I have a confusion about an extra circuit vent needed for this tub. The WC has a 3" stack behind it going up the wall. The lavatory is to the right of the water closet with an 1 1/2" vent tying into the 3" stack at 48".

This is a one story house with a second bathroom on the other side (about 15 feet away with a separate soil stack.)

My drawing is shown as if you were looking DOWN from the attic. The drawing is exact to how the pipes are laid out. (looking DOWN).

I'm pretty sure the tub can vent wet through the 3" soil line past the WC up the stack, but my only thing is will it suck the water out of the tub trap? I some how can't see this happening being that the WC has a 3" directly behind it.

Direction of flow is to the right.

Thanks for any help.

Steve


http://i42.tinypic.com/219otgx.jpg

Im my area you would, by code. It all depends on what your code is, and whether you care about the code. Odds are, you would be okay as far a function goes. But I would hate for you to do it this way just to find out that toilet is siphoning tub trap. If you have access to drains and vents, then vent the tub separately. This would be your best option. You will sleep better at night knowing it was done properly. And if future problems ever arise, you can at least tell yourself that the tub is vented correctly.

Im my area you would, by code. It all depends on what your code is, and whether or not you care about the code. Odds are, you would be okay as far a function goes. But i would hate for you to do it this way just to find out that toilet is siphoning tub trap. If you have access to drains and vents, then vent the tub seperately. This would be your best option. You will sleep better at night knowing it was done properly. And if future problems ever arise, you can at least tell yourself that the tub is vented correctly.

Thanks for the quick reply!

Wow, I thought it would be a few days. I more than likely will run a separate circuit vent to that 3" stack, but wanted to see what others thought about the siphoning. I just can't see it happening with the 3" behind the WC, but like you said, SLEEP at nights. :)

I guess doing it now is easier than ripping open walls later! :eek:

Yep, you will be better off. Hope one or more of the pros here will give you their thoughts.

I really wouldn't mind if you rated my answer.

As Lee pointed out, this configuration could suction out the tub trap. Better safe then sorry. Cut into the 2" tub drain and roll a sanitary tee up on a 45 regree angle and run a vent up and revent back to the stack using a 3 X 2 inverted Sanitary tee.
Good luck, Tom

Or tee

Thanks again guys.

Can I use a 1 1/2" to revent the tub, or does it have to be 2"?

And I'm new hereso I'm not sure how to "rate answers" yet. Sorry. :confused:

Yes you can use 1 1/2 for vent on the tub. But if the vent is under concrete, I like to use nothing smaller than two inch under concrete, once it penetrates the floor I would decrease from two inch to inch and a half.