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Sch 80 vs Poly P for short vents?

Timco Member Posts: 3,026
Laars Mascot LX. Laars says it comes ready for sch 80. Please explain how use of sch 80 puts anyone at risk, for a 4' vent. My business partner and I disagree on this. I say 80 is stronger (more rigid), stronger joints, and does not require any special adapter for it's use. Basically, I cannot see how use of 80 is an inferior or sub-standard install. It seems there's a flavor of Kool-aid for any application, as long as someone is selling a product that reinvents the wheel.

If a snow tire does not actually list mud, do you reason it's approved for the vehicle, it's load, has great tread, has air, DOT lists it as approved, so it is safe to use? Or do you wait for a tire that has the three letters MUD stamped on it?

It seems like this is a waste of money that can go towards more insulation or anything that will actually make a better or safer install or end product.
Just a guy running some pipes.


  • Steamhead
    Steamhead Member Posts: 14,844
    PVC/CPVC, whether Schedule 40 or 80, is not UL listed for venting combustion products. And it never will be- pipe manufacturers get to sell lots of pipe this way without assuming liability.

    If by Poly P you mean polypropylene, several manufacturers have had theirs UL listed for combustion venting, such as this one:

    Me, I'll use listed material every time. That gives some level or protection if there is a problem.

    All Steamed Up, Inc.
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
  • RobG
    RobG Member Posts: 1,850
    Polypropylene is probably cheaper than sch80 CPVC as well.
  • Henry
    Henry Member Posts: 988
    Listed S636 PVC or CPVC is just sch 40 PVC/CPVC in a different colour. They still use the temperature/pressure ratings of sch 40 pipe. The standards used to manufacture S636 are the same as sch 40. There is new labeling and a requirement that you have to use the "system" that is that you cannot use a fitting from another maker.
  • RobG
    RobG Member Posts: 1,850
    I have never been able to find Sch40 CPVC.
  • bmwpowere36m3
    bmwpowere36m3 Member Posts: 512
    Lochinvar allows CVPC on the exhaust vent, so that's what I used with my Knight install. About 10' of 2" Sch80 CPVC and 4 fittings. The CPVC was about $7 per foot. I used PVC for the intake vent.
    Bob Bona_4
  • RobG
    RobG Member Posts: 1,850

    RobG said:

    I have never been able to find Sch40 CPVC.

    Shipping a 10' length is the problem.

    I was able to use two 5' lengths for my situation.
    I'll stick with PP as it is stocked locally, cheaper and approved.
  • SWEI
    SWEI Member Posts: 7,356
    RobG said:

    I have never been able to find Sch40 CPVC.

    Fire sprinkler supply houses stock boatloads, and at good prices.