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lazypants 04-22-2009 09:19 AM

No-Hub Cast Iron Closet Bend / Closet Flange
Bathroom is plumbed using no-hub cast iron. The main stack is 4", which is reduced to 3". So I have a 3" closet bend. The only no-hub cast iron toilet flange my plumbing supply has is one that fits inside the 3" bend and then expands to seal when the bolts are tightened. My problem with this oslution is that it effectively reduces the 3" diameter of the closet bend to 2 1/2." With a kid and a wife flushing G-d knows what down the toilets, I would prefer to have a full 3" diameter drain.

Can I just use a 3" street PVC closet flange and use a no-hub coupler to attach it to the cast iron closet bend? Any other options in this instance?

Thanks in advance for the help.

Grampa Bud 04-22-2009 10:18 AM

What about a 4" flange slid over the outside of the 3" closet bend. You would have to use more Oakum to fill the gap and more lead for the poured seal, but you would have a 2" W.C. going to a 4" flange going to a 3" pipe. Sounds fluid to me.

lazypants 04-22-2009 02:57 PM

Definitely don't want to be using oakum and lead. The drains are all plumbed using NO-hub cast iron piping.

Grampa Bud 04-23-2009 07:42 AM

Well if flow restriction is your problem then a PVC 'street' or male flange will work if the no-hub band fits snuggly to the PVC as it does to the cast iron. The PVC should be a butt fit to the cast iron though; not an internal expansion ring.

lazypants 04-23-2009 12:59 PM

Ever used a torque-set flange. See link. I have never used one and can't really find any good info on them. To me it looks like it sits over a 3" or 4" diam pipe and then by torquing the bolts compresses the neoprene seal to the outside of the pipe?

Any body have any info on these things?


Grampa Bud 04-23-2009 01:29 PM

You are in the right neighborhood. That's a 4" compression flang in the picture and it works very well. It does still have to be screwed to your subfloor and the black rubber compression ring needs to be below the top of the closet bend opening, but that's the critter you need.

lazypants 04-23-2009 03:50 PM

Thanks for the advice.

Electrician Wannabe 06-09-2009 12:25 PM

Unfortunately, because the bend was placed too low, the black rubber compression ring does not reach the top of the closet bend opening.

So, in line with Granda Buds suggestion earlier in this thread about using lead and oakum I have the following question. It turns out a regular 4x3x3 cast iron fitting (one meant to go into a hub) will fit over the top of the end of my 3" no-hub closet bend by about 1/2". The gap between the outside of the no-hub pipe and the flange is maybe a 1/16" all the way around. Can I pack that gap with Oakum and then seal the gap with poured lead? Assuming the flange is bolted to the subfloor is this a valid option?


Grampa Bud 06-10-2009 08:01 AM

Not really. Oakum is the gasket for hubbed cast iron pipe. You have to be able to tightly pack oakum into the channel between the internal pipe and the hub up to about 1" below the top of the hub. Then you need to pour molten lead into that 1" deep channel up to the lip of the hub, let it cool, and pack the lead tight with packing irons to seal the whole affair. This is assuming the hub is on the bottom pipe. It can't be done inverted. How far below the floor surface is the top of the closet bend?? There are several tricks that might work for you.

Electrician Wannabe 06-11-2009 10:19 AM

The top of the bend sits just under the subfloor. So I have 3/4 inch T&G Subfloor + thinset+ 1/2" cement board + thinset + tile (about 3/8" thick if I were to guess). Any advice woudl be greatly appreciated. I may be able to take a street 3" flange and cut it down a little and use a no-hub adapter to connect the flange to the bend. Have to see.


Grampa Bud 06-11-2009 10:48 AM

You can try cutting it down and if it doesn't work try releasing the no-hub band on the horizontal end of the closetbend. Remove the cast iron closetbend and get yourself a 3" long sweep pvc ell (or 90) and say 3 feet of 3" pvc. Hold the pvc 90 so the hubs line up with the runs on the cast iron and measure what you need for only the horizontal run. cut and glue a piece of 3" pvc into one end of the 90 only. Chamfer the outside edge of the pvc, apply some vaseline all around the end of the pvc and push it all the way into the no-hub band. Put a torpedo level on the top of the open hub two ways and make sure it is as close to level as possible and really tighten the no-hub bands. Then when your tile floor is ready drop a 3" pvc collar into the hole and using a tape measure, measure face to face between the 90 hub and the collar hub. Add 3" to your measurement and cut it just on the short side of it. Glue one end into the collar. When it's dry glue the 90 hub and the end of the pvc from the collar and as you are pushing them together make sure the skinny parts of the key hole slots are where the closet bolts will be for the toilet. Screw the collar right through tile to the subfloor and you are good to go.

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