[tacointhesun]

I have a 4" drian with 22DFU. All vents join a 3 inch stack which exits the roof. Do I have enough vent area exiting the roof?

[ballengerb1]

I am not familiar with 22DFU, what does that mean? 3" should be Ok, air moves easier than water. However, ask your building departmnent what plumbing codes theyt follow or have adopted. They may require all stacks and drains to be the same diameter