12
OCH760
2. Heating Calculation
(1) Temporary Selection of Indoor Units
Room1, Room2
PEFY-P63
8.0 kW (Rated)
Room3, Room4
PEFY-P71
9.0 kW (Rated)
(2) Total Indoor Units Capacity
P63 + P63 + P71 + P71 = P268
(3) Selection of Outdoor Unit
The P300 outdoor unit is selected as total indoor units capacity is P268
PUMY-P300YBM
37.5 kW
(4) Total Indoor Units Capacity Correction Calculation
Room1, Room2
Indoor Design Dry Bulb Temperature Correction (24ºC)
0.84 (Refer to Figure 4)
Room3, Room4
Indoor Design Dry Bulb Temperature Correction (25ºC)
0.80 (Refer to Figure 4)
Total Indoor Units Capacity (CTi)
CTi = Σ (Indoor Unit Rating × Indoor Design Temperature Correction)
= 8.0×0.84 + 8.0×0.84 + 9.0×0.80 + 9.0×0.80
= 27.8 kW
(5) Outdoor Unit Correction Calculation
Outdoor Design Wet Bulb Temperature Correction (2ºC)
1.00 (Refer to Figure 5)
Piping Length Correction (30 m)
0.98 (Refer to Figure 6)
Defrost Correction
0.89 (Refer to Table 1)
Total Outdoor Unit Capacity (CTo))
CTo =
Outdoor Unit Rating × Outdoor Design Temperature Correction × Piping Length
Correction × Defrost Correction
= 37.5 × 1.00 × 0.98 × 0.89
= 32.7 kW
(6) Determination of Maximum System Capacity
Comparison of Capacity between Total Indoor Units Capacity (CTi) and Total Outdoor Unit Capacity (CTo)
CTi = 27.8 < CTo = 32.7, thus, select CTi.
CTx = CTi = 27.8 kW
(7) Comparison with Essential Load
Against the essential load 25.0kW, the maximum system capacity is 27.8 kW: 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, 2
Indoor Unit Rating × Indoor Design Temperature Correction
= 8.0 × 0.84
= 6.7 kW
OK: fulfills the load 6.0 kW
Room3, 4
Indoor Unit Rating × Indoor Design Temperature Correction
= 9.0 × 0.80
= 7.2 kW
OK: fulfills the load 6.5 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 to 4.
<Heating>
Design Condition
Outdoor Design Wet Bulb Temperature
Total Heating Load
Room1, Room2
Indoor Design Dry Bulb Temperature
Heating Load
Room3, Room4
Indoor Design Dry Bulb Temperature
Heating Load
<Other>
Indoor/Outdoor Equivalent Piping Length
2ºC
25.0 kW
24ºC
6.0 kW
25ºC
6.5 kW
30 m
Figure 4
Indoor unit temperature correction
To be used to correct indoor unit only
Figure 5
Outdoor unit temperature correction
To be used to correct outdoor unit only
Figure 6
Correction of refrigerant piping length
15
16
17
18
19
20
21
22
23
24
25
26
27
0.6
0.7
0.8
0.9
1.0
1.1
1.2
Ratio of heating capacity
Indoor Temperature [°C D.B.]
Ratio of heating capacity
Outdoor Temperature [°C W.B.]
-20
-15
-10
-5
0
5
10
15
0.5
0.6
0.7
0.8
0.9
1.0
1.1
1.2
20°C D.B.
Indoor temperature
Capacity ratio
Piping equivalent length (m)
0
20
40
60
80
100
120
140
160
180
0.65
0.70
0.75
0.80
0.85
0.90
0.95
1.00
Table 1 Table of correction factor at frost and defrost
Outdoor Intake
Temperature (°C W.B.)
6
4
2
0 -2
-4
-6
-8 -10 -15
-20
Correction factor
1.00 0.98 0.89 0.88 0.89
0.90 0.95 0.95 0.95 0.95 0.95
Capacity of indoor unit
Unit: kW
P•FY Series
Model Number for
indoor unit
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
Model
200
Model
250
Model
Capacity
1.4
1.9
2.5
3.2
4.0
5.0
6.3
8.0
9.0
10.0 12.5 16.0 18.0
25.0
31.5
M Series
Model Number for
indoor unit
Model
15
Model
18
Model
20
Model
22
Model
25
Model
35
Model
42
Model
50
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Model
Capacity
1.7
2.1
2.3
2.5
2.9
4.0
4.8
5.7
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