Has anyone installed geo loops under basement floor? We're building a 1800sqft one story house with full icf basement. Located near ludington MI.

If moisture is present, you risk freezing the soil beneath the floor and frost heaving the concrete. If no moisture is present, you generally have fairly low heat transfer from the loop to the soil and the system performs poorly.

This in not a very good idea. You would need 3-5 feet of earth over the ground loop. Plus there is not enough area there to pull the heat you would need for your house. One of those ideas that sounds good at first , but is not an option in all of the cases that I have seen.

I replied to this question somewhere.......
Anyway, heat migrates to colder, so if you extract heat from under your basement you will have greater heat loss from your basement. You could insulate with 2" foam at a dollar a SF, but that might cost more than simply digging trenches elsewhere.

you are going to be in the neighborhood of a 3 ton system (unless you are really aggressive in tightness of the home) so you are likely (depending on soil) looking at 3, 800 foot slinkies (slinkies are popular over there) which coil to 150 or 200' trenches. You could not fit all of the loops under the house anyway.

If the loops were vertical wells and not horizontal trenches would that improve the feasibility of this idea? Assuming of course you have enough area to set the wells with the correct spacing.

Posted By thescottcav on 24 Mar 2015 04:16 PM
If the loops were vertical wells and not horizontal trenches would that improve the feasibility of this idea? Assuming of course you have enough area to set the wells with the correct spacing.

Not really.  The trench to connect the wells would still have to be several feet below the floor to protect the floor from frost heaving.  Either the drilling would have to be done prior to excavating or there would have to be a way to get the drilling rig  down into the basement.   The size of the excavation would have to be huge to accommodate the rig.

I guess it could be done, but I can't imagine very many scenarios where it would be practical.

Verticals under a building are more common in urban commercial applications where the foot print of the building is nearly equal to the foot print of the lot.
Keep in mind vertical loops are often more expensive than horizontal so for OP to pay for vertical to save money would back fire.

Ok, I just saw the other thread where this question was posed as a potential cost savings. Not to hijack this thread, but for my upcoming build we are drilling vertical wells, the basement is a walkout and there should be plenty of space to put the wells under the basement footprint (the space required for the wells has been discussed by my contractor). That is my interest in this idea.

Considering the depth of the top of the well, and it being under the house, I would think this would add efficiency for winter performance since the ground would (I assume) be warmer there than in my back yard, where our frost line is 3'-4'.

I guess if the driller is OK with it. Any efficiency gain is going to minimal since most of the heat exchange takes place down the hole. As heat is extracted from the ground over the winter, the fluid temp coming out of the ground can get below 30°. Just be sure you plan for this.

So you gain < 10' of extra warmth at the risk of running freezing pipes under your slab. I wouldn't do it unless you have no other choice.

"Considering the depth of the top of the well, and it being under the house, I would think this would add efficiency for winter performance since the ground would (I assume) be warmer there than in my back yard"

Ok if the ground is warmer there, it is because of loss from your basement.......that has to be made up by the heat pump and loops.......which rob the basement.......
I mentioned before there is a kooky engineer out there who suggested this very thing as though it is beneficial to heat the home by taking heat from the home.

Next up: momentum engines.

Points all taken! thanks!!