DIY well drilling / trench digging for GSHP

[Ron342]

The hdpe pipe sizing & designations are confusing. I bought a premade 205' loop - it was 1.05" od but since i only wound up with a 100 ft hole i bought 200' of 160psi hdepo pipe and tried to fuse it to a socket weld u fitting i had bought - didn't work since the hdepo pipe had a smaller OD than the u fitting.
Turns out that pipe intended for socket welding has a controlled od and as the psi rating varies, they vary the inside diameter. But with hdepo pipe, it is intended for barb fittings and so has a controlled id with the od varying with pressure ratings. They have different Astm #s to show what they are intended for.
Then there is also CTS hdpe pipe (i think thats the correct designation) which has a considerable smaller id and od than either of the above in 3/4" designation! And that may be what you have.
Don't ask how i figured this out!
But if you are custom making your u fitying you should not have this problem.
As to grouting, i found that dry sand would slowly sink around my pipe to the bottom if the hole is full of water if you shake the u tubes. But your hole is much smaller.
There is a grout called neat cement which i think is just portland cement and water - i know it is very fluid before it sets but don't know if its pumpable thru 1/2" pipe to any depth?
Let us know where you wind up in grouting

[Sccoupe]

I guess its good to show some failures too. Here the 3/4" drill pipe stripped out. In a few different attempts to get it out, the lip was bent over as shown. As a last resort, a cheap bore camera was sent down to see what was going on. A chisel was welded to more pipe and sent down with the camera for alignment. After being hammered in, it was un-threaded from whatever joint wanted to give up first, and pulled out. Good drill pipe was then sent down and re-threaded and the whole thing removed. The failure was about 15-20 feet down with another 20-25 feet of pipe plus the drill bit below it. Went up to 1" drill pipe at that point. If I had to buy it all again, I would probably have went with 1-1/4" or 1-1/2" pipe. Its all gets so heavy though.



Here is a small video of the bore and the broken pipe.

https://www.youtube.com/watch?v=3CdtykguQ2w

This was a previous project for testing a percussion drill. The tower was not built as I like to test for failure in stages. What I didnt know at the time was that a pounder required 600lbs per inch of bit. Two inches means 1200lbs and this contraption wasn't designed for that. With only 35lbs on the bit, this run for 6 hours and went absolutely nowhere through solid limestone. I later core drilled this out to see if it done anything and it didnt even chip the rock in the slightest.

https://www.youtube.com/watch?v=fghu0TW31DQ

[nokiasixteth]

Originally Posted by Ron342

Did you mean you went 260 ft with the poly gel?
What kind of structure were you going thru and how did you add the poly gel? And how much! I watched a pro driller once who added a few onces of a liquid he said was poly gel to his mud pit - he was careful to add a little at a time - must be powerful stuff!
In much of the middle eastern coastal areas we have clay/loam down to a certain depth (say about 25 ft) then sometimes over a hundred feet of marine clay, and sand and gravel. You can jet a 4" hole in the clay/loam but the marine clay needs at least a good mud pump (5 - 6 hp) and 3 - 5 hp drill. It drills fast but tends to form collars of gooey clay around the drill pipe joints if you go fast without good water flow. The marine clay also forms its own clay slurry in the drill pit like bentonite to seal the sides of the hole against collapse. And all over you too!
For me rock of much over large gravel (think golf balls on up) is the end of drilling.
Also, since you sure seem to be in the business, is there any kind of grout that is pumpable with ordinary centrifical pumps?
I had heard that neat cement makes good easily pumped grout for the hole but have no idea how its mixed or used?

We only use the poly gel in clay to make the hole slicker. And sand to keep the hole open. Yeah dont take much more than a few ounces . A lot of time we wont use it at all . The clay will make it a bit slicker. Best is a little sand every so deep to basically sandblast the clay .Those clay collars. We call boots. If you go to fast it will boot off. From a driller not properly cleanin out the hole. 1 more up and down motion at the end of each joint usually will help on that. The grout is mainly for heat transfer. Where were at the ground will naturally cave in on the pipe and is a bit better at the heat transfer . You need to grout the top though so far up for aquifers . Here is sandy clay and blue clay. Worst place to drill is monroville Al. Sea shells from 20-30 to 140 ft . And a lot of em are blind holes .

[Sccoupe]

So this evening, I was able to drop a 3/4", 100psi hdpe ubend into one 90 foot hole.

Here is the fusing unit that showed up. The sockets are metric, but I was mainly interested in cheap easy heat. I cut up a cheap teflon pan from Big Lots as shown by AC_Hacker and used vise grips and one set of sockets to mount big rectangular plates to the iron. Using one of the touchless laser thermometers, it shows between 550 and 570F.


Made a couple of blocks cut with a miter saw from 1-1/4" hdpe plate picked up on ebay and drilled two 3/4" holes in each at 90 degree angles.


Then fused one block to the end of each pipe trying to stay close to one edge but leaving about 1/16" or so from the pipe to the edge of the block because there will be a little squish when the blocks go together. I gave the block about 20 seconds on the fuser and the pipe about 15 seconds.


Next up was to fuse the blocks together. The blocks were clamped together to be straight and then the pipe taped together a couple a feet back. Then just spread, heat, and fuse.


Next, since the hole is only 2" diameter, the blocks were shaved down. It fits in the hole! No pressure testing yet, i'll pull it out later to test, but no detectable water loss at this testing stage. I ordered and received the claimed thinnest ubend connection available and it didnt fit the hole I drilled. They shouldnt say that they have the thinnest any more. Mine is 1/2" thinner.


This is the 8000btu window unit with the added 1 ton coaxial HX. This is just all hacked together for the moment. Using the laser temp gauge on the pipes after two hours of running, the water out temp is 100F and the water in is 80F. This has been slowly increasing at about a 20F spread. The water started at 53F as I pre filled it from the main well. This is only one 90 foot hole, no grout yet, and the water is about 30 feet from the surface. I'll drop another set of pipes to the other 90 foot hole and add them in tomorrow. The pump is only a cheap 1gpm 12v pump, again only testing, this cannot be a final solution.


I'm just happy to see that heat is being moved into the ground. A reversing valve has been ordered to be able to use it for some test heating as well. Its just running in the garage, but its about 78F ambient and the A/C output is at about 55F. Its not even charged correctly unless I just happened to get lucky. Need to study up on a range of items to get it all tuned in.

[Ron342]

Congratulations!
A pair of 90 ft holes in rock and a 3/4 u tube less than 2" od - you done good boy!
I think the second hole addition will narrow your temp spread and level too.
Your socket weld heater looks just like mine, same color. I had to order US adaters tho for 3/4.
You may want to pressure test before dropping it in - its amazing how the pressure surges with flow changes, like pump on/off

[nokiasixteth]

I wish i had the skill to do this . The drilling is the easy part for me being it is all clay and sand 100+ ft . What are you guys spending on materials sometime?

[Ron342]

You're the lucky one, guy - for most of us drilling even in clay is the hard part!
If your talking about the costs of hvac parts, most of it comes from give away window units, ptac units etc. But for me drilling stuff like swivels, poly gel etc is hard to find inexpensively and hard or impossible to make!

[nokiasixteth]

Originally Posted by Ron342

You're the lucky one, guy - for most of us drilling even in clay is the hard part!
If your talking about the costs of hvac parts, most of it comes from give away window units, ptac units etc. But for me drilling stuff like swivels, poly gel etc is hard to find inexpensively and hard or impossible to make!

Well . Hopefully in just a couple of months the drilling part will become the easy part for most DIYs trying to do this or water wells. Other than the guys in rock for that i havent made a design for. Yet.

[nokiasixteth]

When you guys are doing the diy holes for your geothermal heat pumps . What size hole are you using. Our big rigs are normally around 6 inch holes in diameter for the geothermal.

[Ron342]

I think that for 3/4" u bends, the hole is bored with 3 1/2 to 4" here.
I used 4" with 2 window weights taped to the bottom u bend fitting and the ubend full of water and it went right down easily.