacity of indoor unit
2. Heating 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 Dry Bulb Temperature Correction (69.8ºF)
Room2
Indoor Design Dry Bulb Temperature Correction (73.4ºF)
CT
(5) Outdoor Unit Correction Calculation
Outdoor Design Wet Bulb Temperature Correction (35.6ºF)
Piping Length Correction (230 ft)
Defrost Correction
CTo = Outdoor nit Rating
Correction Defrost Correction
(6) Determination of Maximum System Capacity
CTi = 36.7 < CTo = 38.4, thus, select CTi.
(7) Comparison with Essential Load
Against the essential load 34.4 kBTU/h, the maximum system capacity is 36.7 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
Room2
=
=
Completed selecting units since the selected units fulfill the heating loads of Room 1, 2.
OCH573E
Design Condition
Outdoor Design Temperature Correction
+
OK: fulfills the load 16.3 kBTU/h
+
OK: fulfills the load 18.1 kBTU/h
35.6ºF (2.0ºC)
34.4 kBTU/h
69.8ºF (21.0ºC)
16.3 kBTU/h
73.4ºF (23.0ºC)
18.1 kBTU/h
230 ft
1.3
1.2
1.1
1.0
18.0 kBUT/h (Rated)
0.9
0.8
20.3 kBUT/h (Rated)
0.7
0.6
59 60.8 62.6 64.4 66.2
15 16
Figure 4 Indoor unit temperature correction
1.1
1.4
45.0 kBUT/h 1.0
1.3
1.2
0.8
1.1
0.7
1.0
0.6
0.9
0.5
0.8
0.7
1.00 (Refer to Figure 4)
0.6
0.5
0.4
-25
0.92 (Refer to Figure 4)
Figure 5 Outdoor unit temperature correction
1.00
0.95
1.0 (Refer to Figure 5)
0.90
0.96 (Refer to Figure 6)
0.85
0.89 (Refer to Table 1)
0.80
0.75
Piping Length
0.70
0 20
Figure 6 Correction of refrigerant piping length
68 69.8 71.6 73.4 75.2 77 78.8 80.6
17 18 19 20 21 22 23 24 25 26 27
Indoor Temperature
To be used to correct indoor unit only
-4 5 14 23 32 41 50
-20 -15 -10 -5 0 5 10
Outdoor Temperature [°C W.B.]
To be used to correct outdoor unit only
Total capacity of indoor unit
40 60 80 100 120 140 160 180 200 220 240
Piping equivalent length (ft)
[°F W.B.]
[°C D.B.]
Indoor
Temperature
70.0°F (21.1°C) D.B
[°F W.B.]
59
[°C D.B.]
15
260