Venting water closet on the vertical drop

[jklingel]

New house. I'd like to drop straight down from my toilet for about 16"-18", then turn horizontal via a 3" T-wye. (The upstream horizontal opening of the T-Y will have a clean out in it.) My question is: Can I vent the toilet on the vertical drop at A w/, say, a 3-3-2 Y, or do I have to vent on the horizontal run at B? Pls see pic. Thanks. john

 

[frodo]

..................

 

[jklingel]

Frodo: Thank you. As I was not sure at all if I could vent on the vertical drop, I was sure leaning toward venting on the horizontal run, like we've done before. It just looked tempting to vent on the vertical, to save some fittings. I appreciate your info. john. PS: Out our curiosity, and so I can learn, why can you NOT vent on the vertical? To the untrained, it seems that air would just rush in as the water goes down, and all would be well. But, I know there is a lot of "the rest of the story" to plumbing.

 

[frodo]

best way to plumb a toilet imo is this

 

[jklingel]

Wouldn't it be better to go down with a 45, then into a wye? I did not think you could use a sanitary T on a water closet. Learn something every day. cheers. john

 

[frodo]

if you are under IPC you can use a combination or a tee for a toilet
if you are under UPC you can only use a tee for a toilet

tee is only used in plumbing if it is installed in the vertical position
and combinations in the horizontal there are exceptions to both,

 

[jklingel]

Many thanks! john

 

[jklingel]

On that 6" between the vertical drop on the water closet and the vent, is that measured center to center on the two pipes? Thanks. We have one that is pretty tight.

 

[frodo]

that is the distance between the 90 and the wye on the horizonital

 

[jklingel]

ah so. hmm. and what is the distance if a combo is turned at 45 degrees to vent instead of a wye on the horizontal? so many little things to know..... cheers. john