I'm considering putting a shower into my Brookline, MA condo that has old hubbed cast-iron DWV. Currently there is 4" cast iron with a 1-1/2" copper branch from a tub. This is all on a concrete slab with the current 1-1/2" running on the surface, a 6' run, with a trap about 6" from the tee and 5' from the tub.

I understand that local code requires 2" from a shower to the 4". The current piping is a 4" sanitary tee with a 1-1/2 branch.
1. Is possible to "adapt" this to a 2" branch"?
2. Is is possible to bore out the old 1-1.2" branch on the 4" tee and retap the branch to 2"?
3. How close does the trap have to be to the shower (directly under the drain, where is now, next to the tee, etc.)
4. Or I looking at replacing the whole sanitary tee with a new hubless version?

Thanks!

1. Don't do it. The transition will attract hair, body oil, and shampoo residue and will eventually cause slow drainage and problems down the road.

You certainly could use 1 1/2" pipe and trap. Yes, it is not what Code mandates, but many houses are plumbed on 1 1/2" shower drains/traps and it works. I would definetely go with 1 1/2" line rather than 2" pipe connected into 4" x 1 1/2" San-T.

2. No, never heard of such a thing. Let's see what Tom has to say. He's seen it all...

3. The best way is to install it directly under drain. There is so called "running trap" that is installed away from the shower drain. But I personally do not like them nor would I suggest to install one.

4. Yes, it is a good option. If you can cut it off and slip in a new 4"x 2" San T - than it would be the absolutely best option to follow. Of course, here, you will have to expose that San T which will require some concrete chipping...

Let us know what you did... Good Luck... Milo

Hi Neighbor:

If you want to do this right then you will need to remove the 4"x1.5" fitting and increase the drain line to 2" by installing a 4" x 2" fitting. The 2" trap will need to be located directly underneath the shower drain and there needs to be a vent here... let me know about the vent set up if you can. There should be a vent associated with the old tub... or the lavatory vent should be 2" pipe size... let me know... O.K.

If this is being inspected by local inspector you will need to increase the drain line as mentioned. If not... it MAY or MAY NOT be reasonable to just remove the 1.5" trap, increase the drain line to 2" (using shielded clamp... see picture) and pipe up with 2" trap as directed earlier. Although not ideal... it has been done and very rare to see issues using PVC pipe.

On the other hand, this being a Brookline, MA condo... I see no reason you can't get a couple local plumbers in to provide a free estimate and let you know what you are up against... *hint* *hint*... ;)

LOL... let me know what you are thinking here...

MARK

Milo & Mark -

Thanks for the thoughts! I will pass these along to the guy across the hall whose problem this really is (hey, we do try to learn from other's disasters BEFORE we have our own.)

Milo - I actually found a 2" tap for Cast-Iron DWV on-line, but had no idea how one would bore to that size. See National Supply Source Taps - Pipe

Also - concerning the "adapter" solution, what would be the effect of 1-1/2" to the admittedly awful running trap, and making a 2" trap, with 2" back to the shower.

Mark - yup, Brookline :-(, yup, will be inspected.

Building is circa 1969 and and when wall was ripped open, tub has a "running trap" (and now I understand why my tub drains slowly as I put in insufficient drain cleaner and/or didn't use a long snake.) Despite the length of the run, there is no additional venting for the tub.

Hi again:

If this is to be inspected, you cannot use anything to do with the 1.5" pipe... shower will need to be full size 2" all the way back to the 4".

If this was a blank fitting that was not tapped yet you could use a metal hole saw to cut a hole and then tap the threads using the 2" tap you mentioned, but with the fitting already tapped it would be almost impossible to cut a proper hole. Fact is that you may even get the hole cut, but about 1/2 way through tapping the thread the fitting would probably break. I am confident that it will be quicker and easier to install a new fitting using a SHIELDED CLAMPS or a NO-HUB CLAMPS (see picture).

There will also need to be a vent installed within 5 feet of the trap... unless the lavatory vent acts as the old tub vent..? The lavatory vent would need to be full size 2" all the way until it connected into another 2" vent or larger or you will need to install a 1.5" individual vent within 5 feet of the trap as mentioned above. That 1.5" vent will need to connect into another vent at least 42" off the finish floor.

Let us know if you need more here...

MARK

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The current piping is a 4" sanitary tee with a 1-1/2 branch.

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Are you quite sure you haven't got a 4 X2" san tee with a 2 X 1 1/2" bushing?

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1. Is possible to "adapt" this to a 2" branch"?

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No! You would still be choked down to 1 1/2" at the san tee.

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2. Is is possible to bore out the old 1-1.2" branch on the 4" tee and retap the branch to 2"?

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Thinking outside the box! I like that. However, We have to think OD here.
The OD on a piece of 2" galvanized is 2 3/8ths.". The OD of the boss on the 4 X 1 1/2" Cast Iron san tee is 2 11/16ths.". That leaves you a 5/16ths" boss after you drill out, (and don't forget how hard cast iron is) 2 3/8ths" to cut 2" threads in. The threads by them selves will eat up another 1/8th".( 1 /16th cut on each side) leaving you with a boss of only 3/16ths. Less the 1/4". Sorry! But you just ran out of space

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3. How close does the trap have to be to the shower (directly under the drain, where is now, next to the tee, etc.)

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You're thinking "dogleg" and a running trap. I'm thinking clogs and a smelly lateral drain line.

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Despite the length of the run, there is no additional venting for the tub

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Back then we vented the tub through the overflow. (glug! Glug! Glug!)

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4. Or I looking at replacing the whole sanitary tee with a new hubless version?

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BINGO!
Just fo;ll;ow Marks and Milos excellent advice and you'll be cool with the inspector.
Good luck, Tom

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Originally Posted by qudrcps

Building is circa 1969 and and when wall was ripped open, tub has a "running trap" (and now I understand why my tub drains slowly as I put in insufficient drain cleaner and/or didn't use a long snake.) Despite the length of the run, there is no additional venting for the tub.

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Are you sure this is a 4x1-1/2 tapped Sanitary Tee?

If it is, then it is a real rarity.

Could you upload a photo of it?

Guys -

Thanks for all the comments. I'm away today, but will look tomorrow about the 4 x 1-1/2, and see if there is a minimally sized reducer.

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Originally Posted by qudrcps

Guys -

Thanks for all the comments. I'm away today, but will look tomorrow about the 4 x 1-1/2, and see if there is a minimally sized reducer.

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Y'know, to the best of my knowledge, there has never been a 4x1-1/2 tapped Sanitary Tee.

I've seen tapped 4x1-1/2 Vent Tee's, but never a tapped Sanitary Tee.

Ya just can't beat knowledge! Growler's bang on! According to my Cast Iron Soil Pipe and Fittings Book the smallest threaded branch on a Sanitary Tee is two inches.
However, in a regular 4" tee the tapped branches run from 1 1/4 up to 2":.

I gave you the dimensions for a 1 1/2" boss, but you will still run into problems if you attempt tp bore and tap no matter what you have. Regards, Tom

Uffff... I am really glad he will not attempt to re-thread the 1 1/2" outlet into 2" outlet !:D

Okay - more info... After chipping at more concrete, and looking closer, this "sanitary tee" if FAR more complex. Given that this condo is in a complex of almost 800 apts, I wonder if they had a custom tee cast for the job. Using Visio, it looks like this... http://www.clinical-metrics.com/Data...s/Drawing1.jpg The view on the left has a 3" toilet connection coming straight out, the now 1-1/2" tub connection to the left, the 4" waste straight through and 3" vent connection on left, off-axis, but parallel to the waste. The view on the right is the toilet connection, rotated 90 degrees from the left view.

Yes, these fittings are used in commercial apartment buildings. I am sure Tom will have something to say about it when he logs in... But in the interim:

If I were you I would not attempt to modify it. I don't even think this fitting has hub therefore there is not enough wall to re-tap it into 2" inlet. I am almost sure the wall of the inlet will split when pressure is applied. Then, good luck getting new fitting ...

I would install 1 1/2" pipe for shower to follow the original design of the building. I don't think Inspector will object.

If you really insist on having 2" drain - then get new Multi-San-T fitting with 2" inlet first. Once you have it in your hand than remove the old one and replace it with the new Multi-San-T. Otherwise, if you brake the fitting you may put other condos out of service for few days...

Leave that fitting alone!! If you crack or mess it up Lowe's or Home Depot ain't going to help you replace it.
Milo gave you excellent advice. Follow it! Milo's correct when he states,

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if you brake the fitting you may put other condos out of service for few days...

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Or until they can replace the fitting. It looks to be part of the stack vent that's picking up units above you. I agree with Milo that it's in your best interests to stay with 1 1/2" for the shower. Good luck, Tom,