Sewer gas smell advice / newer Reno / new smell

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by Gary Hancock, Jan 26, 2021.

  1. Gary Hancock

    Gary Hancock New Member

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    Hi Terry , long time reader but first time poster. so in a nutshell.
    Master bathroom Reno . House built in 1984 . Lived here for the last 20 years / no smell from sink . 1.3years ago decided on a Reno . Existing plumbing for duel sinks ran thru the vanity and was built to accommodate. All was well .
    We bought a new vanity $$$ and didn’t want to butcher it for the same fit so we hired a plumber to accommodate us .
    I’m a mechanic not a plumber so bare with me .
    It was plumbed through the wall obviously . so now we are getting a gas smell intermittently coming up through the drain . It’s random / sometimes running slight water ? Sometimes running water to brush teeth and also running water and flushing the toilet beside it ?
    it has happened during hot summer temps and cold so I’m assuming a frozen vent isn’t the culprit?
    Perhaps you may notice something in the before and after pics I post ? Hopefully?
    Fortunately (I think? ) the opposing wall has a similar bathroom setup and it currently gutted for a similar Reno less the drywall removed but it can be if required at this point... hope you can help and advise. Thanks in advance
    Also if it matter the sink drain plumbing was changed from 1 1/4” to 1 1/2” for what it worth
    Once I figure out how to resize my 11mb pics on my iPhone I will add the pics sorry
     
  2. Gary Hancock

    Gary Hancock New Member

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    https://www.dropbox.com/s/v7kdf1lygwwuzab/Photo 2021-01-26, 3 25 25 PM.png?dl=0
    [​IMG]
     
    Last edited by a moderator: Feb 7, 2021
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  4. Gary Hancock

    Gary Hancock New Member

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    [​IMG]
     
    Last edited by a moderator: Feb 7, 2021
  5. Reach4

    Reach4 Well-Known Member

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  6. Gary Hancock

    Gary Hancock New Member

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    Thank you for the reply and solution which makes sense and sounds like a remedy . I do have the room to install such a product . so I’m wondering now in what sense I’m lacking venting?
    This is top floor of 2 story home. The pipe it’s draining into goes straight through the roof so the venting hasn’t changed from previous.

    is the new configuration of plumbing causing part of the siphoning perhaps?
     
  7. Reach4

    Reach4 Well-Known Member

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    http://www.buildingcode.online/1106.html it looks like AAVs must be at least 6 inches above the flood level of the fixtures served. So you could not use the under-the-sink AAV offerings.


    Yes. The trap arm must stay horizontal (2 degrees from mathematical horizontal) until the line is vented. Your trap arm does not get vented right now. The purpose of the venting is to keep the traps from siphoning dry.

    In the attached IMG_1.jpg, if you use two AAVs, they are represented at B and F. They would be behind louvered panels made for the purpose. The green lines would not be used. No drilling of studs required.

    Instead of using AAVs, you would not use B and F, and instead would run pipes C and G. Those would connect to vent pipes. If J and L are both proper vent pipes, you could connect at D and H. The connection points must be at least 6 inches above the flood level (rim) of the lavatories. If only one of J and L are vents, you would connect both to the vent pipe. More drilling thru studs required. Since this is the top level, probably both J and L are vent pipes.

    IMG_1.jpg
     
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  8. Gary Hancock

    Gary Hancock New Member

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    OK so your suggesting extending up with a tee at a and e and simply tie into the vent pipes correct?

    U think the original thought of the AAV's will work even though its not to code?

    I just drove 40 miles to get some to make it work is why I'm asking . I'll know right away if that's the answer and can then open the wall and do the necessary replumb ,,...
     
  9. Reach4

    Reach4 Well-Known Member

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    A and E become sanitary tees (santees) in any case. Then teeing into the vent pipes is the preferred method. Typically you use sanitiary tees (upside down compared to the ones at A and E) for that vent connection.

    I now think AAVs under the sink are not to your code, but AAVs above the sink by at least 6 inches are permitted for you.

    AAVs will work. They are a potential point of failure, so must be accessible. They must have access to air. So the special AAB box kits take care of that. You have these two louvered removable panels in the wall. Real vents let you not have any access ports.
     
  10. Gary Hancock

    Gary Hancock New Member

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    Hello again and thank you for time .

    so as a test I installed an AAV into my horizontal drain line last week . I’ve posted a photo. Now it seemed to have helped but we are still getting a wisp of gas smell when brushing our teeth ?
    I only installed it on the sink we used most often ( the sink on the right looking at the wall) .
    Wondering if I installed another AAV on the other sink if that may alleviate the problem totally ? I’m just not understanding how this can still be happening?
    Hoping to hear from you again

    [​IMG]

    [​IMG]
     
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  11. Reach4

    Reach4 Well-Known Member

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    It only helps if sink 2's trap was siphoning out. You could try running some water slowly into sink 2 drain before brushing your teeth. That would insure the trap was filled.

    You might run a bit of water into the tub or shower in that room before brushing your teeth.

    If those measures don't work, separate things with cheap thin plastic drop cloths. When you detect the smell, check the smell under each drop cloth to see where it is strongest. Once you make sure you don't have dry traps, this detection is very hard. I think you are saying you only smell the odor when you add water into the bathroom drain system. If the odor comes via a sink or tub/shower, that would be good to detect. If it comes through another path, that is going to be hard.
     
    Last edited: Feb 7, 2021
  12. Jeff H Young

    Jeff H Young In the Trades

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    2 traps so both need the aav! The orginal plumbing was bad as well using wye. it could have done same thing but sometimes poor plumbing works . the piping should have been in the wall from day one. With just a little sence job could have been done correctly easily with no need for an aav. might be a slow drain contributing to poor build. Both sinks need AAV ! Id show those pic to the plumber and tell him its totaly wrong
     
  13. Jeff H Young

    Jeff H Young In the Trades

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    No they didnt the first time or the second were both horrible. Homeowner has to fix it himself, it just aint right. Im glad he takes interest to know but shouldnt have too
     
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  14. Gary Hancock

    Gary Hancock New Member

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    Thanks for everyone’s opinion . Appreciate the good and the bad . I’m going to access it further with different scenarios. I’ve tried now numerous times on sink 1 and still have no issues but the problem sink #2 doesn’t respond every single time either ? wife swears it will do it tonight before bed and in the morning first thing ?
    Will update soon . Thanks guys .
     
  15. Gary Hancock

    Gary Hancock New Member

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    Shouldn’t of that AAV I installed cured the venting problem? Or is the problem with the pipe routing after it? Just asking ?
    Thanks
     
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  16. Jeff H Young

    Jeff H Young In the Trades

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    You could try running a snake down clean out . you may have a stoppage. My suggestion is either tear it all out and replumb the 2 sinks or install 2nd aav . your house was plumbed wrong and needs fixed
     
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  17. Reach4

    Reach4 Well-Known Member

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    I think I understand your symptom to be that you initially don't have a smell in that bathroom. You then run some water down one bowl of the sink, and for some reason a smell appears in that bathroom.

    That does not seem like a dry trap problem to me. If you wanted to do a test, there is a way to measure the pressure in that drain line. Venting should keep that pressure close to zero. If the pressure gets to be more than one inch of water column, that could let gas out via one of your traps. One inch is a fair amount. With a real vent, which you probably have in the wall, the pressure gets zeroed by the vent pipe

    So is the smell coming out of a trap, or elsewhere? If out of a trap, what is the pressure in the drain lines? If you want to measure that pressure, I will suggest a possible way.
     
  18. skoronesa

    skoronesa Member

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    I agree with @Jeff H Young , even though it's not plumbed correctly, most of your smell issue is likely due to a clog.
     
  19. Reach4

    Reach4 Well-Known Member

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    Gary, what is behind the wall? Did you make the changes discussed in post #6? Did you take a photo before covering up your work?
     
  20. skoronesa

    skoronesa Member

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    You have the wrong guy buddy.
     
  21. skoronesa

    skoronesa Member

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    Because if someone added auto vents than there might not be a real vent or it was because the real vent was already clogged up above(dead animal/whatever)

    So if there is no vent to let gas out and the downstream is clogged than gas will come out when he puts water in.

    But yeah, could be gas from somewhere else, although I assume he's nailed down where it's coming from. Also, the overflow is probably packed with gook but would smell more often than only when he's using it.
     
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