Vaillant 7kw Arotherm Plus cop for last few days 2

[Andre_K (André Kühne)]

Thanks for the data. A 2K dT is quite low but can be benign. Im leaning towards your true dT being higher and your heat pump having a particularly bad set of temperature sensors that make dT appear lower than it is, translating also to an awful COP. Can you follow the procudures done in this thread:

Why doesn't a low flow temp translate into a decent COP

Great, now we’re getting somewhere . From your earlier measurements we have T_{flow} = 31.3 °C and T_{return} = 28.8 °C. Now we also have the offset between themas measured by T_{flow} - T_{return} when the compressor is off, which is T_{off} = -0.6 °C. The measurement of heating power directly depends on the difference between flow and return temperature \Delta T, in your case \Delta T_{meas} = T_{flow} - T_{return} = 2.5 °C. But this includes the incorrect offset, so we have \Delta T_…