OCH790 _15
5-1-2. Heating
Design condition
Outdoor wet bulb temperature
2°C
Total heating load
13.2 kW
Room 1
Indoor dry bulb temperature
23°C
Heating load
5.4 kW
Room 2
Indoor dry bulb temperature
23°C
Heating load
7.8 kW
Other
Indoor/Outdoor piping equivalent length
60 m
Capacity of indoor unit
P·FY series Model class of indoor unit 10
15
—
20
—
25
32
—
40
—
50
—
63
71
80
100 125 140
Model Capacity (kW)
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
M series
S series
P series
Model class of indoor unit
—
15
18
20
22
25
—
35
—
42
50
60
—
71
80
100
—
—
Model Capacity (kW)
—
1.7
2.1
2.3
2.5
2.9
—
4.0
—
4.8
5.7
6.9
—
8.1
9.3
11.2
—
—
■
Heating calculation
• Tentative selection of indoor units
Room1: PEFY-P50
6.3kW.(Rated)
Room2: PEFY-P71
9.0kW.(Rated)
In this case, the total capacity is 15.3. (6.3 + 9.0 = 15.3)
• Tentative selection of outdoor unit
Proper outdoor unit in this case is P125 as the total capacity of the indoor units is 15.3.
PUMY-P125
16.0 kW
•
Calculation for the corrected capacity of the total indoor units (CTi)
Correction factor for indoor temperature: Room 1 (23°C)
0.88 (Refer to Figure 3.)
Room 2 (23°C)
0.88 (Refer to Figure 3.)
CTi = Σ (Rated capacity of indoor unit × Correction factor for indoor temperature)
= 6.3 × 0.88 + 9.0 × 0.88
= 13.5 kW
•
Calculation for the corrected capacity of the outdoor unit (CTo)
Correction factor for outdoor temperature (2°C WB)
1.00 (Refer to Figure 4.)
Correction factor for piping length (60 m)
0.96 (Refer to "Correcting Capacity".)
Correction factor for defrosting
0.89 (Refer to Table 1.)
CTo = Rated capacity of outdoor unit × Correction factor for outdoor temperature × Correction factor for piping length ×
Correction factor for defrosting
= 16.0 × 1.00 × 0.96 × 0.89
= 13.7 kW
Table 1 Table of correction factor for frosting and defrosting
Outdoor inlet air temp. (°C)
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
•
Determination of maximum system capacity (CTx)
Comparison between CTi and CTo:
CTi = 13.5 < CTo = 13.7, thus, select CTi.
CTx = CTi = 13.5 kW
•
Comparison with essential load
Against the essential load 13.2 kW, the maximum system capacity is 13.5 kW: Proper indoor units have been select-
ed.
•
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 temperature
= 6.3 × 0.88
= 5.5 kW
The capacity is enough for the heating load of Room 1 (5.4 kW): A proper indoor unit is selected.
Room2: Rated capacity of indoor unit × Corrected capacity for the indoor design temperature
= 9.0 × 0.88
= 7.9 kW
The capacity is enough for the heating load of Room 2 (7.8 kW): A proper indoor unit is selected.
Note:
•
If CTx = CTo, refer to the calculation formula in "Cooling" to calculate the maximum indoor unit capacity of each
room.
•
The selection of units is completed when proper units are selected.
