First of all, I plan on finding a foam contractor and having my lines foamed in the ground.  In a recent similar thread, someone mentioned running their underground PEX inside of black drain pipe and then foaming that in place just in case they needed to ever replace the lines, add more, or to ensure there will be 0 water infiltration if the closed cell foam ever does get waterlogged.  I thought that was a great idea, but realized it would make more sense to run separate drain lines to run the PEX inside so you’re not transferring heat between your supply and return lines if they are run together. 

So I just did a little pricing of parts.  My trench is going to be about 100’ long.  250’ of 4” drain tile is about $100.  Foaming 4x8” of tile into the ground with 2-3” all around it would use quite a bit of foam and require one heck of a trench too.  But, 10’ sections of 2” plastic electrical conduit is a little less than $4 each.  For 200’ (supply and return) of that is about $80.  I can seal 10’ sections of the conduit with PVC glue to keep them watertight, although it really isn’t necessary since the foam should keep the water out 100%.  2x4” of piping to foam 2-3” over requires a lot less foam as well.  Plus, should I ever have the need to replace the PEX, the electrical conduit will be much more slippery than the drain tile for sliding 100’ of tubing through.  Although the electrical conduit is “rigid,” it will still be fairly flexible.  Another great plus is that I plan on pouring my concrete pad today and to get the lines from underground and up through the pad, I was already planning on using the large electrical conduit elbows because of their large radius curve which will make a nice gentle turn for the PEX.  I’m going to do 2 2” elbows for the PEX and 2 1” elbows for electrical and control wires.  I might add a couple elbows with nothing to go through them just in case I ever need to use them. 

So here’s my question:
I’m going to be using 1-1/4” PEX.  I realize that size is pretty much the OD of the PEX.  will 1-1/4” PEX slip through 2” conduit OK?  I don’t know what the ID of 2” conduit actually is.

The I.D. of 2” conduit is 2”  My 1 1/4 pex is 1 1/4” I.D. It is thermopex. The O.D. of the 1 1/4 pex is 1 1/2”

theoretically = 1” of styro raises the frostline 1’..................24” wide

woodsmaster - 02 September 2010 02:12 PM

The I.D. of 2” conduit is 2”  My 1 1/4 pex is 1 1/4” I.D. It is thermopex. The O.D. of the 1 1/4 pex is 1 1/2”

So with that 1/2” of play, there shouldn’t be any problem sliding the PEX through the conduit?

I would think that it would work ok but don’t Know.

It’s the joints in the sleeve pipe that can hang you up.  File the sharp edge out of every length of PVC and be sure it goes all the way into the glue socket.  Hold it in for a few seconds until the glue sets, or it may push out and leave a problematic gap.  I’d glue every joint, don’t depend on the foam.

The longer the distance the harder the pull, or push.

Any way to slide the PVC sleeve over the pex as you lay it in?  It’s a lot easier than pulling through 100’ later.  Same goes for those sweeps on the ends.  It is easier to slide the sweep over the pex from both ends, than pull the entire length of pex through it.  You may end up pulling the sweep and sleeve out of the ground.

Here is the rig I use for pulling pex lines. I think it’s an electrical pull rig.  The harder you pull the tighter it grips.  I’ve had to use a “come along’ on some long pulls. pulling two pex into a 4” InsulSeal.  That’s where I learned how those glue joints can hang you up.

Water soluble wire pulling “snot” is another trick if the pull gets tough.

hr

I went to Lowes.  I tried 1” PEX through the 2” elbow.  It was a PITA, but it went through.  I tried 1-1/4” black plastic pipe (since Lowes doesn’t carry 1-1/4” PEX) and I couldn’t get it through.  It was nearly impossible to get it through the 3” conduit elbow.  I ended up buying two 100’ rolls of 3” drain pipe for $96, although I’m not too happy with that idea.  I could slide the conduit sections onto the PEX as I install it.  It’s not too late to go back and buy 2” elbows still and return this stupid drain tile.  Do you think if I set the PEX in the 90+ degree sun for a couple hours, it would soften up enough to stick through the 2” elbow?  I’d much rather have that than drain pipe.

Coat the pex with liquid soap as you pull it into the pvc and it will slide alot easier. Also the “chinese finger” shown in the previous post will help you get by the joints. It’s much easier to pull it through than to push it through. Someone on both ends, pulling and pushing is better yet. Don’t forget to pull a spare string through with the pex for future pulls. You may never need it but it is there if you do.

Also, go to an electrical supply, ask them for a 90 deg sweep. I’m not 100% sure it’s made in 2” but probably is. It’s a much gentler 90 degree turn. Makes it alot easier to pull/push things through.

yes warming the pex will really soften it.  Use a hair dryer, or heat gun, carefully as to not melt the EVOH barrier or any outer coating.

I just talked to a spray foam guy today about spraying a 4” drain tile. He said that foam doesn’t like to stick to plastic.

Any feed back on foam not sticking to plastic? If it doesn’t I wouldn’t think it would stick to pex too well.

Also why not get bigger diameter 90’s and fasten them to the 2” with a reducer?

I also hope you have a very straight run.

gg

Just got in from setting up my concrete forms.  I’m going to return the drain pipe tomorrow and pick up 2” PVC conduit.  I was trying the plastic pipe inside of the sweeping 90’s, but I do think a little heat will make it go through just fine.  I’m going to slip the sections on one at a time as I lay the PEX.

juddspaintballs - 02 September 2010 10:48 PM

Just got in from setting up my concrete forms.  I’m going to return the drain pipe tomorrow and pick up 2” PVC conduit.  I was trying the plastic pipe inside of the sweeping 90’s, but I do think a little heat will make it go through just fine.  I’m going to slip the sections on one at a time as I lay the PEX.

Where is everyone getting the 1-1/4” pex? Did you get the O2 barrier?

gg

Alright, the pads are poured.  Because I was running short on time and some pesky roots were making my digging a PITA, I opted to build a little boxed area that did not receive concrete as originally suggested by the manufacturer of my furnace.  After it’s cured, I’ll then dig under that part of the pad, run the conduit up through, put the dirt back in place, and then fill in the boxed area of concrete with a hand mixed bag of concrete.  Then I’ll finally set the furnace on the pad. 

The pour went well.  I ordered one yard delivered and that was about the perfect amount of concrete.  We only ended up throwing about 2 shovels full out of the frame while we were working.  I purposefully poured the pad 6” thick and I wire screened it using chunks of brick to hold the screen about 2” off of the ground as we poured.  This pad should last a while. 

Pictures once it’s a couple days dry.

2” sweeps are available at home depot, just in the electrical isle.  The grey pvc sweeps will work fine with the white pipe.  You can do the conduit and then pull the pex through.  Here’s a trick from a guy who’s done HUNDREDS OF MILES OF UNDERDGROUND.  If you don’t have a snake long enough you tie a string onto a baloon through the conduit with a shop vac.  Done in less than a minute.  Pull a 1/4” yellow rope through with the string then you can pull anything you want through the pipe.  a single 1 1/4” pex line would have a hard time sliding through a 2” conduit even if it was straight and without 90s.

IF you go to an electrical supply house you can get 36” radius sweep 90’s in 2”