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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.
36
Important:
The system may not be properly charged
although the sight glass is clear. Also
consider 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-SVX044B-EN
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