28 Chapter 2 Mechanical Installation
pipe extension kit onto the outside project pipe of the ball valve on the liquid pipe. The outer side or the bottom of the
unit is allowable.
So, during installing the solenoid valve, you do not need to cut the indoor unit pipes. After the whole system is installed,
you can open the ball valve to keep pressure and carry out the vacuum operation, avoiding the moisture absorption of
the compressor refrigeration oil and ensuring the operation safety and life of the compressor. For the installation
position of the check valve, refer to Figure 2-6.
For the electrical connections of the pipe extension kit, refer to
3.2.4 Connecting Solenoid Valve Of Pipe Extension
Charging refrigerant and adding refrigerant oil
1. Charging refrigerant
The Liebert.PEX air-cooled series air conditioner has been charged in the factory with 2bar nitrogen.
If the connection pipe between the indoor unit and the outdoor unit is longer than 10m, refill the refrigerant to the
system to ensure normal system operation.
The refilling amount of the refrigerant is calculated through the following formula:
Refrigerant refilling amount (kg) = refrigerant refilling amount per unit length of liquid pipe (kg/m) × total length of
extended liquid pipe (m)
See Table 2-8 for refrigerant refilling amount of per meter liquid pipe.
Total length of extended liquid pipe (m) = Total length of liquid pipe (m) - 10m
Table 2-8 Refrigerant refilling amount per unit length of liquid pipe with different ODs
Liquid pipe OD
(mm)
Refrigerant refilling amount of per meter
liquid pipe (kg/m)
Liquid pipe OD (mm)
Refrigerant refilling amount of per
meter liquid pipe (kg/m)
9.52 0.060
19 0.261
12.7 0.112
22 0.362
16 0.181
28.6 0.618
For the refrigerant charge quantity, refer to step 5 in
4.2.2 Commissioning Procedures
2. Adding POE refrigerant oil
The refilled refrigerant will dilute the POE refrigerant oil in the system and affect the lubricating and cooling effects of
the POE refrigerant oil. Therefore, the POE refrigerant oil should be added. See the formula below:
Amount of refrigerant oil (ml) to be added = refrigerant refilling amount (kg) × 22.6
2.6.2 Piping For Water-Cooled Unit
Each cooling system uses a BPHE (or condenser) and an electric valve. The water supply (inlet) pipe and water return
(outlet) pipe of the cooling water should be connected for the system. See Figure 2-29.
A filter (filter mesh: 1mm) and multiple isolation valves should be mounted one side of the water supply pipe of the
cooling water. One of the valves can be a balancing valve.
The cooling water system with a balancing valve can control the water distribution more accurately and its pump has
higher efficiency. On the other hand, the electric valve can keep the optimal condensing temperature by regulating the
internal water flow.
The electric actuator of the regulating valve features a manual override to allow water side balancing by the installer.
It is recommended to arrange the cooling water pipes separately for different systems, so that repairing one pipe will
not affect the operation of the other one.
The water pressure should be high enough to counteract the pressure drops brought about by all the components of
the water system. In addition, because the sediments and impurities cause more pressure drop after long term
operation, you should arrange a redundancy of 20% ~ 25% when selecting the lifting part (such as pump).
See Figure 2-6 and Figure 2-7 for the system arrangement of the water-cooled unit.
Connecting pipes
The pipes to be connected include:
1. Condensate drain pipe of indoor unit
2. Water inlet pipe of infrared humidifier
3. Water inlet and outlet pipe of cooling water
Liebert.PEX2 Series Air Conditioner User Manual
Summary of Contents for Liebert PEX Series
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