Air heat pump or use gas and solar?

I have now received an updated heating concept. Endless documents. What exactly do I have to look for to see that I can replace a gas heating system with a heat pump in 20 years without any concerns? This is not recognizable for a layperson. I am happy to post the relevant documents.

There is a so-called "pipe network calculation", which lists as calculation parameters at the top:
Supply temperature 35°
Return temperature 30°

Then they sent me a "heating diagram". A sheet with technical jargon.

Heating surface design

Heating load calculation

I have now received an updated heating concept. Endless documents. What exactly do I need to look for to see that I can safely replace a gas heating system with a heat pump in 20 years? This is not recognizable for a layman. I’m happy to post the relevant documents.

There is a so-called "pipe network calculation," which lists the calculation parameters at the top:
Flow temperature 35°
Return temperature 30°

Then they sent me a "heating diagram." A sheet with technical gibberish.

Heating surface design

Heating load calculation

One of the previous posters already wrote that it’s probably more about whether you can achieve the desired room temperature (24 degrees in the bathroom? Rest 20-22 degrees?) in the living areas/bathroom with the flow temperature of the heating system, for example 35 degrees.

Exaggerated example:

With a floor heating flow temperature of 30 degrees, you won’t get 35 degrees room temperature.

In new buildings, most people reach 21-22 degrees room temperature even with flow temperatures of 28-35 degrees due to good insulation and narrow pipe spacing.

The narrower the pipe spacing, the lower the flow temperature can be, since more heat is transferred through the floor; if the pipe spacing is larger, the flow temperature would have to be increased.

The plumbing companies we dealt with always referred to the important pipe spacing when it comes to switching from gas to heat pump, which cannot be easily changed afterward. For me, this meant the rest could be "easily" changed afterward.

At least that made sense to me because, as already described, a heat pump would operate highly inefficiently if the pipe spacing, for example, were 20 cm to exaggerate. Gas would probably be cheaper then but also far from sensible to illustrate the point.

All information without guarantee.

In case of doubt, it’s best to ask the heating specialist again which conditions (in his opinion(!)) are required for a switch.

Hello, that is the nature of things, everyone considers their concept to be the best!
Purely from an investment perspective, air heat pumps and GAS+connection costs are usually on par. In order to evaluate the investment of a technical solution, the actual demand (performance, energy) for heating and hot water must be known.
Wrong. Both the energy saving ordinance and KfW require compliance with two parameters: Ht´and qp´´! Who is the culprit?
Gas has the fundamental disadvantage that usually a solar thermal system must be installed, unless you fall back on the 15% rule. If you definitely want to stick with gas, you should absolutely implement this in order to avoid an uneconomical solar thermal system.
General statements without reliability, completely pointless! Hello, but here the problems begin. If an air heat pump, then only with full modulation! Unfortunately, these providers cannot do that!
That is an essential criterion besides the capital service. However, it can only be answered when the essential basics are clarified. => actual demand. Until then, it is all guessing, assuming, and presuming. Overall, not a reliable or dependable basis for a significant investment decision.

Best regards

NB: Forum posts do not replace the necessary planning/dimensioning of the system. Some "advice" from anonymous hobby experts lacks any basis

Oops.....can you explain to me the possibility of the 15%-rule regarding gas and solar thermal system? I am considering using liquid gas for the new building since there is no gas connection and I might not want a blower in front of the house. Also, we currently have it here and it works completely trouble-free. Our plot is large, so sinking a tank would not be a problem.

Oops.....can you explain the 15% rule to me regarding gas and solar thermal systems? I'm considering using liquefied gas in the new building since there is no gas connection and I might not want a blower in front of the house. Besides, we currently have it like this here and it works completely fine. Our property is large, so sinking a tank would not be a problem.

If you have a large property, you might want to consider a ground source heat pump and get some information about the trench collector for that.

Today I visited a local construction company to get a quote. I wanted to have a photovoltaic system + air-to-water heat pump. Both the architect and the managing director of the construction company said that we would never recover the additional costs for the air-to-water heat pump through savings on operating costs. Gas + photovoltaic results in approximately €200-300 additional heating costs. He proposed a gas boiler + photovoltaic with about 10 kW + battery storage.

I am now a bit confused. Is an air-to-water heat pump really worth so little?

Would you take a gas connection if you don't have a gas heating system? If not, then you also have to consider that a gas connection + maintenance gas + heating etc. also incur ongoing costs. I actually don't believe that an air-water heat pump is overall really more expensive (+ the synergy of an air-water heat pump with photovoltaics is greater than with gas, for example, you can very often heat the hot water storage tank with solar power at noon).