Venting WC via stack vent

[gedmeyer]

Are there any issues with using a stack vent as the vent for a WC? In my case, the WC drain is currently the top most drain feeding into the vertical stack (the stack becomes a vent above this point.)

I had a plumber tell me that it's not preferred to do this. Something to do with a slug of water moving real fast when it hits the vertical pipe. I didn't quite follow.

Ultimately, I need to alter this stack to accommodate a relocated sink drain. The 1.5" sink drain currently enters the stack at the same elevation as the WC. I'm not sure if this is even OK or not (I'm thinking no). Regardless, my new sink location is going to force its drain to tie into the stack lower.

 

[hj]

What is on the pipe BELOW this toilet? If it is another toilet THAT one is the one that needs a vent, along with anything else connected to the pipe which does not already have its own vent.

 

[Sponsor]

 

[gedmeyer]

What is on the pipe BELOW this toilet? If it is another toilet THAT one is the one that needs a vent, along with anything else connected to the pipe which does not already have its own vent.

The stack in question will have a sink drain attached below the toilet drain connection. This sink drain will have a separate vent.

So I am gathering that there is no issue connecting other drains to this stack, below the WC, provided they have their own vents?

Is vertical wet venting ruled out bc the WC is the upper most fixture?

 

[gedmeyer]

Here's a sketch of the current configuration. The basement formerly had a bathroom. I would like to add it back, someday.

The kitchen drain needs to be rerouted and some walls are open on the main level, so the time is now to do it right!

 

[Asktom]

The lower lav needs to be vented before it ties into the stack.

 

[gedmeyer]

The lower lav needs to be vented before it ties into the stack.

But does the upper WC and lav meet code?

 

[Reach4]

I added some letters that may help others refer to parts more easily.
I am not a plumber. I am not speaking from authority or experience.
We presume that A is a vent through the roof and not carrying drainage.
B fitting can be discussed. You don't need a sanitary tee. I think your 3 inch (slightly) wet vent will be more than required.
Is C is coming out of that same fitting? Do you have a URL that describes that fitting?
Is G vented before (to the right) the drainage gets here? The place where the kitchen sink drain goes from vertical to horizontal should be a long sweep, and that is a place where clogs are most predictable -- especially if you have a disposal.

In practice, D is going to work very well with your 3 inch wet vent. To meet today's codes literally, I think you would have to add an AAV on the trap arm, or run a vent line up. If not inspected, I would do as you drew it. If inspected, I would add the AAV.

 

[gedmeyer]

I added some letters that may help others refer to parts more easily.
I am not a plumber. I am not speaking from authority or experience.
We presume that A is a vent through the roof and not carrying drainage.
B fitting can be discussed. You don't need a sanitary tee. I think your 3 inch (slightly) wet vent will be more than required.
Is C is coming out of that same fitting? Do you have a URL that describes that fitting?
Is G vented before (to the right) the drainage gets here? The place where the kitchen sink drain goes from vertical to horizontal should be a long sweep, and that is a place where clogs are most predictable -- especially if you have a disposal.

In practice, D is going to work very well with your 3 inch wet vent. To meet today's codes literally, I think you would have to add an AAV on the trap arm, or run a vent line up. If not inspected, I would do as you drew it. If inspected, I would add the AAV.

View attachment 37882

A vents into the attic. This will be routed through roof.

OK, so the WC is vertically wet vented between B and C. If this is OK per code, I'll leave it.

Fitting C looks to be home made. Everything is copper and it appears a 1.5" bung was brazed on to the side of a sanitee or similar fitting.

Drain G is currently vented off the page. This pipe has to be rerouted due to new sink location. It will continue to have its own vent, but it will likely tie into the stack below the WC at Fitting C.

Correct me if I'm wrong, but Drain D can be solved with a AAV or I will have to run a vent and tie into the stack above the upper lav?

The room (kitchen) above is gutted. So I will be redoing everything with PVC since it will be easier than trying to patch-in the copper. This relates to my other Thread regarding how I tie the PVC into the CI wye in the floor (do I leave in a copper stub or not).

 

[hj]

1. You CANNOT "tie the downstairs vent into the stack BELOW fitting C. IT has to connect back at least 42" above the upstairs floor.

 

[gedmeyer]

1. You CANNOT "tie the downstairs vent into the stack BELOW fitting C.

I should've been clearer... The new KS DRAIN will tie in below C. This drain will have its own vent that connects to the 3" stack in the attic

I didn't think of the positive pressure, so I will have to address that.