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Thread: roof vents, septic smell, studor valves

  1. #1

    Question roof vents, septic smell, studor valves


    our house is in a small valley, and it gets very windy. Under certain conditions, the yard smells like sewage. Homeowners in the vicinity have had similar issues, and solved them by installing a charcoal filter on the septic vents exiting through the roof.

    These filters seem to be hard to come by, at least locally. Plumber friends have suggested installing a studor valve instead, and studor valves are much easier to get. Will they be just as effective?

    I've also read that I can't just install a studor valve on every vent in the roof: at least one of the vents must be open to let outgassing occur. Is this true?

    There are 3 vents: one 2" PVC, one 2" ABS, one 3.5" ABS.

    Reading this, does anyone have comments or recommendations?


  2. #2
    Retired Defense Industry Engineer jadnashua's Avatar
    Join Date
    Sep 2004
    New England


    Studor valves only let gas (air) IN, not out. Your vents need to go OUT (well, mostly) to let the sewer gas escape.

    The vent system, if it is working properly, allows the sinks, toilets, etc. to drain properly. The traps in those devices keep sewer gas from sneaking in the house. Assuming thatyour vent system is installed properly, the sewer gas is coming in from an open window or other air vent.

    Check each sink, toilet, tub, etc. and see if you smell anything coming out of it. You probably won't. But, if you do, a faulty or blocked vent may have allowed the water thatis in the trap to siphon out.

    I'm not a pro, but it seems thatthe vent is supposed to be high enough so that the top is 2' above the roof peak. You might want to double check that value, but just like smokestacks, raising the outlet gets it into the airstream and carried away better than getting caught in the air current eddies often present on a roof.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

  3. #3

    Default Fixed.

    Thanks for the reply.

    The instructions that came with the studor valves said that one pipe on every house must be open to the air, to allow gas to escape. So we attached studor valves to two of the roof vents, and capped the third with a charcoal filter (much more expensive than studor valves). The odor disappeared. Everything still flushes/drains. Problem solved!

  4. #4
    Plumber Deb's Avatar
    Join Date
    Sep 2004

    Default Deb

    You put Studor vents on your roof? Your plumber friend told you to do this?

    The Pipewench


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