ᐅ Heating System for New Single-Family Home: Air-to-Air or Air-to-Water?

That is not entirely accurate. Both are surface heating systems and operate in a similar way. With underfloor heating, the radiant heat portion is higher than the convective portion, but not as high as with ceiling heating.

Thanks for the tip (radiation), but with radiation heating, the surface area needs to be relatively large, which is difficult to achieve with warm water pipes. With a high pipe density, the supports also have to be more complex than simply fixing the pipes to the floor. If a covering is added to hide the pipes, the efficiency will likely decrease further. Therefore, in practice, this is probably offered more often as electric panels, which I have also barely seen, so I do not consider it because the effort does not seem reasonable to me. (My subjective opinion)
@hegi___
Currently ~8°C (46°F) average outdoor temperature – inside everything at 21°C (70°F) / postal code Berlin / wall 25cm (10 inches) Ytong plastered,
Supply temperature 50°C (122°F) return 25°C (77°F) // ground floor area ~120m² (1,292 ft²) underfloor heating // roof ~50m² (538 ft²) radiators (not all heated) oil consumption only winter (off in summer, hot water electric) 1,800 liters (475 gallons)
Hot water nonsense – why? I tested it practically and found that even on the west side (at least during summer operation) I generate enough hot water to shower. I now produce my hot water with an average of 3 kW electric per day.
30 days = 90 kWh (30 cents) = $27 per month. Summer 6 months = $162
Flat plate collector (cheap version Cu-Aluminum – was also my test device) 180 each, 3 pieces = 540
540 divided by 162 annually = 3.3 years.
This seems reasonable and acceptable to me. Payback periods over 15 years, which get even longer due to repairs, are unacceptable to me (who knows if I will still be around!) and in my opinion are only for bankers or futurists. The former have already proven (in 2008) how precise their forecasts are.
In anticipation of criticism about the calculation above: Yes, I know, installation costs are not included and it’s not entirely accurate. But I’m a semi-DIY expert and can handle that easily. I feed it directly into the heating coil of the hot water boiler because the heating is off in summer, saving the heat exchanger, which would also cause losses.
The often praised “super” photovoltaic systems, I have dismissed for now after reviewing all the information. Even Prof Quaschning (following link), who carefully calculates, has to admit that the kW output in our latitudes isn’t exactly the best option. Looking at past experience, where profits have decreased due to falling feed-in tariffs, I am skeptical for the future. Optimization with VAT refunds and small business taxation doesn’t help much either.
As posted often here, it’s not done with an Excel spreadsheet!
[MEDIA=YouTube]3F_5hljAKjI[/MEDIA]

By the way: A friend recently told me he had an unexpected expense again. He had his photovoltaic system washed with distilled water because he was told it would bring the efficiency back to like-new condition. I don’t know if it was a scam or if it actually makes sense.
So: Greetings to the photovoltaic users who today, when looking out the window, can only shed tears when looking at their meter. (At least it’s raining for me.)
Don’t be sad, the rain is at least cleaning your panels.

In the annual performance factor calculator, you cannot enter such a low supply temperature, but with a 40°C (104°F) return temperature, the annual performance factor comes out to 4.

It could definitely be worthwhile with a Geisha air-to-water heat pump. Additionally, there is over 30% Bafa funding available.

Using your low-cost solution for hot water can be profitable in that case. Normally, however, it usually isn’t.