Thread: Toilet venting

Heres a first for me.

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And SURPRISE, it didn't work.

Didn't work probably for at least two reasons: 1) the vent pipe is way too small; 2) that is a mechanical vent and not an AAV - Air Admittance Valve.

Makes me wonder what size the soil pipe is.

Jerry -- Other problems notwithstanding, that *appears* to be a 1.5" vent.

Jerry, What is the difference between mechanical valve and air-admitance valve?

What is the physics involved that would prevent the water from going down the waste pipe, if there is too little or no vent. I have seen toilets flush with no vent and only problem I saw was siphoning of the trap?

From the Oatey (biggest name in AAV's) spec sheet on mechanical valves Versus AAV:

It is important to note that a mechanical vent that relies on a spring to open/close IS NOT considered an AAV. A mechanical vent is a device that operates in a similar manner to that of an AAV...it opens to admit air under negative pressure conditions and closes at static/positive pressures. A mechanical vent does not meet this chapter’s requirement noted in these paragraphs due to its reliance upon a spring for it to function properly.

Read all the technical info here:
http://www.oatey.com/apps/catalog/in..._SVA_link3.pdf

Dom.

Doesn't answer why it would not work or why whater would not flow down the crapper!

Perhaps the spring has failed and is keeping the vent closed.

I'm with Vern here. Toilets (most) are designed to be self-siphoning and rely on the fill mechanism to re-seal the trap. UPC allows the "trap arm" to be up to 6' from the flange to the venting stack and the IRC seems to allow unlimited length. Toilets shouldn't need a vent right at the fixture and I also don't see a stuck mechanical vent stopping the toilet from draining. I would suspect a clog somewhere.

Originally Posted by Vern Heiler

Doesn't answer why it would not work or why whater would not flow down the crapper!

You asked the difference between the mechanical valve and AAV, so the info was provided as a reference.

There are numerous reasons, many unrelated to the vent, for poor flushing.

Dom.

Dom, thanks for the reference between AAV and mechanical. I did know the difference, should have used one of those smilie things. Jerry indicated by his post that the problem may be related to it not being a AAV. My thought was that they both have the same function in life just different designs. The reason for the vent in the first place, is to prevent siphoning and keep the water in the trap. I have yet to see a vent problem prevent water from running down the pipe... I think one would do better taking a quick inventory of valuables that little Johnnie might have sent down the swirley!