Thread: how deep to bury thermo pex for oWB?

I've heard conflicting stories and would like some input from those of you that have an OWB. How deep did you bury it? I was thinking like only 2' mainly due to the mountainous rocky terrain here where I live. I have heard anywhere from 18" up to 4 friggin feet!! No way I get get that deep here without a big arse trencher!

Keep it deep about 42", if you keep the temp up on the outside of the pipe it will lose less heat....

I'm also in PA...I'll be using thermopex from CB...my dealer said at least 12" and much more than that isn't needed...it's rated to run ON the ground and he's done that for winter installs then buries in the spring....snow doesn't melt off it above ground so I can see why going very deep isn't needed. I'd say it depends on your insulation of the pex your using....weak insulation go deeper, good stuff not as much need.

It really depends on your water table. If you ground is dry down to 42" put it there, go as deep as the water table will allow. I wouldn't bury any shallower than 18" even if you have a high water table.

What no one seems to be mentioning is that according to the National Weather Service in our area ( I live in the Poconos of NE Pa. ) the frost line is 21
inches. Since your pipe is well insulated the depth doesnt much matter. Zoning regs probably require 2 ft for the electric line and you dont need it deeper than that. Finally and also important, make sure the outside pipe ( pvc or drain ) is seamless so that water doesnt get in.
Good luck..

Mine is Urecon but I think the insulating factor is close to same. I planned on 30" but we found a huge rock that we had to go over and the line is only about 24" there. Been in service over two winters now and at no time have I ever been able to see any difference in the snow cover over the line so I would assume heat loss is minimal. Id put it in as deep as you can without a huge hassle and forget it.

i would go down below frost line, for construction, the frost line for that area if i recall correctly is 42". you can call your code officals for that info.

I'll probably use the CB thermopex

Hi Madspeed,

We installed an uninsulated 3/4 inch underground water line from the house to the barn, a total of 200 feet, buried 36 inches in 1998 here in WPA. It has never frozen and we have never had a problem, so when we installed the insulated pex piping for the OWB, we only went down to 24 inches to top of pipe/conduit. The electrical conduit was placed just above the water pipe, about a 2-4 inches. It is only 65 feet from the house. There is no temperature drop. We also placed masonry sand around the pipe before backfilling. Someone on here on another thread said that should also help keep the pipe warm. Did the same with the barn water line. I have also read about putting rigid insulation above the pipe; not sure if that would help. Also, the comment about ground water (and drainage water) is correct. Try to keep the pipe in dry soil. Good luck digging!

I have one section where there will be running ground water over my pipe, do you think I should SLEEVE it with a larger diameter pipe and insulate between them?

I have Urecon and only went down a foot. No problems.

I went down 36-38" on both loops. Another increasingly popular method is to foam the trench with the lines inside, but not any real cost savings...my CB dealer sells their insulated lines now for $12 / ft.

Originally Posted by Madspeed

I have one section where there will be running ground water over my pipe, do you think I should SLEEVE it with a larger diameter pipe and insulate between them?

I would, if water gets inside your outer jacket and makes contact with the pex it will wick away a lot of heat.

Ground water + pex-pipe = loss of heat
definitely insulate between the pipes, insulation I assume is better the an air gap in between. But, then again, thermo-pex (CB) can stay on the ground in the snow. Maybe just run it straight through your wet land. Call a CB dealer.

i went down 48" just because that is the frost line here, the central boiler and heatmore guy told me 18" but, i just figured if i am digging with a backhoe i might as well keep going. Besides that i like to run a backhoe so the deeper i dug the longer i got to play