Underfloor heating - wet system and dry system

Hello everyone,

we are currently in the process of obtaining various offers for our house construction. In general, it is already difficult to compare the offers. However, we are at a loss with one point. We are generally planning underfloor heating with an air heat pump everywhere.

- 3 developers say they install the underfloor heating as a wet system
- 1 developer (the most expensive) says they install a dry system, which is much faster in heating up and cooling down and more high-quality (more expensive)

On the internet and also from one developer, we have now received the information that wet systems are generally always used in new buildings and dry systems rather in old buildings and wooden ceilings.

We are just totally surprised that especially the most expensive (and actually very good) developer is exactly the one offering the dry system.

Can you help us with the question which system is better or what the advantages and disadvantages are?

Basically, a distinction is made between wet and dry systems: while in the wet system the heating pipes lie directly in the screed and are surrounded by it, in the dry system they are housed in the insulation layer beneath the floor covering. In the case of new buildings, the wet system is usually used because, on the one hand, the floor is being laid for the first time and the installation of the heating is thus simple and comparatively inexpensive, and on the other hand, heat transfer and storage through the heated screed is advantageous. In contrast, for old buildings and renovations, the installation of a wet system would cause considerable effort and cost, which usually only makes sense in the case of a major renovation. Therefore, dry systems, where the heating pipes lie directly under the floor covering in so-called dry screed panels, are the best choice here. In new buildings, however, I would prefer the wet system.

We are just totally surprised that especially the most expensive (and actually very good) developer offers the dry system exactly at that time.

This most likely saves him time, structure heights, and the entire screed trade. Thus, he can complete the construction much faster than others and make more profit.

... that is much faster when heating up and cooling down...

And that is the biggest disadvantage of dry systems. You don’t want temperature fluctuations and you shouldn’t have to regulate the room temperature. You want a consistent temperature in the house and a high heat storage capacity. Since in new buildings this is rarely available anymore in the form of thick ceilings or heavy walls, at least the screed should provide a storage volume.

It still doesn’t get too warm: since the floor is ideally only a few degrees above the air temperature, it cannot release any more heat if the air temperature (due to sun or stove) suddenly rises.