Plumbing: Air Admittance Valves?
lstockton
Peter Shepherd
Posted on: 06/16/2000; Publication date: June 2000
Engineers Recognize AAVs
By Julius Ballanco
Air admittance valves continue to stir up debate.
Air admittance valves (AAVs) are the most controversial devices
introduced into plumbing in the past century (maybe even the last
millennium). Plumbers either hate them or love them. There seems to be no
middle ground. Those who hate air admittance valves flood me, my editor and
our publisher with e-mail, letters and nasty-grams. I guess if you hate
them, you really hate them.
So why mention air admittance valves and risk the possibility of being
cursed, yelled and screamed at? The plumbing engineers issued a position
statement supporting air admittance valves. The American Society of Plumbing
Engineers published it Oct. 30, 1999, but that hasn't put an end to the
rumors and debate about AAVs.
Rampant Rumors
For those of you still in the dark about air admittance valves, let me
review what is and what is not an air admittance valve. If the valve has a
spring in it, it is not an air admittance valve. These devices are typically
called cheater vents. They are only recognized for manufactured housing for
use on one fixture.
An air admittance valve is a gravity-operated valve that opens when
there is negative pressure inside the drainage system and closes when the
pressure differential balances. They do not leak sewer gas when they are
sitting there doing nothing.
The long and short of it is that the ASPE position statement said the
valves work. I know, a lot of you are saying, "We already knew the valves
work, what's the big deal?" It all started a few years ago. Someone passed a
rumor that ASPE was preparing a statement opposed to air admittance valves.
For the haters of AAVs, this was major news. They could proclaim that the
engineers agreed with their position.
What made matters worse is that a draft of a statement opposed to air
admittance valves surfaced that had the appearance of being a document from
ASPE. The problem was that it wasn't from ASPE. Of course, with today's
technology, it is easy for anyone to scan ASPE's logo and apply it to a
draft statement. ASPE was embarrassed, to say the least, and did everything
possible to clear its good name.
But the rumor took on a life of its own. Before the ASPE had issued a
statement of any kind on AAVs, those against air admittance valves began
declaring that "ASPE has not come out in support of air admittance valves."
The implication was clear - it was their way of saying, "If the plumbing
engineers are not in support of air admittance valves, they must be against
air admittance valves." From ASPE's perspective, at that time it had never
issued a statement either for or against air admittance valves.
ASPE debated long and hard whether to issue a statement regarding air
admittance valves. There are engineers who are members of ASPE and are
haters of air admittance valves. Thus, it was extremely difficult for ASPE
to take a position. If you read the position statement issued by ASPE, you
can see the compromising that was necessary to get the statement published.
The haters of air admittance valves will love the vague language used
by ASPE. I expect to hear it twisted around that ASPE has concerns with air
admittance valves and further installation should cease until the concerns
are addressed. However, that is not what is stated. ASPE has concerns about
the design and installation of every plumbing system. They want all systems
installed correctly.
The ASPE wants to make sure that plumbing contractors use air
admittance valves in accordance with the limitation specified in the
plumbing codes and by the manufacturers. If the installation is correct and
the valves properly installed, you will not have a problem.
Pros & Cons
To comply with code, the valves must meet ANSI/ASSE 1051. Some valves,
I've been told, say they meet ASSE 1051; however, they do not. To ensure
that the valve complies with the standard, they are also listed to NSF 14.
The biggest argument used against air admittance valves is that they
don't relieve high pressure in the drainage and vent system. That is
correct: The valves stay closed if the pressure inside the drainage piping
is above atmospheric pressure. Because of this fact, every plumbing code
requires a minimum of one vent to open to the outdoors when using air
admittance valves. Yes, that is good enough.
Furthermore, I would never classify the pressure inside a drainage
pipe as high pressure. The pressure of 1 inch of a water column translates
to 0.036 psi. I don't know about you, but that pressure looks awfully low to
me.
If you are wondering about the limitations of use, check the
International Plumbing Code, the International Residential Code or the
manufacturer's installation requirements. They are all very clear as to the
proper application of air admittance valves.
As to why there has been a proliferation in the use of air admittance
valves, there are two reasons. The valves are convenient, and they are cheap
to install. Why spend $100 to pipe a vent out through the roof when you can
terminate the vent to a $15 air admittance valve?
If you think our objective in the plumbing business is to make the
cost of installations more expensive, you're in the wrong business. Our
objective is to keep costs down while keeping the total project cost the
same. In other words, increase the profit margin. I never heard of
increasing your costs to increase your profit margin. That leads to
bankruptcy.
If you haven't used air admittance valves and your competitor is, I
guarantee you, your competitor is making more money than you are. You might
want to try them.
Julius Ballanco is president of JB Engineering and Code Consulting, P.C. He
can be reached at 1661 Cardinal Drive, Munster, IN 46321. Phone:
219/922-6171.
"lstockton" <lsto...@enxnet.com> wrote in message
news:nTclb.31352$gi2.3220@fed1read01...
Don Phillips
venting of plumbing without having to vent through the roof?
I have not heard of any issues.
Sincerely,
Donald L. Phillips, Jr., P.E.
Worthington Engineering, Inc.
145 Greenglade Avenue
Worthington, OH 43085-2264
dphi...@worthingtonNSengineering.com
(remove NS to use the address)
614.937.0463 voice
208.975.1011 fax
http://worthingtonengineering.com
Matthew S. Whiting
> Does anyone have experience with air admittance valves, which allow venting of plumbing without having to vent through the roof?
My house has one for the kitchen sink and it works just fine. No way to
vent that traditionally since it is on the outside of a solid log wall
house.
Matt
Mark & Shauna
A bow vent.
Mark
Matthew S. Whiting
Not ideal either. Doesn't extend above the water level attainable in
the sink and would have required another 20' run of vent pipe,
clean-out, etc. See:
http://www.thisoldhouse.com/toh/tvprograms/asktoh/qaarticle/0,16588,213139,00.html
Matt
Mark & Shauna
And duely noted, Rich Trethuey (sp) is a plumber from MA, (one of our
subs actually worked in the the city with him when he was a journeyman)
where provents are also illegal and only allowed only by the same
inspector who will tell you to install a bow vent rather than a provent
in the application as they always strive for a nonmechanical option
wherever possible. This is of course speaking of new construction. Many
inspectors (MA) will allow provents in remodeling applications (where
they will work)where running a vent to the attic/main stack or through
the roof is not practical.
Mark
Matthew S. Whiting
> Oh gawd, mow you are quoting TOH? heheh
And you are quoting whom? Oh, yourself, I forgot... LOL.
> And duely noted, Rich Trethuey (sp) is a plumber from MA, (one of our
> subs actually worked in the the city with him when he was a journeyman)
> where provents are also illegal and only allowed only by the same
> inspector who will tell you to install a bow vent rather than a provent
> in the application as they always strive for a nonmechanical option
> wherever possible. This is of course speaking of new construction. Many
> inspectors (MA) will allow provents in remodeling applications (where
> they will work)where running a vent to the attic/main stack or through
> the roof is not practical.
As I said before, I agree that a traditional vent is better when it is
practical to use. However, using a provent or similar where it is
warranted isn't "hack" plumbing to use your characterization. Nor is
putting multiple stacks through the roof. In most home systems, it is
the special cases that really matter, not the standard stuff. Doing
those right often requires some deviation from the ideal. Doing so is
the sign of a knowledeable and creative tradeperson, not a hack. A hack
messes up the routing stuff and is clueless how to handle the special cases.
Matt
Don Phillips
> Oh gawd, mow you are quoting TOH? heheh
>
> And duely noted, Rich Trethuey (sp) is a plumber from MA, (one of our
> subs actually worked in the the city with him when he was a journeyman)
> where provents are also illegal and only allowed only by the same
> inspector who will tell you to install a bow vent rather than a provent
> in the application as they always strive for a nonmechanical option
> wherever possible. This is of course speaking of new construction. Many
> inspectors (MA) will allow provents in remodeling applications (where
> they will work)where running a vent to the attic/main stack or through
> the roof is not practical.
It is not unusual to see codes take time to catch up with new technology.
AAV's were allowed in Ohio, I think, beginning in 2002 when the new building
code was adopted.
Peter Shepherd
Answer:
According to the factory, NSF 24 is for the mobile home industry stds ----
so to simplify -- no our Pro-vent does not meet the NSF 14 req. ----- these
are 2 different NSF stds for different usages --- Dan, Gene Rich & Co., Inc.
----- Original Message -----
From: Peter Shepherd <s...@web.ca>
To: <SA...@GENERICH.COM>
Sent: Thursday, October 23, 2003 6:14 AM
Subject: Pro-vent
> Could you tell me if the Pro-vent is an air-admittance valve that meets
> NSF 14?
> Your www says it meets NSF 24, but I don't know if that supercedes or is
> a lesser rating than the NSF 14.
>
> Thank-you,
>
>
> Peter Shepherd
> 63 Pauline Ave
> Toronto, Ontario
> M6H 3M7
>
"Don Phillips" <dphi...@worthingtonNSengineering.com> wrote in message
news:FqClb.35158$cK5....@fe1.columbus.rr.com...