Old building renovation - gas heating + radiators or underfloor heating?

Hello everyone,

do you happen to know which variant (underfloor heating or radiators) based on a gas heating system is the most economical?

I am not concerned with the purchase prices, but rather with the costs when it is actually heating.

Key data:
- Single-family house with a 1.10m "high" crawl space
- approx. 90sqm living area (which will be expanded by approx. 90 sqm next year)
- Year built 60
- Gas heating system will be newly installed. 2 companies have already been here and want to send me offers. (So far based on radiators. I have not asked about underfloor heating.)

We can initially disregard the aesthetic aspect.

I would appreciate suggestions.
Regards
Farilo

So the energy is needed by the house and not the heating system. In plain terms, this means that under the same conditions, you don't save anything with underfloor heating. Only insulation reduces the heat loss of the house. Above all, windows and the roof/top floor ceiling.

In theory, however, underfloor heating may have a slight advantage. Because even a gas condensing boiler operates most efficiently at the lowest possible flow temperature. But this is likely to be in the low single-digit percentage range.

However, if you might want to switch to a heat pump later, you definitely should install underfloor heating, since the heat pump necessarily requires low flow temperatures to operate efficiently.

The flow temperature is actually significantly lower in comparison.

You also gain some space and flexibility when it comes to furniture positions and the like. So it's not just about appearances.

You also have fewer dust collectors and the warmth from the floor is simply better.

However, there is still a considerable extra cost on top; if the screed does not need to be redone anyway; moreover, the heating distributor is rather central; risers for heating are usually in the corners and only for the rooms above.

In the crawl space; where is the heating system actually located?

Regarding the crawl space; where exactly is the heating system located?

The heater is located in the laundry room at floor level, which is 6 steps below the back entrance. The current pipes then run horizontally into the crawl space and from there go up into the house.

Hm I have to think about what to do there.
The screed probably doesn’t need to be redone. That would cost quite a bit.
Next week the place will be stripped down and then I’ll take a closer look at the floor. If it needs to be redone, which is unlikely, then underfloor heating will be installed. Otherwise, just radiators.

Thanks for the information regarding the cost-effectiveness.

Any tips regarding a proper gas heating system? I would also need a hot water tank of about 100L.
I’m still not sure what to make of these combination units?!

The combination units usually cannot be turned down that far in their performance. What has been used for heating so far and is there any insulation (even planned in the short term)?

The combination units usually cannot be turned down that far in their output.
What has been used for heating so far and is there any insulation (even planned in the short term)?

Ah okay. I still haven’t really understood what this “output can’t be turned down that far” ultimately means. But I will inform myself about that as well.

So far, heating was done with gas. System from ’89.
Regarding insulation, I will first observe this winter (I’m moving in Nov/Dec) how things actually behave. If necessary, I would then insulate only the attic next year.
Everything else remains the same.

Some windows have been replaced (plastic).
However, I am considering replacing all windows. (Wooden windows with double glazing).
I am currently checking what advantages wooden windows have over plastic windows and then I will decide.

Regards
Farilo