Upgrading Cast Iron Main Stack with PVC for Washer Stand Pipe and Sink

[Edward P]

Hi Everyone,

I'm seeking advice on renovating a section of our main stack, transitioning from cast iron/copper to PVC/copper to relocate our washer and sink. Currently, our setup tends to overflow our shop sink when the washing machine is in use. The existing main stack involves a 4-inch cast iron hub emerging from the floor, leading to a 4x4x1.5 CI tee connecting to the old slop sink, followed by a 4x4 CI cleanout, and then a reducer to a 3-inch copper pipe that links to the rest of the main stack. Images of the current setup are included below.

My plan is to swap the 4x4x1.5 CI tee with a Charlotte Pipe PVC 4x4x2x2 double wye. This new setup will branch off: one side connecting to the washing standpipe via 2-inch PVC street 45's leading to a tee before the p-trap, including an AAV for additional venting. The other side will connect the new sink using a 2-inch PVC street 45. Additionally, I aim to replace the 4x4 CI Cleanout with a 4x4 PVC cleanout and introduce a PVC bushing to transition from 4-inch PVC to 3-inch PVC, connecting to the existing 3-inch copper pipe using a Fernco Proflex 3-inch Neoprene Shielded Coupling.

Attached is a visual representation of the intended final layout with the main stack positioned behind the washing machine.

I would greatly appreciate any suggestions or feedback.

 

[Jeff H Young]

Not sure I follow pecisely but generally sounds fine Washer on one side sink on other side of stack remember the sink will need venting as well the copper stack is a drain not the vent for this bottom floor ( basement )

 

[Sponsor]

 

[Reach4]

Hi Everyone,

I'm seeking advice on renovating a section of our main stack, transitioning from cast iron/copper to PVC/copper to relocate our washer and sink. Currently, our setup tends to overflow our shop sink when the washing machine is in use. The existing main stack involves a 4-inch cast iron hub emerging from the floor, leading to a 4x4x1.5 CI tee connecting to the old slop sink, followed by a 4x4 CI cleanout, and then a reducer to a 3-inch copper pipe that links to the rest of the main stack. Images of the current setup are included below.

Are shop sink and slop sink both referring to the sink on the lower left of your first photo?

Where does the washing machine drainage enter-- into the shop/slop sink, or elsewhere?

Is the copper thread cocked/cross-threaded where it enters the cast iron santee?

Is that copper pipe sloped to drop 1/4 inch per foot on its way to the cast iron?

 

[Jeff H Young]

I like the way the cast fittings were clearly marked makes it easy for a helper to shag parts

 

[Edward P]

Are shop sink and slop sink both referring to the sink on the lower left of your first photo?

Where does the washing machine drainage enter-- into the shop/slop sink, or elsewhere?

Is the copper thread cocked/cross-threaded where it enters the cast iron santee?

Is that copper pipe sloped to drop 1/4 inch per foot on its way to the cast iron?

Yes the shop/slip sink is the sink in the lower left hand corner of the first photo.

The washing machine drains into the shop/slot sink.

it was like that when we bought the house, but I do see what you mean. Since we are looking to relocate the washer and sink anyway I figure it would be easier to go with a double wye instead of the current setup.

The pipe is sloped correctly but since it is only 1.5 inches it drains slowly and causes the sink to overflow when a large wash cycle is running.

 

[Jeff H Young]

2 inch to a laundry stand pipe, 1 1/2 shouldnt overflow in the sink but thats going away any how but it might have a stoppage

 

[Edward P]

2 inch to a laundry stand pipe, 1 1/2 shouldnt overflow in the sink but thats going away any how but it might have a stoppage

In the current setup there is just a 1 1/2 connected to the sink and the washing machine is dumping into the sink. This is when the sink is overflowing.

 

[Reach4]

To deal with that without redoing your plumbing, clean out the drain line and trap.

Is there some kind of strainer in the bottom of the sink?

 

[Jeff H Young]

In the current setup there is just a 1 1/2 connected to the sink and the washing machine is dumping into the sink. This is when the sink is overflowing.

I saw all that about it being 1 1/2" in the first post and all the pictures , If it was clear I could see the sink might back up some but wouldnt expect it to overflow . you are rebuilding it so I guess it dosent matter just saying I think there could be a stoppage .