Kfw55 choice of heating Gas vs Air-Water Heat Pump

Hello everyone,
we recently spoke with the GU regarding the KFW55 single-family house offer preparation.

Regarding the heating question, we are undecided. According to GU, for the subsidy, we need either an air-to-water heat pump or a gas boiler + ventilation system + solar thermal system.

GU could not properly name the pros and cons, only that the air-to-water heat pump is more commonly used and the gas combo around the ventilation system is more expensive (but then I also have ventilation and solar thermal).

We would like to avoid the air-to-water heat pump box in the garden, but are generally open.

Could you please post your opinions on the advantages and disadvantages?
Thanks, best regards GD

Both are possible. I prefer air-to-water heat pumps. Affordable, low heating costs with reasonable planning, future-oriented. Would then additionally install photovoltaics. Ventilation as well.

I prefer gas. Even cheaper, even lower heating costs, but perhaps not quite as future-oriented as [Luft-Wasser-Wärmepumpe].

The question is whether theoretically a ventilation system would also be necessary for an air-to-water heat pump. I would not do solar thermal, rather photovoltaic, as it is more efficient.

Have both calculated for you (possibly also with the [Kontrollierte-Wohnraumlüftung] in the case of an air-to-water heat pump). In the end, the water gets warm with both solutions.

The question is whether, in theory, a ventilation system would also be necessary with an air-water heat pump.

The question actually doesn’t arise. Those who are not familiar with it do not miss it. Those who know it never want to live without it again. With today’s regulations and construction methods, always with controlled residential ventilation. Regarding the questions of the OP: It is a matter of belief. It will still take a while until gas becomes as expensive as electricity, and by then the system may already need to be replaced. If an air-water heat pump is sensibly feasible and not just roughly estimated, then possibly take that route. It also depends on the ancillary gas costs. (Is it right outside the door or does it need elaborate connection?) In the end, after a few decades, it all costs about the same. What you save in operating costs with the air-water heat pump goes into the investment and vice versa. Gas is possibly somewhat more expensive in consumption but the fully installed system costs only about a third (roughly speaking).

I only say CO2 tax. The demands of the SPD and the Greens will make gas significantly more expensive than before. Who knows what else is coming. Why does everyone always say that gas is so cheap to purchase or that the heat pump is so expensive?