# Wet venting 2 washrooms

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#### Tuttles Revenge

How to use a double why as a horizontal drainage fitting explained here. Of course, not recognized in all jurisdictions, but apparently OK in Canada and King Co Washington.

#### wwhitney

The alternative is pitch the barrel at 3% and get the two side inlets exactly level with each other. That pitches the side inlets at 2%. Getting it correct can be quite tricky.

Cheers, Wayne

#### Jeff H Young

The alternative is pitch the barrel at 3% and get the two side inlets exactly level with each other. That pitches the side inlets at 2%. Getting it correct can be quite tricky.

Cheers, Wayne
That works , extra fall on the main.

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#### yourlocalhandsyman

##### New Member
There cant be slight pitch built into a double wye other wise it would be marked which side is up if running horizontal.
The double wye looks good on paper and looks kinda cool but can be a little harder to get right in practice especially or mainly when used horizontally. I basically block double wyes out of my mind except when vertical or up against some obstacle
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I'm no understanding what you are getting at? Running the lines 1/4" per foot would give both the centre outlet and the side ones a pitch. If you start from the stack and pitch it there, then for the wye drop a level cross ways you can straighten it out so both sides are even and not one up one down. Finish at fixtures and cut pipe coming from toilet to fit?

How would a double wye connected to a main 4" line running at 1/4" per ft NOT be pitched in line with the pipes it's connected to on the y axis?? You then connect a 45 get in line with the fixture it's connecting to on the X axis, which is also pitched at 1/4" per foot. The only issue I can see is if the double wye is not flat on it's x axis one side outlet will be high and the other may drop down enough to have waste pool inside the fitting.

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#### wwhitney

If a double wye has both of its side entries level (neither is higher than the other), then the slope of the side entries is 70.7% of the slope of the barrel.

That's just vector math: when the wye branch runs one unit parallel to the barrel (which gives it some rise), it also runs one unit perpendicular to the barrel (which provides no rise). That provides a total run on the branch of sqrt(1 + 1) = sqrt(2). That means the rate of rise on the branch is 1/sqrt(2) the rate of rise on the barrel, and 1/sqrt(2) = 70.7%.

Cheers, Wayne

#### yourlocalhandsyman

##### New Member
If a double wye has both of its side entries level (neither is higher than the other), then the slope of the side entries is 70.7% of the slope of the barrel.

That's just vector math: when the wye branch runs one unit parallel to the barrel (which gives it some rise), it also runs one unit perpendicular to the barrel (which provides no rise). That provides a total run on the branch of sqrt(1 + 1) = sqrt(2). That means the rate of rise on the branch is 1/sqrt(2) the rate of rise on the barrel, and 1/sqrt(2) = 70.7%.

Cheers, Wayne
Yes, when you are off axis you don't gain as much rise. Does 3-4" of 70% rise really matter when 95% of the pipe is at correct rise and the water is traveling at the fastest velocity it will reach?
I thought I was autistically OCD.

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Hey, wait a minute.

This is awkward, but...

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