hePEX vs. PERT

Solid_Fuel_Man

What are the advantages and disadvantages or PERT over the more traditional PEX w/ oxygen barrier? I've been given a few sales pitches, but the trusted experience of THE WALL is much better! 

Is it just a lower operating temperature all else being equal? Such as a slab, PERT would be perfectly acceptable? Any long term history with PERT or is it relatively new on the market?

Thanks in advance!

hot_rod

I have not used PERT, sounds like it is a bit more flexible, less tendency to curl up on you. It has been around for sometime and under them major brand names, Roth, Watts and others.

I think A pex is crosslinked as it is extruded and tends to be easier to work compared to B pex which is crosslinked after it is coiled, so it tends to want to stay coiled

mattmia2

That 1" hepex that I was working with sure wanted to stay coiled...

hot_rod

mattmia2 said:

That 1" hepex that I was working with sure wanted to stay coiled...

1" is always a tough go, unless you can get it to about 120F, then it gets much easier to work
Years ago one of the German pex brands, EHT I think, had a uncoiler that was heated.

1" and larger I buy straight lengths and couplings.

Solid_Fuel_Man

FW Webb sells both pex-a and PERT and of course the PERT is notably cheaper. On big radiant slab jobs with 6,000+ feet of tube, I'm contemplating it. Samples of the PERT seem very much in line with the pex-a which I use exclusively. Use both Uponor and Mr.Pex brands. 

Boiler_Jim

In my opinion, I think PE-RT Pex is a very good product. I have done many jobs with it. Very easy to work with, and durable. I have even installed 3/4" Pex in the 30-40's °F and its still reasonably flexible. Just finished up another snow melt project.....

Next up is the boiler piping and mixing valve arrangement for all the zones. Hydro-air, along with in-floor radiant heat, Hydronic towel warmers, etc. on this project. Using Grundfos, Caleffi and Watts products. Also using NA5709 series demineralizer for initial system fill and also for mixing P-glycol.

psb75

Keep in mind that that Uponor fittings have larger i.d. than competing pex fittings for better flow. I also prefer Uponor expander method of fittings install. He-pex has tendency for much "coil memory" esp. at lower temps.

LMacNevin

As a plastic pipe nerd and member of the technical committees that write standards for these products (e.g. ASTM, CSA), PE-RT tubing that is certified to ASTM F2623 or CSA B137.18 is trusted and reliable for radiant heating installations. 25+ year history in Europe.
You can read more at these PPI webpages:
https://plasticpipe.org/building-construction/bcd-pex.html
https://plasticpipe.org/building-construction/bcd-pe-rt.html
*PPI is a non-profit trade association for plastic pipes

hot_rod

Boiler_Jim said:

In my opinion, I think PE-RT Pex is a very good product. I have done many jobs with it. Very easy to work with, and durable. I have even installed 3/4" Pex in the 30-40's °F and its still reasonably flexible. Just finished up another snow melt project.....

Next up is the boiler piping and mixing valve arrangement for all the zones. Hydro-air, along with in-floor radiant heat, Hydronic towel warmers, etc. on this project. Using Grundfos, Caleffi and Watts products. Also using NA5709 series demineralizer for initial system fill and also for mixing P-glycol.

really nice work!

Ironman

PERT is easy to work with and reliable. We haven't done a tremendous amount, but have had no issues other than a roll that was wound too tight and wouldn't fit on our uncoiler.

You can also use cold expansion fittings on it.

hot_rod

Makes one wonder why it is not replacing PEX completely?
Sounds like it does everything and more than PEX, at a lower cost. Or??
I know various brands of pex have different chlorine ratings. Continuous, hot, chlorinated DHW seems to be the concern for some pexs.
With more and more bacteria concerns it may be all buildings continually circulate 140F or higher chlorinated or chloramine water, in the near future. That may separate the lesser rated tube from the pack.

There is a couple feet of listings stamped on PE tube, they all tell a story.

Solid_Fuel_Man

I'm just concerned with using it for slab heating. Many miles of tube go into a slab, compared to potable water. I'll stay with what has worked well for potable water, cooper and pex. 

tocker

I'm tearing out my old 80s Burnham from my 1955 Ranch, and replacing the old fin-tubes with the largest Runtals I can fit into the space. Various heat-load calcs and WAGs have been performed and thus will install a mod-con boiler with water temps that vary up/down from a planned 150-160 degrees. I like Uponors HePEX, however, installers all recommend various brands of PEX-AL-PEX. I prefer HePEX for ease of installation and maintenance/adjustments later. BTW, I should mention that I've had an extremely difficult time of finding installers, which have nothing to do with COVID. NONE are willing to do re-pipes, so I will run the home-runs and the installer will do the near-boiler work. The reasons cited against HePEX: can't take the heat, potential for air and noise using high temps. While there is much general information citing how great HePEX is, I can't find any references to installs to rads where AWT can potentially rise to 180. I've contacted Uponor engineers; HePEX rating is over 200 degrees and they swear it is the best thing since fire. Does anyone have experience or examples of successful or unsuccessful installs using HePEX? Opinions?

mattmia2

HE Pex and Pex Al Pex are both excellent products if installed properly with quality products.

HE Pex tends to stay in the shape of the coil and is less rigid so it needs more support than Pex Al Pex but it can be easier to fish in cavities and can be restored with heat if you kink it. Once bent to a certain shape pex al pex retains that shape so it can be easier to route in open spaces.

Propex fittings reliant on the memory of the tubing are less likely to develop a leak because the plastic creeps than the metal compression style fittings of pex al pex.

The aluminum layer in pex al pex is a better oxygen barrier than the coating on he pex.

PC7060

@Boiler_Jim - your use of electrical pvc as rebar chair is clever.  Won’t tip over or crush when you walk on it and can cut to any length. 

I see you ran the pex through pvc sections tied off to the wire mesh; is that so you can route/capture the pex along the planned route before you do final tie off?

BillyO

Real nice job!!!!

Derheatmeister

hot_rod said:

mattmia2 said:

That 1" hepex that I was working with sure wanted to stay coiled...

1" is always a tough go, unless you can get it to about 120F, then it gets much easier to work
Years ago one of the German pex brands, EHT I think, had a uncoiler that was heated.

1" and larger I buy straight lengths and couplings.

Hello HR...Thermoval...Is this the Tubing you are thinking about ? It was a oval Pex tube that was thermal socket welded... This was from a posting back in 2008 so this Product goes back to over 40 years.

"Make sure that the roll is nice and warm when you go to install the piping.About 30 years ago in Germany we had a Tubing system Called (Thermoval) which we would first hook up to a mini boiler that would circ very hot water Thur the tube and it would become very flexible. Then we would cap the ends of the tubing and "run whit it" the clips were already in place . Once the tubing was cold it stayed in place."

GroundUp

I use a lot of PE-RT for underfloor applications and certain snowmelt jobs due to the higher flexibility, but what I've found for slabs is that it's less durable during the pour. The guys dropping rebar on it or running into it with equipment, it will crush relatively easily compared to PEX. With that said, I see absolutely no reason to use PEX-A in a slab. Once the mud is cured, PEX-B and PE-RT do just as good of a job and the majority of us use compression manifolds anyway so there is literally zero benefit to spending hePex money in slab applications IMO. 300,000+ feet of 1/2" PEX-B buried so far and the only times it was a problem was kinking in 6" spacing applications when not paying close enough attention- which has happened 4 times now.