Running sink drain in same wall as heating vent

[Noodles]

Hello,

I recently bought a newer ranch style house (2014) in New York and I would like to add a washtub sink in the laundry room. Currently, the washer and dryer are stacked in the right hand corner and I'd like to unstack them and put a sink in the other side with a counter top over the washer/dryer. I have not opened any walls yet so my attached picture is what I've gathered from looking in the crawlspace, basement and in the main floor.

• There isn't a trap for the washer stack tube in the basement so I'm assuming it's in the wall in the laundry room
• The vent for the washer drain is in the attic and uses an AAV rather than connecting to the main stack vent
• There is a heating duct in the same wall as the washer stack tube and supply lines, however the vent is installed on the opposite side of the wall to heat the foyer.

I have a few questions

1. Is it a bad idea (code violation or other reason) to route the sink drain through the stud cavity with the HVAC vent over to the washer drain? I can't tap into the drain pipe in the basement because the heating duct goes down and then to the left so there isn't room to tap into it.
2. Can I vent the sink trap to the vent stack leading into the attic with the AAV or will the AAV only handle the washer trap and I will need to install a separate AAV for the sink trap vent?

Thank you in advance for the advice!

 

[Standardairconditioner]

I can't tap into the drain pipe in the basement because the heating duct goes down and then to the left so there isn't room to tap into it.

If you can run a horizontal from the future sink and grade it properly as a wet vent unobstructed through the heat duct, that will work. My guess from your diagram is that it will only be a few feet.

Can I vent the sink trap to the vent stack leading into the attic with the AAV or will the AAV only handle the washer trap and I will need to install a separate AAV for the sink trap vent?

If the above is done correctly, then this will work too.

But since you will be busting up the wall, I would bring the AAV down into the room in a recessed panel, so you can keep an eye on it and replacing it would be as easy as threading a light bulb.

I don't like AAV's in attics, since the condensation they collect can freeze, the ice warps the closing diaghram, scrapping the AAV.

 

[Sponsor]

 

[Noodles]

If you can run a horizontal from the future sink and grade it properly as a wet vent unobstructed through the heat duct, that will work. My guess from your diagram is that it will only be a few feet.


If the above is done correctly, then this will work too.

But since you will be busting up the wall, I would bring the AAV down into the room in a recessed panel, so you can keep an eye on it and replacing it would be as easy as threading a light bulb.

I don't like AAV's in attics, since the condensation they collect can freeze, the ice warps the closing diaghram, scrapping the AAV.

The back wall of the room is 92" across, so I think the sink trap to washer drain tube would be less than 5'. When you say "grade it properly" you're saying 1/4" down per horizontal foot, correct?

Would it be a bad idea to remove the AAV entirely and just connect the laundry room vent stack into the main vent stack that goes out the roof. This would be more work but seems like "the right way to do it". The laundry room is in the dead center of the house and the 2 vent stacks are on opposite sides of the house. Is there a maximum distance you can run a horizontal vent when connecting into the main stack?

Thanks for the help!

 

[Noodles]

Also...if I run a vent stack straight up from the sink trap and connect it over to the existing washer vent, then I won't be wet venting the sink, correct? Any reason not to do this other than more work/material cost? I think I like this approach best since I don't love the idea of wet venting.

 

[hj]

Normally ANYTHING running through a heating duct has to be NON-flammable metal piping, since there is no Raceway certified plastic piping.