Cause
Troubleshooting
Remedy
5. The heat pump has stopped on
HIGH RETURN.
•
Check what the MAX RETURN value is
set at in the heat pump’s control com-
puter. It must be adjusted to the unit’s
maximum supply temperature and the
system’s delta temperature so that it
does not cut at too high a return tem-
perature when the highest supply
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 Measurement points, Page 11.
If the MAX RETURN value is not adjusted
for the system according to the trouble-
shooting window, adjust it.
If the sensor is defective, replace it.
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.
•
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 phases are in the incorrect order,
switch two incoming phases at the main
terminal block and recheck according to
the troubleshooting window.
7. Changed conditions Have you
increased your heating and/or hot
water demand?
•
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.
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.
Table 25.
Problem – The auxiliary heater is in operation but not the compressor
Cause
Troubleshooting
Remedy
1. Operating mode AUX. HEATER is
selected.
If this operating mode is selected, the
auxiliary heater is used for heating and
hot water production, not the compres-
sor.
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.
2. Peak heat operation (anti-legionella
function) is running.
Check if the heat pump runs peak heat.
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.
3. The compressor cannot run due to
an alarm.
Check the alarm that is indicated in the
display.
Rectify the problem and rest the alarm.
Service instructions VMGFJ102 – 29
