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Thread: double bathroom sinks and washing machine through 2 inch drain - no vent - okay?

  1. #1
    DIY Junior Member leet's Avatar
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    Question double bathroom sinks and washing machine through 2 inch drain - no vent - okay?

    Hi,

    Is it permissible and advisable to drain two bathroom lavs and a washing machine through a single 2 inch drain pipe with a run of less that 4 feet to the stack with no vent? The stack in my images also has a bathtub drain and toilet tied to it - all of this on the ground floor with no other drains or vents on this stack. I have provided two images - a photo "current" and the other image is a mock-up of my plan. I intend to move the washer drain over (laundry room is behind this wall) and add two bathroom sinks in place of a single sink.

    Name:  current.jpg
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Size:  55.9 KBName:  move laundry drain - add 2 sinks to same drain.jpg
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    Thanks for your help,

    Lee
    Last edited by leet; 09-11-2013 at 07:25 PM.

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    Forum Admin, Expert Plumber Terry's Avatar
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    The washer needs a vent, the lav needs a vent and the other lav needs a vent.
    Those three vents can tie together at 42" above the floor.

    You need a wye fitting or combo with waste going from vertical to horizontal. A Santee is not allowed in that position.

    A washer does a good job of siphoning traps.
    That's why they are "never" allowed in a wet vent system.

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    DIY Junior Member leet's Avatar
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    Okay, thanks Terry - working on plan "B"

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    DIY Junior Member leet's Avatar
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    I created a new plan with a vent for the washing machine and a shared vent for the 2 sinks - using 2" pipe for all drains and vents. Do I need the washer vent in this setup? Can I share one vent with 2 sinks? Please refer to my mock-up below and let me know what you think.

    Thanks again, Lee
    Name:  mbath with vents.jpg
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    Forum Admin, Expert Plumber Terry's Avatar
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    It's getting late on Friday.
    The last drawing shows s-traps on the lavs.
    The vent comes off the "top" of the trap arm, not below it.

    Here is a nice link to Bert Polk's plumbing tips

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    DIY Junior Member leet's Avatar
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    First, the link you shared was very helpful - thanks!

    Would you mind reviewing the diagram I created in response to your feedback? It is intended to show the flow of the drains and vents but not the fitting details. All pipes are pvc: 3" stack, 2" drains, 1.5" vents, and 1.25" sink drain traps. I would have set up both lavs like the one on the right but there is no room in the wall to cross a drain and a vent.

    Thanks again for your help,

    Lee

    Name:  mbath with vents on sketchup.jpg
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    This drawing does not work
    Terry
    Last edited by Terry; 09-16-2013 at 08:20 AM.

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    Forum Admin, Expert Plumber Terry's Avatar
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    The revent is at 42" or higher off the floor.
    The washer standpipe is at least 18" long.
    I typically rough the lavs at 20" from the floor with a 32" counter.
    The washer box works well at 48" to the top of the box. It can be lower than that, but the standpipe must be 18" at the min. I buy the washer shutoffs with hammer arrestors.
    Last edited by Terry; 09-16-2013 at 08:21 AM.

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    DIY Junior Member leet's Avatar
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    genius! thanks so much for your help! Lee

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