ᐅ KfW 55: Choosing the Heating System – Gas vs. Air-to-Water Heat Pump

Hello everyone,
we recently spoke with the general contractor about the quote for a KFW55 single-family house.

We’re uncertain about the heating system. According to the contractor, for the subsidy we need either an air-to-water heat pump or a gas boiler combined with a ventilation system and solar thermal.

The contractor couldn’t clearly explain the pros and cons, only that the air-to-water heat pump is more commonly used and the gas combination with ventilation is more expensive (but then you do get ventilation and solar thermal).

We would prefer to avoid having the air-to-water heat pump unit installed in the garden, but are generally open.

Could you please share your opinions on the advantages and disadvantages?
Thanks,
GD

Both options are possible. I prefer an air-to-water heat pump. It is affordable, offers low heating costs with proper planning, and is future-oriented. I would also install photovoltaic panels and ventilation.

I prefer gas. Even cheaper, with even lower heating costs, but perhaps not quite as future-proof as an air-to-water heat pump.

The question is whether a ventilation system would theoretically also be necessary with an air-to-water heat pump. I would avoid solar thermal and prefer photovoltaic systems, as they are more efficient.

Have both options calculated for you (possibly including mechanical ventilation with heat recovery in the case of an air-to-water heat pump). In the end, both solutions will heat the water.

Strahleman schrieb:

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

Actually, this question doesn't really arise. If you’re not familiar with it, you don’t miss it. Once you know it, you never want to be without it. With today’s regulations and construction methods, it’s always advisable to have a controlled ventilation system.

Regarding the original poster’s questions:

It’s a matter of preference. It will take some time before gas prices rise to the level of electricity prices, and by then the system may already need replacement. If an air-to-water heat pump is a reasonable and practical option—not just a rough estimate—it might be worth considering.

It also depends on additional gas costs. (Is the supply right on your property, or would an expensive connection be required?)

In the long run, after a couple of decades, the costs tend to balance out. What you save on operating costs with an air-to-water heat pump typically goes into the initial investment and vice versa. Gas might be somewhat more expensive to consume, but a fully installed gas system generally costs only about a third as much (rough estimate).

I’m just going to mention the CO2 tax. The proposals from the SPD and the Greens will make gas significantly more expensive than before. Who knows what else might come.

Why does everyone always say that gas heating systems are so cheap to install, while heat pumps are so expensive?