Gas condensing boiler, air-water heat pump, fuel cells - please advise

2. But leave out the solar thermal system, that should be possible if you have controlled residential ventilation with heat recovery.

I wouldn’t leave out the solar thermal system; I can’t quite understand this recommendation. From April to September, we get hot water on 75% of the days without gas costs. And the creator specifically said that bathing is done daily (like us, at least 2 bathtubs daily).
For me, the solar thermal system is definitely beneficial!

Hi,

if possible, I would also leave out the solar thermal system. It was still no problem for us, but it might be more difficult now after the latest Energy Saving Ordinance. It is certainly not mandatory, you just have to meet certain efficiency requirements in the overall package. How you do that is your business!
Why leave it out?
Quite simple: it’s not economically worthwhile. (at least for us)
It would have cost us about €5000 and from our old house we know that it feeds no more than max 10 kWh into the storage per day. It just couldn’t do more, then the storage was already at 65-70 degrees. On top of that, the control system was so stupid that after the morning shower it reheated with gas instead of just waiting for 3 hours. I was able to reduce this reheating, but couldn’t turn it off. The tradesman explained it to me with some regulations and rules. Whether that’s true or he was just incompetent, no idea.
Anyway:
it ended with the system producing just 1000 kWh of heat per year. If you use a lot of hot water, let it be 2000 kWh for you. But only if you bathe the child during the day, with morning and evening hot water use it reheats with gas...
2000 kWh gas consumption is about €100 savings per year. For the additional €5000 investment, you pay €60-80 in interest alone. That puts the ROI in the range of 125 to 250 years.
I enjoy excellent health (*knock on wood*), but that is clearly far beyond my personal time horizon.

Best regards,

Andreas

Solar thermal energy is mandatory with gas or oil.

That is incorrect. The standard Energy Saving Ordinance house of many general contractors here in the area is without solar thermal, many previously had solar thermal but now do not. So it is definitely possible, you just have to see what makes more financial sense for you. If the child now bathes a lot, solar thermal can also be worthwhile, but if they no longer do so next year, the calculation looks different again.

That is wrong. The standard energy-saving ordinance house of many general contractors here in the area is without solar thermal (ST), many had ST before but now are without it. So it definitely works, you just have to see what is more economical for you. If the child now bathes a lot, ST can also be worthwhile, but if they don’t do that next year anymore, the calculation looks different again.

Then quite clearly a air heat pump is sold (higher margin). Or both worlds are sold: gas for heating, heat pump with integrated storage for domestic hot water. (Also a good margin).

Whether something makes sense unfortunately has to be calculated or questioned by oneself nowadays.

But gas or oil without additional technology doesn’t work. In the standard energy-saving ordinance, controlled residential ventilation is certainly also omitted.
So where is the share of renewable energies supposed to come from?

PS. I don’t think much of solar thermal. Before that, I would install a photovoltaic system. But to my knowledge, that is not credited in the energy-saving ordinance...

Gas and controlled residential ventilation with heat recovery is indeed a great economic and comfortable combination!

There, a simple air heat pump is clearly sold (higher margin). Or both worlds are sold: gas for heating, a heat pump with integrated storage for domestic hot water. (Also a good margin).

But gas or oil without further technology is not possible. With standard energy saving regulations, controlled residential ventilation is certainly omitted.
So where should the share of renewable energies come from?

No, completely off. Gas condensing boiler plus controlled residential ventilation with heat recovery but without ST is the standard in energy saving regulations.