Insulate the water pipeline from the ground through the air to the building

Hello,

I am currently renovating my newly acquired mobile home (50 years old), which is situated on wheels in a holiday area; the "building" is practically elevated. This winter, we had about 4 weeks of frost in the North German lowlands with temperatures down to -20 °C under the house. The copper pipe previously installed in the ground (currently: approx. 3.5 cm OSB boards; soon 10 cm Styrodur + underfloor heating) of the (currently unheated) mobile home froze and burst. As part of the renovation of the house, I am now extending the PE pipe laid underground into the house and installing a branch for garden irrigation in the ground.

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

A branch for garden irrigation will be installed underground using a clamp connector: PE pipe T-piece, double nipple, angled seat valve DN20 with drain; double nipple, PE pipe T-piece

Normally, I am not on site for weeks at a time in winter. The heating is set to "frost protection" mode, but there could still be a power outage, partly because the main power supply in the switch box in front of the house can be switched off by anyone.

I am now trying to be as careful as possible to avoid problems. To do this, I want to protect the pipes from frost as best as possible – insulation and pipe heating come to mind. If the insulation is prone to being attacked by rodents, I will, in turn, have to protect the insulation against rodents.

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

Thank you very much for your help in advance.

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 strong, 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, into which I drill a hole just big enough for the PE pipe to pass through. Then I seal the remaining gap with silicone. This way, the pipe is protected against rodents and even insects on the entry side. Probably also against moisture.
[*]A trace heating below the PE pipe secures the whole system.

That should work. What do you think?

Would also insulate (e.g. Kaiflex) and add a pipe heating cable. If electricity is so critical, you could use a UPS. Even if the power is off, you can bridge some time until you are back on site. Not every winter will be as severe as this one. The KG pipe is not necessary. PE-HD pipe can be buried without protection. There is also PE 100 with a guaranteed 100 years in the ground... Every domestic water connection is laid like this and almost all irrigation systems as well.

Thank you, Rick, for your reply. UPS is a good idea.

I forgot to mention that I have planned a globe valve behind the T-piece for garden irrigation. Sorry for the inaccuracy.

I have read on both major retailers (Am... and Eb...) that there are frost-proof ball valves as tap faucets. (I will not provide a link here now, but I do not mean a self-draining faucet with a 25 - 40 cm long lance that drains itself after each closing. My wall construction is not strong enough for that.) Together with the information that PE can tolerate frost, this results in an interesting possibility:

[*]I connect the garden irrigation without a valve.
[*]The end of the garden irrigation is a frost-proof faucet.

Do I even need a tracing heater if no valves are outside?

In the areas where you get frost and water is standing in the pipe, you need to insulate. For safety, I would also wrap a pipe trace heating around these spots. It is available for little money and only turns on when there is frost. This way, you are on the safe side. Everything that is deep enough in the ground naturally does not need heating.

I don't know if it's like this everywhere, but in Berlin you are not allowed to just lay a branch to a garden irrigation system. A backflow preventer must be installed to prevent possible backflow of dirty water. And I don't know if you are allowed to just put it in the ground.