Power Cut - Heat Pump Evaporator Iced Up

nxdmsandkaskdjaqd

We had a power cut last night and 1 hour later power was restored.  The heat pump was iced prior to the power going out.  Once power was restored the unit powered up again and after 30 minutes I became nervous that the evaporator was at -20C, fully iced up, hardly any air flow across the evaporator, so I have shut it down.

How do you deal with the above situation and a iced up evaporator?

What would of happened if I had let it run in this iced up situation?

Did I do the right thing by turning off, or should I have let it run?

BTW, R32 refrigerant.

matelodave

Have you got TRVs and or thermostats indoors that are controlling the heatpump.

Its not air over the evaporator that defrosts it. Generally heatpumps reverse the flow through the system and extract heat from the circulating water to enable defrosting.  However external controls, especially TRV's, zone controls or that stop the circulating pump can reduce the volume of circulating water and will prolong the defrost cycle (or even prevent it from completing)

My unit tended to ice up and defrost quite a lot before I disabled the external controls and let the unit use weather compensation to control the house temperature. It now runs longer at a lower flow temperature and generally only produces ice when its really cold and damp outside. (we are surrounded by fields in the fens and it gets very damp and misty). We just now see puff or two of vapour from the outside when the system defrosts itself rather than a thick coating of frost or ice.

Normally you are better off letting the unit doing its own thing rather than panicking and shutting it down because all you've done is stopped all flow through the system and allowed it to stay iced for longer.