Ground loop in bottom of new footings
I like to experiment and try new things, so I’d be grateful for any constructive thoughts on the below. I’m respectfully asking for helpful views which may improve the system and help make it a success. I’m not going to pay for an engineer to design me a system. This is a DIY job to take the edge off in the winter, no more, no less. I’m digging trenches anyway, I just need to know if this stands a chance of working.
I live in a temperate climate (UK) where the outside air temp rarely gets lower than say -5°C (23°F) overnight. I have a heavy clay soil and will shortly be laying footings 1 meter (3 feet) deep for a new 2-bay oak frame workshop. To supplement electric heating and frankly just to take the edge off things in the workshop, I’m considering running some 50 mm (2 inch) corrugated plastic pipe in the bottom of the footings, with both ends terminating at head height in the workshop. I’ll then install a low-speed inline 50 mm 12 volt electric fan, driven from a solar panel and spare yacht battery I have, which will drive air from inside the workshop through the 50 mm pipe in the bottom of the footings and back into the workshop, hopefully raising the temperature inside to around 8-10 degrees Celsius (46°F to 50°F), which is much better than -5°C!
The workshop will be well insulated with Celotex or equivalent in both the walls, floor and ceiling and should be fairly well draught proof.
I’m confident that 1 meter depth where I live will give me a fairly steady 8-10 degrees Celsius, but I’m not sure whether laying concrete on top of the pipes rather than covering with dirt will reduce the heat transfer and negate the benefits I’m trying to achieve.
For various reasons, I can’t dig additional trenching away from the footings without incurring additional cost, and as I will already be digging 1 meter deep trenches for the footings, I wondered if this would work for what I require. Worth pointing out that I’m not trying to heat a whole house; just take the edge off the temperature in the workshop so I only need a small but steady temperature rise to achieve that.
With thanks for your help in advance.
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