Danfoss Heat Pump Troubleshooting Guide download pdf (Page 3)

VMIFB202

Troubleshooting Guide Working pressostat and high pressure pipe

The operating pressure switch does not close

Switch o the main switch for the heat pump, wait until the compressor has been stationary for at least 10-15 minutes. Using the

buzzer, check if the operating pressure switch is closed or not.

Action:

Check that both the cables for the operating pressure switch are in position If the pressure switch is closed, bridge the operating

pressure switch cables temporarily and switch on the voltage to the heat pump again. if the compressor now starts in auto or in manual

test there might be a fault in the operating pressure switch, replace the operating pressure switch.

If the indication 0 is displayed in the lower left hand corner of the display it means that the operating pressure switch or discharge pipe

sensor has broken the circuit. In normal operation this is displayed after completed hot water production but can also be shown at high

supply temperature in the heating system or if one has too low a ow over the heat pump.

If the pressure switch is open, try carefully tapping the head of the operating pressure switch with a screwdriver and use a buzzer test

to see if it has closed again.

Replace the pressure switch if it appears to jam repeatedly in the open position.

Fault in sensor, it shows the factory setting value or equivalent >120-140°C

Check what the sensor shows. Is it a plausible/actual value? The factory set stop value is within brackets.

Measure the resistance of the sensor, check against the ohm table in the installation instructions or see the end of the document.

Action:

If the sensor is defective, replace it.

The image shows

bridging on the

operating pressure

switch

The image shows an

open operating

pressure switch or

too high discharge

pipe temperature

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Danfoss Heat Pump Troubleshooting Guide Page 3