In general it in my impression that there can be 135 degrees of bends in a run before having to add another vent. What bends count?

My specific situation is a lavatory. The stub comes out of the wall from san-tee. Above is vent pipe, below is drain. To reach the stack the drain must turn from vertical to horizontal (90 deg.) and then, on the horizontal, another 90 deg. For horizontal run to stack. (Structure does not allow for direct horizontal run to stack.)

My question... do I have 90 or 180 deg. Of bend in this run? :confused: If 180, where do I add the additional vent?

If you're askingt if a relief vent is called for in the two bends of your lavatory drain line we do not require one in my area,(check local codes in yours) nor do I find reference in my Code book. Make your drain line 2" and reduce down to 1 1/4" at the trap raiser. Good luck, Tom

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Originally Posted by OscarG

In general it in my impression that there can be 135 degrees of bends in a run before having to add another vent. What bends count?

My specific situation is a lavatory. The stub comes out of the wall from san-tee. Above is vent pipe, below is drain. To reach the stack the drain must turn from vertical to horizontal (90 deg.) and then, on the horizontal, another 90 deg. for horizontal run to stack. (Structure does not allow for direct horizontal run to stack.)

My question... do I have 90 or 180 deg. of bend in this run? :confused: If 180, where do I add the additional vent?

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There are no limits on changes in direction for vent lines -- The 135 degree limitation is placed on drainage lines and the need for a cleanout if an aggregate change in direction exceeds 135 degrees.

At this point, the only limitation posed by your question is the need to change from vertical to horizontal -- You need to be at least six inches above the flood rim of the fixture before going horizontal.

If this isn't doable because of an inset medicine cabinet or framing issues, then make sure you use long sweep fittings in your transitions from vertical to horizontal and that your tie-in point at the stack is at least six inches above the flood rim.

Growler,

He's referring to a drain not the vent. His question, as I understand it, was asking if a additional vent should be placed on the lavatory drain line because of the bends. Regards, Tom