Studor valve question

[AmbitiousDIYer]

First, thanks for making this forum available as a resource.
I have the waste/vent setup shown in the figure. It works great except for one big problem: When I flush toilet #1, I get a big bubble at toilet #3.
My guess is that the waste coming down the drain line from toilet #1 creates a pocket of air, and when it hits the bottom, some of it goes back up into the other waste vent stack. Since there's a studor valve on top, it can't escape, and so it bubbles the toilet.
My solution is to cut a hole in the roof and put a roof vent there in place of the studor valve.
What do you guys think? This is where I cross my fingers and hope that no one says "it's terrible you have to change everything!!!"

Thanks.

 

[Reach4]

My solution is to cut a hole in the roof and put a roof vent there in place of the studor valve.

That works nicely. A roofer can integrate the vent flashing, which is like a special shingle. An alternative is to cross the attic with a pipe and tee to the existing roof vent.

 

[Sponsor]

 

[MikeGA]

What are the current vent sizes and what what fixtures are attached to each vent. The DFU's (drain fixture units) on the fixtures might exceed the vent DFU's that are allowed.

 

[AmbitiousDIYer]

What are the current vent sizes and what what fixtures are attached to each vent. The DFU's (drain fixture units) on the fixtures might exceed the vent DFU's that are allowed.

Everything I showed is 4" pipe. The leftmost has a full bath upstairs (shower, two sinks, toilet), full bath downstairs (shower, sink, toilet), and washer. The rightmost has full bath (shower, toilet, sink), kitchen sink, and dishwasher.

 

[AmbitiousDIYer]

Everything I showed is 4" pipe. The leftmost has a full bath upstairs (shower, two sinks, toilet), full bath downstairs (shower, sink, toilet), and washer. The rightmost has full bath (shower, toilet, sink), kitchen sink, and dishwasher.

...Actually the two upstairs sinks have their own small AAV due to distance.

 

[MikeGA]

Everything I showed is 4" pipe. The leftmost has a full bath upstairs (shower, two sinks, toilet), full bath downstairs (shower, sink, toilet), and washer. The rightmost has full bath (shower, toilet, sink), kitchen sink, and dishwasher.

Well, that eliminates the possibility of not having enough air. 4" vent has plenty of DFU for your application.

 

[Terry]

Each floor gets vented so what you describe doesn't happen. It looks like you left out a lot of piping.
For an AAV to work in a system, you need at least one vent through the roof, but also, each floor gets vented, and each shower, tub, lav or sink gets a p-trap.