Schreiber Chillers Old 4 ton MRI - Manual (Page 28)

Again, we want to stress that it is essential that WHENEVER ELECTRIC POWER is
applied to the motor-compressor, the terminal PROTECTIVE COVER must be properly
in place.
Servicing refrigeration and air conditioning systems can be dangerous, and extreme
caution in all respects should be exercised by the personnel servicing such equipment.
The precautions discussed in this bulletin deal only with those dangers associated with
VENTING TERMINALS.
CRANK CASE HEATERS
This unit has a CRANK CASE HEATER on the compressor. It is important to the life of
this compressor that you follow the instructions. This low wattage heater protects the
compressor when it is idle by producing just enough heat to keep the Freon from
accumulating in the compressor. Under certain specific conditions this heater will
prevent the compressor from slugging causing damage to its internal parts.
These Heaters are wired at our factory in such away that allows the heater to be on any
time the disconnect switch on the chiller is on. When you want to turn the water pump or
refrigeration compressor off, you must only use the manual switches on the electrical
enclosure as marked. When you use the disconnect to turn the unit off you kill the
power to the crank case heaters. ONLY use the disconnect to turn off power if you are
going to work on the electrical system.
AN IMPORTANT FACTOR - READ
SPECIAL INSTRUCTIONS FOR CRANK CASE HEATER
When the unit is first received, the power to the chiller should be on for 3 hours. That
means you must at this time have the unit disconnect on. The manual water pump and
refrigeration switches should be off. This will allow the refrigeration compressor to warm
up, driving out the freon (R22) that had migrated to the compressor.
This start up time is necessary if you have all the power off for 12 hours or more. Then
you must allow this same warm up time. It is okay to turn the unit off by the manual
switch only and not the main power. Then you do not need to be concern about a warm
up time.
The crank case heater is HIGH VOLTAGE. But it is only very low wattage. Caution
should be taken when working on the crank case heater to make sure the POWER is
off.
Any question call for more details Schreiber Engineering Corporation 562-926-3855.
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