Who knows what an AAV Vent is?

By
Home Inspector with Superior Home Inspections - Greater Albuquerque Area InterNACHI 10041206

We learned a long time ago that plumbing must be vented to allow smooth flow through the drain pipes. The way architecture is in our world today; people are putting water fixtures and sinks everywhere! The problem was the venting. Conventional wisdom had them running up the walls and through the roof. But some houses have island sinks or bathroom sinks that cannot be plumbed this way.

Along came the AAV or Air Admittance Valve. They have been around since the mid 90's or so. They are designed to allow air to enter the plumbing drainage system and equalize pressure when water drains out of the system while maintaining the integrity of the water trap or seal that prevents sewer gasses from entering the home through fixture drains. When water runs into the drain, the negative pressure created by flow causes the AAV to open, allowing air to enter. When the flow stops, a spring closes the valve preventing sewer gasses from escaping. It's as simple as that. They should be installed at least 4" from the top of the branch drain they are being used on. I like to see them just a little bit higher. The manufacturers state that the distance should not exceed 6". Hmmm, ok... gimme 6! You still must have at least one vent pipe extending upwards through the roof though, but these are handy for those special installations.

 

I have been seeing the ones that have been installed for a number of years failing now. They are supposed to last around 30 years, per the manufacturers, but things fail when they fail! Mostly at the kitchen sink. When they fail in that location, the dishwasher discharging will force water out of the vent and into the room, either under the sink in the cabinet or all over the counter tops and onto the fllor. Had one not that long ago that was bad, the Real Estate Agent had his laptop on the counter, when the dishwasher discharged water, the water ran all over the counter top and under his laptop... panic in the streets!

The fix was evident, the owner had the AAV vent replaced and all was good.

 

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Posted by

 
 
Fred Hernden 

 

 Superior Home Inspections

 

  505-588-9559

 

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 Albuquerque, Rio Rancho New Mexico and surrounding areas...

 

“My mission is to provide superior quality home inspections to my clients to ensure peace of mind so they can confidently make the largest investment they may ever make!"

                   

Please visit my website at: www.SuperiorHomeInsp.com for details!

                 

 

                                     

 

 

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Re-Blogged 1 time:

Re-Blogged By Re-Blogged At
  1. Roy Kelley 11/11/2015 06:00 PM
Topic:
Home Buying
Location:
New Mexico
Groups:
Ask the Home Inspector
Bananatude
Sensei Grasshopper
Tags:
home inspection
plumbing vents
aav vents

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Rainmaker
1,846,740
Jay Markanich
Jay Markanich Real Estate Inspections, LLC - Bristow, VA
Home Inspector - servicing all Northern Virginia

My house was built in 1998, before the AAV trend, and my kitchen sink has the "Chicago Loop" behind it.  That's the closed circuitous oval over the drain line to allow air to circle and sometimes there is a glub.

I have never seen the AAV discharge water.  My time will come...

Oct 02, 2015 06:53 PM #14
Rainmaker
2,455,034
Richie Alan Naggar
people first...then business Ran Right Realty - Riverside, CA
agent & author

A place where they auto feed Aardvarks came to mind...AAV vent has to do with the food dispenser unit? This is outside of my "know"....thank you

Oct 02, 2015 11:45 PM #15
Rainmaker
568,350
Fred Hernden, CMI
Superior Home Inspections - Greater Albuquerque Area - Albuquerque, NM
Albuquerque area Master Inspector

Eileen - You are probably right, if you got one and it fails.... you will learn about them :-)

Michael - I am all for having less roof penetrations, I feel that way about skylights too!

Silvia - It didn't work when your friendly Home Inspector tested it! Scared the Agent though....  

 

 

Oct 03, 2015 12:16 AM #16
Rainmaker
568,350
Fred Hernden, CMI
Superior Home Inspections - Greater Albuquerque Area - Albuquerque, NM
Albuquerque area Master Inspector

Tammy - That may be good advice... they're supposed to last longer than that though! But, if you never had a water leak problem... maybe you're on to something!

Myrl - Absolutely, if you're gonna have one, being there is golden!

Praful - A sea of knowledge it is, and fun to share!

 

Oct 03, 2015 12:19 AM #17
Rainmaker
568,350
Fred Hernden, CMI
Superior Home Inspections - Greater Albuquerque Area - Albuquerque, NM
Albuquerque area Master Inspector

Jay - Ahhh the old Chicago loop... I seen them in diagrams, but never in the field. The first time I saw an AAV fail, the dishwasher discharged and it sent a straight stream over the sink to the floor... it was a geyser! 

Richie - LOL, it's merely a vent to allow air into the drain line so it operates correctly without allowing sewer gasses back into the house 

Oct 03, 2015 12:23 AM #18
Rainmaker
679,919
Nicole Doty - Gilbert Real Estate Expert
Zion Realty - Gilbert, AZ
Broker/Owner of Zion Realty ZionRealtyAZ.com

I did not know what an AAV Vent was and now I'm glad I do. Not just for my clients but for my own house!

Oct 03, 2015 01:30 AM #19
Rainer
333,502
Frank Castaldini
Compass - San Francisco, CA
Realtor - Homes for Sale in San Francisco

Totally out of my realm.  Thanks for the post.  I hope my laptop never gets threatened.

Oct 03, 2015 01:47 AM #20
Rainmaker
3,053,138
Tony and Suzanne Marriott, Associate Brokers
Haven Express @ Keller Williams Arizona Realty - Scottsdale, AZ
Serving Scottsdale, Phoenix and Maricopa County AZ

I didn't - but I do now!  Thanks for an educational and informative post!

Oct 03, 2015 03:44 AM #21
Rainmaker
568,350
Fred Hernden, CMI
Superior Home Inspections - Greater Albuquerque Area - Albuquerque, NM
Albuquerque area Master Inspector

Nicole - You may not have them, but they are easy to identify 

Frank - I heard that.... he did scramble!

T & S - Thanks for stopping by... 

Oct 03, 2015 04:56 AM #22
Rainmaker
107,574
Gilbert Real Estate Experts: Colby & Michele Myers
Orange Realty, LLC. - Gilbert, AZ

Good info. Love learning about stuff like this, because eventually I'll run into it. Thanks

Oct 03, 2015 06:11 AM #23
Rainmaker
863,796
Les & Sarah Oswald
Realty One Group - Eastvale, CA
Broker, Realtor and Investor

Now I can raise my hand and say that I know about AAV vent...

I am going to use this knowledge to impress homeowners  and buyers during home inspections... yippee.

Oct 03, 2015 07:17 AM #24
Ambassador
2,079,869
Barbara-Jo Roberts Berberi, MA, PSA, TRC - Greater Clearwater Florida Residential Real Estate Professional
Charles Rutenberg Realty - Clearwater, FL
Palm Harbor, Dunedin, Clearwater, Safety Harbor

I remember a home that had some brain close up the roof vent and just allow the pipe to stop in the attic. Needless to say, my home inspector was NOT thrilled with that one and it had to be taken care of!

Oct 03, 2015 07:46 AM #25
Rainer
304,656
Stephen Weakley
Nationwide Mortgage Services - Rockville, MD

I had never heard of an AAV.  Interesting solution to the problem.

Oct 03, 2015 08:25 AM #26
Rainmaker
482,047
Bruce Kunz
C21 Solid Gold Realty, Brick, NJ, 732-920-2100 - Howell, NJ
REALTOR®, Brick & Howell NJ Homes for Sale

Nice article, Fred Hernden . I wasn't familiar with AAVs and appreciate you sharing this lesson them. It seems a bit of prevention in changing them "early" would be a good plan.
Bruce

 

Oct 03, 2015 11:25 PM #27
Rainmaker
568,350
Fred Hernden, CMI
Superior Home Inspections - Greater Albuquerque Area - Albuquerque, NM
Albuquerque area Master Inspector

C & M - May you never have to expeience one of these going bad and flood your kitchen!

L&S - Awesome, knock em dead!

Barbara-Jo - Sewer gasses in the attic is not a good thing! He saved the day!

 

Oct 04, 2015 12:47 AM #28
Rainmaker
568,350
Fred Hernden, CMI
Superior Home Inspections - Greater Albuquerque Area - Albuquerque, NM
Albuquerque area Master Inspector

Stephen - Good old American ingenuity! 

Bruce - I suppose, I hope I didn't come across as saying these need to be changed out periodically.... they're supposed to last 30 years!

Oct 04, 2015 12:50 AM #29
Ambassador
2,079,869
Barbara-Jo Roberts Berberi, MA, PSA, TRC - Greater Clearwater Florida Residential Real Estate Professional
Charles Rutenberg Realty - Clearwater, FL
Palm Harbor, Dunedin, Clearwater, Safety Harbor

Just stopping by to make sure you are still in here blogging! MISS YOU!

Oct 05, 2015 12:52 AM #30
Rainmaker
568,350
Fred Hernden, CMI
Superior Home Inspections - Greater Albuquerque Area - Albuquerque, NM
Albuquerque area Master Inspector

Barbara-Jo - Missing all you guys back in Florida too!! Hope all is well.

Oct 05, 2015 01:00 AM #31
Rainmaker
5,381,325
Roy Kelley
Realty Group Referrals - Gaithersburg, MD

This is very good information to share with home owners.

Oct 05, 2015 01:17 AM #32
Rainmaker
568,350
Fred Hernden, CMI
Superior Home Inspections - Greater Albuquerque Area - Albuquerque, NM
Albuquerque area Master Inspector

Thank you Roy!

Oct 05, 2015 01:37 AM #33
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Rainmaker
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Fred Hernden, CMI

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