Mitsubishi Electric CITY MULTI PUMY-P112VKM5 Technical & Service Manual page 12

<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
P•FY Series Model Number
for indoor unit
Model
Capacity
M Series Model Number
S Series for indoor unit
P Series
Model
Capacity
2. Heating Calculation
(1) Temporary Selection of Indoor Units
Room1
PEFY-P50
Room2
PEFY-P71
(2) Total Indoor Units Capacity
P50 + P71 = P121
(3) Selection of Outdoor Unit
The P125 outdoor unit is selected as total indoor units capacity is P121
PUMY-P125
(4) Total Indoor Units Capacity Correction Calculation
Room1
Indoor Design Dry Bulb Temperature Correction (23ºC) 0.88 (Refer to Figure 4)
Room2
Indoor Design Dry Bulb Temperature Correction (23ºC)
Total Indoor Units Capacity (CTi)
CTi = Σ (Indoor Unit Rating × Indoor Design Temperature Correction)
= 6.3 × 0.88 + 9.0 × 0.88
= 13.5 kW
(5) Outdoor Unit Correction Calculation
Outdoor Design Wet Bulb Temperature Correction (2ºC)
Piping Length Correction (60 m)
Defrost Correction
Total Outdoor Unit Capacity (CTo)
CTo = Outdoor Unit Rating × Outdoor Design Temperature Correction × Piping Length
Correction × Defrost Correction
= 16.0 × 1.00 + 0.96 × 0.89
= 13.7 kW
(6) Determination of Maximum System Capacity
Comparison of Capacity between Total Indoor Units Capacity (CTi) and Total Outdoor Unit Capacity (CTo)
CTi = 13.5 < CTo = 13.7, thus, select CTi.
CTx = CTi = 13.5 kW
(7) Comparison with Essential Load
Against the essential load 13.2 kW, the maximum system capacity is 13.5 kW: Proper indoor units have been selected.
(8) Calculation of Maximum Indoor Unit Capacity of Each Room
CTx = CTo, thus, calculate by the calculation below
Room1
Indoor Unit Rating × Indoor Design Temperature Correction
= 6.3 × 0.88
= 5.5 kW
Room2
Indoor Unit Rating × Indoor Design Temperature Correction
= 9.0 × 0.88
= 7.9 kW
Note: If CTx = CTo, please refer to the <Cooling> section to calculate the Maximum Indoor Unit Capacity of Each Room.
Completed selecting units since the selected units fulfill the heating loads of Room 1, 2.
OCH740
Design Condition
Model 10 Model 15 Model 20 Model 25 Model 32 Model 40 Model 50 Model 63 Model 71 Model 80 Model 100 Model 125 Model 140
1.4 1.9 2.5 3.2
Model 15 Model 18 Model 20 Model 22 Model 25 Model 35 Model 42 Model 50 Model 60 Model 71 Model 80 Model 100
1.7 2.1 2.3 2.5
6.3 kW (Rated)
9.0 kW (Rated)
16.0 kW
OK: fulfills the load 5.4 kW
OK: fulfills the load 7.8 kW
2ºC
13.2 kW
23ºC
5.4 kW
23ºC
7.8 kW
60 m
4.0 5.0 6.3 8.0
2.9 4.0 4.8 5.7
0.88 (Refer to Figure 4)
1.00 (Refer to Figure 5)
0.96 (Refer to Figure 6)
0.89 (Refer to Table 1)
Table 1 Table of correction factor at frost and defrost
Outdoor inlet air temp. (°C W.B.) 6
PUMY-P112,125,140VKM5
12
9.0 10.0 12.5 16.0
6.9 8.1 9.3 11.2
1.2
1.1
1.0
0.9
0.8
0.7
0.6
15 16 17 18 19 20 21 22 23
Indoor Temperature [°CD.B.]
Figure 4 Indoor unit temperature correction
To be used to correct indoor unit only
1.2
1.1
1.0
0.9
0.8
0.7
0.6
0.5
−20 −15 −10 −5 0 5
Outdoor Temperature [°C W.B.]
Figure 5 Outdoor unit temperature correction
To be used to correct outdoor unit only
1
0.95
0.90
0.85
0.80
0.75
0.70
0.65
0 20 40 60 80 100 120 140
Piping equivalent length (m)
Figure 6 Correction of refrigerant piping length
4 2 0 -2 -4 -6 -8 -10 -15 -20
1.00 0.98 0.89 0.88 0.89 0.90 0.95 0.95 0.95 0.95 0.95
Unit: kW
18.0
24 25 26 27
20°C D.B
10 15
160 180 200