ᐅ Hybrid gas/air-to-water heat pump or gas with power-to-heat

Träumerle schrieb:

Could you explain that?

Gas plus heat pump means you are installing TWO heating systems. It’s quite a significant investment. In the end, it doesn’t matter whether you buy gas or electricity in winter. Financially, it’s about the same.

Träumerle schrieb:

I thought it was more economical than just an air-to-water heat pump, where we'd have to buy a lot of electricity in winter, or just gas, where we couldn’t use our own electricity for heating at all. So my logic was: before excess electricity is just fed into the grid, it could support the heating during transitional seasons or at least provide domestic hot water in summer.

In summer, the photovoltaic system produces hot water, but via the heat pump. In autumn and spring, it supports the heating, supplying part of the electricity needed for the heat pump. In winter, you buy electricity as usual.

Träumerle schrieb:

In winter, the photovoltaic system would never be enough and would cause significantly higher costs than a gas heating system.

The photovoltaic system doesn’t cause costs, it generates revenue. And gas consumption compared to electricity consumption is (more or less) the same.

So why install two heating systems in one house? Choose one system and install the photovoltaic system to go with it. Optimize your self-consumption and enjoy a good investment.

An existing house where the heating system is being replaced?
If yes, please provide some details about the house, such as previous consumption, etc.

Exactly as @nordanney says, you might save a few euros on consumption, but you won’t recoup the higher investment even in 100 to 200 years.

It’s either gas or an air-to-water heat pump; depending on the investment costs, the difference isn’t significant.

I’m a fan of air-to-water heat pumps combined with photovoltaics. I have no electricity or heating costs, and the investment averages about 1,000 €/year over 20 years.

Correction to the above, I actually meant to say: "In winter, however, the photovoltaic system would never be sufficient, and the air-to-water heat pump would incur significantly higher costs than a gas heating system."

Here are some details about the house:
- Large living area (approx. 270 sqm (2,906 sq ft))
- Built in ’66; insulation is rather average
- Windows are now being replaced halfway (the other half dates from 2008; only double glazed but in very good condition; we are postponing their replacement by a few years)
- Only radiators, no underfloor heating
- Last gas bill covered about 42,000 kWh; approximately 156 kWh/m² (14.5 kWh/sq ft). According to various online sources, this is slightly below average. However, I suspect our hot water consumption might be higher than that of the previous owners.

Regarding investment: If we receive a 30% BAFA subsidy for the hybrid heating system, the price difference between a gas condensing boiler and a hybrid gas-air-to-water heat pump would be significantly lower.

Motivation: The pure air-to-water heat pump option would of course be my preference from an environmental perspective. But I am concerned that this type of heating might not suit our house, since the high electricity demand in winter could make it uneconomical. So I considered how we can integrate a renewable energy component while still keeping the "reliable" gas for the cold winter months.

I have a question for @nordanney: Is gas consumption roughly the same as electricity consumption? What exactly do you mean (kWh / costs)? Sorry, I’ve only been involved in building topics for a few weeks and have some catching up to do...

Thanks for all your answers. I’m also looking forward to further critical feedback. Better to learn now than after the heating system is installed ;-)

For an energy-inefficient house like yours, only gas makes sense! You should have said that earlier ;-)

Träumerle schrieb:

The option of a pure air-to-water heat pump would be my favorite for environmental reasons, of course.

Only for new builds or appropriate renovations. And then only with green electricity.

Träumerle schrieb:

I have a question @nordanney: Gas consumption and electricity consumption are more or less the same? What do you mean by that (kWh / costs?)

In terms of costs.

Heat pumps are suitable for low-energy houses (new builds/renovations) with underfloor heating. To be effective, they require low flow temperatures. For your situation, it would definitely lead to a financial disaster.

Based on these figures, I would definitely go with gas at @nordanney.