Two air check valves?

[Jack Feldmann]

Any idea why someone would put to air check vents under a kitchen sink?

[John Arnold]

Maybe it's DIY and the homeowner originally had one valve and thought it was noisy or not venting well enough so he's trying two? Just speculating. Sounds like something I'd do.

[John Kogel]

I'll bet the trap was clogged with bacon fat and the first air valve didn't fix it. :)

[Vern Heiler]

It's a double bowl sink!:D

[Rick Cantrell]

"Any idea why someone would put to air check vents under a kitchen sink?"

Because there's not enough room for 3.:D

[John Arnold]

"Any idea why someone would put to air check vents under a kitchen sink?"

Because there's not enough room for 3.:D

Dang. Why couldn't I have thought of that?

[Ron Hasil]

Here is a good link to see if your state approves a mechanical vent. STUDOR (R) inVENTive Technology (TM) - Air Admittance Valves (http://www.studor.com/approvals.htm)