Critique Drain Conversion Plan for washer/dryer relocation

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by A.T, Jun 13, 2019.

  1. A.T

    A.T New Member

    Joined:
    Jun 13, 2019
    Location:
    AZ
    Hi all, long time lurker - first time poster, posting here in frustration after getting three wildly different assessments/estimates from local plumbers. Trying to decide if the best plan of action is to DIY as shown in the diagram below.

    SITREP: Newly purchased (old - 1956) house; we need to move washer from it's current location as the old location cannot accomodatea dryer. It's AZ so the previous owners used a laundry line; but with two kids, that ain't happening. We are hoping to place new washer and dryer to kitchen. The location in the kitchen has access to two existing sanitary cleanouts that lead to master sink and toilet respectively. The matter is complicated by the fact that the entire wall is solid brick and I cannot access the pipes without completely demo'ing much of the bottom of the wall.

    PLAN: I'm planning (hoping?) to be able to tap into the existing sanitary drain (and adding back another cleanout) as shown in the attached diagram. This will include a P-Trad and a run to a laundry box with H20.

    CONCERN: One of the gentlemen giving us a quote was concerned that in the case of a back up in the sanitary line, water could rise up into the washing machine. I thought this was unlikely since it is located at a higher level than the sink and toilet and those would overflow first.

    Would very much appreciate your thoughts or whether I'm overlooking some fundamental principles of fluid dynamics in this scenario. Also, would it be wise of me to have an inspector come out and approve this change or just go with it?

    DrainMod.jpg
     
  2. Terry

    Terry Administrator Staff Member

    Joined:
    Aug 17, 2004
    Occupation:
    Plumber
    Location:
    Bothell, Washington
    A washer typically has a 2" p-trap and standpipe that is 18" to 30".
    The p-trap also needs to be vented to prevent siphoning of the trap.

    Rubber fittings like what you show aren't allowed. They sag over time which blocks the flow.

    804.1 All plumbing fixtures or other receptors
    receiving the discharge of indirect waste pipes shall be
    approved for the use proposed and shall be of such
    shape and capacity as to prevent splashing or flooding
    and shall be located where they are readily accessible
    for inspection and cleaning. No standpipe receptor for
    any clothes washer shall extend more than thirty (30)
    inches (762 mm), nor less than eighteen (18) inches
    (457 mm) above its trap. No trap for any clothes
    washer standpipe receptor shall be installed below the
    floor, but shall be roughed in not less than six (6)
    inches (152 mm) and not more than eighteen (18)
    inches (457 mm) above the floor.
     
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  4. A.T

    A.T New Member

    Joined:
    Jun 13, 2019
    Location:
    AZ
    Wow! Thanks for the quick reply!

    re: venting. There is a vent to the roof ~ 1 ft from the current sanitary drain. Is that sufficient to prevent siphoning or does it need it's own vent? If not is it possible to use an automatic air admittance valve? in line with the ptrap before it hits the turn?
     
  5. A.T

    A.T New Member

    Joined:
    Jun 13, 2019
    Location:
    AZ
    Since I don't think venting to the roof will be doable, could I do the following using an aav?

    Diagram is not to scale/measure re: offsets etc, but hopefully it gives a rough idea.
     

    Attached Files:

  6. A.T

    A.T New Member

    Joined:
    Jun 13, 2019
    Location:
    AZ
    Follow up to this. The clean out is part of a stack for the toilet. Since the ptrap ties directly into the stack, can I forgo the aav? No different than having an entire bathroom on the same vent run right?
     
  7. Reach4

    Reach4 Well-Known Member

    Joined:
    Sep 25, 2013
    Location:
    IL
    Your drawing seems right.

    Not right. When wet-venting a bathroom group, the toilet is the last thing to join the shower/tub and lavatory drainage.

    The laundry standpipe is not allowed to be wet vented. Use the AAV. I don't think it has to go as high as you drew it.
     
  8. A.T

    A.T New Member

    Joined:
    Jun 13, 2019
    Location:
    AZ
    Gotcha. By extension, since the sink cleanout (~2ft away) is not part of the main stack, it would not be permissible to tie into that as an alternative right?

    Really appreciate all of the help you guys have given me. None of the three plumbers I got quotes from mentioned doing any venting at all...

    Maybe I should get a fourth and ask them to get this work permitted, see if they come up with a different answer.
     
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