Cause
Troubleshooting
Remedy
8. The auxiliary heater is not
permitted to cut in with suf-
ficient output.
Value set too low on MAX-
STEP.
MAXSTEP 1 = 3 kW
MAXSTEP 2 = 6 kW
MAXSTEP 3 = 9 kW
MAXSTEP 4 = 12 kW
MAXSTEP 5 = 15 kW
Check the set value on MAXSTEP in the heat pump’s con-
trol computer.
If necessary, adjust the MAXSTEP value in
the heat pump’s control computer.230V 1-
N MAXSTEP 1 – 3400 V 3-N: MAXSTEP 1 – 5
MAXSTEP 1 = 3 kW
MAXSTEP 2 = 6 kW
MAXSTEP 3 = 9 kW
MAX STEP 4 = 12 kW (cannot cut in when
the compressor is running.)
MAX STEP 5 = 15 kW (cannot cut in when
the compressor is running.)
9. The external auxiliary
heater does not start when
the heat pump’s control
computer requests it.
If an external auxiliary heater is used, check that it is cor-
rectly installed by test running it in MANUAL TEST –
EXT.AUX.HEATER - 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 ac-
cording to the instructions.
Measure the voltage on the I/O card’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 de-
mand.
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 produce at what sup-
ply 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 ex-
ample.
If the room requires a higher output than
the heating system can provide, extend the
heating system.
13. Changed conditions
Have you increased your
heating and/or hot water
demand?
▪
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 tem-
perature.
▪
If hot water consumption increases, a larger propor-
tion of time is used to produce hot water, which
means less time for heat production (only applies to
system solution 1).
If the heat pump cannot cope with the de-
mand, replace it with one with a higher
output or supplement it with a higher out-
put auxiliary heater.
Service Instructions
DHP-AQ
Danfoss Heating Solutions
VMGFJ202
25
