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Background - I have a Saniflo Sanicompact toilet in my basement which is self contained and doesn't need to be vented. There is a bathroom sink that drains into it. Saniflow folks said that the sink doesn't need to be vented but I could put an AAV on it to stop the gurgling that would happen in the toilet when the sink would run. The sink trap would also get sucked dry and gas would leak out. The AAV didn't help the smell besides move it from the sink to the AAV. I knew I wanted to properly vent it to the bathroom sink above once we started our remodel there, which is where I am at now.

I want to make sure my venting is correct since I am tired of not having this done right in the first place. I currently just have the AAV unscrewed and screwed the temporary vertical PVC in place. Basically I would run PVC up and over with 90 degree fittings. The horizontal would have a slope. Then up through the floor to the connect to the sink vent above using a tee.

  1. Does this all look good?
  2. Looking at the second pic, the fitting where the vertical PVC is now isn't completely straight. It has an angle out from the wall to accommodate the old AAV sitting against the wall. The vertical pipe does need to bump out to go around the foam wrapped copper pipes that are strapped to the wall above. My understanding is the vertical pipes in a vent need to be actually vertical. Should I just do a 45 out from the wall and back in to a vertical pipe up to the first 90? Or even back to back 90s? 3. Do I need to cut out that fitting and position a new one to be vertical before bumping out the pipe to up?

Thanks for the help here.

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Current sink vent enter image description here

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  • Under IPC, "Vertical" for a vent pipe is defined as within 45 degrees of vertical. Other codes are likely similar.
    – Ecnerwal
    Oct 6, 2022 at 14:41

1 Answer 1

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  1. Yes, your drawings/markups look good.
  2. Yes, the vent needs to remain nominally vertical until 6" above the fixture's flood-level rim. Using two 45° elbows, as shown in your last picture, is the correct way. Be sure to connect the vent 6" or more above the flood-level rim of the upper sink.
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  • So I guess my question now is just if the current vent coming off of the drain at floor level is OK versus coming off the trap arm? I added a new drawing to show that.
    – junta
    Oct 26, 2022 at 17:55
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    No, that makes the P trap into an S trap. The vent needs to be up at/above the level of the trap arm entry.
    – Ecnerwal
    Oct 26, 2022 at 17:58
  • Yes, as @Ecnerwal states the current vent configuration you describe is incorrect. The fall on the trap arm is not to exceed the diameter of the trap arm pipe. It should be corrected.
    – pdd
    Oct 27, 2022 at 16:12

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