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Condition
Excessive discharge
temperature
The scroll
compressor runs
continuously
Compressor
lubrication problem
Low discharge
pressure
Low suction
pressure
Noise during shut-
of f
34
Cause
Corrective action
For compressors using vapour injection, make sure the
expansion valve is connected at a distance between
150 and 200 mm f rom the economizer inlet and at a
position not lower than inlet connection. The injection
line economizer to compressor should be properly
Insuf f icient
sized to avoid pressure drop. For good refrigerant
cooling
distribution in the economizer respect the
medium
recommendations especially those regarding the inlet
injected
pipes for the vapour injection according to BHE-
manuf acturer. The liquid line from the BHE to the
expansion valve(s) need to be well insulated as well. A
solenoid valve should be installed on the liquid line to
prevent ref rigerant migration.
Too high
Make sure the compressor operates within the
compressor
acceptable superheat range published by Emerson.
superheat
Excessive
cooling/heating
Check the load design; make sure that proper
load or
insulation is applied. Correct it as necessary.
inadequate
insulation
Check the thermostat, measure the temperature of the
room and compare with the thermostat; replace or re-
Control circuit
calibrate the thermostat.
inoperative
Check the LP control switch and replace it if it is found
def ective.
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
Oil trap due to
possible the refrigerant line should travel a direct and
incorrect
straight course between the evaporator and
piping layout /
compressor. It should also be remembered that the
sizing
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.
A high cycling rate will pump oil into the system and
Oil pump out
lead to lubrication failure. Oil leaves the compressor at
due to high
start-up and the short running time is insufficient to
cycling rate
return the oil to the compressor via the suction side. Try
to limit the number of cycles to maximum 10 per hour.
System gas velocity changes depending on
Low gas
temperature and load (capacity control). In low load
velocity
conditions gas velocity may not be high enough to
return oil to the compressor.
Low ambient
Fit a f an cycling control system.
temperature
Ref rigerant
Check the system for leaks. Observe sight glass for
undercharge
bubbles. Add refrigerant until the sight glass is clear.
System design
If the compressor is running in a tandem or in parallel,
load too small
modulate the running process.
Lower normal discharge pressure values can lead to
Inadequate
insuf ficient refrigerant flow to the system.
ref rigerant
This can also be verified by checking the evaporator
going to the
outlet superheat, if it is found unusually high. Check the
evaporator
selection of the expansion valve (likely undersized).
Anti-reverse
This does not have any effect on the durability of the
device
compressor, no action is necessary.
AGL_HP_ST_ZHK1P_EN_Rev00
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