Specifications
60 – Service VMBMH302
Problem – irregular indoor temperature
Cause Troubleshooting Remedy
1. The heat pump’s control com-
puter 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
supply 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 tem-
perature.
CURVE5,0,-5 = The supply temperature
can be adjusted up or down 5°C at these
outdoor temperatures.
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 temperature
must drop to 3°C below the set value.
2. Incorrectly positioned/instal-
led sensors.
Check that outdoor sensors and any
room sensors are installed according to
the instructions and that they are cali-
brated.
• Check that the room sensor is positioned in
a suitable place that is representative of the
building and calibrate 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.
15.4.6 Other
Problem – The heat pump runs and runs but never stops
Cause Troubleshooting Remedy
1. Air in the heating system. Listen for air in the heat pump and hea-
ting system.
Bleed the heating system according to
the installation instructions.
2. Lack of refrigerant, not enough
refrigerant in the system.
Using manometer apparatus and ther-
mometer, check that the unit’s overhea-
ting is correct for the specific refrigerant.
Follow the correct procedure (depending
on type of refrigerant) to add the correct
amount of refrigerant.
If there appears to be a leak in the refri-
gerant circuit, carry out leak tracing and
any necessary corrective action. If leak
tracer is not available, brush soap water
on the suspected leak and look for bubb-
les. Also check for oil as this can come
out from the refrigerant circuit.
3. 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 proportion of time is used to
produce hot water, which means less
time for heat production (only applies to
VL-systems).
If the heat pump cannot cope with the
demand, replace it with one with a hig-
her output or supplement it with a hig-
her output auxiliary heater.