Toilet Won't flush with AAV installed

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fayejames451

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Hello - looking for advice or other things to try for a potentially "airlocked" toilet.

1. New single story manufactured home - two bathrooms, each with double sinks
2. On a septic tank that does have a clean out and tank was pumped before home was installed in February. However, septic system is old.
3. I have roof vents for the bathrooms and each sink has the AAVs.

After about two weeks of use, one toilet started flushing slow (liquid goes down, solid waste does not). Toilet was brand new with house but a cheapy so replaced it with a better one.

New toilet did not resolve the problem. Plunged furiously with both regular plunger and air canister plunger. Air canister plunge resolved issue for a few days but came back. I took the clean out cap off the septic line outside, that helped for a few flushes. Decided to plunge furiously again and noticed that the vent on one of the bathroom sinks pipe was popping as I plunged, I took that off and left the pipe open - toilet worked beautifully - I installed a new valve under the sink and after about 3 days the slow flushing issue returned.

I have done the pour 5 gallons of water down the toilet and fill tub up and flush while its draining tricks (and all the other tips/tricks) - no resolution.

I have not snaked anything as I don't believe its a clog issue unless the manufacturer left something in the plumbing (or roof vent) at the factory, but who knows. No standing water in the pipe at the septic clean out and no backups to the tank, etc. Laundry room is inline (across the hall) with this bathroom but have had not issues with washing machine draining.

Looked down the roof vent related to this toilet and could not see any blockages. Haven't tried running water through it though.

No issues with the other toilet.

Had one plumber come out and they said to replace the field lines. Does that make sense to the experienced plumbers in the forum?

TLDR: Toilet won't flush with AAV value installed. If I take it off to facilitate flushing, house smells like sewer. When I put it back on, toilet stops flushing again after about three days.

Any other ideas would be appreciated.
 

Twowaxhack

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You might have a sagging pipe. Go underneath the home and make sure all the piping is secure and they are no big dips where water would be trapped.

Remove the cleanout at the septic tank and make sure it’s not holding water.
 

Twowaxhack

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If no dips or sags are found and the septic system is operating, it’s time to bring out the drain cleaning equipment and cameras.
 

fayejames451

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You might have a sagging pipe. Go underneath the home and make sure all the piping is secure and they are no big dips where water would be trapped.

Remove the cleanout at the septic tank and make sure it’s not holding water.
Thank you, I had not thought to check for sag in the pipe.
 

CT18

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Try a 2 gallon. Most toilets are 1.6 or less. If it is flushing properly then its not getting the amount of water from the bowl in time to make proper flush. Maybe the flapper is closing to fast. I am just throwing darts with not being able to look at it physically.
 
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