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Air admittance valve vs. venting

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Diehard

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Do you even know if AAV is acceptable in your area?

I'm guessing the use of a piped vent would push the drain pipe deeper. Have you looked at the pipe routing and the elevation where the drain line must connect to existing.

Vent lines have been known to get blocked on occasion, by the way.
 

Jenkins

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Do you even know if AAV is acceptable in your area?

I'm guessing the use of a piped vent would push the drain pipe deeper. Have you looked at the pipe routing and the elevation where the drain line must connect to existing.

Vent lines have been known to get blocked on occasion, by the way.
They are by permit. I have been told that long term vents are more reliable. Still a little undecided
 
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Diehard

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Does that mean they have to be approved for the specific application, in which case, who knows.

Well for what it's worth, I've had one under my kitchen sink for 21 years.
Never experienced any smell but did replace it once when I started hearing a little gurgling.
 

Jenkins

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Does that mean they have to be approved for the specific application, in which case, who knows.

Well for what it's worth, I've had one under my kitchen sink for 21 years.
Never experienced any smell but did replace it once when I started hearing a little gurgling.

Great to know!
 

Diehard

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So you will have an Ice Maker at the island along with the sink and dishwasher?

Why a separate dedicated line since you'll have water for the sink over there?

I'm probably misunderstanding something.
 

jeffnc

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Yes I do hate AAV's and refuse to install them
here is why.

they are usually installed wrong
This is hilarious. Are you saying you usually install them wrong? Because either that, or this statement makes no sense at all.

and lets be truthful. they are used because someone is to lazy to run a vent
Yes, let's be truthful. There are more reasons than that.

now lets talk about how it works.
it lets air into the system when it feels a change in pressure
WELL...to let in pressure means the diaphragm opens [ open means air can flow in both directions]
letting in air as well as letting out funky air
Hmmm. So you're saying that to begin with, the AAV works by following the natural laws of physics, and then as soon as it opens it stops following the laws of physics?
 

Zanne

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@frodo, you would hate what the local plumber did at my friend's grandfather's house. Put in a standpipe for the washing machine, cut a hole in the wall and punched it out through brick. Didn't even seal around the pipe or the hole afterward. Ran it a few inches up & slapped a cheap AAV on top-- and I'm talking OUTSIDE the house. He could have run it up & around the eaves if he didn't want to go through the edge of the roof, but no, he was too lazy. He also didn't slope the drain pipe in the trench that my friend dug for it (plumber refused to dig) & didn't even cover it up afterward.

I was thinking of using some AAVs in my house, but after what you said, I'm going to try to connect to actual atmospheric vents instead.
 

Diehard

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@frodo ...I must ask.

Is this your theory or is it based on any documented facts?

"WELL...to let in pressure means the diaphragm opens (open means air can flow in both directions) letting in air as well as letting out funky air"

As I see it...For the valve to open requires a negative pressure within the pipe, which of course means the pressure is greater within the house. This results in some amount of flow INTO the piping system. Once the pressure are approach being equal they are designed to close.
Are you saying you feel that the smell will travel against the air flow?

Reviews of the following units have found these results. But this is a different subject.
Oatey and Studor reviews say, "DOES NOT prevent nor protect against sewer gas from escaping when subjected to room low vacuum pressure. While the Tuuber dual seal air AAV review says, it does prevent and protect against sewer gas from escaping when subjected to room vacuum pressure.

Perhaps you saw these results somewhere.???
 

Zanne

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@frodo ...I must ask.

Is this your theory or is it based on any documented facts?

"WELL...to let in pressure means the diaphragm opens (open means air can flow in both directions) letting in air as well as letting out funky air"

As I see it...For the valve to open requires a negative pressure within the pipe, which of course means the pressure is greater within the house. This results in some amount of flow INTO the piping system. Once the pressure are approach being equal they are designed to close.
Are you saying you feel that the smell will travel against the air flow?

Reviews of the following units have found these results. But this is a different subject.
Oatey and Studor reviews say, "DOES NOT prevent nor protect against sewer gas from escaping when subjected to room low vacuum pressure. While the Tuuber dual seal air AAV review says, it does prevent and protect against sewer gas from escaping when subjected to room vacuum pressure.

Perhaps you saw these results somewhere.???
I can't answer from Frodo, but from what I understand, the AAVs only handle negative pressure but you'd need a PAPA to deal with positive pressure. I have a septic tank so there is likely to be more positive pressure & it could rupture the diaphragm in AAVs. Not sure how it would work in a traditional city sewer system.
 

Diehard

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Don't forget that every house is required to have a piped vent.
We are only dealing with supplemental AAV's.
 

frodo

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This is hilarious. Are you saying you usually install them wrong? Because either that, or this statement makes no sense at all.



Yes, let's be truthful. There are more reasons than that.



Hmmm. So you're saying that to begin with, the AAV works by following the natural laws of physics, and then as soon as it opens it stops following the laws of physics?
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Jenkins

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So you will have an Ice Maker at the island along with the sink and dishwasher?

Why a separate dedicated line since you'll have water for the sink over there?

I'm probably misunderstanding something.
No ice maker at the island, just running the water line from the sink at the island to the refrigerator.
 

frodo

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I am a firm believer that vent pipes should be tied together and go through the roof whenever it is possible.

AAV's can only pull air. Depending where they are at and the system design, they can create short burst of pressure in the system. Resulting in bubbling toilets until the rush of water sails by. Then allowing the AAV to pull air and operate normally. In instances when you are pushing air as described above, a vent through the roof is the only code legal fix.

AAV's pull air. Vent through roofs allow the system to push and pull air.

In an unpressurized system, it doesn't take much vacuum or pressure to screw things up. Whether its water around a toilet or sewer smells, a poorly operating system screams at us.
 

Diehard

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I totally agree with your first sentence.(Post #34)

The thing is, it's always possible but not always practical.


Individual choice, as to the amount of time and effort someone is willing to put into it. As well as their comfort level to do it.

Another consideration, in my mind, would be where you want to use an AAV. For example, less likely used where it would may be subjected to, as you say, short burst of pressure. Like washing machines and garbage disposals.
 

frodo

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How do you get syphon ?
The only way is for the water to pull the air behind it
Using common sense
if the air is being pulled it is also being pushed in front of the water
This is how the bubbling toilets and the soap bubbles in sinks are created
The biggest culprits are the terlet, tub/shower, washing machine,dishwasher
 

Diehard

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I believe we agree in general.
But in all due respect, your common sense definition doesn't quite agree with how a siphon actually works.
To the best of my knowledge, atmospheric air pressure pushes the water out of the trap to satisfy the vacuum.
The bubbling is the higher pressure air forcing its way through the water in the trap.
 

frodo

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OK, you are going to make me type

. As water passes through a drain it displaces air as it travels. A plumbing vent lets air enter the system so that the water does not “pull” the water in the trap along with it, commonly known as siphonage.
Self siphonage occurs in toilets partly by design. Siphonage is an important factor that helps evacuate the contents of the bowl for an effective flush. However, if the toilet is not vented properly, the trap seal will be compromised by the simple nature of its design. Water leaves the trap during a flush. It is refilled by the fill valve, almost like a built-in trap primer. It is designed to siphon out the trap because it relies on the fill valve to replace the siphoned water. This happens simultaneously when the tank is filling. Self siphonage can occur more than it's supposed to without a vent and the contents of the trap can be siphoned out even after the tank is refilled, allowing sewer gasses into a living area. This can happen, for example on a multi story building. Long after the trap is refilled, the previously flushed water is falling vertically and pulling air behind it for a long time.
Induced siphonage is when the trap seal of a fixture is siphoned by a different fixture on a common sewer branch line. The flush or draining a a separate fixture pulls the water from a different fixtures trap. It occurs because the lack of venting creates negative pressure upstream of the draining fixture. The lack of pressure pulls the water out of a nearby, separate trap, to equalize the difference of pressure within the plumbing system.
They are both problems that are associated with improper venting on a single fixture or several fixtures. The misconception is that vents simply let sewer gasses out of the system. While this is true, it is indirectly true. Plumbing vents allow air into the drain system to maintain the integrity in a trap, which is entirely responsible in keeping sewer gasses out of the living area. Barometric pressure needs to be equal on both sides of the trap during a flush. Such is the fuction of a vent.
There are very specific ways to properly vent a fixture that are frequently ignored by non-professionals or bad plumbers. Vents are an integral part of a sound drain system and cannot be modified or deviated from without creating nuisances or systematically poor systems.
The introduction of an AAV that only allows air in and not out is a poorly designed system




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Diehard

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Yeah it's too bad you took all that time to type, for whatever point you are trying to make.

With all due respect, I know how a siphon works and if you look it up, you will too and will not confuse it when trying to apply it to plumbing.
 

Diehard

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Just clicked on one of those QUORA articles you referenced.
I can see why you get confused with some of this stuff.
The person who wrote, "A plumbing vent lets air enter the system so that the water does not “pull” the water in the trap along with it, commonly known as siphonage." He's likely a plumber and is putting in his own words. When everyone knows it's the atmospheric pressure that pushes a fluid in the direction of a lower pressure that creates a siphon.

Instead of more typing on your part, simply search for "how does a siphon work".
 

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