Installation guide

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Design & installation Guide For McQuay MDS Multi System
3.3.7 Actual Capacity Calculation
Based on the model and combination rate of the outdoor unit, select an appropriate door unit
capacity table. Then find out the capacity of the outdoor unit (kW) and that of each indoor unit
(kW) according to the related temperatures of the indoor and outdoor units.The formula is as
follows:
I
UC
=O
UC
x (I
NX
/T
NX
)
Where,
I
UC
is the actual capacity of each indoor unit.
O
UC
is the capacity of the outdoor unit. unit: kW.
I
NX
is the capacity index of each indoor unit.
T
NX
is the total capacity index.
The capacity of indoor units changes with the length of the refrigerant pipe. If the capacity after
change is less than the load, replace the unit with one with larger capacity and calculate
and select the model again.
3.3.8 Change of Cooling Capacity (3-30HP)
50
40
30
20
10
H
ig
h
-lo
w
fa
lls
(m
)
0
-10
-20
-30
-40
0 10 20 30 40 50 60 70
94.0%97.5%100%
100%
98.5%
94.0%
95.5%
97.0%
92.5% 91.0%  89.5% 88.0% 86.5%
79.0%88.0%91.0%
9080 100
85.0%
110
83.5%
85.0%
120
82.0%
130
80.5%
82.0%
140
79.0%
150
Pipe length (m)
Read the performance correction factor of the refrigerant pipe length and height drop from the
figure. When the height drop is negative, the outdoor unit is installed below the indoor unit.
If there is snow on the heat exchanger or the outdoor temperature drops to 7
-
5
when the
air conditioning system is heating, frosting occurs. As this will reduce the heating performance,
the air conditioner will automatically defrost once every 40 min to 70 min. During the defrosting,
the air conditioner will stop heating and the fan of the indoor unit will also stop for three to
ten minutes.
The heating capacity tables of outdoor and indoor units do not reflect the reduction of performance
caused by defrosting.
3.3.9 Change of Heating Capacity (3-30HP)
H
ig
h
-lo
w
fa
lls
(m
)
50
40
30
20
10
0
-10
-20
-30
-40
010 20 30 40 50 60 70 9080 100
Pipe length (m)
100%
99.0%
98.0%
97.0%
96.0%
100%
98.0% 96.0% 94.0% 92.0%
95.0% 94.0%
93.0% 92.0% 90.0%
110
86.0%
89.0%
120
90.0%
88.0%
130
87.0%
140
88.0%
86.0%
150
85.0%