Danfoss DHP-AL Installation And Service Instructions Manual page 55

Problem – Runs on electric heating element
Cause
1. Operating mode ADD.HEAT
is selected.
2. The compressor cannot run
due to an alarm.
3. The integral value has
reached the start level for the
auxiliary heater.
4. Peak heat operation
(legionella function) is running.
5. The heat pump has stopped
on HIGH RETURN.
6. The compressor runs back-
wards. Incoming phases are in
the incorrect order.
If the compressor runs back-
wards, it will not cope with
compressing the refrigerant
and therefore does not pro-
duce the correct power, which
leads to the control computer
requesting auxiliary heating.
7. Changed conditions. Have
you increased your heating
and/or hot water demand?
Problem – The auxiliary heater is in operation but not the compressor
Cause
1. Operating mode ADD.HEAT
is selected.
2. Peak heat operation
(legionella function) is running.
Troubleshooting
If this operating mode is selected, the auxiliary
heater is used for heating and hot water produc-
tion, not the compressor.
Check the alarm that is indicated in the display.
Check what the integral value is in the control
computer.
Check if the heat pump runs peak heat. See the
instructions for the relevant model.
• Check what the MAX RETURN value is set at in
the heat pump's control computer. It must be
adjusted to the unit's maximum supply tempera-
ture and the system's delta temperature so that
it does not cut at too high a return temperature
when the highest supply temperature is transmit-
ted.
• Check what the return pipe sensor shows, is it
a plausible/actual value? If not, take a resistance
reading from the sensors and check against the
ohm table in the "Measurement points" section.
• 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
delivery pipe temperature by feeling the delivery
pipe that should be hot (not just warm) even a lit-
tle distance from the compressor if the phases are
correctly sequenced.
• When the compressor runs with the phases
incorrectly sequenced a strange noise may be
heard (loud, rattling) when the compressor runs
backwards.
• If the heat pump has been dimensioned 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 VL-systems).
Troubleshooting
If this operating mode is selected, the auxiliary
heater is used for heating and hot water produc-
tion, not the compressor.
Check if the heat pump runs peak heat. See the
instructions for the relevant model.
Remedy
If ADD.HEAT mode is selected and you no longer
want it, change to AUTO, the heat pump then con-
trols both the compressor and auxiliary heater.
Rectify the problem and rest the alarm. See the
"Operational problem – Alarm" section.
If the auxiliary heater is in operation because the
integral value has counted down to the start value,
the computer reacts as it should, see the "Heat
pump" section for further information.
Peak heat operation occurs in connection with hot
water production with the set interval. The com-
pressor should then start to produce hot water
and 2 minutes later the auxiliary heater starts, the
compressor should then stop and the stop tem-
perature is reached with only the auxiliary heater
connected. Take no corrective action.
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.
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 supple-
ment it with a higher output auxiliary heater.
Remedy
If ADD.HEAT mode is selected and you no longer
want it, change to AUTO, the heat pump then con-
trols both the compressor and auxiliary heater.
Peak heat operation occurs in connection with hot
water production with the set interval. The com-
pressor should then start to produce hot water
and 2 minutes later the auxiliary heater starts,
the compressor should then stop and the stop
temperature is reached with only the auxiliary
heater connected. Take no corrective action, this
is normal.
VMBME102
55