Cause
Troubleshooting
Remedy
3. Defective 3-way valve motor.
The motor should set the valve to the
relevant position depending on oper-
ating conditions. If it does not, hot
water from the water heater will mix
with the radiator water.
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.
Is the motor being supplied with voltage
according to the wiring diagram in both
operating instances?
MANUAL TEST – REV.V. HOT WATER
0=Radiator mode
1=Hot water mode
If there is voltage to the motor but it
does not shift mode, replace it.
4. Jammed reversing valve.
If the valve is not sealed, hot water
from the water heater will mix with the
radiator water.
Detach the motor and test closing and
opening the valve by turning the shaft by
hand.
If it is sluggish or jams, replace with a
new one.
Table 22.
Problem – Irregular indoor temperature
Cause
Troubleshooting
Remedy
1. The heat pump’s control computer
is not set/adjusted to the customer’s
requirements/wishes.
Check the ROOM and CURVE, MIN, MAX
CURVE5, CURVE0, CURVE-5 and HEAT
STOP settings.
Adjust incorrect values in the heat
pump’s control computer.
ROOM = Desired indoor temperature
CURVE = Should be set so that the
desired indoor temperature (ROOM) is
maintained regardless of the outdoor
temperature.
MIN = Lowest set-point value on the sup-
ply line regardless of the outdoor tem-
perature (on the condition that heat stop
does not apply).
MAX = Highest set-point value on the
supply line regardless of the outdoor
temperature.
CURVE5,0,-5 =
The supply temperature can be adjusted
up or down 5°C at these outdoor tem-
peratures.
HEAT STOP = Stops all production of
heat when the outdoor temperature is
the same as or greater than the set value.
To exit heat stop the outdoor tempera-
ture must drop to 3°C below the set
value.
2. Incorrectly positioned/installed sen-
sors.
Check that outdoor sensors and any room
sensors are installed according to the
instructions and that they are calibrated.
•
Check that the room sensor is posi-
tioned in a suitable place that is rep-
resentative of the building and cali-
brate it if necessary. Avoid placing
near external doors, windows and
heat sources.
•
Install the outdoor sensor according
to the instructions and calibrate it, if
necessary.
Service instructions VMGFJ102 – 27
