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Thread: Venting Problem?

  1. #1
    Navy Instructor Pilot FlyBoyd's Avatar
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    Question Venting Problem?

    Hey guys...great site. I have looked for my answer but my situation doesn't fit any others I could find. In fact I may have two problems with the same line. I will provide as much info as possible anticipating likely questions I have seen on other post.

    Symptom: Kitchen island sink p-trap gurgles sometimes and bubbles others...facts below...

    1993 built on slab, I purchased 6/07

    On the side of the house in question I have an island kitchen sink, a toilet, a utility sink, and the washer drain.

    I can't say if the island is vented properly but the vents (on that side of the house) I see are a 2" (3"?) directly above/behind toilet and a 1.5" located centrally between the utility sink, washer drain and island sink.

    FYI...the other side of the house has a 1.5" for each sink a 2" (3"?) for one toilet and a huge (4"?) centrally located above another toilet.

    Troubleshooting:
    Utility sink use has no effect on problem.

    Kitchen Island sink gurgles after use almost a drip drip drip sound..very consistent. Viewing water in the trap I see the level drop as the sound is made. Also, after this gurgling sound I can hear the pipe filling (you know the sound) when I run water again... then it gurgles again if the sink is run a fair amount. No sewer gas smell. OBTW, same sound when dishwaser drains through same line.

    Island sink trap water bubbles up when clothes washer drains. No change in water level (just air?). Slight smell if any.

    Island sink trap bubbles when toilet is flushed. Again, no change in water level and slight smell if any. FYI, we have discontinued use of the toilet as I think I could be taking a growler in my kitchen sink....lol. I really think it is air but still.....forcing toilet sewer "air" towards my kitchen sink limits my appetite.

    To be clear the "bubbling" is not small bubbles. They are large and very loud. The trap water returns to its former level after they work through.

    My 2 cents
    1- I think the p-trap is draining when I use the sink and it gurgles (siphoning or excessive slope???). How can I verfiy this and/or fix it?

    2- I think when the washer and toilet drain there is air trapped downstream in the drain line and the first(only?) place for it to go is up the sink line. Why not the vent line (clogged?) Improper/poor design? How can I tell the difference?

    I waited to post this gathering information I thought you all would need. Please help!!!

    Thanks in advance!!!
    Last edited by FlyBoyd; 12-29-2007 at 04:43 PM.
    Boyd

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  2. #2
    Moderator & Master Plumber hj's Avatar
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    Default drain

    Island sinks are a special breed of cat. In effect they are essentially a "vented" S trap. When there is a problem anywhere in the drainage system, not necessarily that sink's drainage, it can cause the symptoms you describe, even if everything else is working properly, for now.

  3. #3
    DIY Senior Member construct30's Avatar
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    Quote Originally Posted by hj View Post
    Island sinks are a special breed of cat. In effect they are essentially a "vented" S trap. When there is a problem anywhere in the drainage system, not necessarily that sink's drainage, it can cause the symptoms you describe, even if everything else is working properly, for now.
    You have made statements like this in the past. I don't understand. If you have a tee with a vent out the top of it before the trap goes down, vertically, then it is a p-trap. If the trap goes down, vertical without a vent, then it is an s-trap.

    There are three methods for venting a p-trap in an island, an AAV, the UPC method that Terry posts with the loop and a vent off a tee heading to to a vent in the nearest wall, and the IPC allows a simple loop vent with the vent loop simply connected back to the drain upstream on a vented drain. All aproved methods depending on where you live or your inspector. I like the AAV to come off the top of a tee, but the picture gives a rough idea.
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  4. #4
    Plumber Winslow's Avatar
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    Assuming the island sink rough-in was inspected/ done to code there should be a cleanout located on the foot vent. Finding it could be a mystery, most likely located near another fixture, near another sink, maybe in a cabinet.

  5. #5
    Navy Instructor Pilot FlyBoyd's Avatar
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    I took a few pics to help clarify.

    Pic #1 is the sink as a whole. The other fixtures in question are to the right.

    Pic #2 shows the sink p-trap and two, just discovered today (thx winslow), cleanouts (foot vent?) in the cabinet to the right.

    Should I snake these? both directions?

    What are those exactly and where do you think they fit into the equation?
    Boyd

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  6. #6
    Navy Instructor Pilot FlyBoyd's Avatar
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    Of course it helps if you attach the pics...lol
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    Boyd

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  7. #7
    Navy Instructor Pilot FlyBoyd's Avatar
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    More troubleshooting...

    In the right picture above if I remove one or both of the cleanouts the sink doesn't make a sound when any fixture mentioned above is operated. I snaked each one with negative blockage or even moisture. I could not get far going up though (18"). Shouldn't these be conected? I was trying to get the snake to show itself in the other cleanout but no luck.

    When I put a piece of tissue over the cleanout hole and I flush the toilet it initially moves out (blows air) then sucks in (sucks air). After a large initial movement each way it oscillates back and forth as it "equalizes." I hear the gurgling sound in the pipe (faint and distant). No smell present.

    Sidenote: The toilet in question has been hard to flush at times. We initially thought it was because it was an older low flush model. BUT...when the cleanout caps were off it flushed easily every time. Caps back on... noises returned.

    What does this suggest?

    1--trapped water (plugged?) in the line... the toilet has to overcome the pressure of the block with multiple flushes??

    When I first started looking into this I thought an AAV would fix it but with the positive airflow coming back it would only fix half the problem right?

    I am a pretty experienced DIYer and was hoping to tackle most of the troubleshooting/work myself. I will call in a pro if it gets over my head i.e. changing plumbing in the foundation . I hate calling a pro and watching them do something I am fully capable of once I get the right info. Looking forward to any advice and I will continue to provide amplifying info as it becomes available.

    Thanks!!!
    Boyd

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  8. #8
    DIY Senior Member gardner's Avatar
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    How hard is it to get onto your roof and look down the vents? I would start looking for a bird's or squirrel's nest blocking the vent.

  9. #9
    Navy Instructor Pilot FlyBoyd's Avatar
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    Update...

    Toilet vent mentioned above sounds (on roof) like the other toilets vent in the house.

    Other vent on this side of house is clear and I can only hear water running when utility sink is used. Neither the washer or the kitchen sink can be "heard" in the other vent. Tops of vents and as far as I can see down with a flashlight is clear.

    FYI...I was finally able to snake the top of the island vent loop and it does indeed connect. I have run 25' of auger down the right of the cleanouts with the occasional bend but no blockage and dry to 25'. On the left cleanout I was able to run about 15-17' before it stopped. I feel it was a 90 turn or the like and not a blockage since the auger tip came back clean.

    Am I right in assuming (look at picture) the right cleanout (should) goes to the vent pipe and the left (should) be the drain line?

    My sound test above would make you think the vent line portion of my island plumbing is blocked or it was not vented correctly in the first place. All exposed plumbing looks correct to me here and in the rest of the house.

    Running out of options...
    Boyd

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  10. #10
    Navy Instructor Pilot FlyBoyd's Avatar
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    Bump.........
    Boyd

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  11. #11

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    Quote Originally Posted by FlyBoyd
    Am I right in assuming (look at picture) the right cleanout (should) goes to the vent pipe and the left (should) be the drain line?
    Yes. However, the system still won't work if the plumbing beneath the slab isn't done correctly. That's something that you cannot determine easily. Still, there's no reason that I know of to suspect that it isn't correct, other than the gurgling problem.

    Does it make any difference which sink you're draining water from when it gurgles? Can you run a hose down each of the cleanouts?

  12. #12
    Navy Instructor Pilot FlyBoyd's Avatar
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    Herk,

    If by which sink you mean "What side of the kitchen sink?"...No...it gurgles no matter which side and only after the water has been turned off. If you mean any other sink ...no other sink makes the gurgle.

    Hose down the vent is next on my list. Cold front came through and the wind has been up. Steep gable + high winds = broken Boyd

    Should I run water to just see if it fills up or try to use a high pressure to dislodge a clog (both?)
    Boyd

    Fly Navy!!!

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