Laundry Sink Drainage/Vent Question

[jgold47]

Hi All -

Here's what I've got...

my laundry sink seems to be dumping directly into a old main stack (I think I'm describing this right). Recently, we've had issues with the wet vent in the floor backing up on heavy usage days. We've attributed this (with a scope) to a partially blocked main drain that we are imminently getting jetted clean. However, even when things were/are normal, we have a couple of issues with the tub. It surges and gurgles like crazy, which when the tub is fully loaded and draining (I think) causes the wet vent infront of it to spill over, and we can often smell sewage which despite the sink having a trap (im guessing is from the trap getting sucked out).

so two very different questions related to getting to an answer of how to keep this thing running smoothly...

1. would adding an AAV (after the trap) help? The line doesnt seem to be vented anywhere else, and I'm not 100% sure this ties directly to the main stack which is in a different part of the basement and where the vent is. If nothing else, would that help smooth out the flow of water into the drain and limit the surging?

2. is there a way to 'slow down' a drain, in that if the tub drained out slower, the line could better handle this?

I've contemplated this for a while, but we've only had issues with back ups for the last few months.

Open to other suggestions as well.

 

[Gary Swart]

You have an illegal S trap. An AAV vent after the trap and before the drain turns down would likely solve the problem.

 

[Sponsor]

 

[jgold47]

So at the top of the second loop? Like turn that into a T with the AAV coming off the top?

I could probably turn that into a p trap with a fairly short leg?

 

[Terry]

Here is one.

One more.

 

[jgold47]

Thanks guys - two last questions. Given the way the tub is positioned over the drain, it wont be particularly easy to modify the setup and keep the positioning, unless I was to go straight back, then turn 90, and then another 90 and then a 45 or whatever line up with the stack. as long as I'm pitching it down the whole way, is there an issue with that (think a u shape)?

Last question.

the s trap terminates into the drain via a threaded connection using what looks like a compression nut (hence all the chrome). If I switch this to PVC, is that going to be an issue, mating into the cast drain? Can I get a threaded piece of PVC and the solvent the rest of it?

thanks again!