Connect PVC to CPVC


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Old 03-29-05, 06:28 AM
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Connect PVC to CPVC

Can PVC fittings be glued to CPVC pipe? If not, is there any way other than something like a Fernco coupling to join PVC pipe to CPVC pipe? This is in a sink drain application.
 
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Old 03-29-05, 07:52 AM
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Is there a specific reason you are switching types of pipe? CPVC and PVC are different outside diameter fittings and pipe. They DO make glues that will work on both (or so the can says). Let us know what you are doing and perhaps we can give you some ideas. Good luck.
 
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Old 03-29-05, 08:54 AM
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It's sort've convoluted to explain but I'll try. My house was built in 1960, and was originally on a septic system. It was connected to city sewer some 25 years ago.

All the original drain piping is copper. For the kitchen sink, the drain drops into the basement and goes to the left about two feet into a drain tee. Another leg of the tee goes to the vent and the third, which used to connect to a pipe going out the wall to the septic tank, now connects to an added CPVC drain line which runs along the wall and hooks into the city sewer line several feet away.

Now to the problem: the drain tee in the original piping is incorrectly installed. Instead of having the inlet horizontal, the vent leg up and the outlet down, the tee is rotated 90 degrees. It sits just like a letter "T". Drainage enters on the right, the vent is to the left, and the drainage outlet (which should actually be the drainage inlet) is down. The plumber who looked at it said this is causing the sink (and dishwasher) to not vent properly and to drain slowly.

What I'd like to do is cut out the drain tee and replace it with a PVC tee and whatever assemblage of elbows and PVC pipe I need to line things up. I think I can use Fernco couplings where the PVC connects to copper, but I'd save a few bucks if there is a way to connect the PVC to the CPVC some other way.

Or is there yet another way to fix this?
 
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Old 03-29-05, 07:41 PM
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an added CPVC drain line which runs along the wall and hooks into the city sewer line several feet away.

Explain to us why CPVC is being used for DWV instead of water line piping like it was intended for.


You cannot intermix CPVC with PVC even with water piping.......let alone the mix with drain piping.


They make mission no-hub couplings that join dissimilar material.......which in your case is PVC to copper. These are banded couplings that are code approved for above ground use.

If you do not like that approach......then sweat a 1 1/2 copper male adaptor onto the copper piping you have......then use a PVC female adaptor and thread the dissimilar components together. Dope up the threads with a good teflon thread sealant.


I understand the incorrect tee config you described. Best way for all viewers of the thread to understand specific plumbing situations is to take pictures and provide images or links to images. Makes the advice given to you more precise.


No CPVC should be used in your drainage system whatsoever......if it is in there......it is wrong.
 
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Old 03-30-05, 05:21 AM
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Thanks for the reply. I have no idea why CPVC was used for this line. As I said, the city sewer hookup was done maybe 25-30 years ago; I bought the house in 2003. This is small-town West Virginia so you do find some strange things - after all, the incorrectly installed drain tee is part of the house's original plumbing. I also just got the City to install an outside service shutoff valve because the house has never had one.

I do intend to use Mission couplings to connect the PVC to the copper. But I'm probably still going to have to connect PVC to CPVC at one point. Code compliant or not, I presume I can use a Mission there as well? I really don't want to replace the entire drain line. It's over 40 feet long and passes through a cinderblock wall.
 
 

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