Pex choice for radiant heat

[challenger]

Looking for some wisdom on which pex to choose for radiant floor heat under the slab. I have to get some ordered ASAP. But I am having paralysis of analysis from all the types of oxygen barrier pex.

To be honest in all my searching, I am not finding.... any.... pex that is failing out there in a slab. Unless it freezes or the concrete crew hits it with a shovel.

Anyone have any wisdom to impart? Thanks!!

 

[readhead]

I asked my plumber on one of my metal building jobs about in floor heat because the owner was trying to decide which way to go. The plumber said that using oxygen barrier allowed him to use less expensive iron pumps. The regular pex required the use of stainless steel pumps and components. Take that for what you paid for it.
The customer went with a unit heater for a fraction of the cost.

 

[Firebrick43]

Readhead reason is why oxygen barrier is important. If there is no oxygen there can be no oxidation, aka corrosion. It not only protects the pumps, but the valves, and boiler as well. Air leaks are bad for a system. Also why a micro bubble air seperator is important for long system life.

 

[jblnut]

The customer went with a unit heater for a fraction of the cost.

Oh jeez don’t do that. The cost difference of in floor vs anything else isn’t nearly as bad if you only price in floor and nothing else. Radiant in floor heat is soooooo nice and it’s very quiet vs a unit heater blasting away randomly.

As far as what pipe to use, I used whatever oxygen barrier pex my local hvac guy had on hand. Couldn’t tell you what it was or how much it cost but its heating just shy of 7,000sq/fr between the shop and house.

 

[challenger]

Oh jeez don’t do that. The cost difference of in floor vs anything else isn’t nearly as bad if you only price in floor and nothing else. Radiant in floor heat is soooooo nice and it’s very quiet vs a unit heater blasting away randomly.

As far as what pipe to use, I used whatever oxygen barrier pex my local hvac guy had on hand. Couldn’t tell you what it was or how much it cost but its heating just shy of 7,000sq/fr between the shop and house.

Thanks for this feedback. I have heard this more times than not.

"I got it from X place and it was colored (red, or white, or etc.) Don't remember what brand it is."
Makes me think I'm stressing of which one unnecessarily. It sounds like most everyone just picks a PEX, puts it in, and has little to no issues in the short and long term.

 

[fitter30]

Oxygen barrier prevents diffusion of oxygen molecules into the water through walls of the pipe. Just use a name brand.

 

[Mr onetwo]

pex-a with the proper fittings

 

[rlitman]

PEX-A is more flexible and forgiving. It can also be heated to repair a kink. For those reasons alone, I would recommend PEX-A for an in-floor loop.

Expansion fittings are an option and they sometimes make some installs easier, but they are NOT necessary and I'm not a huge fan of them. I have seen them leak when the line enters after a bend.

 

[beanbread]

I’ve put 1/2” oxygen barrier Pex in my slab and am getting ready to pipe the system together to my heater. I’m having trouble finding sticks of 1” oxygen barrier Pex. I don’t see any mention of which fittings brass/plastic etc are actually an oxygen barrier? Doesn’t sound like copper is either? Wondering if just plain old Pex b from Home Depot will suffice

 

[Chuckster in NJ]

I used WIRSBO pex (and manifolds) in my slab when I built my house 30 years ago and to date I have had no problems………. The basement and garage have in slab heat.
www.uponor.com

 

[rlitman]

I’ve put 1/2” oxygen barrier Pex in my slab and am getting ready to pipe the system together to my heater. I’m having trouble finding sticks of 1” oxygen barrier Pex. I don’t see any mention of which fittings brass/plastic etc are actually an oxygen barrier? Doesn’t sound like copper is either? Wondering if just plain old Pex b from Home Depot will suffice

Anything made of metal is inherently an oxygen battier. Copper, brass, you're all good. I can't say that the plastic fittings are oxygen permeable, but I will say that the exposed area from PEX fittings is very small (since the fitting goes INSIDE the barrier PEX), so I doubt it matters. However, plastic fittings do have smaller interior diameters, so if you care about flow, stick with metal connections.

Why are you looking for 1" oxygen barrier PEX? You wouldn't be making 1" loops, so build the 1" parts of your manifold out of metal. Black pipe or copper.

 

[Highbeam]

I used barrier pex but I have to wonder how much oxygen can really get through the wall of regular pex and whether the extra little shiny paint they add makes that much difference.

 

[T444e]

The oxygen barrier PEX I am familiar with is an aluminum intermediate layer. I don't know how permeable PEX is, but oxygen is detrimental to hydronic heating systems from a corrosion aspect.

 

[Mezz2006]

I went with the PEX A from PexSuperstore costs is just a little more than PEX B. I had no issues rolling it out and installing it. I would use it again. I got the RHT SS manifolds from Blue Ridge Company. They seem pretty nice as well.