ᐅ Mill the subfloor for underfloor heating or install a new screed?

SaniererNRW123 schrieb:

Sorry, there was a missing "k". This is a basic standard insulation that is better than nothing but does not seriously prevent heat loss from the basement.

Okay. I had suspected that from the overall message. What would be a good insulation, then? Maybe we should also ask another screed installer.

SaniererNRW123 schrieb:

That’s exactly why you do it together with the heating technician. You install and staple it yourself. The heating technician compresses it and takes responsibility for the warranty. This is standard practice in construction. That’s the approach I suggest as well.
I do everything myself at my place — then at least I know exactly who made a mistake 😉

We will ask our heating installer about this.

SaniererNRW123 schrieb:

Costs are manageable – as far as I know, also eligible for funding. For example, like this – you also get the installation plan for the underfloor heating included.

That sounds good. So in your opinion, the best approach is to start with the design of the underfloor heating (1) and the heat load calculation, meaning sizing the heat pump (2)?

The tip about the pipes and the spacing is useful. I think the effort could be worthwhile if the material costs are not too high. A 10cm (5 inches) pipe spacing sounds good, and then thicker pipes (16mm (0.63 inches)).

I’ve also heard about the BAFA funding. Does this come under the program for “hydraulic balancing,” or what are the funding rates there? Or is this handled through BAFA’s “regular heating funding” (heat pump currently 25 percent + 10 percent replacement bonus for gas heating)?

In this context, I have another question: What about the so-called “ancillary measures”? Due to the renovation, there will be a new floor covering (tile, vinyl, or wood), possibly a new screed or milling work, new door frames and possibly doors, new painting, etc. Can someone tell me which measures for restoring the surrounding areas are eligible for funding, assuming the €60,000 (sixty thousand euros) maximum cost limit has not been exceeded, and if so, at what rate (the same funding rate as for the heating system)?

Many thanks and best regards!

FCBenne04 schrieb:

In this context, one more question: What about the so-called "surrounding area measures"?

Basically, everything is subsidized – this is also stated in the BEG information sheet:

SaniererNRW123 schrieb:

Calculation of the heating system sizing outsourced (e.g., Heckmann).

Good evening again! I followed up on your tip regarding Heckmann and inquired there. The design and sizing are normally funded through the individual BAFA measure and, as a planning service, do not affect funding if done before the application.

I also took the opportunity to ask about the milled-in underfloor heating. Mr. Heckmann said he would favor this option because it is more cost-effective and faster, and not really worse than doing everything new. Regarding the missing insulation with this method, he said that otherwise, you would have to increase the build-up height again and redo everything: door heights, etc.
If you keep the build-up height as is, you would hardly gain any additional insulation. In that case, it would be better to insulate the basement ceiling.

Does that reasoning make sense? I thought that with the new screed variant, you could install more insulation and then make the screed layer thinner, which wouldn’t be a problem here since the underfloor heating is installed on top.

After my previous engagement with the topic, I was leaning more towards a complete rebuild. But based on the statement from the specialized engineering office for heating sizing and design, this can now be reconsidered.

Is it possibly feasible to mill the channels slightly wider to install thicker pipes? Apparently, the pipe spacing can be adjusted to 10cm (4 inches).

Thank you and best regards!

FCBenne04 schrieb:

After dealing with the topic so far, I was leaning more and more toward a complete replacement. But after the statement from the expert engineering firm specializing in heating sizing and design, that can now be reconsidered.

I value Mr. Heckmann’s opinion a lot. I’ve had very good experiences with him—and there’s an online community where he is almost revered as the pope for DIY heating installers (Panasonic Geisha). I’ve never heard anything negative about him.

FCBenne04 schrieb:

On one occasion, I also asked about the milled-in underfloor heating. Mr. Heckmann said he would favor this option because it’s more cost-effective, faster, and not really worse than doing everything new. Regarding the missing insulation in this setup, he said that otherwise, you would have to increase the build-up height anyway and redo everything: door heights, etc.
If you keep the build-up height as is, you would hardly gain any insulation. In that case, it’s better to insulate the basement ceiling.

If the wet system really causes a lot of work because of the height (and it will cost money), this argument makes sense. In my case (also a wet system), I only have 2cm (1 inch) of insulation under the screed/underfloor heating— but 10–12cm (4–5 inches) of rigid PUR insulation beneath the basement ceiling. This results in a KfW55-level ground floor ceiling construction compared to the now much colder basement.

FCBenne04 schrieb:

Is it possibly an option to mill the channels a bit wider so that thicker pipes can be installed? The pipe spacing can apparently be adjusted to 10cm (4 inches).

No idea

Does an inverter function make sense for a heat pump (in this case geothermal)? Also considering the possibility of installing a photovoltaic system later on. The additional cost is about a one-time 2,000 € (approximately 2,200 USD). Thanks for your help!