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Larger pex tubing.

Paul Pollets
Paul Pollets Member Posts: 3,656
Viega makes 11/4-11/2" in straight lengths. The fittings are pressfit. We stay with copper at the near-boiler piping, and convert to pex within 5 ft of the boiler. This dramatically reduces the cost of distribution piping.

The same could be done with Uponor Multicor, but it doesn't come in straight lengths, only coils.

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  • jwade55_5
    jwade55_5 Member Posts: 14

    Anyone using larger (1 1/2", 2") Pex in place of copper. I'm working on a couple of jobs that the cost difference in pex vs copper could influence the design to stay more hydronic. We are looking at Wirsbo tubing, any input?


  • SAC
    SAC Member Posts: 1

    Surely Pex will reduce the cost of the copper on the job, Uponor (Wirsbo) makes up to 2" HePEX, which is nice. The fittings may seem a tad pricey but the install will be quicker and just as, if not more, professional than if done with Copper.
    Go for it!
  • Couderay
    Couderay Member Posts: 314
    More professional

    What could you possibly be talking about more professional, than copper.
  • Robert O'Brien
    Robert O'Brien Member Posts: 3,537

    years ago someone said almost the same thing,"Copper?What could be more professional than black iron"

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  • Be prepared to wrestle with a BOA constrictor with an attitude,,

    and a MAJOR erection. I kid you not.

    Also, be prepared to handle the SIGNIFICANT increase in piping expansion. PEX (regardless of ID size) expands at 1.1 inch per 100 feet of pipe per 10 degree F change in temperature. Compared to copper, that is a BUTT load of expansion.

    Other than those characteristics, and the inability to install it straight, its great stuff.

  • Derheatmeister
    Derheatmeister Member Posts: 1,514
    Easier Install ..

    Make sure that the roll is nice and warm when you go to install the piping.About 30 years ago IN Germany we had some Tubing system (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 when 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.Maybe just use a Waterheater/circ. just some suggestions to make it easier install.One question from me : if the "PROPRESS" fittings and piping would be less.(i.e. Metal fittings and piping) would you consider the usage of this? HM.
  • Steve Ebels_3
    Steve Ebels_3 Member Posts: 1,291

    That's exactly why I wish Viega or someone else with a good PAP product would bring 1 1/4" through 2" to the market. PAP is more in line with copper expansion rates.

    On the subject of expansion, where do the pex expand when it's buried in cement or underground? We buried a pair of 2" (Rehau) pex lines with a length of 273' this past fall for a wood boiler install. I've been back to the job numerous times to monitor the performance of the whole sheebang. There are no signs of expansion whatsoever on the above ground portions of the pex. We incorporated swing joints on each end and they haven't budged. Makes me wonder.....that length of tubing should have grown about 2'+.
  • jwade55_5
    jwade55_5 Member Posts: 14

    Thanks for the responses. Expansion is one concern, but we can deal with that. We plan on near boiler/chiller piping of copper. We are running a 2" loop around this house, which will be concealed, so not being perfectly straight is not a huge concern. One thing I'm concerned is the cost of the uponor fitting tool, WOW.

    I agree, if someone made 2" PAP, that would solve several issues, but.. How about temperature, this system is designed with MAX water temp of 150 deg f, should we be concerned with loss of o2 barrier?

  • Jaws


    Does it require a specific set of jaws to press the Viega? Or will a normal 1 1/4" press jaw for copper work?
This discussion has been closed.