Danfoss Heat Pump Troubleshooting Guide download pdf (Page 29)

VMIFB202

Incorrect ow in the brine circuit

Action:

Check the dierence between the supply and return line using a digital thermometer. The dierence should not be more than 4°C . A

greater delta-t results in reduced eciency in the heat pump. If the dierence is greater than 4°C note what is causing it.

Example: Dirt in the lter, system restrictions, system with high pressure drop.

The interval for peak heat operation has changed to a lower value than the factory set value.

This results in the heat pump going into peak heat operation more often than calculated

Action:

Check the specied interval for peak heat operation in the control computer, see instructions for relevant model.

If there is a shorter interval between the peak heat productions, this explains why the unit consumes more current than calculated, but

this does not mean for sure that it should be increased, there might be a reason why the interval has been changed.

The heat pump has stopped on HIGH RETURN

Action:

Check what the MAX RETURN value is set at in the heat pump’s control computer.

Check what the return line sensor shows. Is it a plausible/actual value? If not, take a resistance reading from the sensors and check

against the ohm table in the installation instructions.

The value of MAX RETURN in the heat pump control computer should be adapted to the unit’s maximum supply temperature and the

system’s temperature delta. It must not break at too high return temperature when the highest supply temperature is sent out. If the

MAX RETURN value is

not adjusted for the system according to the troubleshooting window, adjust it. If the sensor is defective, replace it.

The compressor runs backwards

Action:

Check that the phases for the heat pump are correctly connected (only applies to 3-phase heat pumps).

If the compressor runs backwards, it will not cope with compressing the refrigerant and therefore does not produce the correct power,

which leads to the control computer requesting auxiliary heating.

If the phases are in the incorrect order,

reset the two incoming phases at the main terminal block L1 and L3.

When the compressor is running, check the pressure pipe temperature by feeling the pressure pipe. If the phases are correctly sequen-

ced it should be hot (not just warm) even a distance from the

compressor if the phases are in the correct order.

When the compressor runs with the phases incorrectly sequenced a strange noise may be heard (loud, rattling) when the compressor

runs backwards.

Lack of refrigerant, not enough refrigerant in the system

Action:

NOTE! A refrigeration technician with the correct qualications is required for work on the refrigerant circuit

Using manometer apparatus and digital thermometer, check that the unit’s overheating is correct for the specic refrigerant.

Check that the unit cooling is correct in the same way. See separate instructions for cooling techniques.

If cooling is not at the correct level compared with the specic refrigerant and is too low, there is insucient refrigerant in the unit.

Add the correct amount of refrigerant (depending on type of refrigerant).

If there appears to be a leak in the refrigerant 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 bubbles. Also check for oil as this can come out from

the refrigerant circuit.

Troubleshooting Guide High operating time additional heater

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Danfoss Heat Pump Troubleshooting Guide Page 29

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