System Superheat; System Subcooling - Trane CGWF Installation Operation & Maintenance

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Unit Start-up
The system may not be properly charged although the sight glass is clear. Also
consider superheat, subcooling and operating pressures.
• Once oil level, amp draw and operating pressures have stabilized, measure sys-
tem suction superheat.
• Measure system liquid line subcooling.
• If operating pressure, sight glass, superheat and subcooling readings indicate
refrigerant shortage, gas-charge refrigerant into each circuit. Refrigerant shortage
is indicated if operating pressures are low and subcooling is also low.
If suction and discharge pressures are low but subcooling is normal, no refriger-
ant shortage exists. Adding refrigerant, will result in overcharging.
Add refrigerant with the unit running by charging through the Schraeder valve
between the expansion valve and the evaporator refrigerant inlet until operating condi-
tions are normal.
CAUTION
Compressor Damage!
To prevent compressor damage, do not allow liquid refrigerant to enter
the suction line.
To prevent compressor damage and insure full cooling capacity, use
refrigerants specified on the unit nameplate only.
• If operating conditions indicate an overcharge, slowly (to minimize oil loss)
remove refrigerant at the liquid line service valve. Do not discharge refrigerant
into the atmosphere.
• If the unit is equipped with hot gas bypass, check regulating and solenoid valve
for proper operation. Valve operating setpoints for 44-45 F evaporator leaving
water temperature are:
Full open @ 61 psig,
Full closed @ 69 psig
For other conditions, adjust the valve so that it is full open at normal suction pressure
when the unit is operating at minimum cooling level.
• If the remote condenser (CCAF) is equipped with low ambient dampers, check for
proper actuator and blade travel in relation to condensing pressure. Damper oper-
ating setpoints are:
170 psig = Dampers fully closed;
250 psig = Dampers fully open.
• Once proper unit operation is confirmed, inspect for debris, misplaced tools., etc.
Secure control panel doors in place.

System Superheat

Normal superheat for each circuit is 10-12 F at full load. If superheat is not within this
range, adjust expansion valve superheat setting. Allow 5-10 minutes between adjust-
ments for the expansion valve to stabilize on each new setting.

System Subcooling

Normal subcooling for each circuit is 10 to 15 F at full load. If subcooling for either cir-
cuit is not in this range check superheat for the circuit and adjust, if required. If super-
heat is normal but subcooling is not, contact a qualified service technician.
CGWF-SVX01A-EN