Danfoss DHP-H - Page 76

76
VMBMA602
Cause Troubleshooting Remedy
6. The heat pump has stopped on HIGH
RETURN.
•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 temperature and the system’s delta
temperature so that it does not cut at too
high a return temperature 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 the
Measurement points section.
If the MAX RETURN value is not adjusted for
the system according to the troubleshoot-
ing window, adjust it.
If the sensor is defective, replace it.
7. Heat production is stopped by the
HYSTERESIS function.
If the flow temperature rises as soon as
heat production is stopped by HYSTERESIS
before INTEGRAL reaches 0, there may be
heating deficit in the house.
•Checkifheatproductionstopsbecause
the hysteresis value is set too low? (See the
installation instructions for factory setting.)
•Checkifheatproductionstopsbecause
thermostats/valves in the heating system
are closed or partially closed?
•Checkifheatproductionstopsbecause
the heating system is under dimensioned?
•Tryincreasingthehysteresisvalueuntilthe
heat pump stops on INTEGRAL instead.
•Openthermostats/valvesintheheating
system and check that the heat pump stops
on INTEGRAL.
•Iftheheatingsystemisdeemedtobe
under dimensioned, the system must be
extended (increase the heat emitting sur-
face).
8. The auxiliary heater is not permitted to
cut in with sufficient output.
Value set too low on MAXSTEP.
MAXSTEP 1 = 3 kW
MAXSTEP 2 = 6 kW
MAXSTEP 3 = 9 kW
MAXSTEP 4 = 12 kW (only DHP-A)
MAXSTEP 5 = 15 kW (only DHP-A)
MAXSTEP+4=12kW(onlyDHP-A)
MAXSTEP+5=15kW(onlyDHP-A)
Check the set value on MAXSTEP in the heat
pump’s control computer.
If necessary, adjust the MAXSTEP value in
the heat pump’s control computer.
MAXSTEP 1 = 3 kW
MAXSTEP 2 = 6 kW
MAXSTEP 3 = 9 kW
MAXSTEP 4 = 12 kW (only DHP-A, -AL, can-
not cut in when the compressor is running.)
MAXSTEP 5 = 15 kW (only DHP-A, -AL, can-
not cut in when the compressor is running.)
MAXSTEP+4=12kW(onlyDHP-A,-AL,can
cut in when the compressor is running.)
MAXSTEP+5=15kW(onlyDHP-A,-AL,can
cut in when the compressor is running.)
9. The external auxiliary heater does not
start when the heat pump’s control compu-
ter requests it.
If an external auxiliary heater is used, check
that it is correctly installed by test running it
in MANUAL TEST – ADD.HEAT - 1.
If it does not start at manual test operation,
check that the start signal/voltage comes
from the heat pump. See wiring diagram.
Connect the external auxiliary heater
according to the instructions.
Measure the voltage on the control compu-
ter’s probe L2 Oil/Electricity.
10. Closed or partially closed thermostats/
valves in the heating system.
Check that the thermostats/valves in the
heating system are open.
Open closed thermostats/valves.
11. The total output of the heat pump and
auxiliary heater is too low in relation to the
building’s power demand.
What is the building’s power demand?
What is the output of the heat pump?
What is the output of the auxiliary heater,
what is it set to?
Ensure that available power is at least as
great as the building’s power demand.
12. Under dimensioned heating system. Check existing heating system.
What output is it dimensioned for to pro-
duce at what supply temperature?
What output is required to keep the room
warm?
If the heating system is dimensioned for
greater supply temperatures than the heat
pump can provide, it must be adjusted by
increasing the heat emitting surface for
example.
If the room requires a higher output than
the heating system can provide, extend the
heating system.