Design and Technical Manual

2. MODEL SELECTION
EXAMPLE 2

(When the connecting capacity for indoor unit is 100% or less)
Branch
box
Branch
box
Outdoor unit
Indoor unit 1 Indoor unit 2 Indoor unit 3 Indoor unit 4
Room 1 Room 2 Room 3 Room 4
Main Piping length, L1=32.8ft. (10m) Branch Piping length, L2=32.8ft. (10m)
Design conditions
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Design temperature

●
Indoor : 75°F DB / 63°F WB (23.9°C DB / 17.2°C WB)
Outdoor : 86°F DB (30°C DB)
Pipe length
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●
Main piping length : L1=32.8ft. (10m)
Branch piping length : L2=32.8ft. (10m)
Operation mode: Cooling
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●
Selection of indoor unit
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Room 1 Room 2 Room 3 Room 4
Remark
A-1 Cooling heat load Btu 8000 8000 11000 11000
A-2 Indoor unit models ASU9 ASU9 ASU12 ASU12
A-3 Rated capacity (TC
in
)
r
Btu 9000 9000 12000 12000
See 2-2.
A-4 Total rated capacity ∑(TC
in
)
r
Btu 9000 x 2 + 12000 x 2 = 42000
Sum of A-3
A-5
Connecting indoor unit
capacity (Cp)
42000 / 48000 = 87.5%
(80%≤Cp≤130%)
A-6
Capacity at design
temperature (TC
in
)
d
Btu 8420 8420 11200 11200
See 6-1.
A-7
Total capacity at design
temperature ∑(TC
in
)
d
Btu 8420 x 2 + 11200 x 2 = 39240
Sum of A-6
Calculate the Maximum capacity of outdoor unit
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Remark
B-1 Outdoor unit model AOU48RLXFZ1
B-2 Rated capacity (TC
out
)
r
Btu 48000
See 2-1.
B-3 Capacity change rate by temperature conditions 47.4 / 48.0 = 0.988
See Fig.1
B-4 Capacity change rate by indoor units connecting capacity Btu 48000 *1
B-5 Compensation coefcient of pipe length 0.98 x 0.942 = 0.923
See 5-1.
B-6 Maximum capacity of outdoor unit (TC
out
)
c
Btu 48000 x 0.988 x 0.923 = 43770
(B-4) x (B-3) x (B-5)
*1: When indoor units connecting capacity is 100% or less, rated capacity is used.
Decide system capacity
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Remark
C-1 System capacity Btu 39240
Smaller one of (A-7)
and (B-6)
Calculate actual capacity of each indoor unit
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Room 1 Room 2 Room 3 Room 4
Remark
Actual capacity of each indoor
unit
Btu 8410 8 410 11210 11210
(A-3) x (C-1) / (A-4)
Actual capacity of all indoor units is larger than cooling heat load of each room.
- (02 - 06) -
MODEL SELECTION MODEL SELECTION