Problem - Loud Compressor Noise; Problem - Shrieking Whistling Noise - Danfoss DHP-H Installation And Service Instructions Manual

Cause
5. Circulation noise (whistling noise in the
heating system).
Problem – Loud compressor noise
Cause
1. Phase drop.
The compressor attempts to start or oper-
ates on two phases.
2. Touching pipes – vibrations.
3. Compressor fault.
Problem – Shrieking whistling noise
Cause
1. Whistling expansion valve.
2. Noise from the soft-starter.
3. The compressor's IPR valve opens.
Troubleshooting
Check the heating system.
• Closed valves, choke valves, adjuster
valves or other restrictions in the radiator
system can cause circulation noise.
• Is the heating system correctly adjusted
for flow?
• Too great a flow in the heating system can
cause circulation noise.
Troubleshooting
1. Check that there is 400 V between incom-
ing phases on the heat pump.
2. If there is supply to the heat pump, meas-
ure the voltage for all electrical components
all the way to the compressor, see wiring
diagram.
Establish which pipe(s) is/are causing the
problem.
Determine whether the compressor is unu-
sually loud.
Troubleshooting
1. Take overheating readings, adjust to the
recommended value.
2. Open and close the valve fully in and out.
3. Adjust the expansion valve to recom-
mended overheating value again.
Measurement check the input and output
phases for the soft-starter as well as the
control signals from the control computer,
see wiring diagram.
The compressor has an integrated IPR valve
that opens at 28 ±3 bar.
When the valve opens, pressure equalizes
between the compressor's high and low
pressure side and a milling/whistling sound
is heard.
To establish whether the valve opens at the
correct pressure, connect a manometer on
the high and low pressure side.
When the valve opens, this is indicated by
the pressure on the low pressure side rising
and reaching the pressure on the high pres-
sure side.
Check at what pressure the valve starts to
open.
VMBMA602
Remedy
If the incorrect type of valve is used to
choke the flow, replace with the correct
type.
If the heating system is not correctly adjust-
ed, make adjustments.
Can the heating system be run at a lower
flow?
Remedy
Check where the phase drop is and rectify.
Try to release any tensions that cause the
vibrations.
If the compressor is defective, replace it.
Remedy
Check if the noise has stopped, if not, con-
tinue with point 2.
Continue with point 3.
If the problem persists, replace the expan-
sion valve.
If the soft-starter is defective, replace it.
If it opens at a too low pressure, replace the
compressor.
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