Sterlco GP Series 20-60 HP Packaged Chillers - Manual (Page 15)

GP Series Portable Chillers Chapter 2: Functional Description 15 of 93
• Multiple refrigeration access ports
• Liquid line shut-off ball valves
• Filter-dryer
• Sight glass
• Externally equalized thermal expansion valve
• Liquid line solenoid
• Compressor crankcase heater
Controller Features
• Off-the-shelf microprocessor-based PID controller with To Process, From Process and
Set Point readout
• Time delay for proof of water flow/pressure (models w/pump only)
• Low refrigerant pressure time delay for low ambient start-up on remote air-cooled and
air-cooled chillers with the variable-speed fan option.
• 8 line x 22 character display with status, alarm, and service screens
• Display has magnetic back and can be mounted anywhere.
Other Features
• One year labor warranty and one year compressor warranty
• Two year parts warranty
• Three year limited controller warranty
2-4 Safety Devices and Interlocks
Protect the system from freezing with inhibited industrial grade glycol 20ºF
below the leaving water temperature set point. Condensation may form inside
the pump tank and dilute the mixture, therefore the freezing point should be
verified periodically. See Figure 6 on page 18 for the correct mixture.
Crankcase Heater
All of the chillers are equipped with a compressor crankcase heater. It is wired through the
control transformer that operates continuously whenever power is applied to the chiller, and
the compressors are off.
Energize the crankcase heater for at least 24 hours before initial startup to
drive dissolved refrigerant from the compressor oil. Failure to do so will
damage the compressor. If unit is mounted outdoors, power to the unit (and
the main power switch) must remain on 24 hours per day, 7 days per week to
prevent liquid migration to the compressor.