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Operation
Important: A clear sight glass does not necessarily mean that the system is
sufficiently charged; be sure to consider system superheat, subcooling, and
unit operating pressures and ambient temperatures.
Proper unit refrigeration charge -per circuit- is indicated on the unit name-
plate and also under "Refrigerant Charge Information" on page 39 of this
manual.
[ ] Measure system superheat.
Normal system superheat is 12 to 15 degrees F for each circuit at ARI condi-
tions (54° entering water, 44° leaving water, and 95° ambient temperature). If
the superheat measured for either circuit does not fall within this range, alter
the setting of the superheat adjustment on the thermal expansion valve to
obtain the desired reading. Allow 15 to 30 minutes between adjustments for
the expansion valve to stabilize at each new setting.
[ ] Measure system subcooling.
Normal subcooling for each circuit is 12 to 22 degrees F at ARI conditions
(54° entering water, 44° leaving water, and 95° ambient temperature). If sub-
cooling for either circuit is not in this range, check superheat for circuit and
adjust, if required. If superheat is normal but subcooling is not, contact a
qualified service technician.
[ ] If operating pressure, sight glass, superheat and subcooling readings
indicate refrigerant shortage, find and repair leaks and, gas-charge refriger-
ant into each circuit. Refrigerant shortage is indicated if operating pressures
are low and subcooling is also low.
Refrigerant Charge Information
The 10 ton units have 9 lbs. 8 oz. of refrigerant per circuit, and the 15 ton
units have 12 lbs. 7 oz. of refrigerant per circuit.
CAUTION
Equipment Damage!
Do not add refrigerant to unit when suction and discharge pressures
are low and subcooling is normal. Failure to follow all instructions
could result in equipment damage.
Add refrigerant vapor with the unit running by charging through the access
port on the suction line until operating pressures are normal.
CSRA-SVX01A-EN
39
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