Samsung measures the electricity use pretty accurately, although it doesn’t include the power used by the pump(s).
However, Samsung does a very poor job of measuring heat output. At least on my system, the heat output displayed by Samsung is 30% less than my heat meter. I think this is party down to Samsung assuming glycol is used (I’m not using glycol) and party due to the Samsung temperature underreporting the temperature of the flow/return. Samsung’s temperature measurements are about
1° C below what my MID approved heat meter and my own digital DS18B20 sensors report. 1° C equates to about 1kW difference at a flow rate of 16.5L/min e.g yesterday Samsung reported 33kWh of heat while the heat meter reported 50.7kWh.
The result of this is that in December Samsung reported a COP of 2.9 while my MID approved heat and electricity meters reported a COP of 3.9.
I’m inclined to believe the readings from the MID approved meters, I’ve also double-checked the temperature readings from the heat meter which another set of independent sensors and confirmed that Samsung’s readings are wrong. What I’m not sure is do all Samsung ASHPs underreport heat deliverd? Or is it just my unit? It would be interesting to find another Samsung with a heat meter fitted to compare.
Here’s a graph comparing the dT between the Sontex (heat meter) temp sensors, some DS18B20 strap on digital temperature and the Samsung sensors as reported via Samsung modbus, as you can see the Samsung dT is significantly lower by an average of 0.5C:
My guess is that Samsung’s sensors are negatively affected by the outdoor temperature, since they are strap on sensors located in the outdoor unit. The heat meter uses wet pocket sensors to accuracy measure the temperature of the water. Here’s a photo of one of the Samsung sensors inside my ASHP, this sensor is on the evaporator rather than the plate heat exchanger, but I’m guessing the other sensors are the same:
Here’s a photo of the heat meter and the temperature sensor pocket-tee:
