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Thread: Laundry Room Drain Set-Up - is it okay?

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    Default Laundry Room Drain Set-Up - is it okay?

    I am replumbing the laundry room in our house. I staged the fittings that I am planning on using to see if it is an okay setup. I am using a 2 inch vent (out the roof) and drain with combination tee wye fittings for the washing machine drain with a separate vent before draining vertically (also a separate sanitary tee for the sink). I am hoping this will provide excellent flow for the washing machine drain. Thanks for any pointers and checking my work/thoughts.

    See attached image/link.

    http://picasaweb.google.com/BriceBer...28355001721874

    -Brick
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    Plumber krow's Avatar
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    loose the 45 degrees between the trap and the vent, unless its on the same plane. Pipe will slope between the trap and vent , 1/4" per foot or 2% or not exceeding 1 pipe diameter.

    I'm not sure in your state, but some northern states require the vent to penetrate through the roof in 3" minimum (to combat build up of frost from condensation), but inside the house it can be 2"

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    I see, so basically just use some gradual slope instead of using the two 22.5s between the trap and vent, which give a steeper slope.

    Just curious, is there a reason the 22.5s would cause a problem in the system or are they just pointless to have.

    I am in Missouri and am only required to have a 1.5 inch roof vent, but am using a 2 inch, so I should be fine on that.

    Thanks much for your help.

    -Brick

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    Plumber krow's Avatar
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    Quote Originally Posted by bmb2m9 View Post
    Just curious, is there a reason the 22.5s would cause a problem in the system or are they just pointless to have.
    Aside from being pointless, you would be creating an S-trap, which is against code. The S-trap will have a tendency to syphon the water out of the p-trap, causing sewer gases to come back into your home

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    Wow, my question seems stupid with your superb explanation. That makes perfect sense, I just never thought of it like that.

    FYI - I have an S-Trap in one bathroom sink because it was done years ago in my 1960s rancher. But you are right, I need to do it right, to code.

    Thanks!

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    Aside from the 22.5s I assume I am in good shape?!

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    Plumbing Contractor for 49 years johnjh2o1's Avatar
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    You are also creating a S trap by using the combo on the washer waste. A san tee is the better choice.

    John

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    You are also creating a S trap by using the combo on the washer waste.
    I see... I thought that it would be okay (maybe even better) since it is vented before going into the combo and down the vertical drain?! Am I wrong? Is this idea another pointless part of the setup?

    Thanks for the help and insight.

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    Nuclear Engineer nukeman's Avatar
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    Do it like this (picture stolen from Terry):



    If yours will be at the base of a stack (new stack in basement or bottom floor), add a cleanout like you have at the base of the stack. Are you under UPC or IPC? Under IPC, the stack has to be a minimum of 3" for a washing machine. The standpipe and p-trap are still 2". Under UPC, 2" is fine for all of it. For the standpipe, normally it is between 18" and 30" in height, but IPC allows you to go up to 42", I believe.

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    Moderator & Master Plumber hj's Avatar
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    The combo in the vertical stack for the washer is perfectly okay, but just more costly than a sanitary tee. The vent between it and the trap prevents it from causing a 3/4 "S" trap. The washer vent only has to be 1 1/2" and the upper turn can be a regular 1/4 bend, not the long radius one you show. At the bottom is it connecting to a "floor drain" as it says, or a "drain pipe in the floor"?

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    Plumber jimbo's Avatar
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    hj has the best eye of anyone on the forum! Some pointed out, and I was starting to comment, on the vertical combo. Normally, that is not used because it does create an S but taking the vent off BEFORE the combo prevents the S.

    As for the horizontal line, on a branch drain, there is no limit on slope, as long as it is at least 1/4" per foot. But your situation is not the branch, it is the trap arm. Dropping it too much could cause the vent take off to be below the trap seal level. That will cause siphon, and thus is prohibited. Plastic pipe joints have enough "wiggle" that you can achieve the necessary slope without using sixteenth bends.

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    At the bottom is it connecting to a "floor drain" as it says, or a "drain pipe in the floor"?
    It connects to a drain pipe that goes into the floor in the basement. I am using 2" PVC with a gasket going into a 2" cast iron hub.

    Would using a combo in the vertical pipe be of any benefit over a sanitary tee? (such as better water downflow)

    How high should the washer vent go before tying back into the main line?

    Thanks for all the responses and help.

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    Under IPC, the stack has to be a minimum of 3" for a washing machine.
    I am sure that the stack is only required to only be 2" here in Jefferson City, MO. I think in northern states they require 3" due to ice build up etc., right?!

    Thanks for the help everyone.

    By the way, the picture from Terry looks great, I think I will just mimic it!

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    Nuclear Engineer nukeman's Avatar
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    I am talking about the drain. This is not an ice issue. The IPC requires a washing machine to connect into a 3" minimum stack or horizontal branch. Most agree this is probably overkill, but the thought is a buildup of lint over time + high pump output of newer machines could lead to backup/flooding if the line is too small.

    I took a quick look online and it looks like MO is based on UPC, so the 2" will be fine in your case. Just wanted to make sure you knew about the 3" thing if you happened to be under IPC. VA is IPC based, so I have to do a 3" stack.

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    Thanks for all the help guys. One last question and I will be out of your hair, should you just always use a sanitary tee to intersect a vertical drain rather than a combo (even if it is vented before the vertical)?

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