Renovate/extend the house, keep the heating?

Good morning!

We are renovating a fully basemented bungalow, i.e. it will be slightly expanded, topped up, and refurbished. The bungalow currently has about 100 square meters on the ground floor plus an extension with 60 square meters. There are radiators in every room, i.e. no underfloor heating. The expansion is supposed to bring the ground floor to 110 square meters, the first floor to the same size, and the extension remains the same size.

However, there is a nearly new gas heating system in the basement, about 1.5 years old:





Next to it stands a man-high Weishaupt storage tank. We would like to install underfloor heating in the house (ground floor and first floor, the basement could remain with radiators). Now the question arises whether we can use this equipment for that or if it needs to be removed and replaced with a "new" one.

Is it even possible to say based on my information? A heating engineer has not yet been involved; I just wanted to roughly find out in advance whether this even has potential.

So you will have 270 sqm? Due to the renovation, it must then be brought up to the energy saving ordinance standard.

Then I’ll take a look into my crystal ball and claim that the heating will easily be sufficient, or even too large.

Have a heat load calculation done, room by room. You need that anyway for the design of the underfloor heating.

I would keep the heating until it kicks the bucket.

In terms of performance, the over 20KW should easily be enough. We heat 220m2 + basement with 19KW and there is still reserve. From experience, I can say that the mixed operation (underfloor heating + radiators) is actually rubbish. You still need a high flow temperature for the radiators and in addition, you then have 2 heating circuits with 2 pumps, a mixer, etc. If I could change that with reasonable effort, I probably would.

Hello Hello

The gas heating should cover the required power.
As it looks, there are already two heating circuits present, presumably without a mixer.
Were there two separate apartments in the house?
The hot water generator appears to be an exhaust air heat pump.

Olli