Vertiv | Liebert CRV CCD10 Condenser | User Manual
4
Overview
Figure 1-2 The liquid receiver
1.3.2
Head pressure valve
As shown in figure 1-4, the head pressure valve is a three way modulating valve that responds to discharge pressure,
connecting compressor discharge outlet, condenser outlet and receiver inlet separately. When the outdoor ambient
falls, the condensing pressure falls. This causes the discharge pressure to fall as well. When the discharge pressure falls
below the set value, B and C are partially opened as shown in figure 1-3. Which allows discharge gas to bypass the
condenser. Mixing the discharge gas with the liquid creates a high pressure at the condenser outlet, reducing the flow
and causing liquid to back up in the condenser. Flooding the condenser reduces the area available for condensing. This
reduction in effective condenser surface area results in a rise in condensing pressure. During summer conditions, the
discharge pressure is higher than set value thus closing the discharge port (CD). Hence, there is full liquid flow from the
condenser to the receiver (BD).
Figure 1-3 The working principle diagram of head pressure valve
The head pressure valve model used in the Low Ambient Kit of the CRD10 is LAC-4-295HP-1/2
’
*1/2
’
*1/2
’
. Care must be
taken not to overheat and damage valves during the soldering process, and the connect direction must be correct.
Figure 1-4 The structural diagram of head pressure valve
Discharge
Receiver
Condenser
A
B
C
D
Condenser
Head Pressure Valve
