Will my toilet suck my trub trap dry?

[Rocknice21]

Great title huh?

So thanks to everyone for what you've taught me since I've been asking questions on here. I have two pictures. The first is my overall bathroom plan. The two lavs and shower all have 1.5" vents right after the traps. (Don't worry, that toilet on the left side ties directly into the stack!)

The second picture is really my question. If there is not vent between the toilet tying into the 3" horizontal and where the 2" tub drain ties in, will a siphon be created when I flush the toilet that will pull the water out of the tub trap?? Will it not pull the water out of the toilet trap?


Thanks for the final help!

BTW, the blue lines are 2" horizontal and the red lines are 3" horizontal.

-Ryan

 

[Plumber Jim]

While i don't think it will siphon the water out of your tub trap, I would have placed a 3x2 wye between the toilet sweep and the 3" wye and added a 2" wye with the tub coming in the side and one of your vented sinks or shower going into the back of the wye. then you have the toilet and tub wet vented and all is good. according to 2003 IPC you can have upto 4 DFU on a 2 inch pipe.

 

[Sponsor]

 

[Master Plumber Mark]

no it cannot....

it cannot suck the trap dry....

you have it wet vented into a 2 inch vent....

being installed into a 3 inch drain like it is
, even a full load of water from
both lavs and the shower going cannot
suck the trap dry...


if you are reallly worried about it,

put in a deeper tub trap...
or install an auto air vent on that line


or if I am wrong, and the trap does suck dry,


just turn on the tub faucet and fill the trap up again...


problem solved...

 

[Rocknice21]

There's not a 2" vent anywhere. There are 3, 1.5" vents way upstream at the lavs and shower.

I guess here is the money question. Would you plumb it this way in your house?? And aren't you only allowed to install AAVs above the fixture flood level?

Plumber Jim, I would have to drill like 10 holes in 10 joists to run vent pipes all the way back to the shower or sinks. Doesn't seem to be much payoff there.

-r

 

[Master Plumber Mark]

you are worrying too much

you are fine...you are perfect...

you have 3 1 1/2 vents up stream

and that will do the job almost three times over....

also from your plan the tub drain is dropping into a
3 inch drain line which cannot be siphoned by anything upstream...

the toilet cant siphone tha trap becasue you have it vented
and it will draw what air it needs from your three vents..



it has to work...it cannot not work....


if you are really still worried about it,
just add port to install that extra
auto air vent behind the tub......

or add an extra deep tub trap for good measure...


you would have to be nuts to drill 10 joysts
when you already have 3 wet vents for the tub...

 

[Rocknice21]

Haha, okay I'm convinced!! thanks a million Mark!