Thread: AAV vent installed at an angle

Must an AAV vent be installed vertically? I know it to be a device that is mechanically operated by negative air pressure within the drain it serves but am not sure. I can't think of a reason it wouldn't operate properly at an angle but it sparked my curiosity. Comments?

Similar Threads:

• Plastic power vent to metal vent at brick chimney
• PA man says improperly installed dryer vent caused fire - Southeast Texas Record
• Exterior installed commerical Freezer
• Checking if vinyl siding is properly installed.
• Can this be explained? Wooden box installed in firnace

Originally Posted by Luc V. L.

Must an AAV vent be installed vertically?

AAVs that I have seen must be installed within 15 degrees of vertical - that looks to be at 45 degrees from vertical.

Yeah, that's what Oatey suggested in their online .pdf tech document for their version of the unit but it just didn't jive with my understanding of how they work. Jerry, you're about to hit 20,000 posts!

Originally Posted by Luc V. L.

Must an AAV vent be installed vertically? I know it to be a device that is mechanically operated by negative air pressure within the drain it serves but am not sure.

It's not "mechanically operated", it is "atmospherically operated" in that the negative pressure inside the vent lifts the seal, and a neutral pressure allows the seal to remain in place by gravity, and a positive pressure in the vent causes the seal to be sealed tighter.

For the seal to remain in place so that it will seal with neutral or positive pressure the AAV must be close enough to vertical to keep all in proper alignment, and that within 15 degrees of vertical does that.

At 45 degrees, it may not even be sealing properly, or maybe not even sealing at all.

Originally Posted by Luc V. L.

Jerry, you're about to hit 20,000 posts!

Yeah, but who's counting anyway?

I believe I had over 22,000 or so when Brian changed from the old forum to this new forum, but I'm not paying attention or tracking them.

Okay, I will admit that I noticed it when it went over 19,000, and I said to myself 'Well just lookie there at that, I just hit 19,000 again.'

What Jerry said with his 3 posts , the plunger part is binding on the lower side. It will not close properly.
There is no reason to install it wrong except for the reasons of ignorance or indifference.

From the photo that appears to be a Mechanical Vent which are not allowed by the IPC. Air Admittance Valves have a different appearance (that of a sealed unit). Mechanical Vents with springs and mechanical movements are prohibited. Reference the IPC Code and Comentary.