32
AGL_HP_ST_YHK1E_E_Rev02
Condition
Cause
Corrective action
Compressor
lubrication
problem
Oil trap due to
incorrect piping
layout / sizing
Check the piping layout design. Installations of pipe being routed
over or around obstacles can inadvertently create unwanted traps
for the oil return. As much as possible the refrigerant line should
travel a direct and straight course between the evaporator and
compressor. It should also be remembered that the entire system
will be coated in oil to some extent. Oil viscosity changes with
temperature. More oil stays in the system than was originally
expected. Make sure the line is correctly sized.
Oil pump out
due to high
cycling rate
A high cycling rate will pump oil into the system and lead to
lubrication failure. Oil leaves the compressor at start-up and the
short running time is insufficient to return the oil to the compressor
via the suction side. Try to limit the number of cycles to maximum
10 per hour.
Low gas
velocity
System gas velocity changes depending on temperature and load
(capacity control). In low load conditions gas velocity may not be
high enough to return oil to the compressor.
Low discharge
pressure
Low ambient
temperature
Fit a fan cycling control system.
Refrigerant
undercharge
Check the system for leaks. Observe sight glass for bubbles if
fitted. Add refrigerant until the sight glass is clear. If no sight glass
is fitted, check the evaporator superheat and fill in with refrigerant.
Low suction
pressure
System design
load too small
If the compressor is running in a tandem or in parallel, modulate
the running process.
Inadequate
refrigerant
going to the
evaporator
Lower normal discharge pressure values can lead to insufficient
refrigerant flow to the system.
This can also be verified by checking the evaporator outlet
superheat, if it is found unusually high. Check the selection of the
expansion valve (likely undersized).
Noise during shut-
off
Anti-reverse
device
This does not have any effect on the durability of the compressor,
no action is necessary.
Summary of Contents for Copeland Scroll YH16K1E
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