Connect the chilled water supply to the
bottom of the coil and return to the top.
Water supply lines must be insulated with
closed cell type pipe insulation or insulation
that includes a vapor barrier. Lines must be
properly fastened, drained and supported
according to local code requirements, and job
specifications.
Table 13 - Minimum and Maximum Coil
Pressures and Temperatures
Direct Expansion (DX) Systems
All DX refrigerant coils are factory charged
with a nitrogen holding charge. All DX
systems include evaporator coils and thermal
expansion valves (TXV).
Never turn off the main power supply to the
unit, except for servicing, emergency, or
complete shutdown of the unit. When power
is cut off from the unit, crankcase heaters
cannot prevent refrigerant migration into the
split system condensing unit compressors.
This means the compressor may cool down
and liquid refrigerant may accumulate in the
compressor. The compressor is designed to
pump refrigerant gas and damage may occur
when power is restored.
Piping shall be in accordance with
national and local codes. Pressure
limiting devices, backflow preventers
and all other safety requirements are
the sole responsibility of the installing
Ensure water piping entries into the
unit are properly sealed. Failure to
seal the entries may result in damage
to the unit and property.
CRANKCASE HEATER
OPERATION
Some units are equipped with
compressor crankcase heaters, which
must be energized at least 24 hours
prior to cooling operation, to clear any
liquid refrigerant from the
compressors.
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