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Who knows what an AAV Vent is?

Reblogger
Industry Observer with Retired

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. 

Original content by Fred Hernden, CMI 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.

 

***************************************************************************************

  Fred Hernden 

 

 Superior Home Inspections

 

  813-526-0900

 

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Posted by

Roy Kelley, Retired, Former Associate Broker, RE/MAX Realty Group

Gaithersburg, Maryland  

Comments (12)

Roy Kelley
Retired - Gaithersburg, MD

Please be sure to leave comments at the original blog by Fred Hernden

Nov 11, 2015 07:25 PM
Gita Bantwal
RE/MAX Centre Realtors - Warwick, PA
REALTOR,ABR,CRS,SRES,GRI - Bucks County & Philadel

Thank you for reblogging the post. I missed reading the original one.

Nov 11, 2015 09:19 PM
Scott Godzyk
Godzyk Real Estate Services - Manchester, NH
One of the Manchester NH's area Leading Agents

I had to leave a comment thanking you for the reblog or i may have never seen it. I will check out his blog to learn some more.

Nov 11, 2015 09:58 PM
Rob Thomas
Prestige Homes of The Tri Cities, Inc. CALL....423-341-6954 - Bristol, TN
Bristol TN-VA & Tri Cities Agent, ABR, GRI, e-Pro

I learned what this was a long time ago ...before that I had no clue ...Thanks for the re-post Roy Kelley 

Nov 11, 2015 10:02 PM
Debbie Reynolds, C21 Platinum Properties
Platinum Properties- (931)771-9070 - Clarksville, TN
The Dedicated Clarksville TN Realtor-(931)320-6730

I hadn't heard the term that I can remember but just heard them called plumbing vent pipes and knew how important they are.

Nov 11, 2015 10:10 PM
Roy Kelley
Retired - Gaithersburg, MD

Thank you very much for your comments. Your feedback is always appreciated.

Nov 11, 2015 10:51 PM
Fred Hernden, CMI
Superior Home Inspections - Greater Albuquerque Area - Albuquerque, NM
Albuquerque area Master Inspector

Thank you for the reblog Roy!!

Nov 11, 2015 10:58 PM
Kristin Johnston - REALTOR®
RE/MAX Platinum - Waukesha, WI
Giving Back With Each Home Sold!

Great information and by the title I had no clue, so I am glad I read it!

Nov 11, 2015 11:38 PM
Robert Bob Gilbert
Berkshire Hathaway HomeServices Anderson Properties - Katy, TX
Your Katy TX ( West of Houston) Real Estate Expert

Roy, Thanks for the re-blog of fred's informative post as this is very good information. 

Nov 12, 2015 03:48 AM
Evelyn Johnston
Friends & Neighbors Real Estate - Elkhart, IN
The People You Know, Like and Trust!

I love how we educate each other on ActiveRain.  I did not know what an AAV Vent was!

Nov 12, 2015 10:11 AM
Roy Kelley
Retired - Gaithersburg, MD

Your feedback is always appreciated. Have a great Friday and an outstanding weekend.

 

Nov 12, 2015 08:52 PM
Roy Kelley
Retired - Gaithersburg, MD

I hope you enjoyed the weekend. Dolores and I took a Saturday day trip to Westminster, Maryland and returned in time to attend the Kentlands/Lakelands wine and beer tasting event on Saturday night. Life is good!

Nov 15, 2015 07:33 PM