Mitsubishi Electric SMART MULTI MXZ-SM36NAM2-U1 Data Book page 22

7. CAPACITY TABLES
2. Heating Calculation
(1) Temporary Selection of Indoor Units
Room1
PEFY-P15
Room2
PEFY-P18
(2) Total Indoor Units Capacity
P15 + P18 = P33
(3) Selection of Outdoor Unit
The P36 outdoor unit is selected as total indoor units capacity is P33
MXZ-SM36NAM2
(4) Total Indoor Units Capacity Correction Calculation
Room1
Indoor Design Dry Bulb Temperature Correction (69.8ºF)
Room2
Indoor Design Dry Bulb Temperature Correction (73.4ºF)
CT
= 35.4 kBtu/h
(5) Outdoor Unit Correction Calculation
Outdoor Design Wet Bulb Temperature Correction (35.6ºF)
Piping Length Correction (328 ft)
Defrost Correction
Total Outdoor Unit Capacity (CTo)
CTo = Outdoor Unit Rating × G(CTi)
× Piping Length Correction × Defrost Correction
= 41.0 × 1.0 × 0.94 × 0.89
= 34.3 kBtu/h
*1 G(CTi) is used only when greater than 100% indoor model size are connected in total,
refer to "7-3. Correction by total indoor".
Table 1 Table of correction factor at frost and defrost
Outdoor Intake temperature <W.B.°F (°C)>
Correction factor
(6) Determination of Maximum System Capacity
Comparison of Capacity between Total Indoor Units Capacity (CTi) and Total Outdoor Unit Capacity (CTo)
CTi = 35.4 > CTo = 34.3, thus, select CTo.
CTx = CTo = 34.3 kBtu/h
(7) Comparison with Essential Load
Against the essential load 34.0 kBtu/h, the maximum system capacity is 34.3 kBtu/h: Proper outdoor units have been selected.
(8) Calculation of Maximum Indoor Unit Capacity of Each Room
CTx = CTo, thus, calculate by the calculation below
Room1
Maximum Capacity × Room1 Capacity after the Temperature Correction/(Room1,2 Total Capacity after the Temperature Correction
= 34.3 × (17.0 × 1.00) / (17.0 × 1.00 + 20.0 × 0.92)
= 16.5 kBtu/h
Room2
Maximum Capacity × Room1 Capacity after the Temperature Correction/(Room1,2 Total Capacity after the Temperature Correction
= 34.3 × (20.0 × 0.92) / (17.0 × 1.00 + 20.0 × 0.92)
= 17.8 kBtu/h
Completed selecting units since the selected units fulfill the heating loads of Room 1, 2.
M-P0890
17.0 kBtu/h (Rated)
20.0 kBtu/h (Rated)
41.0 kBtu/h
*1
× Outdoor Design Temperature Correction
43(6) 37(4) 36(2) 32(0)
1.00 0.98 0.89 0.88 0.89
OK: fulfills the load 16.3 kBtu/h
OK: fulfills the load 17.7 kBtu/h
1.3
1.2
1.1
1.0
0.9
0.8
0.7
0.6
59 60.8 62.6 64.4 66.2
15 16
Figure 4 Indoor unit temperature correction
To be used to correct indoor unit only
1.4
1.3
1.2
1.1
1.0
1.00 (Refer to Figure 4)
0.9
0.8
0.7
0.6
0.92 (Refer to Figure 4)
0.5
0.4
-13
-25
Figure 5 Outdoor unit temperature correction
To be used to correct outdoor unit only
1.00
1.0 (Refer to Figure 5)
0.94 (Refer to Figure 6) 0.95
0.89 (Refer to Table 1)
0.90
0.85
0.80
0.75
0.70
0 50
Figure 6 Correction of refrigerant piping length
0.90 0.95 0.95 0.95
SMART MULTI
68 69.8 71.6 73.4 75.2 77 78.8 80.6 [°F D.B.]
17 18 19 20 21 22 23 24 25 26 27 [°C D.B.]
Indoor Temperature
21.1°C (70.0°F) D.B.
-4 5 14 23 32 41 50 59
15
-20 -15 -10 -5 0 5 10
Outdoor Temperature
Total capacity of indoor unit
100 150 200 250 300 350 400 450 500 550 600
Piping equivalent length (ft)
0.95 0.95 0.95
Indoor
Temperature
[°F W.B.]
[°C W.B.]
20