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AAV vents in tiny house with no black water

gmtinyhouse | Posted in General Questions on

I am currently building a tiny house and am planning the plumbing system. I do plan on consulting a professional plumber but am wanting to fully understand my options while I am planning.

Concerning venting, as I would like to minimize terminations in the metal roof, holes through the studs and top plates for structural reasons, as well as side wall due to width limitations, I am looking into using AAV vents where possible.

The overall system is very basic, a kitchen sink, bathroom sink, and shower. Will possibly install plumbing for a future washing machine. There is no sewage in the house as we will have a composting toilet.

My main question is about any potential risks with the AAV vents for gray water only, given my lack of experience. I am wondering if there are any potential gases that could be produced by gray water pipes that could get into the house if the AAV fails in the same way the sewage gas is a concern?

I am open to any thoughts, additional options, or other foresought problems with using the AAV vents.

Thanks a lot!

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  1. Expert Member


    Go ahead and use AAVs throughout. There is no risk associated with grey water off-gassing into your tiny house. Further, the most common way traps fail is through evaporation by disuse. That can happen more easily with wet vents than AAVs.

  2. Expert Member
    AKOS TOTH | | #2

    You can use a single AAV for multiple fixtures, just plumb all the vents as with normal venting and mount the AAV above the flood height of the highest fixture. You can vent a full 4 piece bath+washer with a single AAV.

    One thing to watch for is that there is a positive pressure vent wherever your greywater drains to, AAV only relieve vacuum.

    1. gmtinyhouse | | #3

      Thank you!

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