Possible Kitchen Drain Relocation

[Turbo98]

Ok. I want to run this by you all to make sure I’m not missing anything. Here is the situation… I have a kitchen bump-out where the counter and sink are. As usual, the drain pipe runs to the back wall which is an exterior wall. The previous owner installed a ~2’ piece of PVC from the back of the sink cabinet to join the original 2” copper (looks like 2” anyway). It runs along the back wall a total of about 5’ then at some point joins the vent. It comes out about foundation level and then 90’s down into the top of a cast iron stack (about 2 feet down) once it clears the foundation. Within the last few years, this pipe has frozen up. It happens when it gets down to around 0* or below for more than a day or so. Then it won’t thaw until it’s above freezing again. I thought maybe the 45 year-old copper drain pipe is getting some build-up in it which accelerates and enhances the freeze-up situation. But I’m not sure. I thought if I replace it with PVC, maybe it would work better. Again, no guarantees since it’s on an outside wall on a bump-out that is more vulnerable to the cold. I also thought about insulating it better. But there is no easy access to this pipe without tearing out all of my cabinets in which I just had granite installed. I could possibly cut into the wall from the outside by cutting the cement asbestos siding off, etc. But that is pretty unreasonable. So I’m thinking of doing this. Find a spot in the bottom of the cabinet as close to the front as possible (and off to the side) and go down with the pipe right after the j-bend. Then to a 90 then come forward about 12”-16” to clear the foundation. Then 90 over to the stack which I will replace with PVC. Then use the old copper as a vent and adapt it into the top of the stack similar to how it is now. But it would only function as a vent which is upstream a couple feet I believe. Then plug the old pipe in the wall behind the cabinet. It will be a hassle because there isn’t much room from downstairs under the bump-out but I think it’s doable after looking at it. Is there anything wrong with doing something like this? Then I can put some insulation behind it and it will never freeze like that ever again. I just can’t deal with this anymore. I will probably also move the cold and ho 1/2" water pipes forward also. They have frozen in the past so now I keep an eye on them. I actually have small heating pads wrapped around them and kick them on when it gets down near 0*. They will be more of a hassle to move but again, I think it’s doable.

Thanks for any input!

 

[Mr_David]

You lost me at the BUMP-OUT.
pictures help, sometimes.

 

[Turbo98]

The bump-out is the inset where the counter/sink it. It is cantilevered and hangs out over the foundation.

 

[Mr_David]

Okay.

" It runs along the back wall a total of about 5’ then at some point joins the vent."

Doest it connect to a vent with a santee and turn down vertically going through the bottom of the cantilever?
or does the drain continue on horizontally after the vent????

" It comes out about foundation level and then 90’s down into the top of a cast iron stack (about 2 feet down) once it clears the foundation "

Is this exposed under the cantilever? or on the side wall of bump out???

Like I said picture help. Hard to visualized what you're describing.

I'm lost again at "90's down into cast iron stack

 

[Turbo98]

I thought about taking pictures but most of it is not seen. I could maybe take a pic of the copper pipe/stack but that won’t tell you much. If I’m standing in front of the sink, the drain pipe leaves the p trap and goes straight back to the back wall which is an exterior wall. It then goes to the left about 5 feet until it hits the corner and has to make a 90 to come back forward about 2 feet which is the depth of the bump-out. This is also an exterior wall. At that point, it is at the foundation/basement wall of the house in the basement. It comes out far enough to clear the concrete basement wall then turns down about 2 feet before entering the top of the iron stack. The stack is in the corner of the basement. Now somewhere along the way, a vent joins in. I cannot tell where this is. I’m assuming somewhere near the corner but can’t be for sure. So most of the pipe is in the section of the house that is hanging out over the foundation-some of which is in the walls and some of which is probably at floor joist level. I guess it just doesn’t get enough heat to stay liquid. It’s a bad design IMO.

Sorry for the confusion.

 

[Turbo98]

For what it's worth, here is a picture of the drain pipe coming in from the bump-out into the basement and into the top of the iron stack. I was proposing replacing the stack with PVC and using this old drain as the vent since I have no access to where the vent ties in. The new PVC pipe from the sink would come along the top of the wall from the right side of the picture and T into the new stack.

Kitchen Drain 1

 

[Mr_David]

That picture does help and what propose not good. You’re proposing to turn drain down after j-bend ( p-trap ) down through floor. Any vent connection after the turns down is useless. Vent tack off has to be above the p- trap arm ( j-bend).

The connection of copper to cast is often a choke point and hard scale build up. Use the cast clean out and clean line going up at transition. Just box the exposed drain insulate it

 

[Turbo98]

That's why I didn't post the picture to begin with. Not much to see.....

With regard to the vent, the current vent isn't above the J-bend arm. Assuming the drain pipe slopes as it goes over 5' to where the vent ties in, that area would be lower than the j-bend arm. So I'm missing what you are saying.

 

[Turbo98]

I'm not a plumbing expert by any means. But if the vent comes off the drain a few feet before the drain dumps into the iron stack, it seems that cold air pouring in from the vent could aid in cooling the drain at that point and downstream. From my limited experience, all the vents I've seen come off the top of the stack-the stack basically continues up through the roof. So having it upstream from the stack seems like it could promote the drain to freeze up.

Any thoughts?