Passage underground through foundation membrane for geothermal pipe - ok?

[Alko]

Hello, posting in this forum instead of the heating forum as it is more about penetration in the basement wall than the actual ground source heat pump installation.

We installed ground source heating 4 years ago, which has worked well. The two pipes for refrigerant were routed through the old oil pipes above ground, into the basement. A "metal box" was installed over the pipes as protection.

The problem is that the metal box looks quite ugly as it is very visible on the front of the house (plastered foundation and facade).

These days we are draining around the house and will be installing drain pipes + Platon and gravel (no insulation or Pordrän as insulation doesn't add much due to the high foundation and rock half a meter down).

I would then like to take the opportunity to drill new holes below ground, through the Platon mat and the foundation to the heat pump in the basement. The ground source heat installer does not recommend this as "sooner or later moisture will get in there". The draining guys are convinced that it will be fine. Haven’t been able to reach Isola/Platon to see what they say.

So what does the wise forum folk say about this issue? The metal box really isn’t attractive where it stands, but I don’t want to invite moisture problems either!

Kind regards,
A

 

[FredrikR]

Check out this thread: http://www.varmepumpsforum.com/vpforum/index.php?topic=35676.0
Hope it helps.

 

[Alko]

Check out this thread: [link]
Hope it's of some help.

Thanks for the tip!
I would like to hear from someone who has done it and seen that it works.

However, I got hold of a guy at Platon (what a compelling name by the way ) who said it worked perfectly well if you followed their advice. They are as follows:

You open for the pipes (KB pipes are probably around 50 mm in diameter?) in the Platon mat by cutting a small 'b' with the slit starting at the nearest end, probably at the top of the mat. Insert the pipes into the holes via the slit. If the pipes are mounted afterwards, you obviously just cut the hole like a small 'o' instead. Hope you understand

With the pipes in place, seal with butyl sealant/sealant or "Platon joint compound" from Isola. Seal between the pipe and the edge of the hole in the mat. On the outside, that is. Use plenty of sealant, which can also be pressed into the backside a bit.

Take two "Isola Self-adhesive membranes" that you make holes in for the pipe, with slits, of course. Cut the slits in opposite directions in the two membranes. Make the holes slightly smaller than the pipe diameter, and cut small slits around the hole, so the membrane can also cover a bit on the pipe.

Lay one membrane with the slits downwards, and then the other membrane with the slits upwards (or vice versa) so you get at least one membrane layer all the way around the holes.

Also, make sure the pipes are drawn with a slight slope outwards, so they do not bring moisture into the wall. If the holes are marginally wider than the pipes (which I think is desirable), it means that the holes are drilled a bit obliquely as well.

That was all the Platon guy said, this should absolutely work well and minimize the risk of moisture damage.

FredrikR, feel free to link to this thread from the Heat Pump Forum thread, I don't have an account there myself.

/A