ᐅ Insulate water pipes running from underground to the building through the air

Hello,

I am currently renovating my newly purchased mobile home (50 years old), which is located on wheels in a holiday area; the “building” is essentially elevated on supports. This past winter, we had about four weeks of frost in the lowland region of northern Germany, with temperatures dropping to -20°C (-4°F) under the mobile home. The copper pipe that was previously installed in the ground (currently under approximately 3.5 cm (1.4 inches) OSB panels; soon to be covered by 10 cm (4 inches) of extruded polystyrene insulation plus underfloor heating) inside the (currently unheated) mobile home froze and burst. As part of the renovation, I am now extending the underground PE pipe into the home and installing a branch underground for garden irrigation.

The setup is as follows:

00 cm Lower edge of the mobile home
35 cm Soil
60 cm PE pipe, outer diameter 25.3 mm (1 inch)

A branch for garden irrigation is being installed underground using compression fittings: PE pipe T-joint, double nipple, angled seat valve DN20 with drain; double nipple, PE pipe T-joint.

Normally, I am not on site for weeks at a time during winter. The heating is set to run in “frost protection” mode, but there is a risk of a power outage, especially since the main power supply in the control box in front of the home can be switched off by anyone.

I am trying to be as cautious as possible to avoid problems. To do this, I want to protect the pipes against freezing as well as possible — I am considering insulation and electric trace heating. If rodents tend to damage the insulation, I will also need to protect the insulation from them.

How would you insulate the pipe against frost and protect the insulation from rodents?

Thank you very much in advance for your help.

Best regards,
Andreas

Sometimes it helps to write something down to get new ideas. I just came up with the following idea:

I am installing a pipe-in-pipe system:

• I insulate the PE pipe with a thick, waterproof insulation.
• Over that, I slide an orange KG pipe DN 100, preferably DN 150.
First, an end cap on the incoming PE pipe,
then insulation for the incoming PE pipe,
then a PE T-piece inside the KG T-piece,
then the two PE branches,
then insulation and end caps on the branches.
• I lead the PE pipe through KG end caps, where I drill a hole just big enough for the PE pipe to pass through. I then seal the remaining gap with silicone. This way, the pipe is protected at the entry point against rodents and even insects, probably also against moisture.
• A trace heating system below the PE pipe secures the whole setup.

This should work. What do you think?

I would also insulate (e.g., Kaiflex) and add a pipe heating cable.
If electricity is that critical, you could use an uninterruptible power supply (UPS).
Even if the power goes out, you can bridge the gap for some time until you can return onsite.
Not every winter will be as severe as this one.
The sewer pipe (KG pipe) is not necessary. HDPE pipe can be buried without protection. There is also PE 100 with a guaranteed lifespan of 100 years underground.
Every residential water connection is installed this way, as are almost all irrigation systems.

Thanks, Rick, for your response. A UPS is a good idea.

I forgot to mention that I have planned an angled seat valve behind the T-piece for the garden irrigation. Sorry for the lack of detail.

I have read from both major suppliers (Am... and Eb...) that frost-proof ball valves are available as outdoor taps. (I won’t post a link here, but I don’t mean a self-draining tap with a 25 – 40cm (10 – 16 inches) long lance that drains itself after each closing. My wall construction isn’t strong enough for that.) Together with the information that PE can tolerate frost, this creates an interesting option:

• I connect the garden irrigation without a valve.
• The end of the garden irrigation will be a frost-proof tap.

Do I still need a trace heating system if no valves are located outside?

In areas where you experience frost and water remains in the pipes, you need to insulate them.
As a precaution, I would also recommend wrapping a pipe trace heater around these sections. It is inexpensive and only turns on when there is frost.
This way, you are on the safe side.
Anything buried deep enough in the ground obviously does not require heating.

I’m not sure if this is the case everywhere, but in Berlin, you’re generally not allowed to just install a branch pipe for garden irrigation. A backflow preventer must be installed to stop any possible backflow of contaminated water. And I don’t know if you’re allowed to simply bury it in the ground.