Tennman foamed trench line pics

New to this stuff - can I ask what you're doing?

Is this the install that the water penetrated ?

I also am convinced that this is the way to go (at least for me) but where is the best place to buy this uninsulated PEX?? And what size?? I just bought the Econoburn 100 and it will sit about 60 feet from the house I was thinking of using 1 1/4 lines... Any thoughts?? Great pictures and thanks for posting these... any help I can get is MUCH appreciated

I like your idea of the plastic liner below the Pex. I did not have this when we did mine and the sand wanted to spray around when the applicator made the first layer against the bottom of the trench before I lowered the Pex on top of the first layer. Good job! These photos will help others when they foam their lines.

Looks good.
I like the plastic barrier underneath (and around?) the pipes.

No more grass in winter or early Tulips!!

Caulk one up for energy efficiency!

are the supply and return pipes separated to keep from loosing heat to the return?
did the ground stay frozen over the pipe this year?
how much did it cost per foot? my 1" thermopex was $12.50/foot

This will be what I'll be doing as well. I think that's the best way to install. I was planning on 1.25" PEX, until I realized I could do double runs of 1" PEX, which two side by side have a cross sectional area of slightly more than 1.25" PEX. 1" PEX is considerably cheaper and a lot easier to find fittings for.

taxidermist said:

Pictures of tennman trench project

Click to expand...

Tennman,
Congrats! That looks really good. I also like the idea of the plastic in the trench. I used tar paper, and it worked o.k, but was not nearly as flexible. Just a couple of questions:
1) The PEX looks thick in the pics, did you pre-insulate, or is it just large diameter PEX?
2) What do you figure your per foot cost to be excluding the tear-up of the previous pex lines?

I bet you will see zero temp loss over your run, and you will be very pleased with the performance.

Great Job!

First I want to thank Rob for getting these pics up for me. I was wrestling with the process and just don't have a lot of spare time.

I wanted you guys to see the process, sequence of events, and objectives. My first underground approach was hastily done because November '09 was near at hand and I wanted to move on to the IMPORTANT stuff, install the boiler etc. If I say this once I'll say it a thousand times, the potential energy loss from this component of the system poorly done will dwarf all the gee whiz stuff we do with controllers, the latest boiler technology, etc. AND this is compounded if you have a relatively long run like ours. Our home is a historic dwelling so I was committed to having the boiler barn appear as part of our other outbuildings away from the house which resulted in a 160-170 foot underground run.

Goals:
1) Use Closed cell polyurethane foam to prevent water contact with the Pex.
2) Provide at minimum 3" all around each line with 2"-3" insulated spacing between the lines.
3) Protect the foam as best possible from being contaminated as a result of the blowing gun. Even if the foam is closed cell, voids with dirt clods and trash will hurt the insulation properties. The 4 mil plastic was an insignificant cost for this insurance.
4) Completely enclose the lines, void free to prevent water migration down the lines into my root cellar.

How:
1) I used a trencher for the first attempt which provided about a 6" wide trench. To prevent damage to the expensive 1 1/4" pex we used a mini-backhoe to dig up/recover the pex and make the trench you see here. This resulted in a trench about 12" wide which I really didn't want (extra foam, more cost) but acutally worked well allowing us to get in the trench as you can see.
2) After extracting the homebrew insulated approach, leveled the bottom of trench and laid the plastic. 4 mil worked well, thinner would have blown around too much and thicker would have been too stiff.
3) Hooked up the pex lines at BOTH ends. My pex fittings were already on so if we had foamed the lines with them shifted even several inches I'd been screwed and would have needed to add another joint. Once foamed obviously the pex will no longer move.
4) Neither the foam contractor or I had ever done this before so after the foam equipment was out and ready we had a team meeting to discuss what we were going to do and how.
5) We decided on a 3-man team. 1-the foam gun guy, 2- the guy managing the pex spacing close to the foaming process, and 3- the guy keeping the pex suspended so the foam guy can spray onto the plastic under the pex lines and then lower the pex at the right time into the expanding foam underneath.
6) We started and filled the access tube where the pex lines go thru the slab into the boiler barn. We started at the barn and worked towards the house. Guess I figured that if we were going to screw up while learning I wanted that to be out at the barn.
7) The pex lifter (me) held up the pex so the foamer laid foam on the plastic. As the foam expanded to about 3" underneath I lowered the pex lined while the spacing guy held them apart then the foamer just sprayed the snot on top making sure there where no voids.
8) Repeated this in roughly 2' sections working continuously and literally within 10-20' we were cooking like a team. It took us about 30 minutes to do 170'. We were walking on the foam immediately when done. The heavy mini-backhoe drove over the stuff repeatedly leveling and putting the dirt back within an hour.

As a result of all this our Wirsbo-Uponor oxygen barrier hePEX is encased in a solid block of foam about 10" wide x 7-8" deep. It was easy and cost competitive with the commercial pre-insulated stuff. Lord willin' I never see this part of my system the rest of my life. Come December '10 I'll be able to give the delta T's. It should be amazing.

Just wondering how deep the trench is? Only looks to be 18 - 24 inches depp am I correct? Is that deep enuff? I put mine anywhere from 3 - 4 ft deep.

The average winter temperature here in southern Tennessee/northern Alabama is almost 40F. So for us we really don't worry about frost line much. I'd say the average depth is about what you guessed. I wanted it a bit deeper but the guy running the backhoe has 30 years experience installing waterlines in the area. BTW, we can't relate to the discussions about seeing snow melt over our lines. We get a 1/2" of snow and the schools shut down.

if your pex is properly insulated it doesn't need to be that deep, my thermopex is 12" for most of the run (85') and the snow doesn't melt over it.

Thanks for the break down of the pex procedure... where did you buy your pex?? I also will be doing this with a foamer that has never done this before!