Danfoss DHP-A Service Instructions Manual page 22

Service instructions
Cause
4. The 3-way valve has jammed in
hot water mode.
5. Defective electric heating ele-
ment.
6. The heat pump has stopped on
HIGH RETURN.
7. Heat production is stopped by
the HYSTERESIS function.
22
Domestic heat pumps
Troubleshooting
1. Check the function of the 3-way valve motor
by test running it manually. If the motor does
not shift mode during manual test operation,
check that there is voltage to the motor, see
wiring diagram.
2. Detach the motor and test closing and open-
ing of the valve by pressing the control arm.
Use a buzzer and check if all coils in the electric
heating element are intact.
▪ 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 tem-
perature and the system's delta temperature
so that it does not cut at too high a return
temperature when the highest supply tem-
perature is transmitted.
▪ Check what the return line sensor shows. Is it
a plausible/actual value? If not, take a resist-
ance reading from the sensors and check
against the ohm table in the Measurement
points section 19.3.
If the flow temperature rises as soon as heat pro-
duction is stopped by HYSTERESIS before INTE-
GRAL 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 instal-
lation instructions for factory setting.)
▪ Check if heat production stops because ther-
mostats/valves in the heating system are
closed or partially closed?
▪ Check if heat production stops because the
heating system is under dimensioned?
VIGFI102
Remedy
1. Is the motor being supplied with volt-
age according to the wiring diagram in
both operating instances? MANUAL
TEST – REV.V. HOT WATER
0=Radiator mode, arm out from valve.
1=Hot water mode, arm positioned to-
wards the valve. If there is voltage to
the motor but the arm does not shift
mode, replace it.
2. Take out and clean the jammed insert,
or replace with a new insert.
If the electric heating element is defective,
replace it.
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.
▪ Try increasing the hysteresis value un-
til the heat pump stops on INTEGRAL
instead.
▪ Open thermostats/valves in the heat-
ing 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 (the heat emitting sur-
face increased).
Danfoss Heating Solutions