FläktGroup Multi-DENCO - Page 110

Commissioning Multi-DENCO
110 FläktGroup DC-2013-0101-GB • Subject to modifications • R5-08/2020
8.3.11 Systems fitted with a Pressure Relief Valve (PRV)
Pressure Relief Valves could be fitted:
– On W-Version units on the liquid receivers in the WaterCool Module
– On P-Version units on the shell and tube condenser in the WaterCool Module
– On outdoor units (condensers) that are fitted with liquid receivers or winter kits
(A-Version)
8.3.12 Variances for winter kit
Units operating in low ambient temperatures may be fitted with a winter kit. The system
operates as a 'liquid backup'. At high ambient temperatures, the system regulates so
that liquid refrigerant is stored in the liquid receiver. At low ambient temperatures liquid
refrigerant is stored/backed-up in the condenser coil instead.
The components of the winter kit are:
– Electronic Regulation Valves (ERV)
– Condenser fans
– Liquid receiver with trace heating
– Control circuit transformer for controlling the ERVs (Evolution Driver)
– Control panel heater
– Mains Circuit Breaker (MCB) in the indoor units electrical panel (power supply to the
winter kit)
Commissioning engineers must observe the good practices with the following addi-
tional requirements for winter kits.
Procedure
1. Calculate the 'system refrigerant'.
– This is the refrigerant required to charge a standard system without a winter kit
option (indoor/outdoor unit and interconnecting pipework).
2. Calculate the refrigerant required to fill the liquid receiver to 80% (see Tab. 8-4).
Pressure Relief Valves (PRV) are essential safety devices to prevent the risk of
excess pressure within the direct expansion circuit / liquid receiver causing an
explosion or rupture.
During pressure testing, PRVs are isolated using in-line shut off valves (SOV) to
prevent any relief whilst operating in a control environment.
If the SOV(s) are not set to the “Open” position AFTER testing, there is a HIGH
RISK of explosion if excessive pressures are created within the direct expansion
circuit.
At any time, outside of pressure testing:
• Ensure all SOVs that isolate PRVs are in the OPEN position
NOTICE
Overfilling of liquid receivers can result in poor system performance or failure.
• The liquid receiver should never exceed 80% full.