Danfoss DHP-A Service Instructions Manual page 14

Service instructions
Problem – Incorrect phase sequence
Cause
The incoming phases have the in-
correct sequence (only applies to 3-
phase heat pumps).
Problem – Alarm AH (auxiliary heat)
Cause
1. The overheating protection has
tripped.
2. Phase drop.
The alarm occurs when 230 V is not
registered between L2 on the circuit
board and N.
3. Overheating protection fault,
cannot be reset.
4. Flow sensor fault.
5. No or insufficient circulation in
the heating system.
6. The submersible tube in the elec-
tric heating element is against the
coils.
14
Domestic heat pumps
Troubleshooting
▪ If the text ERR PHASE SEQ. appears in the dis-
play when the heat pump is powered, (only
appears in the first 10 minutes) this means
that the phases have the incorrect sequence.
▪ When the compressor is running, check the
pressure pipe temperature by feeling the
pressure pipe. If the phases are correctly se-
quenced it should be hot (not just warm) even
a distance from the compressor.
▪ When the compressor runs with the phases in-
correctly sequenced a strange noise may be
heard (loud, rattling) when the compressor
runs backwards.
Troubleshooting
Check if the overheating protection has tripped.
▪ Check if the overheating protection has trip-
ped.
▪ Check if any cables at the circuit board or
overheating protection are loose or damaged.
Press the reset button, measurement check for 230
V on the incoming and outgoing connections.
Check what the flow sensor shows. Is it a plausible/
actual value?
Measure the resistance of the sensor, check against
the ohm table, see chapter Measurement points.
Check:
▪ That the circulation pump spins
▪ That the shut-off valves are open.
▪ That the strainer is not blocked.
▪ That there is no air in the heating system.
Check what the flow temperature is when the over-
heating protection trips. This normally trips at 95°C.
VIGFI102
Remedy
If the phases are in the incorrect order,
switch two incoming phases at the main
terminal block and recheck according to
the troubleshooting window.
Remedy
If the overheating protection has tripped,
reset it.
If the overheating protection has tripped,
reset it.
If the cables are loose or damaged, secure
or replace them.
If the overheating protection is defective,
replace it.
If the sensor is defective, replace it.
The circulation pump may have jammed. If
so, open the bleed screw and try to release
the paddle wheel using a screwdriver for
example.
Open closed valves or taps.
Check, and, if necessary, clean the strainer.
If necessary, bleed the heating system ac-
cording to the installation instructions.
The submersible tube can be prised out
slightly from the coils using a screwdriver
or similar. The submersible tube must be
vertical.
Danfoss Heating Solutions