Sterling GP Series Safety Devices and Interlocks, Refrigeration Features, Controller Features

Refrigeration Features

•HFC-410a refrigerant

•Electronic hot gas bypass capacity control

•High refrigerant pressure cutout switches

•Suction and discharge pressure transducers.

•High pressure spring actuated relief valve

•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 auto-tuning 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.

•4 line x 20 character display with status, alarm, and service screens

Other Features

•One year labor warranty and one year compressor warranty

•Two year parts warranty

•Two year limited controller warranty

2-4 Safety Devices and Interlocks

Caution! Protect the system from freezing with 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

5 hp through 15 hp portable chillers have a crankcase heater. It is wired through the control transformer that operates continuously whenever power is applied to the chiller.

Caution! 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.

GP Series Portable Chillers Chapter 2: Functional Description 9 of 44