Connecting PVC to Cast Iron. Fernco likely will not fit... :(

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pandamoneum

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Hello,

Just wondering if anyone can give some insight on my plumbing problem. I am replacing a toilet in the basement, and am wondering the best way to connect the new PVC to the existing cast iron drain.

The Cast iron has an OD of 6" and an ID of 5". There are no Fernco couplings which show an acceptable ID of 6", and I have tried similar couplings with an ID of 5.5" (too small) and 6.5" (too large).

Also, since the ID of the cast iron is 5", and the OD of the PVC is 4.5", it does not give much room for a gasket.

If anyone has any ideas or comments, they would be greatly appreciated.

Thank you,
 

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pandamoneum

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The 'hub' is a female connection. The connector goes inside of the 'hub'

Google "connect pvc to cast iron hub."

I was hoping to avoid going the oakum and lead route if possible... but it is looking like that may be the only option. This is what was there previously, however the entire toilet elbow was also lead.
 

Reach4

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Search for "Fernco donut" here and elsewhere.
 

DougB

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I was hoping to avoid going the oakum and lead route if possible... but it is looking like that may be the only option. This is what was there previously, however the entire toilet elbow was also lead.

I don't think you read what I wrote. If you would google: connect pvc to cast iron hub you would get this picture:

PVC_Hub.jpg


These are 'male bushings' that will fit into your cast iron hub, and the PVC fits inside the bushing.
 

pandamoneum

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I don't think you read what I wrote. If you would google: connect pvc to cast iron hub you would get this picture:

View attachment 27737

These are 'male bushings' that will fit into your cast iron hub, and the PVC fits inside the bushing.

Okay thanks, I misunderstood what you were saying. I'll see if I can find one of these locally (Canada)
 

FullySprinklered

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If you go with the donut, and have trouble with the connection, give me a holler, at they say. I've done half a dozen of them and had a bit of trouble. The best solution I found involved a tube of personal lubricant and a cinder block. This is not a joke.
 

Jadnashua

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The OD of the PVC is controlled (as well as the ID). On CI, it's similar EXCEPT for the size of the hub. Fernco makes LOTS of different sized 'donuts' for that connection mostly because there are so many different foundries that made the CI piping. So, you really need to measure CAREFULLY, and get the proper one. Too small, it will leak. Too large, and you'll have great difficulty getting the PVC pipe inserted - and, if it's way off, it might pucker and leak as well. Just like in Goldilocks, you need it 'just right'. In general, the CI pipe itself comes in two varieties: normal, and heavy duty (thicker), and the hubs are different, but again, similar but not identical foundry to foundry.
 
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