I could add a ,studavent? but I think it will drain fine anyway without the vent. I'm in Ohio and I'm not sure what the code requires on this issue although I suspect it says to vent it even in my case. I am concerned about the siphoning aspect of losing my water seal. The place I'm tapping into the main drain is fairly close,7', from where the waste stack leaves the house.

I am installing a new washer hookup in a first floor room.(moving it from the basement).I was going to run a 2" standpipe from the washer to the main drain in the basement which is only 4' away from where I will go through the floor with the drain. Do I put the trap in the riser or close to the main drain tie in. And do I need to vent it other than the venting it will get from the main stack vent. If I have to vent it I may have to use a studavent since my main stack vent is hard to get to and cut into in the attic.(which is the only place it is exposed).

Hi Jhopfd...

You want to install the trap and the vent pretty close to each other... see image below.

Pitch the drain pipe at 1/4" per foot of pipe and hang the pipe every 4 feet.

Be sure to install a 2" cleanout in the drain pipe as well... code required and darn handy to have when you need it in the future!

Back to you...

MARK

Thanks for the input. I was hoping to get away without the aav but I figured I would have to install one since all the rest of the waste from all other sources in the house are above the point where I will be tying in to the main stack. Is the aav a product that can be relied on for along time, If I need to I will take the vent up a chase shaft from the basement to the attic and out the roof but it's winter here right now and I'd rather not cut the hole through the roof and try to seal it now.

I am a big fan of installing vents without mechanical parts, but AAVs are considered very reliable, however, they can fail. Code requires that they are accessible via putting the AAV under the cabinet or installing an access panel.

You definitely need to add a vent somehow... ;)

Back to you...

MARK

Thanks again. I was intending on going through the floor to my basement with a straight 2" from my washing machine hookup box, then putting the trap/w/cleanout in the basement where I came through the floor and then going appox. 4' horizontally with the fall you suggested to a sweep 90 and into my main 3" waste stack. If I put a t where I tie into my waste stack and install an aav there is that close enough to work. I'll be running the horizontal section close to the ceiling in the basement since my main stack runs essentially horizontal/slight slope only 18" from the basement ceiling. It exits the house about halfway up the basement wall. There is already a 3" cleanout a few ' before where I am tying in. That would allow me to hug the basement ceiling until I get to the main. Otherwise I will have to install my trap lower in the basement to give me enough room to install the aav immediately after the trap. I'm trying to avoid using up headroom where my 2" comes down into the basement since it's a little more out into the middle of the basement room compared to where the main drain is (against a wall).

The trap doesn't belong in the basement. Install the PTRAP above the floor. The AAV can also go in the wall... you'll need an access panel for that. Home depot sells a great spring loaded access panel... can be painted or wall-papered.

Mark

OK, Thank You!

Glad to help!