Danfoss DHP-A Service Instructions Manual page 19

Service instructions
Problem – Shrieking, whistling noise
Cause
1. Whistling expansion valve.
2. Noise from the soft-starter.
3. The compressor's IPR valve
opens.
Problem – Noise – miscellaneous
Cause
1. Vibrating protective sleeves on
the pressure switches.
2. Vibration noise from the electrical
installation.
3. The heat pump is not level.
4. General noise problems
Danfoss Heating Solutions
Domestic heat pumps
Troubleshooting
1. Take overheating readings, adjust to the rec-
ommended value.
2. Open and close the valve fully in and out.
3. Adjust the expansion valve to recommended
overheating value again.
Measurement check the input and output phases
for the soft-starter as well as the control signals
from the I/O card (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 sides 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 sides.
When the valve opens, this is indicated by the pres-
sure on the low pressure side rising and reaching
the pressure on the high pressure side.
Check at what pressure the valve starts to open.
Troubleshooting
Establish where the vibration noise is coming from. Prevent the protection sleeve vibrating by
Check for electrical steps or similar devices screwed
to the heat pump and wall. These can cause vibra-
tions and noise.
Check that the heat pump is level by using a spirit
level.
Check that the heat pump is supported by all four
feet.
Carry out preventative measures. See Installation
instructions.
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 too low a pressure, replace the
compressor.
Remedy
using insulation tape for example.
Carry out according to the installation in-
structions.
If the heat pump is not level, adjust using
the feet.
Example:
▪ Improve the acoustic environment in
the area where the heat pump in loca-
ted by installing acoustic panels on
the walls and ceiling.
▪ Install a hood on the compressor
(most effective for high frequencies).
VIGFI102
19