Engineering Manual

B-118
<Heating>
Design Condition
Outdoor Design Wet Bulb Temperature 35.6ºF (2.0ºC)
Total Heating Load 34.4 kBTU/h
Room1
Indoor Design Dry Bulb Temperature 69.8ºF (21.0ºC)
Heating Load
16.3 kBTU/h
Room2
Indoor Design Dry Bulb Temperature 73.4ºF (23.0ºC)
Heating Load
18.1 kBTU/h
<Other>
Indoor/Outdoor Equivalent Piping Length 230 ft
2. Heating Calculation
(1) Temporary Selection of Indoor Units
Room1
MSZ-FH15 18.0 kBUT/h (Rated)
20.3 kBUT/h (Rated)
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 45.0 kBUT/h
(4) Total Indoor Units Capacity Correction Calculation
Room1
Indoor Design Dry Bulb Temperature Correction (69.8ºF)
1.00 (Refer to Figure 4)
Room2
Indoor Design Dry Bulb Temperature Correction (73.4ºF)
0.92 (Refer to Figure 4)
CTi = Σ (Indoor Unit Rating × Indoor Design Temperature Correction)
= 18.0 × 1.00 + 20.3 × 0.92
= 36.7 kBTU/h
(5) Outdoor Unit Correction Calculation
Outdoor Design Wet Bulb Temperature Correction (35.6ºF)
1.0 (Refer to Figure 5)
Piping Length Correction (230 ft)
Defrost Correction
0.96 (Refer to Figure 6)
0.89 (Refer to Table 1)
Total Outdoor Unit Capacity (CTo)
Total Indoor Units Capacity (CTi)
CTo = Outdoor Unit Rating × Outdoor Design Temperature Correction × Piping Length
Correction × Defrost Correction
= 45.0 × 1.0 × 0.96 × 0.89
= 38.4 kBTU/h
(6) Determination of Maximum System Capacity
Comparison of Capacity between Total Indoor Units Capacity (CTi) and Total Outdoor Unit Capacity (CTo)
CTi = 36.7 < CTo = 38.4, thus, select CTi.
CTx = CTi = 36.7 kBTU/h
(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
Maximum Capacity × Room1 Capacity after the Temperature Correction/(Room1,2 Total Capacity after the Temperature Correction
= 36.7 × (18.0 × 1.00) / (18.0 × 1.00 + 20.3 × 0.92)
= 18.0 kBTU/h OK: fulfills the load 16.3 kBTU/h
Room2
Maximum Capacity × Room1 Capacity after the Temperature Correction/(Room1,2 Total Capacity after the Temperature Correction
= 36.7 × (20.3 × 0.92) / (18.0 × 1.00 + 20.3 × 0.92)
= 18.7 kBTU/h OK: fulfills the load 18.1 kBTU/h
Completed selecting units since the selected units fulfill the heating loads of Room 1, 2.
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
-4 5 14 23 32 41 50 59
-25
-20 -15 -10 -5 0 5 10 15
0.4
0.5
0.6
0.7
0.8
0.9
0.8
0.5
0.6
0.7
1.0
1.1
1.2
1.0
1.1
1.3
1.4
Ratio of heating capacity
Outdoor Temperature [°C W.B.]
70.0°F (21.1°C) D.B
15 16 17 18 19 20 21 22 23 24 25 26 27
59 60.8 62.6 64.4 66.2 68 69.8 71.6 73.4 75.2 77 78.8 80.6
0.6
0.7
0.8
0.9
1.0
1.1
1.2
1.3
Ratio of heating capacity
Indoor Temperature
[°C D.B.]
[°F W.B.]
[°C D.B.]
[°F W.B.]
Indoor
Temperature
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
Total capacity of indoor unit
Capacity ratio
Piping equivalent length (ft)
Table 1 Table of correction factor at frost and defrost
Outdoor Intake temperature <W.B.°F (°C)> 43(6) 37(4) 36(2) 32(0) 28(−2) 25(−4) 21(−6) 18(−8) 14(−10) 5(−15) −4(−20) −13(−25)
Correction factor 1.0 0.98 0.89 0.88 0.89 0.9 0.95 0.95 0.95 0.95 0.95 0.95
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 10.9
13.6*
1
14.4*
2
13.0*
3
18
20.3*
1
21.6*
2
21.0*
3
27.6 ─ ─
P series ─ ─ 13.5 ─ 18.0 26.0 34.0 40.0
SEZ ─ 10.9 13.6 18.0 17.2 ─ ─ ─
SLZ ─ 10.2 13.7 17.1 ─ ─ ─ ─
MVZ ─ ─ 12.0 ─ 18.0 27.0 34.0 40.0
*
1
For MSZ-FH/FE12,18NA
*
2
For MSZ-GE/GL12,18NA
*
3
For the models other than *
1
and *
2
above