Possible house purchase - air-water heat pump possibly a money pit

Let's take the 8000kwh and subtract for normal electricity, resulting in 6000kwh. Good air-to-water heat pumps with good hydraulics have a COP between 3.5-4.5. But even with a COP of 3, that would be 18000kwh of heat demand. That either sounds like 300sqm, poorly adjusted heat pump, or bad insulation. I would actually be cautious.

So, after I just briefly spoke with the seller again, his advance payment for electricity is actually €210 per month. So your bill is really correct. The house has 198 square meters, no insulation.

Regarding COP: A7/W35 heating capacity just under 10kW, COP 4.4.

Are these details sufficient?

It all seems a bit too much to me as well. Can the pump be adjusted better (if yes, how or what should I pay attention to) or is the missing insulation the limiting factor in the bill?
Thanks for your feedback

What does the energy certificate say regarding the annual primary energy demand? Not that you can take the values at face value, but if they are miles away from reality, then I would have some concerns... There is an energy consultation from the Verbraucherzentrale here for a very low price. Maybe you can make use of that and show up there with all the available facts/documents. The COP sounds okay at first (practical value or data sheet)?

There are no uninsulated houses from that year of construction. It may be that it was built with thick aerated concrete, which was then merely plastered. But such a wall structure is also insulated, namely the air in the stone is the insulation. I wouldn’t assume it is uninsulated. The pump is certainly not well adjusted, yet it will probably still be a hefty electricity bill even with corrected settings. But let's look at it differently. Do you like the house? Is it affordable? Even cheap? Then go for it. If you pay 210 for electricity, that’s 2520 per year. For energy. With gas, for a house that size, you’d have 1500 plus 800 electricity, totaling 2300,- So what, there’s always something. Karsten

How old is the house? The data you provided is probably from the datasheet. With the construction description of the house, you could estimate a heating load. Pay attention to insulation, etc. Also, windows are important. In some new houses, there are completely misadjusted heat pumps. That can be managed. But first, please provide data about the house.

COP is taken from the datasheet. Primary energy demand is 65 kWh per square meter per year. Thanks for the tip from the energy consulting at the Verbraucherzentrale.