Geothermal Polytunnel

Building a Geothermal Polytunnel

Before I got started digging the geothermals in I prepared the ground to receive the full size of the polytunnel with a 5 ton excavator.

Next I dug two channels which would cap the ends of the pipe runs and ultimately be the exit for the tubing.

I then dug a 60ft trench about 7ft deep and 4ft wide.

The first layer I put in was gravel, which was made more difficult by the tight work site.

Levelled out it created a unique trench environment 😀

Next me and Alice lay the piping back and forth like a radiator, over the gravel.

We used duct tape cross members to keep the tubes equally distributed.

On top of the first layer we put gravel and then sand.

Here’s an example of the exhaust coming out of one end point.

Slideshow of laying the geothermals beneath the polytunnel:

The finished Polytunnel base with the in and out end points.

Next up the polytunnel arrived and was built over the geothermal central axis.

I built some simple doors using tung-oil treated timber and spare polytunnel plastic.

Straight away we got lots of tomatoes in and had a great harvest that first year.

Later I added a mature lemon tree.

… and beds made from scaffold planks attached to the polytunnel frame. Again treated with Tung oil.

Over the years the setup is evolving, I’ve found the scaffold board beds to be very effective.

To help foster a longer year I built this raised heated bed, (so I could bring on seedlings even earlier).

… because the weather can be a challenge here.

Daikon radishes make the best kimchi!

Lots of produce over the years.

Luna the cat loved to prowl the polytunnel catching crickets.

As of 2024 the polytunnel is now shared with my friend Sue, who’s built extra beds. The lemon tree is now living in the ground, (and despite a bout of Scale doing well). I’ve added figs, peaches, grapes and more.