I have an LG Therma V 16kW, that I recently added a modbus module to and can now access a lot more data and telemetry via Home Assistant
Combined with a Shelly energy monitor on the main power cable into the heat pump, I now have:
Power consumption in W
Water temp leaving in C
Water temp return in C
Flow rate in liters per minute
It seems that it's perfectly possible to calculate COP from this, especially as I have a good idea of the glycol mix in the water too.
The thing is, my pump also has a buffer tank, and at this time of year it's perfectly possible for, on the few occasions the water pump to be flowing and yet the heat pump compressor not actually be active. This seems to me to be heat that I have previously generated and am now only making use of...but it doesn't half push my COP up to high figures.
Is my methodology right here?