Do I need air admittance valve?


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Old 07-31-17, 09:33 PM
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Do I need air admittance valve?

I was told to install a sink drain vent pipe system called "abs in-line vent" on the red box. He said that flushing the toilet might empty my drain trap, however my drain trap is doing fine after I flush. Do u think I need to install it?
 
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Old 07-31-17, 10:34 PM
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By U.S. national code you do to prevent syphoning. I can't say for Canadian code.
 
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Old 08-01-17, 12:07 AM
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He said that flushing the toilet might empty my drain trap
Who is HE ?

An air admittance valve is like the path of last resort. Your plumbing system is supposed to have vent lines in the wall and up thru the roof.
 
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Old 08-01-17, 12:36 AM
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An employee at Home Depot, he's a licensed plumber. BTW how do u reply with quote on this forum?
 
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Old 08-01-17, 01:39 AM
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To quote click the Quote Icon.
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Then copy and paste.

Paste only the minimum amount needed for clarity.
 
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Old 08-01-17, 11:14 AM
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Current code (US) requires venting for all fixtures. In this case, if it was a new install, it would need a vent, either direct vent to the outside or an AAV.

Considering this has been here for a while and you're not seeing issues, I don't know that I'd go through the hassle of replacing all of it just to add an AAV. Up until the '70s or '80s, S-traps (like you have) were quite common. There are a LOT of them still around, mostly not causing big problems.

If it was a new installation, I'd definitely push to correctly venting. It's really up to you whether you want to add the AAV since it's likely grandfathered in code-wise.
 
 

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