4 x 3 reducing bushing versus reducing coupling

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tlfamm

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In the process of converting the clapped-out CI DWV system in my 100-year-old house. Planned on a 3" toilet drain line fitted into a 4" SanTee in the 4" stack, using a 4 x 3 reducing coupling. (In the first-floor ceiling)

Then I got a look at the structural butchery used during the original CI installation: 20" of floor-joist removed ('patched' with a 2 x 2.5 x 24 scab), and cracks in the tile under the toilet. So, I need to sister the floor-joist, but any repair will interfere somewhat with the hub of the 4 x 3 reducing coupling. Space is at a premium.

Is a 4 x 3 reducing bushing an acceptable alternative to fit the 3" horizontal toilet drain line?




Note: a 4 x 4 x 3 SanTee is not an option in this case.
 

hj

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If the tee with a bushing is acceptable, I cannot visualize why the "smaller" 4x3 would NOT be. But also not sure, from your description, whether a san tee of any size is acceptable.
 

tlfamm

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If the tee with a bushing is acceptable, I cannot visualize why the "smaller" 4x3 would NOT be. But also not sure, from your description, whether a san tee of any size is acceptable.

The fitting I need to replace with PVC is a 4" CI closet bend about 16" in overall length. About 1" downstream from the upward bend was a 1-1/2" side port at 60 degrees (horizontal), into which the lead drain line from our bathtub was plumbed (via a 45 degree bronze ell). The only 4" PVC fitting I could find that duplicates that capability is:


http://www.pvcfittingsonline.com/4-...nitary-tee-with-left-side-inlet-p416-420.html

which locks me into a 4" tee inlet for the toilet waste line.
 
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tlfamm

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Well, if I am reading this correctly, you can't do that either unless you put in a vent for the bathtub before it connects to the toilet drain.

I plan on venting the bathtub - sink also (neither is currently vented).
 

tlfamm

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Using a flush bush to reduce to 3" is fine.
Thanks, Terry, (and HJ also) - very helpful to have a sounding board for technical questions.


I rehabbed my house 35 years ago. In hindsight I wish I had dealt with DWV replacement then, while the walls and ceiling were open - on the other hand, I did get 35 years of use out of the existing system.


The first inkling of trouble occurred about 34 years ago when I noticed corrosion bumps on the horizontal CI waste line from the kitchen. I had it replaced with PVC by a professional plumber. He said, "you know your drain system was built with service-weight cast iron, right"?

I said, "what's 'service-weight'"?

I certainly found out. :)

(The upstairs bathroom was created in 1943; given wartime materials shortages, I'm surprised it was even possible - maybe they plumbed with used pipe?)
 
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