Lowboy Geothermal with horizontal boring/directional drilling

[SkyHeating]

This system was finished up the end of March and is an Envision dual capacity 3 ton split system that we turned into a low boy, we also sealed the ductwork, insulated the ductwork and added a desuperheater.
The video of the horizontal bore can be viewed here.


We also perform live energy monitoring on this unit via a WELserver so you can see if the unit is running, the EWT/LWT and desuperheater, refrigerant and air temperatures all in realtime with approximate COP calculations(not fully functional yet)
http://www.welserver.com/WEL0626

[waterpirate]

Nice looking work!
How much seperation did you have between the loops? The trench the loops were inserted into seemed short? Does the directional bore fan out from that initial ditch? Last question is about grout. Does the drill backfill the bore when extracting the rods with a grout or do they use the native material in a slurry?
Eric

[SkyHeating]

The lines are close only about 3 feet apart so not only do they fan out byt the first line is 15'the deep at the end and the second is 30'the deep and it keeps alternating. Its not 100%only grout its 50%on grout and 50%the slurry mixture.

[waterpirate]

Thank you for the reply I have been curious about this for some time and no one has been willing to share specs. Alternateing depth makes good common sense to me. Did the driller use the cost prohibitive grout that is enhanced with graphite, or standard grout?

Everyone made alot of noise about the grout with graphite, but I have yet to see it used un less it spec'd on a commercial project.
Eric

[SkyHeating]

It was a bentonite grout mixture as we were not trying to get as efficient as a vertical due to about a 12' average depth and cost of 100% grout was a little cost prohibitive vs drilling an extra few feet after liquid waste disposal and spillage onto the property of extra materials.

[CallaDrilling]

Same question I had too Eric,
There is a Horizontal bore guy in my area who uses NO grout in the loop field. He claims it "Works fine".

[SkyHeating]

Same question I had too Eric,
There is a Horizontal bore guy in my area who uses NO grout in the loop field. He claims it "Works fine".

Well if there is enough pipe in the ground you don't need grout, just fill the holes in with slurry. I use 800' per ton in horiztol loop, 600 feet per ton horizontal bore and 400' per ton vertical as a rough number before checking soil and loop sizing programs.

[CallaDrilling]

I am assuming your talking total pipe length.
We start out with 180'/ton 1"loops, or 200'/ton 3/4" loops.
Seems like its fairly similar. We drill mainly through sand, and clays here.

[SkyHeating]

I am assuming your talking total pipe length.
We start out with 180'/ton 1"loops, or 200'/ton 3/4" loops.
Seems like its fairly similar. We drill mainly through sand, and clays here.

Yes total pipe length so 200' vertical is 400' of pipe.