Danfoss DHP-A Service Instructions Manual page 16

Service instructions
Problem – Alarm circulation pump
Cause
The circulation pump's integrated
alarm has deployed. (Only applies
to speed controlled heat pumps)
Problem – Operating pressure switch open alternatively high hot gas temperature
Cause
1. Operating pressure switch, func-
tion.
2. Sensor fault.
3. Hot gas temperature too high.
4. Overheating too high.
5. Lack of refrigerant, not enough
refrigerant in the system.
16
Domestic heat pumps
Troubleshooting
▪ Air in the circulation pump?
▪ Has the circulation pump jammed?
Troubleshooting
1. Switch off the main switch for the heat pump,
wait until the compressor has been stationary
for at least 15 minutes.
2. Disconnect the two cables on the pressure
switch, using a buzzer check if the pressure
switch is closed.
Check what the sensor shows. Is it a plausible/
actual value?
Measure the resistance of the sensor, check against
the ohm table in Measurement points.
Check the set value on DISCH. PIPE in the heat
pump's control computer (factory setting 140°C)
Using manometer apparatus and thermometer
check what the overheating reading of the unit is.
Also check that bulb and capillary tube are undam-
aged and that the bulb is correctly installed.
Using manometer apparatus and thermometer,
check that the unit's overheating is correct for the
specific refrigerant.
VIGFI102
Remedy
Air in the brine circuit. See the installation
instructions for information on how to per-
form filling.
If the circulation pump has jammed, there
is an integrated shake function that at-
tempts to shake itself loose up to a maxi-
mum of 5 times, if it does not succeed, an
alarm will occur.
Try cutting the voltage to the heat pump to
stop the alarm and then manually run the
circulation pump. If the alarm recurs, repeat
the procedure several times. If this does not
help, replace the circulation pump.
Remedy
If the pressure switch is closed, bridge the
pressure switch cables temporarily and
switch on the voltage to the heat pump
again. If there is an indication 0 (zero) in the
display this means that the pressure switch
is fault-free and the problem is in the wiring
or in the circuit board.
If the pressure switch is open, try carefully
tapping the head of the pressure switch
with a screwdriver and use a buzzer test to
see if it has closed again.
Replace the pressure switch if it appears to
jam repeatedly.
If the sensor is defective, replace it.
The square symbol appears when the deliv-
ery pipe temperature is as high or greater
than the set value for DELIVERY PIPE.
If the overheating reading does not corre-
spond with the instructions for the specific
refrigerant, adjust the expansion valve until
the correct value is obtained. See separate
instructions for cooling techniques.
If overheating cannot be adjusted with the
expansion valve or if the capillary tube/
bulb is damaged, replace it.
Follow the correct procedure (depending
on type of refrigerant) to add the correct
amount of refrigerant.
If there appears to be a leak in the refriger-
ant circuit, carry out leak tracing and any
necessary corrective action. If leak tracer is
not available, brush soap water on the sus-
pected leak and look for bubbles. Also
check for oil as this can come out from the
refrigerant circuit.
Danfoss Heating Solutions