16 Chapter 2 Mechanical Installation
DM Series 16kW Air Conditioner User Manual
Connecting copper pipe (exhaust pipe and liquid return pipe) between indoor unit and outdoor unit
The indoor unit and outdoor unit are connected through welded copper pipes. The connection of discharge pipe / liquid
pipe of indoor unit is shown in Figure 2-21. Note that the ball valve must be wrapped with a wet cloth before welding. In
addition, many notes and instruction labels are pasted onto the base board and side board close to the ball valve. Do
not have them burned during the welding operation.
Note
The exposure time of system pipes do not exceed 15min. Otherwise, it will lead to the POE refrigeration oil moisture effect the
life of the key components and the system operation stability.
Horizontal sections of discharge pipes should be sloped downward from the compressor, with a slope of at least 1:200
(5mm down for each 1m run). Discharge pipes should be heat insulated where they are routed in the conditioned
space (including under a raised floor).
The liquid pressure drop should not exceed 40kPa (5psi ~6psi), provided that there is no loss of refrigeration. The
liquid line pressure drop is the sum of liquid flow resistance from the tubing and fitting (including the drier), plus the
loss of head pressure due to elevation above the condenser. If the liquid temperature is 38
℃
, the static pressure loss
is 11kPa (1.6 psi) per meter of lift.
Ball valve(liquid line)
Ball valve(discherge line)
Figure 2-21 Connection of discharge pipe / liquid return pipe
Considering the effect of the pipe OD to the system pressure drop, the pipe OD of indoor unit and outdoor unit should
be determined according to the specifications listed Table 2-7.
Table 2-7 Recommended pipe sizes
Eq.Lgth
D
L
10m
22
13
20m
22
13
30m
22
13
40m*
22
13
50m*
22
13
60m*
22
16
Note
1. Extension subassembly should be added to the “Eq.Lgth” marked with *.
2. D: discharge line, L: liquid line.
3. Consult factory if the line length exceeds 60m.
Installing the extension subassembly (be applicable to site installation)
When the equivalent length of pipe exceeds 30m, the extension subassembly should be installed. It is recommended
to install the solenoid valve of the extension subassembly to the outside project pipe of the ball valve on the liquid pipe,
or the outer side (or on the bottom) of the unit.
So, during installing the solenoid valve, you need not to cut the indoor unit pipes. After the whole system is installed,
you can open the ball valve to keep pressure and carry out vacuum operation, avoiding the moisture absorption of the
compressor refrigeration oil and ensuring the operation safety and life of the compressor. For installation valve of the
check valve, refer to Figure 2-6.
