Heating with air-water heat pump with cooling function

Hello,

...Does this mean that it is a game of chance?

If you forego an exact plan/calculation, with high probability.

... I'd rather stick with gas and the house is definitely warm.

You can get it sufficiently warm with any heat generator, provided the design is correct.
With gas, the option to "cool" is missing and mostly an uneconomical solar thermal system has to be "purchased along" in a single-family house if no substitute measures (EEWG) are planned.
With a heat pump, also an air heat pump, for example KFW 55 is possible even without a solar thermal system. The additional repayment subsidy is not uninteresting.

Best regards.

Hello Bubb,
slightly oversizing is not a problem, the heat pump regulates its output downwards by itself! That means it runs in partial load operation. The reason I prefer 3-phase devices is because their lifespan is much longer than that of single-phase devices. And the smallest 3-phase heat pump has 11.2 KW, but as I said, you can set it to partial load operation where it runs even quieter and more efficiently. I see no disadvantage here.
At 28°C, it is a completely normal flow temperature for new buildings, it is very well insulated from below, and the heat naturally moves downwards. You just have to lay the pipes very close together, then it works.
As I said, many of my colleagues have done it this way and are all satisfied.

Sorry, I didn't mean the Bubb but the €uro I have the feeling, the colleague knows a lot about everything

Has anyone had longer experience with an air-to-water heat pump? So more than 1 year and can say something about the electricity costs?

My builder claims that the monthly costs are lower than with a gas condensing boiler.

I am a bit skeptical because the air-to-water heat pump works worse at colder outside temperatures. On cold days, you even have to heat electrically with heating rods.

The builder claims that the average monthly costs over the year are only 50€ (KfW70 and 120m² semi-detached house) and that a gas condensing boiler would cost about 70€ with the same consumption.

Do you think that is accurate? Then the air-to-water heat pump would speak in its favor for me. I would also save the gas connection.

Hello,

So more than 1 year and can say something about the electricity costs?

The question is quite strange! Comparable to: Which car is more efficient, the red one or the green one.
In other words, any answer would be wrong!

...My developer claims the monthly costs are lower than with a gas condensing boiler.

You can claim almost anything. A developer probably won't be the one, but a general contractor!

...I am a bit skeptical because the air-water heat pump works worse at colder outdoor temperatures. On cold days, it must even be heated electrically with heating rods.

That can be, but does not have to be a disadvantage! It depends on the characteristic curve and the bivalence point! With good planning, the pure share of the heating rod is only about 0.8...2% of the annual heating work, depending on the climate location. Usually, general contractor systems are poorly or not planned at all, then the heating rod can become a nightmare.

...The developer claims that the monthly costs average only €50 over the year (KfW70 and 120m² semi-detached house) and that a gas condensing boiler would cost about €70 with the same consumption.

I would send the "developer" into the desert because he understands absolutely nothing about building services engineering. At best, the demand can be the same, but the consumption is always higher with conventional heat generators, lower with heat pumps. But beware: here kWh are meant, not €!

...I would then also save.

Anyone who wants to save must first invest, i.e., proper and sales-independent professional advice and planning; otherwise, only one will make the business—and with very high probability, that will be the general contractor!

Best regards

Hello Wallace, The good air heat pumps already have a good efficiency at lower temperatures. Take a look at Mitsubishi Zubadan, the air heat pump heats at -25°C without an electric heater, which is not even connected to the heat pump. And 50€ per month (average) is realistic. I would just not do without a stove. We are building 130 m² living space this year also KfW 70, according to my calculations I should not exceed 50€. You just have to design the underfloor heating with the lowest possible flow temperature (about 28-32 °C), then the efficiency is even higher. Regards Max