Will PVC bond to CPVC?

Discussion in 'Plumbing Forum, Professional & DIY Advice, Tips & ' started by Flipperman2a2w, Mar 17, 2011.

  1. Flipperman2a2w

    Flipperman2a2w New Member

    Messages:
    33
    Location:
    North Carolina
    I have a 3/4" PVC to 3/4" CPVC adapter. I know that I have to use CPVC cement (as PVC cement is not strong enough to work on CPVC).

    Having said that, will CPVC pipe actually bond to PVC? I assume it would, since they make an adapter for that very purpose. The slip adapter itself is made of PVC.
  2. Gary Swart

    Gary Swart In the Trades

    Messages:
    7,349
    Location:
    Yakima WA
    Many folks do not understand about how the various plastic pipes are joined. There are 3 basic kinds of plastic pipe; ABS, PVC, and CPVC. They are chemically different. That much is easily understood. The problem comes in the fact that what we all commonly call pipe "glue" or "cement" is neither of these. They are solvents that melt the top surfaces of the pipe and fitting briefly. When the two surfaces are joined, the liquid surfaces combine into what is actually a chemical weld. So, it's not a matter of bonding, strength, or sticking. Each type of pipe has its own solvent, so the answer to your question is, No, you can't join different types of plastic pipes, except by using appropriate adapters. Not known what you are doing and why you would need to join CPVC to PVC, it's hard to advise you on what you may need to do. A couple of problems with PVC and CPVC pertain to why you are mixing media and size incompatibility. In other words, 3/4 PVC is not the same size as 3/4 CPVC.
  3. PM5K

    PM5K New Member

    Messages:
    154
    Location:
    San Antonio, TX
    I thought CPVC was typically used for supply lines and PVC for drains and vents?
  4. Flipperman2a2w

    Flipperman2a2w New Member

    Messages:
    33
    Location:
    North Carolina
    Here's my situation. . .

    The water line that comes into my garage from underneath the house is PVC. I'm installing a water filtration system, and I want to add a brass hose bib to the PVC line before it goes into the filtration system (that way I can draw unfiltered water for yard maintenance).

    This is how I want to install the hose bib: 3/4" PVC main line -> 3/4" PVC to 3/4" CPVC adapter (this adapter is specifically made to transition 3/4" PVC to 3/4" CPVC) -> 3/4" CPVC pipe -> slip CPVC/threaded brass transition adapter -> brass hose bib.

    I considered using a brass hose bib with PVC, but I know you're not supposed to use a male brass thread with a female PVC thread. So, I ultimately want to use the CPVC/brass transition adapter to attach the hose bib.

    Here's what I don't understand. . . Why would they specifically make an adapter for PVC to CPVC if there's no way you can successfully join the two materials?
  5. cacher_chick

    cacher_chick Test, Don't Guess!

    Messages:
    3,246
    Location:
    Land of Cheese
    They are not commonly found in stores, but such a transition fitting normally has a brass nipple between the 2 types of plastic. There are also plastic fittings with brass or stainless steel threaded inserts.
  6. Inspektor Ludwig

    Inspektor Ludwig Journeyman/Inspector

    Messages:
    167
    Location:
    In the good ol' UPC
    Get a male pvc coupling and a female copper thread by cpvc adapter and screw em together to transition.
  7. Laurihill

    Laurihill New Member

    Messages:
    1
    Location:
    Mn
    I need to find an adaptor that will tie 3/4 inch PVC to 3/4 inch CPVC. Is that a common adapter? I can't come up with a connector....
  8. Terry

    Terry Administrator Staff Member

    Messages:
    15,005
    Location:
    Bothell, Washington
    PVC and CPVC don't mix. Inside a home, only CPVC is legal. PVC is for cold water pipes underground.

    Since they are not the same size, the only way to connect the two pipes is with threaded fittings. The post above by the inspector mentions that.
  9. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,642
    Location:
    Cave Creek, Arizona
    IT would only work, and be "legal", if the two sides were different materials so their proper primers and glues could be used on each side.
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