Brass pipe drain stub out too long for vanity

[ShaunS]

So I'm kicking myself because I just had this wall open and plumbers in here, but didn't think ahead on the sink plumbing. I'm putting in a vanity with drawers (IKEA), so the plumbing all needs to be tight to the wall--about 4" from the wall to the back of the drawers. I've got a 1 1/4" NPT brass stub out currently that is way too long. No fitting combo I've come up with will be <4". Even if I cut the nipple back and use a Fernco it's a bit too long. My only ideas are: 1) Cut even more off and open a little drywall enough to tighten the Fernco slightly behind the wall surface or 2) Replace the stub out with a shorter one. Would it be safe to attempt just unthreading this pipe and threading a shorter one in? It's all cast-iron plumbing the wall. I don't have any experience touching cast iron. Would you thread in PVC to get to a modern stub out? Some other idea I don't know about?

Soooo close. Maybe it'd work out?

Failed attempt at threading on an elbow. Way too long still

 

[Reach4]

How about something like this
https://www.homedepot.com/p/Everbil...-with-Rubber-Reducing-Washer-C8030C/205154410
Screw onto your brass 1-1/4 pipe, and insert a slip joint p-trap with the trap arm cut to the length you need. Plastic is easier to cut, and costs less. Those nut-washer combos also come in plastic. You can mix and match plastic and metal for slip joint stuff.

I don't have anything to offer on adapting to the Ikea sink and drawers.

My 2 attempts with working with cast iron santees at the wall ended with me opening the wall. Only one of the two was failure in the santee, and the other was that I really had to get rid of the steel pipe below the santee.

 

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[ShaunS]

How about something like this
https://www.homedepot.com/p/Everbil...-with-Rubber-Reducing-Washer-C8030C/205154410
Screw onto your brass 1-1/4 pipe, and insert a slip joint p-trap with the trap arm cut to the length you need. Plastic is easier to cut, and costs less. Those nut-washer combos also come in plastic. You can mix and match plastic and metal for slip joint stuff.

I don't have anything to offer on adapting to the Ikea sink and drawers.

My 2 attempts with working with cast iron santees at the wall ended with me opening the wall. Only one of the two was failure in the santee, and the other was that I really had to get rid of the steel pipe below the santee.

This doesn't seem any shorter? Maybe I'm not understanding? Also, I'm pretty sure those slip joint nuts are not NPT thread and won't thread onto the brass wall pipe.

 

[Reach4]

Also, I'm pretty sure those slip joint nuts are not NPT thread and won't thread onto the brass wall pipe.

I once assumed that. I had already gone destructive before somebody set me straight.

But if the length doesn't work for you, it doesn't matter.

And if the Ikea tailpiece is not 1.25 inch, it probably does not matter either.

Your tailpiece is probably not exactly in line, so a bottle trap won't work for you either -- unless you could move your Ikea left or right. https://www.homedepot.com/p/Kingsto...Decorative-P-Trap-in-Chrome-YDD8401/311656356

 

[ShaunS]

I once assumed that. I had already gone destructive before somebody set me straight.

But if the length doesn't work for you, it doesn't matter.

And if the Ikea tailpiece is not 1.25 inch, it probably does not matter either.

Your tailpiece is probably not exactly in line, so a bottle trap won't work for you either -- unless you could move your Ikea left or right. https://www.homedepot.com/p/Kingsto...Decorative-P-Trap-in-Chrome-YDD8401/311656356

I don't think I've explained the issue very well. The brass stub out as it stands is too long with any possible fitting on it. Here's a diagram from the installation instructions.

The IKEA-ness of the plumbing parts themselves I think is irrelevant as it's just 1.5" drain pipes. Any of them can be replaced except the sink connection.

The picture I posted in the OP with the Fernco on it was suggesting cutting the brass pipe back as much as possible such that the worm drive screw was just accessible at the wall surface. It's damn close thought.

 

[Reach4]

The IKEA-ness of the plumbing parts themselves I think is irrelevant as it's just 1.5" drain pipes. Any of them can be replaced except the sink connection.

You are not supposed to be feeding 1.5 inch drains into 1.25 pipes.

 

[PlumbNuts]

That is a fairly good looking brass nipple coming out of the wall, it should come out fairly easy so that you can replace it with a shorter one.
Try a pipe wrench on it, it will take cosiderable force to cause any damage to the cast iron in the wall.
If you feel that you are fighting it too hard then stop.
You are lucky that it is brass, I might not be saying the same if it were galvanized like most.

 

[PlumbNuts]

You are not supposed to be feeding 1.5 inch drains into 1.25 pipes.

Just read this after my previous reply.
Reach4 is correct, if the drain that is supplied from IKEA is an 1 1/2" then your stub out will not work. You will have to open the wall or find another type of drain.
You cannot decrease in size for a drain,

 

[ShaunS]

You are not supposed to be feeding 1.5 inch drains into 1.25 pipes.

Understood, but 1) It's 1.5" tubular into 1.25" pipe. The ID difference is almost nothing and 2) I don't have much choice.

 

[ShaunS]

That is a fairly good looking brass nipple coming out of the wall, it should come out fairly easy so that you can replace it with a shorter one.
Try a pipe wrench on it, it will take cosiderable force to cause any damage to the cast iron in the wall.
If you feel that you are fighting it too hard then stop.
You are lucky that it is brass, I might not be saying the same if it were galvanized like most.

Thanks. Would you put in another brass one or a PVC? What's the proper way to seal the threads into the cast iron? Teflon tape?

 

[PlumbNuts]

Thanks. Would you put in another brass one or a PVC? What's the proper way to seal the threads into the cast iron? Teflon tape?

If you are determined to use the 1 1/2" drain that was provided with the sink you will have to open the wall and change the threaded tee that is inside the wall to a 1 1/2" threaded outlet or change it to PVC. You cannot connect a 1 1/2" trap into a 1 1/4" trap connection.
You might see if IKEA offers a 1 1/4" drain assembly for your sink.

" The ID difference is almost nothing and"
The "ID" (inside diameter) is not the issue, the issue is th OD (outside diameter).
Can you take the trap arm that is provided and insert it into the existing brass nipple?

 

[ShaunS]

If you are determined to use the 1 1/2" drain that was provided with the sink you will have to open the wall and change the threaded tee that is inside the wall to a 1 1/2" threaded outlet or change it to PVC. You cannot connect a 1 1/2" trap into a 1 1/4" trap connection.
You might see if IKEA offers a 1 1/4" drain assembly for your sink.

" The ID difference is almost nothing and"
The "ID" (inside diameter) is not the issue, the issue is th OD (outside diameter).
Can you take the trap arm that is provided and insert it into the existing brass nipple?

Nope, but I can thread on a 1.25" FPT to 1.5" adapter then slap on a 1.5" trap adapter.

 

[Terry]

Or you can go with the 1-1/4" trap and on the vertical to the sink use an extension that works with 1-1/2" and 1-1/4"
The trap would be a standard 1-1/4" going into the wall, the only part to clean would be the tailpiece section which is removable.

I have also seen a trap that goes into the wall 1-1/4" and takes a 1-1/2" tailpiece. I can't find that at the moment.

Ikea used to have a drain that was 1.25" into the wall.

And now this one.

 

[ShaunS]

Or you can go with the 1-1/4" trap and on the vertical to the sink use an extension that works with 1-1/2" and 1-1/4"
The trap would be a standard 1-1/4" going into the wall, the only part to clean would be the tailpiece section which is removable.

I have also seen a trap that goes into the wall 1-1/4" and takes a 1-1/2" tailpiece. I can't find that at the moment.

Thanks, another good idea to complete it. Still wondering what you would replace the brass nipple with and how to seal the threads into the cast iron?

 

[PlumbNuts]

Nope, but I can thread on a 1.25" FPT to 1.5" adapter then slap on a 1.5" trap adapter.

But that wouldn't help you with your clearance issue would it?

 

[PlumbNuts]

Try to remove the brass nipple that will dictate what your next step would be.

 

[ShaunS]

But that wouldn't help you with your clearance issue would it?

With a shorter nipple installed, it would. So two problems:

1)Clearance. Either cut pipe back and use the Fernco and hope it's just enough or replace the nipple with a shorter one.
2) 1.5" to 1.25" adaption. Two options posted above.

 

[Reach4]

Thanks, another good idea to complete it. Still wondering what you would replace the brass nipple with and how to seal the threads into the cast iron?

See post #7. You may be able to put a piece of 1 inch schedule 40 steel inside the brass pipe to inhibit crushing, if crushing concerns you.

On the shorter nipple, you could use both ptfe tape and pipe dope. Or either. Both is more sure.

Adapting 1.5 to a 1.25 trap before the trap sounds like a great idea.

 

[Terry]

If you remove the brass nipple and pick up a shorter one, the threads into the cast iron at the wall can be taped or doped.
You could perhaps pick up a threaded 90 for where it exits the wall, or see if you have room for the trap with the shorter nipple without the 90.

 

[PlumbNuts]

If you can get the nipple out safely then use a 1 1/4" male adapter with a 1 1/4 PVC stub out cut to length, use a 1 1/4" trap and then use a reducer like Terry posted the picture of on your tailpiece.