Mill underfloor heating or apply new screed?

Sorry, there was a missing "k". This is a simple run-of-the-mill insulation, which is better than nothing, but does not seriously keep the heat from the basement.

All right. I had already suspected that considering the overall message. What would be a good insulation then? Maybe we’ll also ask another screed fitter.

That’s exactly why you do it together with the heating engineer. Lay and staple it yourself. The heating engineer compresses (presses down) and takes over the warranty. Very common practice in construction. That’s how I recommend it as well. I do things completely myself – at least then I know who screwed up ;)

We’ll ask our heating installer.

Costs are manageable – to my knowledge 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 would be the design of the underfloor heating (1) and heat load calculation, i.e. sizing of the heat pump (2)? The thing with the pipes and the installation spacing is a good tip. I think the effort could be worthwhile if the material costs don’t weigh too heavily. 10 cm installation spacing sounds good and then thicker pipes (16 mm). I’ve also heard about the BAFA funding. Does that run through the program “hydraulic balancing” or what are the funding rates there? Or does it run via the “normal heating funding” from BAFA (heat pump currently 25 percent + 10 percent replacement bonus for gas heating)? In this context one more question: What about the so-called “circumstance measures”? Due to the renovation there is a new floor covering (tile, vinyl or wood), possibly a new screed or milling, new door frames and possibly doors, new painting etc. Can someone tell me which measures for restoring the surroundings are co-funded, if the maximum costs of €60,000 have not yet been exceeded and if so at what level (same funding rate as for the heating?). Many thanks and best regards!

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

Actually, everything is subsidized - as it also says in the BEG leaflet:

Calculation of the heating design outsourced (e.g. Heckmann).

Good evening again! I took your tip regarding Heckmann and asked there. The design and dimensioning is normally funded through the individual BAFA measure and as a planning service it does not affect funding even before the application is submitted.

I also asked again about the milled underfloor heating when I had the opportunity. Mr. Heckmann said he would favor this option because it is cheaper and faster and not really worse than doing everything new. Regarding the insulation which is not provided in this way, he said that otherwise you would have to increase the build-up height and do everything new: door heights, etc. If you keep the build-up height this way, you would hardly gain any insulation. Then it would be better to insulate the basement ceiling.

Does that make sense? I would have thought you could lay new screed with more insulation and then make the screed lower, which would not be a problem here since the underfloor heating is laid above it.

After my previous dealings with the topic, I was increasingly in favor of doing everything completely new. After the statement from the specialist engineering office for heating dimensioning and design, this can now be questioned again.

Is it possibly feasible to mill the channels a bit larger so that thicker pipes can be laid? The pipe spacing is apparently adjustable to 10 cm.

Thanks and best regards!

I was increasingly in favor of completely redoing it after dealing with the topic so far. After the statement from the specialist engineering office for heating dimensioning and design, one can now question that again.

I put a lot of value on Mr. Heckmann's opinion. I have already had very good experiences – and there is a place on the internet where he is practically praised as the pope for DIY heating builders (Panasonic Geisha). Never heard anything bad about him.

I also asked again on the occasion regarding the milled underfloor heating. Mr. Heckmann said that he would favor this option because it is cheaper and faster and not really worse than doing everything new. Regarding the insulation which is thus not provided, he said that otherwise, you would have to increase the build-up height again and do everything new: door heights, etc. If you leave the build-up height as it is, you would hardly gain anything in terms of insulation. Then it would be better to insulate the basement ceiling.

If you really have a lot of work with the height in the wet variant (and that will cost money), the argument makes sense. I only have 2 cm of insulation below the screed/underfloor heating in my case (although in the wet system) – but 10-12 cm of PUR insulation under the basement ceiling. This results in a KfW55-capable ground floor ceiling construction compared to the (now considerably colder) basement.

Is it possibly feasible to mill the channels a bit larger so that thicker pipes can be laid? The pipe spacing can apparently be adjusted to 10 cm.

No idea

Does an inverter function make sense for a heat pump (here geothermal)? Also with regard to possibly having a photovoltaic system later. The additional costs are about a one-time €2,000. Thank you for your help!