3" PVC stack into Cast iron cleanout

Users who are viewing this thread

snelson57

New Member
Messages
1
Reaction score
0
Points
0
I am adding a full bath into the 2nd floor of a Cape Cod. I have run a new 3" stack over to the existing cleanout in the floor, which is 4" cast iron. The cleanout has a 3 1/2" brass plug. Is there an adaptor available to bring me from 3" PVC to thread into a 3 1/2" cast iron fitting? What are my options?
Thank you.
 

Phatbrain

New Member
Messages
17
Reaction score
0
Points
0
Location
Pacific North Wet
Pipe Sizes - now and then

Greetings Snelson,


I’m curious about your 3.5†pipe. A common mistake with pipe is trying to measure it with a tape measure. If your clean-out plug measures 3.5â€, then what you have is a 3 inch pipe.

It’s kinda like trying to find 2 inches or 4 inches on a 2 x 4 stud. A long time ago (in a land far – far a way…) when steel chemistry was crappy, the pipe walls were thicker. So, an I 1/2 pipe I.D. was 1.5â€.

As steels improved, they were able to make the wall thinner, but to keep the pipe “backwards compatible†with existing fittings, the pipe O.D. was kept the same as before.

Pipe
Size:

1/2" =0.840" o.d.
3/4" =1.050" o.d.
1" =1.315" o.d.

1 1/4" =1.660" o.d.
1 1/2" =1.900" o.d.
2" =2.375" o.d.

2 1/2†=2.875" o.d.
3" =3.500" o.d.
4" =4.500" o.d

5" =5.563" o.d.
6" =6.625" o.d.
8" =8.625" o.d.

10" =10.750" o.d.
12 =12.750" o.d


Phat
 

hj

Master Plumber
Messages
33,599
Reaction score
1,037
Points
113
Location
Cave Creek, Arizona
Website
www.terrylove.com
co

About the only common bushing you will find is a 3 1/2" x 2" one. But the cleanout is not an approved sanitary fitting so you should not connect your drain to it, but should install a proper sanitary tee for the connection and be sure to retain, or provide a new, cleanout in that area.
 

hj

Master Plumber
Messages
33,599
Reaction score
1,037
Points
113
Location
Cave Creek, Arizona
Website
www.terrylove.com
Phatbrain said:
Greetings Snelson,


I’m curious about your 3.5†pipe. A common mistake with pipe is trying to measure it with a tape measure. If your clean-out plug measures 3.5â€, then what you have is a 3 inch pipe.

Cast iron cleanout tees and cleanout ferrules have a 3 1/2" plug tap. It goes back to the original specification that a cleanout opening had to be the size of the pipe, and a 3 1/2" tap was 4" o.d. and thus was adequate for a 4" pipe. It is still the same with cast iron, but plastic cleanout tees use a plug the same diameter as the pipe. 3 1/2" plugs are made in plastic also for use in cast iron fittings.
 

Macska

New Member
Messages
32
Reaction score
0
Points
0
Why can't I use the cleanout to connect an auxiliary DWV stack if I install a new cleanout into the new stack so that it can be used to reach both?
 

Macska

New Member
Messages
32
Reaction score
0
Points
0
Edited: HJ, plumguy and Kristi have kindly begun to address my question on another thread. No need to have two threads on the same issue.
 
Last edited:

jimmie

New Member
Messages
30
Reaction score
0
Points
0
ummmm

anyways just to answer your question...they do make a 3 1/2" tp 3" reducing bushing =) it's available in both black, and galvanized.
 

Finnegan

New Member
Messages
248
Reaction score
2
Points
0
Location
CT
As Jimmie said, A plumbing supply store should carry the fitting you need. I just bought a black fitting and my store had it in stock. It is not a Home Depot item.
 
Top
Hey, wait a minute.

This is awkward, but...

It looks like you're using an ad blocker. We get it, but (1) terrylove.com can't live without ads, and (2) ad blockers can cause issues with videos and comments. If you'd like to support the site, please allow ads.

If any particular ad is your REASON for blocking ads, please let us know. We might be able to do something about it. Thanks.
I've Disabled AdBlock    No Thanks