Daikin Altherma periodic low COP phenomena

[alibloke (Ali)]

It looks quite similar to this issue. AFAIK it was never resolved:

Something has gone quite wrong with my 8kW Daikin today!

I don’t know what has happened and I have never seen it behave like this before. I haven’t changed anything. There is no back up or booster heater, I don’t even have feeds for them anymore and my Daikin doesn’t have a back up heat anyway. Ignore the room temperature as the sensor is on top of a radiator that I keep forgetting to move. This is today [image] And this is normal [image] Any ideas?