Danfoss DHP-A Service Instructions Manual page 23

Service instructions
Cause
8. The auxiliary heater is not permit-
ted to cut in with sufficient output.
Value set too low on MAXSTEP.
MAXSTEP 1 = 3 kW
MAXSTEP 2 = 6 kW
MAXSTEP 3 = 9 kW
MAX STEP 4 = 12 kW (only DHP-A )
MAX STEP 5 = 15 kW (only DHP-A )
MAX STEP +4 = 12 kW (only DHP-A )
MAX STEP +5 = 15 kW (only DHP-A )
9. The external auxiliary heater does
not start when the heat pump's
control computer requests it.
10. Closed or partially closed ther-
mostats/valves in the heating sys-
tem.
11. The total output of the heat
pump and auxiliary heater is too
low in relation to the building's
power demand.
12. Under dimensioned heating sys-
tem.
13. Changed conditions
Have you increased your heating
and/or hot water demand?
Danfoss Heating Solutions
Domestic heat pumps
Troubleshooting
Check the set value on MAXSTEP in the heat
pump's control computer.
If an external auxiliary heater is used, check that it
is correctly installed by test running it in MANUAL
TEST – 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.
Check that the thermostats/valves in the heating
system are open.
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?
Check existing heating system.
What output is it dimensioned for to produce at
what supply temperature?
What output is required to keep the room warm?
▪ 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 wa-
ter, which means less time for heat production
(only applies to system solution 1).
Remedy
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
MAX STEP 4 = 12 kW (only DHP-A , cannot
cut in when the compressor is running.)
MAX STEP 5 = 15 kW (only DHP-A , cannot
cut in when the compressor is running.)
MAX STEP +4 = 12 kW (only DHP-A , can cut
in when the compressor is running.)
MAX STEP +5 = 15 kW (only DHP-A , can cut
in when the compressor is running.)
Connect the external auxiliary heater ac-
cording to the instructions.
Measure the voltage on the I/O card's
probe L2 Oil/Electricity.
Open closed thermostats/valves.
Ensure that available power is at least as
great as the building's power demand.
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.
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.
VIGFI102
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