ᐅ Older apartment with gas boiler heating – underfloor heating now, heat pump later

Created on: 24 Mar 2022 16:27

Hello dear community,

I have a quick question. We will soon be moving into our 80m2 (860 sq ft) condominium and are planning some renovations. The building has an energy rating of D, was built in 1890, but the apartment itself dates from the 1990s (top floor).

Currently, the apartment has a 26 kW gas boiler for heating and hot water. Since we want to replace the flooring, we are considering whether now is the right time to install underfloor heating. We haven’t really budgeted for it, but I figure it’s now or never with the new floor. We were also planning to install an air conditioning system in the medium term, basically a light heat pump.

Question: Would underfloor heating also reduce the gas boiler’s consumption without any other changes? I’m wondering if, in a worst-case scenario, you could just switch on the air conditioning as backup. And if we do install underfloor heating, should we remove the existing radiators or leave them in place?

Does a “proper” heat pump make sense here? For example, on the roof? Or would a combination of the gas boiler, underfloor heating, and air conditioning as backup create an energy mix that doesn’t encourage Putin to invade more countries and doesn’t demand five-figure costs for an unplanned heat pump installation (not to mention getting approval from the homeowners association)?

Basically, if I spend a lot of money installing underfloor heating now, is that just future-proofing, or can it also directly reduce gas consumption?

Thanks in advance for your feedback.

Myrna_Loy25 Mar 2022 10:40

Tolentino schrieb:

I would say it depends on the declaration of division. Especially with a later attic conversion, it could be its own sub-community that can basically do what it wants, since it is clearly separable and the maintenance responsibilities would actually need to be handled differently.

For a house from the 1890s, I also doubt that the beams can support the additional load of underfloor heating.

Benutzer20025 Mar 2022 10:49

Tamstar schrieb:

Is it really not allowed without involving the homeowners’ association?

You are allowed to add another layer. But do you want to lose that much installation height?

Tamstar schrieb:

Or milling?

Milling is not allowed without the homeowners’ association’s involvement. Neither is changing the heating system.

selterdurst25 Mar 2022 18:07

Benutzer200 schrieb:

You can add a layer. But do you really want to lose that much floor height?

I've seen solutions where it’s only about 2 cm (0.8 inches), although you obviously have to be careful with the door and so on. The points about the beams and such are also something that needs a closer look. It definitely doesn’t seem straightforward, but if I don’t do it now, I probably never will, so some research here is well worth it.

Cutting into the screed is really out of the question, and since we want to finish the floors before moving in, we don’t have the luxury of waiting until the next homeowners’ association meeting in November.

selterdurst28 Mar 2022 11:50

#10

I did some additional research over the weekend. Does anyone here have experience with baseboard heaters? They are considered a type of radiant heating because they warm the wall, which then radiates the heat. This leads to the next question: would this principle also work in drywall construction? Since we are doing quite a bit of renovation anyway, this could be a good opportunity. However, there is very little information available on this topic, apart from “oh yes, that exists, but no one really knows about it”...

Benutzer20028 Mar 2022 12:09

#11

selterdurst schrieb:

Does anyone here have experience with baseboard heating?

No, I only know the concept from forums, as it is a very specialized heating technology that is actually outdated and only used for specific requirements. It has many disadvantages:
- requires high supply temperatures – which are usually avoided for efficiency reasons
- risk of dust burning due to the high temperatures
- you can no longer place anything directly against the wall or run cables along the baseboard
- strong convection currents can develop, which may cause "cold feet." Due to the strong air circulation, dust spreads widely.

During renovations, the goal is usually to reduce supply temperatures. For this, modern low-temperature radiators, underfloor heating, and wall heating systems are used.

Why do you find little experience with it? As mentioned above, it’s too specialized. Possible applications include apartment renovations where night storage heaters are replaced by connection to a central heating system (which provides high supply temperatures).

Of course, it will heat your apartment. But if you already have radiators, nothing really changes—except that you lose the use of your baseboards.

selterdurst28 Mar 2022 12:16

#12

Benutzer200 schrieb:

No, I only know the principle from forums, as it is a very specialized heating technology that is actually outdated and only needed for specific requirements.

I understood that yes, it still requires a higher supply temperature than underfloor heating, but since the heat is emitted through the wall instead of radiators, air circulation is reduced and slightly lower temperatures feel comfortable, allowing the temperature to be lowered.

The main issue mentioned was that the wall must remain free.

Irrelevant for new builds, but maybe interesting for renovation of older buildings? As far as I know, the supply temperature is at least somewhat lower than traditional radiators. Thanks for the feedback. I am looking for alternatives to underfloor heating.

There are also low-temperature radiators, which are not underfloor heating either, but better than old-fashioned cast-iron radiators.

ᐅ Older apartment with gas boiler heating – underfloor heating now, heat pump later

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