Posted by: @bontwoody

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The seem to think that the situation is the same as the Vaillant one

FWIW, the Vaillant app gives the energy efficiency (=COP) as (total heat generated including heat pump energy used)/ energy used. See this screenshot. However, the numbers don't quite add up.

Posted by: @bontwoody

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Using the adjusted calculation for the Samsung alters its COP to 4.76. Much closer to mine.

@bontwoody I think the fact that your Samsung displays generated energy as less than OEM generated energy whereas mine is the reverse may just demonstrate the inaccuracy of how Samsung measures flow rate and delta T. It uses external temperature probes whereas the heat meter uses pockets and paired probes. 

I monitored what Samsung was displaying as delta T and flow rate through ESPHome and it correlated well with its displayed heat output of around 4kW. After an hour of stable heat output, generated energy had increased by 4kWh. So I am pretty sure that generated energy includes electrical input energy and is different to the Vaillant. It is noteworthy that the latter calls it environmental yield. 

@mike-h Im not sure I follow you Mike. I can see that external temperature probes may differ from internal, especially if there is a long pipe run.

My interest in the correct formula is academic really, but there seem to be people on both sides of the fence.(see @technogeek here https://renewableheatinghub.co.uk/forums/renewable-heating-air-source-heap-pumps-ashps/new-heat-pump-owner-questions)

I think the argument about whether its called environmental yield or something else might be a translation one from the Korean.

Posted by: @bontwoody

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@mike-h Im not sure I follow you Mike. I can see that external temperature probes may differ from internal, especially if there is a long pipe run.

@bontwoody Sorry for the lack of explanation. I was taking my comment from Glyn Hudson's recent observation on the OEM forum - "I found the onboard Samsung flow and return temperature sensors are quite inaccurate, if you do a mass flow rate calculation to calculate heat delivered it could be significantly inaccurate because of the inaccurate onboard sensors. My Samsung is 20% out. Heat meters use matched pairs of temperature sensors in wet pockets, which have maximum 2% error."

I was concerned that users with poor COPs might be falsely reassured that all was OK if they added electricity usage to generation before dividing by usage. Of course, if the Samsung consistently underestimates generation, then the poor COP might be completely false and using the G+EU/EU formula might be closer to reality. But if it overestimates it as often as it underestimates it then using the correct formula might be more important. At the end of the day, if you are happy with your electricity consumption then that is what matters.

@mike-h Yes, totally agree about false reassurance Mike. I was thinking that an error would always be in the same direction but I guess that doesnt have to be the case.