Toilet vent

I think I know the answer to this but I thought I'd ask anyway. Having problems finding a long sweep 90 w/low heel inlet 3x3x2 locally. I'm wanting to use this to transition from horizontal toilet drain to vertical toilet drain and use the low heel part for the toilet vent. There are plenty of the 3x2x3 regular 90's w/low heel inlet but I thought it would be better to find the one with the long sweep to better help with the "logs", right? I'm thinking this is not to code, but what about using a 3x2x3 combo wye with the vent coming off the top of the 2" straight leg of the wye? I'm guessing not because the vent opening in the wye would be starting below the upper most part of the horizontal drain. Also guessing that's why the low heel inlet was invented, to start the vent higher up in the elbow?

Thanks, Jeff

I just used a low heel 90 in my installation, and at the three local suppliers I use, I haven't run into a long sweep. My understanding has been that the sweep is only necessary at a vertical to horizontal transition, to ease the fast fall into a slower-moving slide, but has no benefit or necessity in a horizontal to vertical change in flow.

That fitting is basically a sanitary tee. The heel inlet, either high or low can not be used for venting in the horizontal position.

speede541 said:

I just used a low heel 90 in my installation, and at the three local suppliers I use, I haven't run into a long sweep. My understanding has been that the sweep is only necessary at a vertical to horizontal transition, to ease the fast fall into a slower-moving slide, but has no benefit or necessity in a horizontal to vertical change in flow.

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Thanks, I will go with the regular sweep with the low heel 90 then. I knew there was the issue with horizontal to vertical or vice versa, I just couldn't remember it at the box store and the employee was of no help

Wally Hays said:

That fitting is basically a sanitary tee. The heel inlet, either high or low can not be used for venting in the horizontal position.

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Wally, I didn't describe what I was trying to do very well, that 90 w/heel will be used in the vertical position, what I was wondering about was if a long sweep 90 could have been used instead of the 90 w/heel, turning it vertical and running the vent off the top part of the straight portion of the long sweep wye. I'm sure it's not ok so I will go with the 90 w/heel.

They only make the Santee bend in the lo-heel, which is what is always used for venting.
It it was a shower or lav, it would have to be a santee bend going from horizontal to vertical.

As far as the function of the toilet goes, you have a 2" trapway dumping into a 3" pipe. It's gone at that point.
If the waste can navigate through all the bends in your little trapway, it's free sailing after it hits the 3".

I know this is an old thread, but I'm curious about Terry's very logical last observation...

Given that the toilet trapway is less than 3", why do some people recommend using a 4" riser going into a 4x3 closet bend? Seems like overkill ...
Likewise there sees to be a vigorous debate on whether the toilet flange should go outside or inside the riser. What is your preference and how does it impact ease of installation and any future repairs?

I really have come to appreciate the art of plumbing given all the possible (to code) variations, and it sure helps to understand the rationale for choosing one approach over another.

I've installed a lot of these over the years for toilets. A lo-heel Santee.
The toilet, since it is meant to siphon anyway, can also be vented below the arm. That means a combo would work, or even a wye below a 90.

As far as closet flanges go, I believe that as long as the waste can drop straight down you're fine. Most horns on modern toilets are 2-5/8" or less with an open hole around 2". The Caroma brand has some 3" trapways, and even some 4". If you're installing that brand, I can see the argument for the 4" closet flange, or at the least the 3".
The largest trapways by manufacturer are:
American Standard, Champion, 2-3/8" and smaller in other models
Caroma, 3" and 4"
Gerber, 2-1/8" or smaller
Kohler, 2-1/8" or smaller
Mansfield, 2-1/8" or smaller
TOTO, 2-1/8" or smaller

Average stool, 3/4" x 4"

When I replace lead bends, I normally use a 4" closet flange, with a 4" x 3" spigot closet 90. It allows me to work with an arm that is often too close to the floor. When I'm doing new construction I install 4x3 closet flanges with 3" bends.
On some commercial jobs on concrete slabs, I sometimes use a 4" closet flange, mainly because I have some room to shift the location after the pour and the framers have done their walls. If something is off, I can make up some of that.



Typical 4"x3" closet flange.

As far as a 3" riser and closet flange, I have NEVER used them. I only use a 3x4 closet bend and a 4" flange which goes on the outside of the riser.