Simple Venting Advice

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by Totalhack, Sep 10, 2020.

  1. Totalhack

    Totalhack New Member

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    I want to add a washing machine to the lower walkout level. Above is the kitchen with sink and dishwasher (nothing else).

    There is a 2 inch soil stack coming down (at some point vented to roof) from kitchen sink (goes into floor and I assume to a bigger pipe to other side of house).

    I want to add a typical P trap and washer drain standpipe.

    Do I need any additional venting? Add an AAZ or a revent?

    It will be quite difficult to connect to the vent up to the kitchen.

    Sorry for my crapy artwork!
     

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  2. Reach4

    Reach4 Well-Known Member

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  4. Totalhack

    Totalhack New Member

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    No idea on MN code. They sell AAVs at the HD, etc. - so they must be used in some cases.

    I understand the idea of water rushing by the incoming pipe and sucking out the water in the P trap.

    Will this work? It should let air in as the stack itself is ventilated.
     

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  5. Reach4

    Reach4 Well-Known Member

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    You are asking if you could join a vent line instead of connecting to an AAV. It will work, and may meet code. For a regular sewer pit, you want the vent to be 2 inch. But that little tub really doesn't need 2 inch. In fact, it only has a 1.5 inch vent pipe. So venting should be great.

    The main reason I think that what you have now backs up is when the water comes in, there is no way for the air in the sump to escape. That air could escape out of a real vent, so washer water makes it in. Now the pump might not be able to keep up. It may. Pulling the AAV and testing should show that.

    You still don't have a trap in place for the standpipe, however. The main concern is that your stinky vent air makes its way out of your standpipe. The other concern is that air is worse than bad smelling and could be harmful. Some would rank those two the other way.
     
    Last edited: Sep 10, 2020
  6. Totalhack

    Totalhack New Member

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    Thanks for your reply. I am not quite clear on what you wrote. I am not 100% solid on plumbing terminology / assumptions.

    I have the kitchen sink (only) draining down the stack. The stack is vented to the roof.

    I will add the washing machine. But I can't easily get to the main vent that vents the sink (the best choice).

    Logically, to me, it seems I can just make a vent from a higher place on the stack. But not being a plumber I am not sure. A kind of "revent." My new jpeg is more clear on what I am trying to do!
     

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  7. Reach4

    Reach4 Well-Known Member

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    I did not attempt to check whether a 2 inch pipe is rated to carry both drain loads. I suspect it is OK.

    What you picture is not ok, because the revent has to occur at least 6 inches above the rim of the kitchen sink.
     
  8. Sylvan

    Sylvan Still learning

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    "There is a 2 inch soil stack "

    NO SUCH thing as a 2" "soil" stack Soil = water closets TOILETS
     
  9. Totalhack

    Totalhack New Member

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    Sorry, I meant Waste Stack! It is coming from kitchen sink, not a toilet.
     
  10. Jeff H Young

    Jeff H Young In the Trades

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    W/M needs a vent and not tied back into the waste line from floor above. an AAV will work , I don't like them and might not be legal in Mn but they work and are being used by the millions (literally) for purposes just like this. other wise open the wall up 42" above floor and connect your vent at kitchen.

    [​IMG]
     
    Last edited by a moderator: Sep 11, 2020
  11. Totalhack

    Totalhack New Member

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    Thanks everyone.

    Called plumbing company and they wanted $2500 to install it. We found the vent in the kitchen above. It is behind the dishwasher and would require some demo to the wall.

    So it is AAV or bust!

    Also, I will put in a utility sink for the washer to drain in. That will give me some leeway if the drain ever backs up.

    I had a plumber bid on another job a month ago and he wanted $2000 for one days work. I think my area may be more expensive than others. Seems expensive to me.

    I certainly could bring the kitchen vent down to the lower level myself. But I don't think it is really worth the effort. I had some AAVs at other properties and they were fine. They had a date written on them in marker saying "replace 2025." I assume the plumber that installed them when house was built in the 2000s wrote the note.

    AAVs have a life of 15 to 20 years. They just screw off - easy to replace.
     
  12. Jeff H Young

    Jeff H Young In the Trades

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    no one ever going to change an aav till they smell a stink. shoulda asked the plumber how much to change that out .
     
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