Geothermal lite for 380 gal garage build with a window view - titanium tubing build

[karimwassef]

Ok - so I know that a real geothermal needs to go down to the below the watertable and that the heat exchanger lines should be finned and separated enough to get the best possible cooling.

I live in TX and it gets blistering hot in the summer, the ground a foot below can be 40 degrees cooler than the 110 degrees I may expect to experience in my garage (where the tank is). This is to supplement my soon-to-be-overworked 1/3hp chiller. I'm also working on cooling and venting the garage (different project).

However, I've had 180 ft of 3/4" titanium tubing for 7 years waiting for the right opportunity... We're putting a new patio in and there's fresh soft dirt in the backyard. This isn't going to be the best build, but I'm going to do the best I can. I live across from a lake, so I'm hoping the earth will be cool enough to make a difference. It's an experiment.

I have 18 sections of 10 foot pipe. I'm using vinyl tubing and connectors to assemble them into a heat exchange (4 sections x 4 lines + 2 for feed/return). It'll be a 40 ft x 2 ft section about 1 foot under the patio (yes, I know this is futile and it should be 4 foot or more... but I'm doing it anyway). The 1" OD 3/4" ID vinyl is very snug around the titanium but I'm working it down about 4" and using hose clamps and vinyl straps as well.

Here's the starting point

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Today I assemble, dig, and test - wish me luck.

 

[karimwassef]

now testing with city water pressure behind it. no leaks so far... will let it run for about an hour to test.

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[karimwassef]

Now to dig 220 feet of trench. Decided to rent a trench digger for 4 hours ($160) since I'm on a deadline to complete this by the end of today. At least now I get to go 2 feet down instead of 1 foot.

 

[on the spot]

I'm all in for using what you got but those connections just scream failure to me. Multiplied by the number of them, I don't believe you will be happy with this for long.

I hope I'm wrong though.

 

[karimwassef]

The titanium has very little give, and the vinyl has plenty. The hose clamps do apply quite a bit of compression on the vinyl-metal interface. The ground temperature should not vary too much, but there's no telling how much thermal cycling it will take to failure. There's also the potential for stresses from the dirt slowly moving and slowly applying pressure in an in-opportune direction.

All I can confirm is that it doesn't leak today.

 

[DaveMorris]

Sounds like a very cool project, no pun intended. I am sure it will work to drop the temp, it just isn't clear how efficient it will be. Please do update us. I am very curious about how this will work.

 

[on the spot]

So our summer is over, how is this project working out?