Engineering Manual

B-117
<Cooling>
Design Condition
Outdoor Design Dry Bulb Temperature 98.6ºF (37.0ºC)
Total Cooling Load 29.6 kBTU/h
Room1
Indoor Design Dry Bulb Temperature 80.6ºF (27.0ºC)
Indoor Design Wet Bulb Temperature 68.0ºF (20.0ºC)
Cooling Load 13.6 kBTU/h
Room2
Indoor Design Dry Bulb Temperature 75.2ºF (24.0ºC)
Indoor Design Wet Bulb Temperature 66.2ºF (19.0ºC)
Cooling Load 16.0 kBTU/h
<Other>
Indoor/Outdoor Equivalent Piping Length 250 ft
1. Cooling Calculation
(1) Temporary Selection of Indoor Units
Room1
MSZ-FH15
15.0 kBTU/h (Rated)
Room2
MSZ-FH18
17.2 kBTU/h (Rated)
(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
36.0 kBTU/h
(4) Total Indoor Units Capacity Correction Calculation
Room1
Indoor Design Wet Bulb Temperature Correction (68.0ºF)
1.02 (Refer to Figure 1)
Figure 1 Indoor unit temperature correction
To be used to correct indoor unit only
Figure 2 Outdoor unit temperature correction
To be used to correct outdoor unit only
Figure 3 Correction of refrigerant piping length
Room2
Indoor Design Wet Bulb Temperature Correction (66.2ºF)
0.95 (Refer to Figure 1)
CTi = Σ (Indoor Unit Rating × Indoor Design Temperature Correction)
= 15.0 × 1.02 + 17.2 × 0.95
= 31.6 kBTU/h
(5) Outdoor Unit Correction Calculation
Outdoor Design Dry Bulb Temperature Correction (98.6ºF)
0.98 (Refer to Figure 2)
Piping Length Correction (250 ft)
0.93 (Refer to Figure 3)
Total Outdoor Unit Capacity (CTo)
Total Indoor Units Capacity (CTi)
CTo = Outdoor Rating × Outdoor Design Temperature Correction × Piping Length Correction
= 36.0 × 0.98 × 0.93
= 32.8 kBTU/h
(6) Determination of Maximum System Capacity
Comparison of Capacity between Total Indoor Units Capacity (CTi) and Total Outdoor Unit Capacity (CTo)
CTi = 31.6 < CTo = 32.8, thus, select CTi.
CTx = CTi = 31.6 kBTU/h
(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 Unit Rating × Indoor Design Temperature Correction
= 15.0 × 1.02
= 15.3 kBTU/h
OK: fulfills the load 13.6 kBTU/h
Room2
Indoor Unit Rating × Indoor Design Temperature Correction
= 17.2 × 0.95
= 16.3 kBTU/h OK: fulfills the load 16.0 kBTU/h
Go on to the heating trial calculation since the selected units fulfill the cooling loads of Room 1, 2.
Indoor
Temperature
Ratio of cooling capacity
Indoor Temperature
[°F W.B.]
[°C W.B.]
-15 -10
-5 0 5 10 15 20 25 30 35 40 45
5 14
23 32 41 50 59 68 77 86 95 104 113
0.5
0.6
0.7
0.8
0.9
1.0
1.1
1.2
1.3
1.4
Ratio of cooling capacity
Outdoor Temperature
[°C D.B.]
[°F W.B.]
67.0°F (19.4°C) W.B
15 16 17 18 19 20 21 22 23 24
59 60.8 62.6 64.4 66.2 68 69.8 71.6 73.4 75.2
0.4
0.6
0.8
1.0
1.2
0 20 40 60 80 100 120 140 160 180 200 220 240 260
0.70
0.75
0.80
0.85
0.90
0.95
1.00
18 [kBTU/h]
27 [kBTU/h]
36 [kBTU/h]
Capacity ratio
Piping equivalent length (ft)
Total capacity of indoor unit
46.8 [kBTU/h]
Capacity of indoor unit
Model Number for indoor
unit
Model
06
Model
09
Model
12
Model
15
Model
18
Model
24
Model
30
Model
36
M series Model Capacity [KBtu/h]
6.0 9.0 12.0
14.0*
1
15.0*
2
17.0*
3
17.2*
4
22.5 ─ ─
P series ─ ─ 12.0 ─ 18.0 24.0 30.0 36.0
SEZ ─ 8.1 11.5 14.1 17.2 ─ ─ ─
SLZ ─ 8.4 11.1 15.0 ─ ─ ─ ─
MVZ ─ ─ 12.0 ─ 18.0 24.0 30.0 36.0
*
1
For MSZ-GE/GL15NA
*
2
For the models other than *
1
above
*
3
For MFZ-KA/KJ18NA
*
4
For the models other than *
3
above