ᐅ Renovating an Old Building – Gas Heating with Radiators or Underfloor Heating?

Hello everyone,

Do you happen to know which option (underfloor heating or radiators) is more cost-effective when running on a gas heating system?

I’m not concerned about the initial purchase price, but rather the operating costs once it’s heating.

Key details:
- Single-family house with a 1.10 m (3 ft 7 in) high crawl space
- Approximately 90 m² (970 sq ft) of living space, which will be expanded by about 90 m² (970 sq ft) next year
- Built in 1960
- Gas heating system will be newly installed. Two companies have already visited and will provide quotes. (So far, they have quoted based on radiators. I haven’t asked about underfloor heating yet.)

We can set aside the aesthetic aspect for now.

I would appreciate any suggestions.
Best regards,
Farilo

The house itself requires energy, not the heating system. In simple terms, this means that under the same conditions, you don’t save energy with underfloor heating. Only insulation reduces the heat loss of the house, especially windows and the roof/top floor ceiling.

In theory, underfloor heating might have a slight advantage. This is because even a gas condensing boiler operates most efficiently at the lowest possible flow temperature. However, this difference is likely only in the low single-digit percentage range.

If you might want to switch to a heat pump later on, it is essential to install (or have installed) underfloor heating, as heat pumps require low flow temperatures to operate efficiently.

The flow temperature is actually significantly lower in comparison.

You also gain quite a bit of space and flexibility when it comes to furniture placement and similar aspects. So it’s not just about aesthetics.

Additionally, there are fewer dust collectors, and the warmth from the floor is simply more pleasant.

However, this comes with a substantial additional cost; especially if the screed doesn’t need to be redone. Also, the heating distribution manifold is usually located centrally; the riser pipes for the heating are mostly in the corners and only serve the rooms above.

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

Caspar2020 schrieb:
Regarding the crawl space; where exactly is the heating system located?

The heating system is installed in the laundry room at floor level, which is 6 steps below the rear entrance. The current pipes run horizontally into the crawl space and from there go up into the house.

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

Thanks for the information regarding cost-effectiveness.

Any tips for a reliable gas heating system? I would also need a hot water tank of about 100 liters (26 gallons).
I am not sure yet what to think about those combi units?!

The combination units usually cannot be adjusted to such a low capacity. What heating system has been used so far, and is there any insulation, even if only planned for the short term?

Joedreck schrieb:
Combined units usually cannot reduce their output that much.
What type of heating has been used so far, and is there any insulation (even planned in the short term)?

Ah, okay. I haven’t quite understood yet what “cannot reduce output that much” actually means. But I’ll do some research on that.

So far, heating has been with gas. The system dates from 1989.
Regarding insulation, I will first observe how things perform this winter (I’m moving in November/December). If necessary, I would insulate only the attic next year.
Everything else will remain as is.

Some windows have been replaced (plastic frames).
However, I am considering renewing all the windows (wooden frames, double glazing).
I am currently evaluating the advantages of wooden windows compared to plastic ones and will then make a decision.

Regards,
Farilo