Heat pump: buffer tank, capacity and modulation

Not that. But the manufacturers state the max. power there, not the minimum possible power/maximum throttling.

At least for ours they have that listed there (as far as I have interpreted it correctly).

Morning,
I checked the temperatures yesterday morning. Outside temperature was around zero, flow temperature at 33 and return temperature at just under 28°C. You really can’t read those gauges exactly. In other words, I probably don’t need the spread of almost 10 degrees as in the heating load calculation...



Best regards,

Andreas

I have another question about the hot water storage tank. Our current offer includes a 190-liter hot water storage tank. Is that sufficient for a 4-person family? The heating engineer was not sure whether he should recommend 290 liters instead.

Depends on the showering and bathing habits. Is a circulation installed? A fresh water one?

No, at least I cannot infer that from the offer and do not remember that we talked about it.

An advantage of the larger storage is also that the temperature can be lowered enough so that sufficient hot water is available at all times, but also a daily circulation is ensured. Lower temperatures have a significant impact on the COP of the heat pump. For comparison: heating water is produced by my heat pump with a COP of 5.5-6, hot water at the highest setting (56°C) only just under 2. I have 300 liters and it is currently set to 42°C.