Heat pump: better inside the house or in the garden?

Heaters must be within the thermal envelope.

Our air-to-water heat pump is located in a utility room behind the garage. This room is only equipped with a small radiator and was built with 24 cm Ytong blocks (lambda 0.12), just like the garage. During the coldest period in winter, the temperature inside was only about 10 degrees. Is that not sufficient?

Can you explain that a bit? I don't understand the reason.

Sebastian has already explained it; the HAR belongs in the thermal envelope. So if a pure utility basement is planned, but the heat generator is supposed to be in this basement, the HAR must be insulated. Common "healthy" sense says that it should be sufficient if the exterior wall of the HAR is insulated in the usual way – that is, with 4 cm – unfortunately, the designers of the Energy Saving Ordinance and accompanying regulations see this quite differently and require insulation of the entire HAR.

Our air-water heat pump is located in a technical room behind the garage. This is only equipped with a small radiator and was built like the garage with only 24 cm Ytong blocks (lambda 0.12). During the coldest time in winter, the temperature inside was only about 10 degrees. Isn't that sufficient?

In my opinion, no, because your technical room may be sufficient for you, but it is not insulated as required. But as always: no plaintiff, no judge. What does your energy consultant say about this location? Rhenish regards

Thank you very much for the feedback. Maybe as a note: I built last year according to the old Energy Saving Ordinance. Was the regulation already like that there?

Imho Nein, denn Dein Technikraum ist vlt. für Dich ausreichend, nicht aber gedämmt, wie es erforderlich ist.

If the regulation was like that, then I will ask my GÜ about it. It is already too late, but it should definitely be clarified.

Aber wie immer: wo kein Kläger, kein Richter. Was sagt denn Dein Energiefachberater zu diesem Stellplatz?

Who do you mean by Energiefachberater? The one who calculated the heating load calculation, the energy certificate, and the documents for the KfW? - Nothing. Neither GÜ, architect, nor heating engineer said anything about it. That is also usual with this GÜ and is actually done almost always like that. <= Which does not mean that it is correct. I am aware of that.

It was the same back then - a colleague also installed his geothermal heat pump in the garage 3 years ago. It was also prohibited, but as the construction expert said, where there is no plaintiff...

Ok, thank you.
Does this bring any advantages or disadvantages with it?

Advantages: More space in the house, no noise Disadvantages: Longer pipe routing, more energy required to maintain the heat My colleague has very low electricity costs with his pump, so it can't be that bad. Of course, he doesn't have a comparison either Nothing has been optimized even remotely – the question is always what all the insulation and adjustments actually yield in the end.