Uponor HePex installation

JS41190 · October 12

We are installing several loops of 1/2” HePex from the underside of the subfloor for an existing space. I’m wondering if you need to use the Uponor clips, or could it be installed using plastic two hole straps? The homeowner did not want to use the transfer plates, so we’re trying our best.

Ironman · October 13

That’s a huge mistake!

You’re only gonna get about 7 btus per square foot without plates.

You’ll get about 20 btus per square foot with plates @ 120* SWT.

You’re the pro. Don’t let the homeowner design the system! He’s wanting to do it cheap, but the laws of physics don’t yield to the laws of economics.

JS41190 · October 13

https://forum.heatinghelp.com/discussion/comment/1906242#Comment_1906242

I agree! We discussed the issue with no plates and the homeowner didn’t want to hear it. Luckily we told them it won’t work as good as it could with the plates and they still wanted us to proceed. Unfortunately we can’t force someone to do something. Would it be better though to use the Uponor clips, or just plastic flat straps?

hot_rod · October 13

is this intended to heat the rooms, or floor warming?

Uponor calls it joist bay heating, they have a track for installing the Pex.

These tend to need high supply temperatures, 140 plus.

Do you have heat load numbers for the various rooms?

The key to any radiant installation method is getting the floor surface temperature up. You get about 2 btu/ square foot per degree difference.

So a 82 degree floor surface in a 70 degree room = 12x= 24 btu/ ft

Getting the floor surface that warm by heating the air in the space is the question.

mattmia2 · October 13

will it or something else cover the heat loss?

hot_rod · October 13

Watts Radiant has been claiming up to 20 btu/ square foot per ft with suspended pex. It may take 180 supply to get that.

JS41190 · October 13

https://forum.heatinghelp.com/discussion/comment/1906249#Comment_1906249

This is intended to heat the space, along with (2) toe-kick heaters. I saw the tracks, but the homeowner was dead set against using them because of cost. We explained it may not work as well, but I can’t argue with them.

JS41190 · October 13

https://forum.heatinghelp.com/discussion/comment/1906253#Comment_1906253

Thank you for this. So essentially securing the tubing directly to the underside of the subfloor below would be the best bet if not using the tracks?

JS41190 · October 13

https://forum.heatinghelp.com/discussion/comment/1906257#Comment_1906257

Nope, I just found your post online and it’s saying the pex will cause noise. Guess I’ll be using the clips instead.

JS41190 · October 13

https://forum.heatinghelp.com/discussion/comment/1906250#Comment_1906250

There are also two large toe-kick heaters in the space.

hot_rod · October 13

https://forum.heatinghelp.com/discussion/comment/1906259#Comment_1906259

yeah Pex squirms a lot especially when you run it up to high temperatures needed with joist bay application. Use an attachment designed for quiet movement. Avoid the pex touching or crossing itself. The outer layer can create a squeaking noise when it rubs. The loop ends need to be unfastened to allow the pex to grow in length, quietly.

GroundUp · October 13

This is the part of the job where I cease progress and send a bill for the work provided. These are the people that will run your name into the ground when the system underperforms.

Dave Carpentier · October 14

Im not in the game, but I think I would make it clear multiple times during the install that "we should leave the ceiling open to allow us to improve it down the road" or similar.

I know with my mechanic, when he tells me we can do it this way or that and why the cheaper one might fail… when it does I dont gripe about his work, I just realise he was right and I go back to fix it properly.

Alan (California Radiant) Forbes · October 14

https://forum.heatinghelp.com/discussion/comment/1906348#Comment_1906348

If you're talking about leaving the insulation off, there will be less heat moving up. An already compromised heating system will definately need you to "improve it down the road".

Simply Rad · 5:00AM

I agree with Ironman first ….you are the pro not the homeowner. I have always believed that’s it’s my responsibility as a reputable contractor to not allow the homeowner to make pour decisions.
Next I also agree with ground up. This might be the best job you didn’t get.
I am sure there are plenty of other projects to do it right. Jeffrey

Uponor HePex installation

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