Has anyone considered installing a ground loop by digging multiple 12" round by 12' deep holes using a tractor mounted auger? Holes could be dug on a 6' grid. you could take a 12' x 12" x 4" piece of rigid foam insulation and wrap it with tubing and lower the unit into each hole and then backfill. Just a thought.

HDPE pipe is not that flexible.

That would be a problem!

Maybe a company could create a radiator of some sort that could be dropped into the holes. Maybe even out of an inexpensive molded plastic.

You may be able to heat the pex with a heat gun and mold it around a form but I don't think it would be an efficient way to transfer heat to the ground. You would have to have a bunch of holes with trenches between them. Easier to just dig the trenches and put the pipe in at the depth needed. Someone needs to come up with a better material- cheaper, better heat transfer and just as tough as HDPE.

I was imagining that the connecting trenches could be very simple and narrow 4" trenches dug about 2 feet deep with a ground hoe. The connecting tubes could be slightly insulated or laid in sand.

Or a 6" whole could be dug even more easily every 3' and a 1" steel pipe could be bent into a U and one of these could be placed in each hole.

Auger: http://www.littlebeaver.com/prod_bigbeaver.php
http://www.littlebeaver.com/pdfs/bigbeaver/BigBeaver.pdf


You could easily go 16" in diameter and 20 feet deep.

I have 6000' of 1" pipe buried for my ground loop heat exchanger. How many holes would you have to auger to get 6000' of pipe buried? Remember that the pipe needs to have at least 5' of ground cover.

I bet this would be a lot harder than you are thinking.

It might be possible to stick multiple U-tubes in each wide borehole, but I doubt it would work well - u tubes would be too close to each other.

Off the top of my head another option might be vertical slinkies of much thinner pipe, perhaps 1/2", but there would be a series of sub manifolds and then those would all get manifolded together. Lots of joints and possibilities for leaks and unbalanced flows - probably more aggravation than it is worth.

Best case scenario:

12" Diameter foam with coil on 2" spacing. Lets say it is easiest to dig holes up to 20 feet deep. Then we get (15' feet of usable depth per hole) x ( (.5 feet) ^2 * 3.14) x 6 = 287 feet per 'core'.

I know that 2" spacing would be very tight, but if you fill in the space in the holes around the tube with grout, I think that it might work.

Or... another way to look at it -

You have approximately 3141 square feet of surface area (6000 * (1/12) * 2 * pi), very effective surface area.

Assuming that each core basically acts like a 12" tube, each hole would give you 94 square feet of surface area (15 * (1) * 2 * pi), at some other effectiveness. It might be equivalent. Many factors to take into account.

Digging 60 holes would be a lot! But what was required for your 6000 feet of tubing? I bet they had to tear up a pretty big hole with heavy equipment.

I live on a 1/4 acre lot in a subdivision.  My  trenches were dug using a  mini track hoe excavator.

 That little drill rig you are looking at might drill a 12" x 20' hole in soft dirt.  Any hard dirt or rocks would put an end to it.  The probably of the rig doing what you want it to do is very slim.

Have you seen one of these rigs drill?  The claims on the website are extremely exaggerated.

Thanks for working this through with me. It was just an idea I want to throw out there.

Discussion closed.