ᐅ Ground slab penetration for heat pump outdoor unit

Hello everyone,

since our construction will begin soon (earthworks), I am now wondering about the best way to install the necessary lines for the heat pump (connection from the indoor unit to the outside). I’ve heard that some people simply use a wastewater pipe. I find that a bit strange for a newly built house from 2022.

What have you used here? There are building entry systems available for purchase. According to the heating engineer, this doesn’t work so well with the refrigerant pipes (copper). However, I’m curious about the difference compared to a 125mm (5 inch) wastewater pipe.

Thanks in advance.

Best regards

The wastewater pipe is the cheap option. The proper solution would be a multi-utility conduit for the foundation slab.

Basically, both are just empty conduits. As long as they are properly sealed from the inside (using a compression ring), there is absolutely no problem with using a KG pipe.

In any case, do not make the mistake of forcing your construction company to use a new system, as it will be installed incorrectly in 90% of cases.

The interior sealing around the pipe does not replace the external waterproofing of the building structure – meaning that without additional measures, a KG pipe is neither waterproof against pressurized water nor radon-tight. There are solutions for this (such as sealing collars), but these must also be installed correctly.

The problem is often that standard multi-service conduits are simply undersized for certain types of pipes – with DN125 (approximately 5 inches), it is much easier to install rigid pipes, even bundled together.

However, there are larger single and multi-service systems – for example, Kraso BKP 110 or Doyma Quadra E-BP-Max – which come with appropriate sealing inserts for common refrigerant pipes. The downside: they are relatively expensive and, as Gecko1925 correctly points out, are often installed incorrectly.

Okay, thanks for the information.
Another option would be the Hauff ADS150 floor sleeve for floor slabs, which has a slightly larger internal diameter.
There are also ring seals available with matching diameters for cables and pipes.

A 100mm (4 inch) conduit only has an internal diameter of 78mm (3 inches). Maybe the 150mm (6 inch) version would make things easier?
I just want to avoid any leaks into the technical room (which is directly connected to the house).
I don’t want water, radon, or “pests” coming in through a poorly sealed underground pipe.

EFH_Neuling schrieb:

Since our construction will start soon (earthworks), I am now wondering what is the best way to run the necessary pipes for the heat pump (connection from the indoor unit to the outside). I’ve heard that some people simply use a sewage pipe. I find that a bit odd for a new build in 2022.

Question: Does the pipe really have to go through the floor slab? Where is the heat pump located? If it is “just” outside the utility room (on the ground floor), the pipes can simply go through the wall. The route should always be as short as possible.