So we recently bought an older farmhouse that has had some additions made over the years. The newest bathroom addition has a toilet that barely flushes. I noticed in the attic there are two vents that are capped with an AAV. One vent is for the sink/shower the other is for the toilet. Also after researching it I found that capping a toilet vent with an AAV does not meet code. Approximately 16 ft from the toilet vent is another vent for the kitchen that extends through the roof. The main vent stack is around 30 to 35 ft away with limited room to get to it.

Can I connect the toilet vent to the kitchen vent in order to properly vent the toilet without cutting a new hole in the roof? Should I connect all 3 vents (toilet, sink, and kitchen)? All of the vents are 2" dia. pvc (Main is larger)

Below are a couple of diagrams of what I'm thinking. 1st is existing condition, 2nd is connecting vents. None of the vents are aligned with each other.

A single 2" vent is big enough for the kitchen and bathroom. I would combine them.

Unless your area has an amendment to the code the aav is legal, as long as there is at least one vent that does exit through the roof. But since I do NOT like aavs, my preference would be to tie the vents together. One caveat, as far as the code may be concerned, is that often the vent out the roof should have the same cross section area as the sewer entering the building.

tie the bathroom sink in as well.
san tees are acceptable for vents.

Thanks

Which direction should the san tee go? I'm assuming down? Also I would guess that eliminating the AAV's would help the toilet flush better?

No guarantee about that, since if there are no other problems, the toilet does NOT really need ANY vent at all.

Thanks. Going to connect them and do away with the AAV's and see what happens. Can't be any worse than it is now

On a vertical vent you install a sanitary tee it so it curves up.



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Thank you. Went back into my attic a little while ago and noticed one attached to the vent as you described.

combine as planned and be happy


ps. the 'principle' behind vent fittings and vent pitch is to allow condensation formed inside the vent to flow BACK to the piping of the fixture the vent serves (away from the roof penetration) - juuust a liiiitttle pitch is needed

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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638

codewise, the fittings are installed according to the "flow", but since the vents are servicing air, and air is a gas, the "directional flow" curvature of the fittings serves no purpose, which is why "square" turn elbows and tees are permitted.

not a pro here but even though the code is much more relaxed in dictating how to install vent fittings because it's air, I still prefer to install them such that if a snake is sent down from the roof vent it will still be "directed" in such a way that the snake can clear one of your drains. For example in your situation I would combine the vents in such a way that when I sent a snake down the 2" vent it will run to the toilet drain.

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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638

whether it is a snake or rain water, it has to flow downwards.

Thanks for the help everyone. Connected all the vents to the roof vent. Pitched about 1/4 to 12 up towards the roof. The toilet flushes like it was intended to. Mission accomplished!



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packy I have seen a roof vent in the attic meets a horizontal pipe with a vent tee fitting. That horizontal pipe is how the other vents tie in. The snake would have stopped right there.

I also have a property with a kitchen vent that's 2". For some reason above the cabinet inside the wall the original plumber did an offset with two vent elbows back to back. Whenever I need to snake the kitchen from the roof it's almost impossible to send a snake down it.

@ OP,


the reason the toilet NOW works is that a piped vent to atmosphere allows air flow both ways (in and out) whereas an AAV only allows air in


soooooo the 'hard vent' now allows the air to exit ahead of the 'solids rush'


however


as hj stated the toilet should NOT need a vent ASSUMING all the other piping works PERFECTLY

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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638

This house is 100 years old with two additions over time. Every time I start to upgrade something I have to take 3 steps back to fix other things. I'm guessing all the other plumbing isn't perfect as nothing else here is. But the toilet flushes now!

Thanks again for the help.

That's the joy and curse of home ownership.

But I have to say, in my experience with dealing with home improvements of older homes, the original work of the old homes are usually sound and solid, except for deteriorating materials which is understandable. The bad workmanship, unsound practices are usually in the NEW "improvements" done later.

very sad, BUT, very correct

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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638

And that is where they are. The older part has issues also but I expect that and am dealing with them whenever I have the time and $$$. All of the things I've run up against so far have been in the additions.

What you might do first is eliminate the air admittance vents first then test fixtures then tie together the san tees slope downward think about if it rained into the pipe the water would go down towards the sewer OK?