36 Chapter 7 Start-Up
Liebert.CRV Series Air Conditioner User Manual
Ensure that the temperature and relative humidity are being controlled, and that the humidifier and heating steps
operate when required.
Ensure that the compressor operates when required.
Ensure that the fan operation controller on the external condenser/Dry cooler (if fitted) is calibrated correctly, and
that it controls the fan operation.
7.2 Automatic Restart
If desired, the unit will automatically restart on the return of power after a supply interruption. If the power interruption
is expected to be of several hours, to avoid an automatic cold restart of the compressor stop the unit before the
black-out and, on the return of power, allow the compressor to preheat before restarting the unit.
7.3 Checking The Refrigeration Piping Pressure Drops
Liebert.CRV is equipped with connections to check the refrigeration piping pressure drops: room unit
→
condenser
→
room unit.
To carry out this operation it is necessary to use two calibrated manometers and connect them as follows:
M1 is connected to the compressor delivery valve; M2 is connected to the Schrader valve (2) in Figure 7-1.
1
2
3
4
5
6
1. Liquid receiver valve
2. Filter dryer inlet Schrader valve
3. Filter dryer
4. Sight glass
5. Solenoid valve
6. Thermostatic expansion valve
Figure 7-1 Components of refrigeration pipeline
When the compressor is running, you should check M1 and M2.
Note: Repeat this test, inverting the manometers to calculate the correct pressure drops, consider the average value
of the two readings.
At 45°C, the refrigeration pipeline pressure drops (Dp bar) are as follows:
At the same geodetic level: Dp (bar) = M1 - M2
When condenser is above the room unit: Dp (bar) = M1 - M2 + geodetic difference (m x 1.1:10.2)
When condenser is below the room unit: Dp (bar) = M1 - M2 - geodetic difference (m x 1.1:10.2)
7.4 Chilled Water Valve Of Chilled Water (C) Units
The three-way valve controls the chilled water flow and operates as follows (Figure 7-2):
When the valve is fully open (i.e. max. chilled water flow), the actuator slot is set to ‘1’.
When the valve is closed (i.e. no chilled water flow), the actuator slot is set to ‘0’.
