Struggling to get good COP from Daikin 9kW

[squarepeg77 (Jonathan)]

Back up heater
One more thing, consider turning off the back up heater:

Daikin 9kW ASHP application discussion

Hi @squarepeg77 Here is the relevant info: Disable BUH through configuration: Daikin Controller —> Installer settings —> Backup Heater —> Operation —> “Restricted” Check running hours here (mine is still 0hrs since September’22) Daikin controller → Information → Running Hours → BUH Also as covered in these links, I’ve flipped the switch for the BUH breaker in the consumer unit outside next to the heat pump:

The wisdom here is that we don’t typically need it in the UK. If you find your system is unable to heat your home or hot water during a cold snap, you would re-enable it. But it seems to come on more often than it should in normal operation, and is just a 3kW electric heater with a COP of 1.0.

There might be an argument that it helps the system get up to temperature more quickly, but most people here who are getting good efficiency have the BUH disabled.