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In-floor heat

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burnt

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Anybody have experience in laying PEX in place before pouring the concrete? I got the pipe last night and have been laying awake wondering how it's done. . . :roll:

Originally, my supplier was going to lay the pipe for me, but I didn't give him nuf lead time and now he can't do it in time for our planned pour on Friday.

There are a few good sites for DIY but any advice would be appreciated.

Like, do you set the roll on a turntable/spinning jenny and pull it off like high tensile wire? Or do you carry it on something and spool it off as you go?

We are using 5/8 inch pex-r-pex pipe on 18"centers. It comes in 400' rolls.

This is going into the workshop floor. One obstacle is a section of floor that is 12" thick along one wall where we may set some iron-working machinery in the future.

Thanks.
 
The last one I did Burnt was the office I am enjoying warm feet in right now. The turntable works great. I like to tie the pex to the re-bar with plastic wire ties. (cut pig tail off) It holds it into place when pouring. Some like the pex above and some like it below the re-bar. I like the pex to be closer to the surface. This last job we layed insulation below with the theory being we don't want to sink energy and waste the heat. I am not sure on a shop but in this application it allows us to not have a long cool down time when the temp outside swings. That can be a problem when you have the ground heated up. If you can use a pump truck it will help with the stress of the cement placers squishing and wrecking the pex. Hope some of that helps.
 
I never layed pex but have worked for a plumber in the past and also been to a few shops while it is being done. I would think a person would want to make sure if you had anything you needed to secure you marked out spots that had no pipe to drill holes in the floor. Secondly i think a person would want to do it in loops , not make one pipe do a whole section of the shop, that way if one ever leaks and you have to shut one off it is not a whole piece of the shop. Hopefully that makes sense, good luck .. can't beat a heated shop!!!!
 
Thanks, guys. The shop is 32 x 60 and will have 3 loops, dividing the floor into 3 - 20' zones. That way, I can heat the main working area a bit warmer if I want and leave the back zone, which will be storage area, a bit cooler.

I hear you on knowing where the lines are in order to avoid drilling into them when fastening equipment down with cement anchors.

We are laying "double bubble" concrete foil insulation down on the "A" gravel subsurface and then a layer of 2" of Styrofoam insulation "door-cutouts" for a heat trap.

On top of that, we are placing 8' x 20' sheets of 9 gauge wire mesh to which we will wire tie the pex. Then 6" of concrete.

A common piece of advice has been to leave the mesh and pipe on the bottom to avoid drilling into it when securing equipment to the floor.

It all sounds easy but since I haven't done it before, it seems a little intimidating . . . well I'll just have to cowboy up and do it!!
 
Some here heat the apron in front to avoid any shoveling duties. Might waste some energy but could be good when it is too icy to shovel. What good is the mesh if it is on the bottom? It should be in the middle for concrete strength. Keep your lines straight and with 18 inch centres you should be able to map out drill spots.
 
The mesh will not be doing much good for reinforcing, but is there to keep the lines straight. Of course, since I got it, I have seen some cheaper options. :roll:

Heating the apron sounds like a nice but pricey idea. We are facing south with the door, so that should keep the ice down, I hope. But you just gave me an idea - why not put an asphalt apron down instead of concrete? The black surface should draw more heat and help it stay clear?
 
Take notes!! Then you'll be R.net's resident expert :)

You may wish to take some pictures with a tape measure pulled out over the top of the PEX in critical areas that you can reference back to in the future, kinda like making a map of where a person buries their underground water and power lines on their place.

HTH & I'm sure you'll do just fine.

bart.

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When they did mine they put 1/2" Pex over 1 1/2' blue board insulation and stapled the pex with special plastic staples to the blue board on 12" centers. The pex is in 200' loops. The rebar was installed over that. that way the pex is in the bottom of the slab and the rebar is in the middle.

Pex tubing
PA230158.jpg


With rebar
PA290183.jpg
 
Cedarcreek, it doesn't look like you have any manifolds on the ends of your pex on the poured section on the right. One thing that I have been advised to do is pressurize the loops before pouring the concrete so that we can tell if the pipe gets damaged during the pour. It looks like the pipe we are using is much like yours and should take a bit of punishment though.

Your system looks really tidy and those plastic staple guns are pretty cool. I saw them on another site for in-floor heat supplies. They won't work with the door-cutouts insulation that we are using. But it was a cost factor that made me decide to go this way rather than ESP or SM board.

Did you belt your concrete into place?
 
They put manifolds on the pex a couple of days ahead of the pour and pressured them up to make sure there wasn't any leaks. He took the manifold off to use on the next section after the concrete had set up to use it on the next pour. They did the 50' X 60' floor in three pours 20' X 50' at a time.
They put foam pipe insulation around the pex to protect it where it comes out of the concrete.
DSCN0110.jpg


Pouring concrete
PA220154.jpg
 
That is so cool, and such a wise way to go in my opinion. lazy ace and I often talk that we wish we'd put in floor heating under our basement. If we ever get enough cash saved up to have a garage, I'll campaign pretty hard to have heat in the floor. Cedarcreek, it looks like you could rent out your services! :lol:

This has been a very interesting thread, thanks for starting and sharing.

Have a great day everyone!

Cheers---

TTB :wink:
 
Just a word of warning for anyone doing this in their shop. There is a large possibility of taking extra long to do jobs because cat naps are a real danger while laying under a piece of machinery. :shock:
 
We got the pipe laid today. The concrete contractor has Redimix coming at 8 in the morning and I don't have the manifold hooked up yet. They short shipped some parts for it and I only got them here at 10 tonight . . . :(

Now I have to figure out how to set the manifold up and get the air pressure into it in the morning. Then we hope there are no leaks.Gonna be an early start but I'm out of gas tonight.
 

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