PEX Tubing questions

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craigerlitz

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I am planning on laying down some PEX tubing in about 2 weeks for in my garage. From what I've been told, I want the 1/2" oxygen barrier tubing. What brands are any good? I have heard different stories on the lengths of the runs. I am currently planning 250 foot runs. Does that sound alright? I doubt that I will have an operational system (heat) by the time the cement is poured. Would there be a problem if I didn't have an operational system when the cement is poured?

Thanks for your help.
Craig
 
I don't remember the brand of my pex, but I can see where it comes out of the floor, it is black with a thin red stripe. It is however, 5/8" tubing. My runs vary. They are 220', 320', 344', 350' and 163' running through my office and bench area. You definitely don't need your heating system rigged up, but if you had the runs tied into the manifold it would be nicer because they will enter the floor properly. Otherwise just make sure you have them tied into position really good. You can see in my pics the general idea.

I just found a cut off piece. It's kind of rubbed off but I think it is Otega, ViegaPex Barrier. It has a bunch of numbers that don't mean anything to me! It is made in the U.S.A.
 

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Not sure brand really matters, so long as it meets the spec for what your intended use is.
 
Just pressure test the system before pouring the concrete. While the pex is pretty damn durable, care should still be used if, for instance, you need to push a wheel barrel full of concrete over any of the pex......
 
Your tubing diameter will depend on the length of your runs. If you keep the total length of each run under 250' you should be ok with 1/2". When I built my house I found a site that listed your length of run vs tubing size and followed that. It worked well for me. The oxygen barrier is preferred for in floor heat as opposed to standard plumbing but I don't know why. The best thing that you can do, and our local building inspector won't let you pour concrete without it, is to have the pex under pressure while you are pouring, that way if you have a problem you know it right away. It's a heck of a lot easier to push wet concrete out of the way than to chip around a broken line. I would suggest that you keep a few coupling around on pour day for just in case. My experience has been if you have the back up plan all ready to go, you usually don't need it. For the pressure test, couple all of your runs together and splice a tee in with a pressure gauge and a shut off valve. The sharkbite fittings work well for this because they can be undone without cutting the pex and I have never had one leak in a variety of situations.
 
i use 200 to 250ft runs and dont put any heat to it for at least a couple months you dont want it to shrink to fast it may crack. i done my work shop 15 years ago and my basement last fall both are 30 x50 ft. you will love it ...the best move i made i would never run cement again without putting pipe under it and it dont cost much if you use it or not. i used insulation both times under it .
 
All the "zones" should be close to equal in length and should not exceed 250' as previously mentioned. This will keep the return water close to the same temp of each zone and not shock the boiler.
Do not install the lines at the bottom of the slab with plastic staples on top of the styrofoam below the slab.
Try to keep the lines on top of the rebar with all return corners well tied. This will minimize damage while you are pouring the cement.
Pressurize the system at 20-30 psi through a common header connecting all lines before the pour.
Have a small propane torch handy or extra coupling should a line get damaged during the pour. The concrete will bubble should damage occur.
I highly suggest installing a slab sensor. I installed two, this way When and of if one doesn't work you will a backup.
Are you using a electric or gas boiler?
Cheers.
 
jimjimjimmy said:
i used insulation both times under it .
Click to expand...

DO NOT use double bubble foil wrap, I believe that is what it is called. Absolutely worthless. There are some general guidelines that need to be followed if using it for radiant heat, staying away from crapper drains a certain distance, a certain distance to stay away from the outside edge etc. I may still have the manual from the company I got all of my stuff from......
 
Thanks for all of your input. I placed an order for the PEX last night.


MiradaMegaCab said:
I use Uponor Pex tubing.
You need an expanding tool for the fittings.
Click to expand...

Is the expanding tool for splices? I ordered Uponer tubing and will be using the QS-style Compression Fitting Assembly with o-ring. No special tools are needed for it.



DA4AD said:
Are you using a electric or gas boiler?
Cheers.
Click to expand...

I plan on hooking it up to an outdoor furnace in a year or two.

Thanks,
Craig
 
Being in the HVAC field, the type per you use depends on the type system you are using if its a open loop system or a closed loop system, Open loop system you can use regular pex pipe like for water lines and it will with stand temps for what u need rad flooring water temps usually run around 140 deg. If you are using a closed loop system u will need to use what they call heat pex it has a oxygen barrier that prevents air from seaping into the pipe, use a 2" foam board with a 1'6" spacing between loops and your better off to buy in large footage rolls that way u don't have any joints under the slab that's big problems in the future cause concrete will eat through the fittings, Open system would be like a outdoor wood boiler, Centeral, Taylor etc are some brand names, if u are going closed loop Burnam is a name brand, u can also save your self some money and buy a water coil blower combo with a t-stat that operates the pump and would heat ur shop great,:happy1:
 
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