Relocating a toilet in our half bath.Problem is the 3" copper pipe is 3" OD. House was built in 78 and ALL the plumbing is copper! I want to use 3" PVC pipe and flange,but the 2 sizes are different. Does anyone sell flex couplers that go from old 3" copper to modern day 3" PVC? Looked online at the big box stores and I'm not finding anything that looks like it will fit.

You want a CK33 coupling. Google it.

How far are you moving the toilet ? It would make a more professional looking job if you stayed with copper.

while i agree with my frien from NC, i think working with 3" copper tubing is beyond the skill level of the average homeowner. not to mention the extraordinary costs involved..

Yes they make those types of couplers, go to a plumbing supply or order online from the sponsor here. The big box stores carry 3" cast iron to 3" PVC and the outside diameter is too big for copper they will leak. Get the right part and you won't have any issues.

i have found that some of the old cast brass fittings have an OD that is just about the same as plastic pipe. if that is the case here, cut back to a cast brass fitting and slip a banded coupling over it and tighten to prescribed torque.
obviously if the fittings are wrought copper this will not work..

IF the copper were 3" o.d., there is no way they could have used it for a plumbing system because NONE of the fittings would have worked with it. It is standard 3" copper DWV tubing, and as mentioned, a copper to PVC transition coupling will work. Also, as mentioned, redoing it in copper would be more expensive, but also more rigid/secure.



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When I can, I cut back to the brass fitting and join to it with a no hub coupling. If that is not possible, I use a CK33 as already posted.

Oughtta see what liquid drain cleaners do to no-hubs,and similar connectors, even though they may be safe for the pipes.

let me see if I understand:

you have an existing bath with first class copper plumbing

you wish to 'improve' same by adapting to second class plumbing using rubber clamps and plastic tube/pipe

got it !


just remember:

"NEVER STOP IMPROVING"

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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638

Isn't that the same way the plumbing industry has been "improving" over the last few decades?
Cast iron or copper to PVC or ABS
galvanized to copper to polybutylene, to PVC or CPVC, to PEX.
Schools are "dumbing down" their students and the industry is "dumbing down" the incoming plumbers.



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look up 3"CLAMPALL BUSHING

I use them for copper all the time...its a bushing that will fit in a Fernco or Clampall to size down for copper

Ive seen copper pipe rot...the top 1/2 rots from sewer gas from what I can tell...ive seen tons of them with pin holes right above the water line

pvc is better

the OP's house was built in 1978

it is 36 years old with working plumbing

sounds like quality to me

ps. they used to PROPERLY vent which 'diluted' and dissipated the sewer gas

? not to say private homes have them, but, "FRESH AIR INLET" ?

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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638

The copper DWV I have found failed was BELOW the water line where the drain cleaning chemicals flowed.

I have replaced much copper 3"DWV but it has always been due to erosion from acidic water combined with neglected toilet flappers that trickle water thru the waste line 24/7.

You guys must be doing OK in the plumbing biz if you can afford to buy 3" copper DWV pipe. My previous house was built in 1973 and was all copper. If I recall 2" copper was like $10/ft, I couldn't even find 3" but assume you can get it somewheres. PVC certainly not as pretty as copper but will definitely outlast it.

If you can pay for 3" copper DWV pipe, you can find it.