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Unit Start-Up Procedures
Checking Operating Conditions
NOTICE
Evaporator/Condenser Damage!
Water (fluid) flow must be established in evaporator
and condenser before adding refrigerant, removing
refrigerant, or pulling vacuum to protect heat
exchangers from freezing.
NOTICE
Compressor Damage!
Do not allow liquid refrigerant to enter the suction line
as excessive liquid accumulation in the liquid lines
could result in compressor damage.
To prevent compressor damage and ensure full cooling
capacity, only use refrigerant specified on unit nameplate.
•
If operating conditions indicate an overcharge, slowly (to
minimize oil loss) remove refrigerant at the liquid line
Schrader fitting. Do not discharge refrigerant into the
atmosphere.
•
Once proper unit operation is confirmed, inspect for debris,
misplaced tools, etc. Secure control panel doors in place.
Once the unit has been operating for about 10 minutes and the
system has stabilized, check operating conditions and
complete the checkout procedures that follow.
•
Recheck evaporator water and condenser water flows and
pressure drops. These readings should be stable at proper
levels.
•
Check suction pressure and discharge pressure.
•
Discharge pressure: Take at Schrader fitting provided
on the discharge line. Normal discharge pressures are:
•
90°F to 120°F Condenser LWT: 275 to 430 psig
•
120°F to 140°F Condenser LWT: 430 to 560 psig
•
Suction pressure: Take at Schrader fitting provided on
the suction line. Normal suction pressures are:
•
42°F to 60°F LWT: 104 to 155 psig
•
15°F to 39°F LWT: 60 to 103 psig
•
Check compressor oil level. At full load, oil level should be
visible in the oil level sight glass on the compressor. If it is
not, add or remove oil as required.
•
Check the liquid line sight glass. Refrigerant flow past the
sight glass should be clear. Bubbles in the liquid line
indicate either low refrigerant charge or excessive
pressure drop in the liquid line. Such a restriction can often
be identified by a noticeable temperature differential on
either side of the restricted area. Frost often forms on the
outside of the liquid line at this point also.
Important:
The system may not be properly charged
although the sight glass is clear. Also consider
36
superheat, sub-cooling and operating
pressure.
•
Once oil level, amp draw and operating pressures have
stabilized, measure system suction superheat.
•
Measure system liquid line sub-cooling.
•
If operating pressure, sight glass, superheat and sub-
cooling readings indicate refrigerant shortage, charge
refrigerant into each circuit. Refrigerant shortage is
indicated if operating pressures are low and sub- cooling is
also low.
Important:
If suction and discharge pressures are low but
subcooling is normal, no refrigerant shortage
exists. Adding refrigerant, will result in
overcharging.
•
Add refrigerant with the unit running by metering liquid
refrigerant through the Schrader valve between the
expansion valve and the evaporator refrigerant inlet until
operating conditions are normal.
System Superheat
Normal superheat is 10°F to 16°F at full load. Expansion valve
superheat is factory set. Contact factory before making any
adjustment.
System Subcooling
Normal subcooling is 5°F to 10°F at full load where saturated
discharge pressure and liquid line temperature are measured
at chiller liquid line.
CG-SVX044F-EN
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