What type of heating is used in old buildings?

Hello,

next year we want to renovate my parents' house and move in.

On the ground floor my parents live, who heat with simple wall-mounted radiators. (The radiators are to remain)

On the upper floor and attic we want to do a "core renovation".
This topic also includes replacing radiators...
Is it more sensible to keep the existing radiators, or to install underfloor heating?
I have heard that there are already underfloor heating systems that can be installed over the screed... What are the experiences with this? Are they just as good as the underfloor heating systems installed in the screed?

In addition, we want to install a completely new heating system in the basement. (We want to share the heating system with my parents. Each will then receive their own heat meter).
Which type of heating system is recommended nowadays?
Currently, I am considering installing a gas heating system in combination with solar. Are there supply temperatures, cheaper or alternative methods?)
How many solar panels do I need (4 adults and 1-2 children live in the house)? We have a usable area of about 250 m². The living rooms are mainly heated by means of a wood stove (in the evenings and on weekends).

Hello,

the combination of underfloor heating with radiators is certainly possible, but it would definitely make sense to provide 2 separate heating circuits here, since you probably need higher flow temperatures for the existing radiators of the parents than for the underfloor heating. Regarding the consideration to keep old radiators or install underfloor heating, the budget is certainly a decisive factor and also whether the radiators are sufficiently sized to achieve the desired temperature, but this must be assessed by a professional on site and with the help of a heat load calculation.

Yes, there are various systems that can be laid on the existing screed, the question here is how to deal with the height differences or whether the room height is still sufficient and again certainly also a question of budget. Now regarding the heating systems: currently, for a typical house, most heating systems are roughly on par in terms of overall costs; with regard to purchase costs, which are often the decisive factor, gas condensing boilers certainly still have a clear advantage. Regarding the size of the solar panels, it is difficult to make a statement without further knowledge about the location, orientation, inclination, and shading. But here, too, I would have a professional planner carry out the dimensioning; investing a little more here is certainly not money wasted.

Best regards Erik from moderne-heizung