P-trap in-line with vent

[Gasser]

To keep this simple, lets assume this is the only way to accomplish what I am doing without major structural changes. If that's what I end up needing to do, I'll go into detail on that aspect because I'm sure I'll need some second opinions before I go forward. I am installing a new tub which has changed how the drain needs to be connected by a few inches...and that is all it takes to cause a lot of headeaches!

Anyway, what problems might I create by having my vent pipe inline with the p-trap on a tub drain rather than have the vent connected after the p-trap?

So both the vent and the tub drain come together in a Y then connect to the p-trap and then to the sewer.

Thanks for you help!!

 

[Terry]

Well, for one thing, there would be nothing to prevent siphoning of the p-trap.

 

[Sponsor]

 

[Jimbo]

Plain and simple, the vent comes AFTER the trap. A vent before the trap does absolutely nothing. The open drain inlet at the bottom of the sink is the vent before the trap. It is why fixtures do not need ANY vent to drain, they need a proper drain to not siphon the trap.

 

[hj]

If you were to do that and then connect the vent to the rest of the drainage system you would create the perfect source for sewer gases to enter the building, and it would be IMPOSSIBLE to prevent them without redoing your brand new remodel job. In most cases a couple of inch adjustment is NOT a problem, nor should it require any major revisions, but that depends on the drain you are using. Knowing the easy way to do it is why we are plumbers.

 

[MACPLUMB]

you can use a thing called a drum trap i think. Then you don't need a vent at all and they fit in real tight places.

a. You can not use a drum trap that are not legal ! !
B. But if you were to use any type of trap they all requre a vent to prevent the trap from siponing and allowing all that "good" sewer gas into the house with all the germs,
and bacteria ! !
That is why we are plumbers also to protect the health of the people that don't know better ! !

 

[Nukeman]

Are you sure you are thinking of a drum trap? Maybe you are thinking of a bottle trap (used for lavs)? Maybe you are thinking of an AAV (for venting)? I've never seen a drum trap at HD and I am there a lot. HD does sell many items that are not legal/code. AAVs are not legal in some states. Bottle traps are generally considered not legal also. Just because they are sold, doesn't mean they are okay to use.

Bottle trap

 

[Shacko]

they sell them at Home Depot, they must be legal. Besides, who's ever going to see it once its in the floor. Prtotect the health of the nation. give me a break. What you guys do is rip off homeowners.

Like one of the other posts said, they sell a lot of things that you can't use at Home Depot. Drum traps are a very poor design, thats why most areas don't allow them! It's been at least a week since I ripped anyone off; starting to get the shakes!!