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Larger PEX piping for hot water heating?

Chuck_17
Chuck_17 Member Posts: 145
in THE MAIN WALL
How practical is it to use PEX piping for heating hot water systems in commercial (old churches) exposed installations?
It makes total sense in wood frame construction. The only time I have seen larger PEX used, it was strapped to wood floor joists (of a church).
What about in installations where it would have to be hung by regular hangers?
What about risers exposed through a floor to ceiling (to the floor above)?

The reason it is being considered is for cost reasons (a old church that as a small cash poor congregation). (plus copper has a habit of disappearing)

Comments

  • Jamie Hall
    Jamie Hall Member Posts: 24,863
    The problem with PEX is that when it gets hot it sags and tends to stay sagged. If you can support it adequately, not a problem.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Ironman
    Ironman Member Posts: 7,550
    edited March 2017
    Another consideration is the fittings and tools required to join it. They can be very expensive and unless you're planning on continually using them in the future it makes no sense to purchase them for one job.
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
  • Zman
    Zman Member Posts: 7,611
    There are metal trays the allow you to support pex like conventional rigid piping. Another factor to consider is the wall thickness of the larger pex. You often have to go up a pipe size in order to get the same flow. In the end, you may not save money with pex.
    What size pipe? Is steel pipe with Vitolic connections an option?
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • hot_rod
    hot_rod Member Posts: 23,398
    watch the ID also. The pex doesn't always cross over with copper, capacity wise.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 16,488
    and something I have difficulty getting answers on. The od of pex seldom matches pipe, difficult to insulate and problems if used for chilled water with condensate between the pex and the insulation
  • Zman
    Zman Member Posts: 7,611
    hot rod said:

    watch the ID also. The pex doesn't always cross over with copper, capacity wise.

    That's what I was getting at. Especially on the larger pipes, the inner diameter is much smaller because of the pipe wall thickness. It has significant impact on flow rates.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • Chuck_17
    Chuck_17 Member Posts: 145
    Thanks for the comments.
    Black steel is an option.
    Copper with press fittings is an option.
    Any mix.
    2" or less except near the boiler for which it will be steel (or copper).
  • Jamie Hall
    Jamie Hall Member Posts: 24,863
    If you are in an area where copper has a way of wandering off... first, my sympathy. Second, it probably would be worth the effort and trouble to use the PEX, supported in a tray or at least at very frequent intervals. All things considered.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Zman
    Zman Member Posts: 7,611
    Dan wrote and article about painting the copper black so it would get stolen. Still makes me chuckle....
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • Chuck_17
    Chuck_17 Member Posts: 145
    I didn't see the article (I'd like to). Sounds like an idea.

    It's not that bad (though I have seen a few situations....) First cost is more of an issue.
  • Grallert
    Grallert Member Posts: 780
    I've hidden my vertical pex risers in black pipe to get from one floor to another. Looks like a steam pipe and in my area there are a lot of steam systems so it's not an unusual thing to see.
    Miss Hall's School service mechanic, greenhouse manager,teacher and dog walker
  • Erin Holohan Haskell
    Erin Holohan Haskell Member, Moderator, Administrator Posts: 2,354
    Chuck said:

    I didn't see the article (I'd like to). Sounds like an idea.

    @Chuck, here's the article about the copper in NYC: https://heatinghelp.com/blog/nyc-one-pipe-steam/

    And here's an article about PEX for hydronic distribution piping that you may find helpful: https://heatinghelp.com/systems-help-center/pex-for-hydronic-distribution-piping/

    President
    HeatingHelp.com

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