Trying to troubleshoot a blocked toilet - thinking its a venting problem - but AAV doesnt completely

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by JJ I, Aug 28, 2019.

  1. JJ I

    JJ I New Member

    Joined:
    Aug 28, 2019
    Location:
    ma
    Hey All,
    We've got a toilet that just clogged up. Here are the facts. and what I've done so far.

    Toilet is on first floor of 2 story home with a basement. The toilet overflowed at the wax ring several times. When we ran water down the sink adjacent to the toilet, it air bubbled up the toilet and caused it to overflow as well. We had line professionally snaked when it first clogged, but it re-clogged right away. Same for sink issues.
    1st thought was the drain line from toilet to stack was clogged. We know the main and other branches are not clogged because other appliances (washer, and utility sink) run fine. So we thought the problem is isolated to the 5 or 6 feet of drain from toilet.

    However, we recently thought it might be a venting problem. After checking pre-construction pics to verify that there is at least vent piping, we tested the vent problem theory by pouring water down the open drain, and running the sink. Both ran smooth for at least 10 minutes. We poured a lot of water down, no clogs. That makes me think it is indeed a venting issue.
    As it turns out, our other toilets on the second floor may be slightly gurgling as they flush, but not sure if its true gurgling.

    So I tried snaking the vent line from the roof, but the vent line doesnt run straight down, it breaks into two in the attic and splinters many times more, I'm sure, till it gets to all the appliances. So the small hand crank snake I ran didnt get past the first 90 degree turn or two. Important point, the vent pipes in attic are 1 1/2 inch, so I cant run a sewer jetter pipe down them. A motorized snake eel is really too heavy for me to get up two stories on a ladder and then maintain on a 3/12 pitch roof. Plus how can I know where the potential clog is and where to direct the snake.

    I then ran our garden hose down the vent pipe. Didn't help.

    I'm thinking of installing an AAV for the first floor toilet in the sink box, but its a really tight space and I'm not sure how to fit it, as the trap is set 2 inches or so from the wall, and I only have another inch to the sink structure.

    Plus, that doesn't solve the clog that may be impacting the other toilets.

    I've though of cameraing the lines, but how would I be able to find the clog and navigate the different branches etc?

    More facts, we used to have a straight 4 inch sewer stack/main vent combo go right through he roof, but had a remodel several years back that moved some of the fixtures and so from the second floor till the roof penetration, the vent is only 1 1/2 inches and follows the fixtures

    Any help or suggestions are appreciated. Thanks so much!
     
    Last edited: Aug 28, 2019
  2. Stuff

    Stuff Well-Known Member

    Joined:
    Mar 7, 2013
    Location:
    Pennsylvania
    "The toilet overflowed at the wax ring several times." Not sure what you mean by this. Do you mean toilet leaking at the base?

    A venting issue shouldn't cause a clogged toilet. Likely when the drain was snaked it put a hole in the clog but didn't fully clear it so the next big item going down the drain blocked things again. Have the line re-snaked but pull the toilet so that a bigger auger can be used.
     
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  4. hj

    hj Master Plumber

    Joined:
    Aug 31, 2004
    Occupation:
    Plumber
    Location:
    Cave Creek, Arizona
    "Vents" must feel like the little brother who always gets blamed for everything. A blocked vent, by itself, not only does NOT cause poor drainage but usually IMPROVES drainage. The only way it can cause a problem is if there is some other major problem with the drain.
     
  5. James Henry

    James Henry In the Trades

    Joined:
    Jul 23, 2019
    Occupation:
    Plumber
    Location:
    Billings, Montana.
    Remove the toilet. run a garden hose to the toilet flange, turn the water on and wait. if it fills up then its a clog. Or you might be able to fill the drain by turning on the sink.
     
    Last edited: Aug 29, 2019
  6. JJ I

    JJ I New Member

    Joined:
    Aug 28, 2019
    Location:
    ma
    I will do that and report back, but we've dumped bucket loads down the drain with the toilet removed, and had the sink running at the same time with no backup.
    Maybe cameraing the lines is the next best option here.
     
  7. JJ I

    JJ I New Member

    Joined:
    Aug 28, 2019
    Location:
    ma
    So how else to explain the removal of the toilet as seeming to improve water flow?
     
  8. James Henry

    James Henry In the Trades

    Joined:
    Jul 23, 2019
    Occupation:
    Plumber
    Location:
    Billings, Montana.
    disconnect the vent in the attic as close to the toilet as possible and flush the toilet to test. you can reconnect the vent with a coupling of your choice.
     
  9. Reach4

    Reach4 Well-Known Member

    Joined:
    Sep 25, 2013
    Location:
    IL
  10. JJ I

    JJ I New Member

    Joined:
    Aug 28, 2019
    Location:
    ma
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