View Full Version : Underground Pex Installation Questions

10-12-2009, 08:18 AM
Hey guys, I am new to this forum though I have read many threads on here with interest over the last few months. I am hoping to get some expert opinions :)

I am not a plumber. That said I have done a lot of plumbing and been fortunate enough to have worked with professionals who have been plumbers by trade for 30+ years. I tend to do a little of everything and have been blessed with the ability to learn well and as I enjoy learning I do my best not to just do a hack job and know that often it is best to differ to or get advice from a pro.

So.... I am running water to my detached workshop in northern Vt. The run is 65 feet long. My soil is basically all sand. Very few rocks. Decent grass cover.

I currently have run a 3/4 pex 190psi line 54" under the ground. The pex is inside 1 1/4 pvc pipe. There is one single joint in the pex using a slip on tool free compression fitting. Starting 3.5 feet down on each end where the run becomes vertical I used a rubber adapter to go from the 1 1/4 width up to 3" diameter. pvc. At the point where the circumference increases I ran waterproof, capped self regulating heat tape up the line with fiberglass insulation filling the cavity between the pex and 3" pvc. The 3" pvc continues all the way up below the garage (wood floor overhang with insulated sides down to the ground.) and through the floor into the heated area. The setup is the same on the house side.

I do programming and am good with mechanical things, so building my own automated purge system for when the garage is not in use is not out of the question. My question however is, would this be overkill? Is what I have currently setup and the depth I am at enough to avoid freezing?

My understanding is that pex can freeze, often without bursting, but I am concerned about the joint and would prefer to always have water available.

Any pointers or thoughts would be welcome.


Peter Griffin
10-12-2009, 08:28 AM
Gets pretty cold it VT but I think what you have done will be OK.

10-12-2009, 09:06 AM
Good, I am hoping that is the general consensus. As much fun as it would be to make a purge system, if I can avoid the work then all the better!!! :)

10-12-2009, 02:48 PM
Too late for your project but Uponor sells insulated PEX tubing now.

10-12-2009, 07:13 PM
Too late for your project but Uponor sells insulated PEX tubing now.

Bummer, that would have been useful. I was going to wrap it all in insulation inside the pvc tube but I couldn't fit it all in there without going up in size a lot. In retrospect I wish I had just done it.