Re-Plumbing Drain

matt151617 · 01-21-2012, 07:10 AM

I'm replacing my vanity top and want to swap out the old galvanized steel drain pipe; judging by the water damage underneath the taped up part, this has leaked a lot in the past. What's the best way to replace this? (I want to use PVC.) I checked in the basement and the drain pipe never goes through the floor, I'm guessing it must go through the wall and connect to the cast iron drain pipe where the toilet is about 3 feet to the left. Should I just plug the old pipe going into the wall, drill a hole through the floor and bottom of the vanity, and add a T to another existing drain pipe? Whoever installed the vanity didn't center it very well and it'll require lots of angles to fit properly.

Just Bill · 01-21-2012, 07:19 AM

There should be a nipple(1 1/4) in the wall elbow. It is likely rusted at the threads and should be replaced. They are often very hard to get out, sometime requiring removal of the vanity top for better access. Once out, a new version made with PVC can be installed. Clean out the elbow, they are often partially clogged. Don't forget to wrap the threads with teflon tape or I use plumbers putty. The rest should be easy, using the old as a guide. You need a new P trap with a slip loint connection, probably a 45(other angles available) out of the nipple, and you are ready to go. All of the old chrome looks bad so replace everything.

TarheelTerp · 01-21-2012, 09:26 AM

Quote:

Originally Posted by matt151617

I'm replacing my vanity top and want to swap out the old galvanized steel drain pipe; judging by the water damage underneath the taped up part, this has leaked a lot in the past. What's the best way to replace this? (I want to use PVC.)

What you're looking at is literally "the tip of the ice burg"
If this is the only problematic drain in the house consider yourself lucky.

Plan to OPEN THE WALL behind the vanity some in order to inspect and (likely) have room to replace the (tee) fitting your drain attaches to.

If your luck holds... you'll be able to replace the threaded nipple with a PVC threaded adapter and then attach your vanity trap fittings to that.

matt151617 · 01-21-2012, 02:03 PM

So it'd be easier to cut through the bottom of the vanity and floor and run new pipe?

**TheEplumber** · 01-21-2012, 02:24 PM

Quote:

Originally Posted by matt151617

So it'd be easier to cut through the bottom of the vanity and floor and run new pipe?

No, how would you attach to the vent? Follow TarheelTerp's method and suggestions. I'm sure he has done this task multiple times and knows the secretes and tips.

TarheelTerp · 01-21-2012, 03:17 PM

Quote:

Originally Posted by TheEplumber

No, how would you attach to the vent? Follow TarheelTerp's method and suggestions. I'm sure he has done this task multiple times and knows the secretes and tips.

ha

Matt, in the first post you said:
"I'm replacing my vanity top and want to swap out the old galvanized..."

When you have the top off... also pull the vanity cabinet away from the wall.
AT THAT TIME you can inspect and evaluate... then do what is needed.
Until you get in there it is all supposition.

When you're all done you can reinstall the cabinet and your new top.

hth

matt151617 · 01-21-2012, 10:17 PM

Well, I'm just thinking it'll be easier to drill a hole as opposed to tearing up a wall. The drain line for the shower runs right under the sink in the basement so it'd be easy to tap into that (and be connected to the vent).

I'm just figuring once I pull the vanity away from the wall it'll just be a pipe sticking out of drywall and won't tell me anything.

TarheelTerp · 01-22-2012, 10:05 AM

Quote:

Originally Posted by matt151617

...judging by the water damage underneath the taped up part, this (fitting and pipe in the wall) has leaked a lot in the past. What's the best way to replace this? (I want to use PVC.)

Until you open up the wall to get in in there and see...
it is all supposition.

Plan to OPEN THE WALL behind the vanity some in order to inspect and (likely) have room to replace the (tee) fitting your drain attaches to.

Quote:

Whoever installed the vanity didn't center it very well and it'll require lots of angles to fit properly.

If you need to redo or just to fix... those will be easier to do with PVC.

Quote:

Well, I'm just thinking it'll be easier to drill a hole as opposed to tearing up a wall. The drain line for the shower runs right under the sink...

In addition to opening the wall some to inspect and maybe even more to work...
you may have to open the floor as well. Drywall repair is the easy part.

Again, until you open up the wall to get in in there and see...
it is all supposition.

Quote:

I'm just figuring once I pull the vanity away from the wall it'll just be a pipe sticking out of drywall and won't tell me anything.

Again, until you open up the wall to get in in there and see...
it is all supposition.

plummen · 01-22-2012, 12:30 PM

If the line doesnt go through the floor id be willing to bet theres just a 90 in the wall tied to a pipe running laterally over to the stack.
Id pull the vanity out and just open the area directly around the fitting coming out of wall to check things out first,easy to hide behind the new vanity

matt151617 · 02-17-2012, 07:28 PM

Quote:

Originally Posted by plummen

If the line doesnt go through the floor id be willing to bet theres just a 90 in the wall tied to a pipe running laterally over to the stack.
Id pull the vanity out and just open the area directly around the fitting coming out of wall to check things out first,easy to hide behind the new vanity

Great call, that's exactly what it was. 1 1/4" female adapter was needed, along with a 22.5 degree angle. Sawed a big hole in the drywall to have room to work. Everything was tightened down and is working great!

Question though... I've read stuff that says not to use a female PVC connection on a male metal connection. Is this only for pressure applications? Because that was the only way to hook this up.

joecaption · 02-17-2012, 08:11 PM

Your info is wrong. It's fine to go PVC to metal drains.
It would have been far better to remove all of that old steel pipe before it plugs up or starts leaking (and it will at some point).

01-21-2012, 07:10 AM	#1
matt151617 Member Join Date: Jun 2011 Location: Plattsburgh, NY Posts: 229	Re-Plumbing Drain I'm replacing my vanity top and want to swap out the old galvanized steel drain pipe; judging by the water damage underneath the taped up part, this has leaked a lot in the past. What's the best way to replace this? (I want to use PVC.) I checked in the basement and the drain pipe never goes through the floor, I'm guessing it must go through the wall and connect to the cast iron drain pipe where the toilet is about 3 feet to the left. Should I just plug the old pipe going into the wall, drill a hole through the floor and bottom of the vanity, and add a T to another existing drain pipe? Whoever installed the vanity didn't center it very well and it'll require lots of angles to fit properly.

01-21-2012, 07:19 AM	#2
Just Bill Member Join Date: Dec 2008 Location: Wilmington, DE Posts: 3,098	Re-Plumbing Drain There should be a nipple(1 1/4) in the wall elbow. It is likely rusted at the threads and should be replaced. They are often very hard to get out, sometime requiring removal of the vanity top for better access. Once out, a new version made with PVC can be installed. Clean out the elbow, they are often partially clogged. Don't forget to wrap the threads with teflon tape or I use plumbers putty. The rest should be easy, using the old as a guide. You need a new P trap with a slip loint connection, probably a 45(other angles available) out of the nipple, and you are ready to go. All of the old chrome looks bad so replace everything.

01-21-2012, 02:03 PM	#4
matt151617 Member Join Date: Jun 2011 Location: Plattsburgh, NY Posts: 229	Re-Plumbing Drain So it'd be easier to cut through the bottom of the vanity and floor and run new pipe?

01-21-2012, 10:17 PM	#7
matt151617 Member Join Date: Jun 2011 Location: Plattsburgh, NY Posts: 229	Re-Plumbing Drain Well, I'm just thinking it'll be easier to drill a hole as opposed to tearing up a wall. The drain line for the shower runs right under the sink in the basement so it'd be easy to tap into that (and be connected to the vent). I'm just figuring once I pull the vanity away from the wall it'll just be a pipe sticking out of drywall and won't tell me anything.

01-22-2012, 12:30 PM	#9
plummen retired elect/hvac/plumb Join Date: Jan 2010 Location: south east of omaha Posts: 2,391	Re-Plumbing Drain If the line doesnt go through the floor id be willing to bet theres just a 90 in the wall tied to a pipe running laterally over to the stack. Id pull the vanity out and just open the area directly around the fitting coming out of wall to check things out first,easy to hide behind the new vanity

Re-Plumbing Drain