Danfoss DHP-AX Installation And Service Instructions Manual page 51

Problem – Incorrect phase sequence
Cause
The incoming phases have the
incorrect sequence (only applies
to 3-phase heat pumps).
Problem – Alarm AH (addition)
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 (220).
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
electric heating element is
against the coils.
Problem – Alarm Brine out
Cause
1. Defective sensor.
Troubleshooting
• If the text ERR PHASE SEQ. appears in
the display when the heat pump is powe-
red, (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 cor-
rectly sequenced it should be hot (not
just warm) even a distance from the com-
pressor .
• When the compressor runs with the
phases incorrectly 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
tripped.
• 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 out-
going connections.
Check what the flow sensor shows, is it a
plausible/actual value?
Measure the resistance of the sensor,
check against the ohm table in section
15.3 Measurement points.
Check:
• That the circulation pump spins.
• That the shut-off valves are open.
• That the strainer is not blocked.
• That no air is in the heating system.
Check what the flow temperature is
when the overheating protection trips.
This normally trips at 95°C.
Troubleshooting
Check what the sensor shows, is it a plau-
sible/actual value?
Measure the resistance of the sensor,
check against the ohm table in section
15.3 Measurement points.
VMBMH302
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/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 screw-
driver for example.
Open closed valves or taps.
Check, and, if necessary, clean the strai-
ner.
If necessary, bleed the heating system
according 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.
Remedy
If the sensor is defective, replace it.
Service – 51