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5.2 Water/Glycol Cooled Systems
5.2.1. Water/Glycol Cooled Systems Charging
All water/glycol cooled units are factory charged. The water regulating valve should be adjusted
to maintain 230 to 260 psi head pressure. Suction temperature should be 58 psi or greater. The
superheat at the compressor suction line at least six inches away from the compressor should be
8-15 degrees.
Field charging water/glycol systems should be done by referring to the unit electrical nameplate for
the factory charge. Although this fi gure represents the original factory charge, it is still necessary
to measure and note proper unit operation including superheat, head and suction pressure. Some
adjustment to charge may be required.
Adjust the refrigerant charge until the sight glass has sparse bubbles. The unit should be allowed
to stabilize for several minutes before meaningful measurements can be taken and the conditioned
room should be at or near the temperature setpoint.
All water/glycol cooled units have a water regulating valve. A head pressure sensing transducer is
connected to a shrader fi tting on the discharge line and water is regulated into the condenser coil.
Condenser coils may be plate fi n or coaxial type.
Before starting a compressor, if there has been a refrigerant holding charge, the crankcase
heaters should be energized for a minimum of 12 hours to reduce the possibility of liquid
slugging on start-up. Failure to energize crankcase heaters could result in compressor
damage.
Note: Charging to a full liquid line sight glass should never be the sole means of
determining the correct refrigerant charge. Other parameters such as superheat, suction
pressure, head pressure, subcooling and ambient temperature are also important
parameters. A system charged to a clear sight glass is often over-charged.
5.2.2. Factory Charge for Water/Glycol Cooled Systems
Evaporator Factory Charge per
Model Ckt, Lbs. R-22
DAMW 0112 2.00
DAMW 1.512 2.00
DAMW 0212 2.25
DAMW 2.512 2.25
5.3 Refrigerant Handling
The use of recovery/recycling units is required by U.S. Environmental Protection Agency (EPA)
regulations. Technicians who service and dispose of air conditioning and refrigeration equipment
must recover the refrigerant instead of venting to atmosphere.
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