Danfoss DHP-A Service Instructions Manual page 57

Cause
6. The compressor runs backwards.
The incoming phases have the incor-
rect sequence (only applies to 3-
phase heat pumps).
If the compressor runs backwards, it
will not cope with compressing the
refrigerant and therefore does not
produce the correct power, which
leads to the control system request-
ing auxiliary heating.
7. Changed conditions Have you
increased your heating and/or hot
water demand?
Table 35. Problem – The auxiliary heater is in operation but not the compressor
Cause
1. Operating mode AUX. HEATER is
selected.
2. Peak heat operation (anti-legionella
function) is running.
3. The compressor cannot run due to
an alarm.
4. The heat pump has stopped on high
return.
Troubleshooting
•
If the text ERR PHASE SEQ. appears in
the display 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 sequenced it
should be hot (not just warm) even a
distance from the compressor.
•
When the compressor runs with the
phases incorrectly sequenced a
strange noise may be heard (loud, rat-
tling) when the compressor runs back-
wards.
•
If the heat pump has been dimen-
sioned for a certain demand and this
demand is increased, the heat pump
might not be able to maintain the
desired room temperature.
•
If hot water consumption increases, a
larger proportion of time is used to
produce hot water, which means less
time for heat production (only applies
to system solution 1).
Troubleshooting
If this operating mode is selected, the
auxiliary heater is used for heating and
hot water production, not the compres-
sor.
Check if the heat pump runs peak heat.
See the instructions for the relevant
model.
Check the alarm that is indicated in the
display.
•
Check what the MAX value is set at in
the heat pump's control computer. It
must be adjusted to the unit's maxi-
mum supply temperature and the
system's delta temperature so that it
does not cut at too high a return
temperature when the highest sup-
ply temperature is transmitted.
•
Check what the return line sensor
shows. Is it a plausible/actual value? If
not, take a resistance reading from
the sensors and check against the
ohm table in Mätpunkter.
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.
If the heat pump cannot cope with the
demand, replace it with one with a
higher output or supplement it with a
higher output auxiliary heater.
Remedy
If AUX. HEATER mode is selected and
you no longer want it, change to AUTO,
the heat pump then controls both the
compressor and auxiliary heater.
Peak heat operation occurs in connec-
tion with hot water production with the
set interval. The compressor should then
start to produce hot water and 2
minutes later the auxiliary heater starts.
The compressor must then stop and the
stop temperature be reached with only
the auxiliary heater connected. Take no
corrective action, this is normal.
Rectify the problem and rest the alarm.
See Alarm.
•
If the MAX RETURN value is not
adjusted for the system according
to the troubleshooting window,
adjust it.
•
If the sensor is defective, replace it.
Service instructions VMGFC302 – 55