Why are crown vented traps illegal? Just reading through my code book and was curious.

Because in essence they make a S trap.

any bottom fouling of more than 1/3 of the diameter of the front side makes then useless.as water weigh siphons the seal dry.



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Too close to the stack and/or vent

Wind

Oscillation and evaporation

No Crown stuff?

Plumbum

i thought that too.
vent too close to the water seal hastens evaporation.

Sorry guys you are all wrong!

A "Crown Vent" is a vent that is located within 2 pipe diameters of the trap it is serving.

When a vent is that close it is more subjected to fouling of hair, soap oils, grease, and other debris because; the flow of water does not have a chance to dissipate thus reaching the top of the pipe where the vent is during discharge causing premature failure.

How many guys remember the teaching of hydraulic jump? Not tobe confused it with hydraulic surge.



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Hmmm! Five answers and it took the fifth one to come up with the correct answer.

I vote we discuss the suject over some Crown Royal.

Thank u PBwrencher for that...We are always Learning...

Don't be afraid to ask a stupid question and be a fool for a few minutes..


It's better than not asking that question and being a fool for life!!!



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Many years ago I saw S traps with a vent off of the top of the trap. That is a crown vent I take it? I am not at all familiar with this subject.

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Retired after 50 years of plumbing and heating.

where the trap and vent are of equal size!where the vent is larger?

Yes RWP, that is what I was referring to. This is only because I read the term, and then did a Google search to see what it looked like.

They were much more common when lead traps were used, but there were a few tubular ones made.