Operating manual – DualPAC with reciprocating compressors
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If the oil continues to disappear from the compressor, the oil return and recovery system must be
checked.
Cause
Solution
Defect oil return/
oil recovery system
1.
Check the function and position of the oil float switch (see de-
scription of oil recovery pot). When the float is up, the switch
must be closed (ON) and vice versa.
2.
Check that the piston in the oil recovery pot is able to move
smoothly.
3.
Check all solenoid valves and filters.
4.
Check timers in Unisab III.
See Unisab III settings list for timer settings.
5.
Check if the oil separator is filled with oil. If so, adjust the
timers in Unisab III. Increase the solenoid valve “ON” time.
In the period after start-up and at low-load operation, the oil recovery system will return more oil
to the compressor than during full load.
At part-load operation, the oil will settle easier because of less boiling in the evaporator.
Drop in oil temperature
Cause
Solution
Wet suction gas due to too high R717
charge
Reduce charge.
Wet suction gas due to fluctuating load
Check secondary system.
Wet suction gas due to quick changes in
compressor capacity
Adjust settings for load/unload compressor capacity
in Unisab III.
Too much compressor cooling
Reduce water flow or temperature to compressor
cooling. See compressor manual for more
information.
5.6.3
Testing of DualPAC units
DualPAC units supplied by Johnson Controls Denmark have, as far as possible, been function and
performance tested.
A performance test consists of simultaneous measurements of cooling or heating capacity, power
consumption and condenser capacity.
It is not a simple task to measure performance. High quality measuring and logger equipment is
required to make reliable and accurate measurements. Contact your Johnson Controls represen-
tative if a performance test is needed.
