Special offer

Never---ever----pass gas again!

By
Home Inspector with Charles Buell Inspections Inc.

     When I first started doing plumbing in 1971----at least for money----venting island kitchen sinks was a bit of a problem.  Every plumbing fixture needs a means of venting the drain line so that water doesn’t get sucked out of the trap----which could allow sewer gases to enter the home.  Somehow sewer gases and the smell of fresh baked bread or homemade pizza just don’t go together.

     We had to create all kinds of strange assemblies of pipes to create this venting----it worked, but was time consuming to construct and took a lot of additional pipe.  Pipe and time equal money.

     Along came the “auto-vent” or “air-vent.”  This mechanical device had a spring loaded gasket inside that would allow air to flow into the pipe but not let sewer gases out-----or, in the event of the pipes flooding, the device would not allow sewage out either.  How is that for a plan?  These vents could be installed right at the fixture location----saving tons of time, pipe and money.  Unfortunately most jurisdictions did not allow them----except in the mobile home industry----where they are still allowed----go figure.  Here is a picture of one of these vents that I found installed at a kitchen sink in new construction that had to be replaced after the inspection.

 Auto-vents have springs inside

     If you can see a spring inside the cap, it is an Auto-Vent.

Auto-vent with the spring showing

     At some point in the 90’s, a new type of air-vent could be found in the neighborhood----called the Air Admittance Valve---or AAV.  AAV’s quickly gained acceptance in most jurisdictions and are now widely used.  These valves are different from Auto-Vents in that there are no spring mechanisms that can fail and they have screens to keep out critters.  They have a simple EPDM diaphragm that allows air into the drain under negative pressure and seals tight under positive pressure (trust me you don’t want to know what the initials stand for---synthetic rubber for short). 

     AAV’s, to meet approval for use in residential construction, have to demonstrate that they can go through 500,000 cycles without ever passing gas----roughly equivalent to 30 years----man I sure wish I could do that!  Here is a picture of a modern AAV on a laundry sink drain.

Air Admittance Valve

     While a really simple device, they must be installed within 10 degrees of vertical, they must be installed on the welded-pipe side of the trap, they have to remain accessible and they cannot be the only means of venting the plumbing system.

Air Admittance Valve

     These Air Admittance valves come packaged with a rubber band that needs to be removed at the time of installation----I frequently find them with the rubber band still in place----rendering them non-functional.

Don't forget to remove the rubber band

     So, never----ever----pass gas again!

     Now what fun would that be? sunsmile

 

 

Charles Buell, Seattle Home Inspector

 

 

Posted by

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

Seattle Home Inspector

 

The Human Rights Campaign   QR code for Charles Buell Inspections Inc  ASHI.org

 

WA State, Home Inspector Advisory Licensing Board

Comments (32)

Alan May
Jameson Sotheby's International Realty - Evanston, IL
Home is where the hearth is.

why then Blazing Saddles would never have been filmed.

Sep 26, 2010 04:27 AM
Kate Kate
San Diego, CA

One of our daughters needs this post. Okay I actually mean the drains in her house need this post. :)

Sep 26, 2010 05:19 AM
Gene Riemenschneider
Home Point Real Estate - Brentwood, CA
Turning Houses into Homes

Better not show this to my wife.  I am not sure I want one installed.  I am not sure how comfortable it would be.

Sep 26, 2010 05:19 AM
Craig Rutman
Helping people in transition - Cary, NC
Raleigh, Cary, Apex area Realtor

You need to be a headline writer for a major newspaper Charles!

Sep 26, 2010 06:52 AM
Jack Gilleland
Home Inspection and Investor Services, Clayton - Clayton, OH

Charles, are you saying that running loop vents behind the sink was a pain in the butt.  Those are my sentiments too.

Sep 26, 2010 09:15 AM
Charles Buell
Charles Buell Inspections Inc. - Seattle, WA
Seattle Home Inspector

Steve, I think Nutsy needs one of these things

Alan, I think the saddle horn could easily be turned into an AAV

Kate, wouldn't beano be cheaper?

Gene---they come in different sizes :)

Craig----do they get paid?

Jack, venting has gotten a lot simpler with these things that is for sure.

Sep 26, 2010 09:42 AM
William Johnson
Retired - La Jolla, CA
Retired

Hi Charles, a very interesting devise. I have not seen them here in CA. But I must say it is certainly interesting ( will check out ), not to mention that your title drew me right in, :-).

As an aside, I really like the clean finished cabinet under the sink. They don't do much of that here ( CA) either. 

Sep 26, 2010 10:24 AM
James Quarello
JRV Home Inspection Services, LLC - Wallingford, CT
Connecticut Home Inspector

I find it very funny that you find them with the big orange rubber band still around them after installation.

Sep 26, 2010 10:47 AM
Charles Buell
Charles Buell Inspections Inc. - Seattle, WA
Seattle Home Inspector

William, I would be surprised if they are not available in your area.

Jim, at least that bright orange sticks out like a sore thumb

Sep 26, 2010 11:04 AM
Lorraine or Loretta Kratz
Crescent Moon Realty, Inc. & Land N Sea Auctions. - San Marcos, CA
Certified Negotiation Consultants

#19 comment is a reflection of what is not happening in Southern California. I learned a lot and thought you made it easy to understand.

Sep 26, 2010 02:32 PM
Reuben Saltzman
Structure Tech Home Inspections - Minneapolis, MN
Delivering the Unbiased Truth.

Good info - I never knew the difference between the two.  Here in Minnesota those AAVs aren't allowed.  I see very few of them.

Sep 26, 2010 02:38 PM
Charles Buell
Charles Buell Inspections Inc. - Seattle, WA
Seattle Home Inspector

Lorraine or Loretta, thanks

Reuben---I am surprised you can't use them there----lots of differences around the country.

Sep 26, 2010 03:26 PM
Steven L. Smith
King of the House Home Inspection, Inc. - Bellingham, WA
Bellingham WA Home Inspector

Mr Charles,

Can you save the rubber bands for me and Wheat, they are wonderful trampoline springs.

Nutsy

Sep 27, 2010 02:43 AM
Charles Buell
Charles Buell Inspections Inc. - Seattle, WA
Seattle Home Inspector

Nutsy sure----but they make a way better muzzle

Sep 27, 2010 02:58 AM
Diane Osowiecki
Diane O and Friends - Benchmark Realty - Franklin, TN
Greater Nashville Real Estate

As always....get catchy title and an informative post.

Sep 27, 2010 03:32 AM
Lyn Sims
Schaumburg, IL
Real Estate Broker Retired

I've never heard of it but now I know.  Plumbers can't read I guess with the 'warning' remove this rubber band?

Sep 27, 2010 03:53 AM
Kate Kate
San Diego, CA

#25/#26 or noose. heheh

Sep 27, 2010 05:02 AM
Charles Buell
Charles Buell Inspections Inc. - Seattle, WA
Seattle Home Inspector

Diane, thanks

Lyn---or more likely Uncle Harry :)

Kate---placed just right it would likely cover both breathing apperatus :)

Sep 27, 2010 09:06 AM
Kate Kate
San Diego, CA

Sep 27, 2010 12:28 PM
Jay Markanich
Jay Markanich Real Estate Inspections, LLC - Bristow, VA
Home Inspector - servicing all Northern Virginia

I for one would like to see what you look like after 30 years of not passing gas...

Or maybe not!

I had an inspection once, new construction, where they put all the drain apparatus under the kitchen sink, but handily forgot the cap (AA valve)!  It was a new home so there was no evidence yet, but a week after moving in I bet I would have gotten a call about the kitchen smell.  The supervisor even chuckled!

Sep 27, 2010 11:40 PM