Residential plumbing question

[ODB_PE]

Hey,

At my tract home, I have a ridiculous number of penetrations through my roof deck. Most of these, of course, are plumbing/sewer vents. Several seem to be of the 2-inch diameter sink drain variety.

Anyhow, my boss is remodeling his house and ended up with several "sure-vent air admittance valves" for 2-3" PVC pipes. (Air goes into the pipe when needed but not out)

I didn't know about these, but I understand the thought is that you put these in your attic so that you don't have to go through the roof deck.

I'm about to drop a chunk of money to put on a new roof, primarily because 2 of these vents currently leak. If I can eliminate those penetrations I would like to but not sure where to look for code direction. figured I'd ask you guys.

TIA

 

[Dleg]

I'm not a plumbing expert, but I do know that part fo the function of the vents is to vent sewer gas, particularly if you are on a septic tank. If you vented it to your attic, your attic could fill with sewer gas, which would be smelly and potentially explosive.

 

[Dleg]

Oh, forgot to mention this: while I was renovating my house, an ME buddy of mine recommended that I connect as many of the vent pipes together in the attic as I could, to minimize the number of penetrations. So if you're consideiring roof repairs, you could try to do that while you're at it. I didn't, because by the time he told me this, my contractor had already done the roof.

 

[IlPadrino]

I'm not a plumbing expert, but I do know that part fo the function of the vents is to vent sewer gas, particularly if you are on a septic tank. If you vented it to your attic, your attic could fill with sewer gas, which would be smelly and potentially explosive.

That's the point behind air admittance valves...

A discharge of wastewater causes the AAV to open, releasing the vacuum and allowing air to enter plumbing vent pipe for proper drainage. Otherwise, the valve remains closed, preventing the escape of sewer gas and maintaining the trap seal.

I've seen these in Italy. You might need to check your local building codes, but it seems the International Residential Code and the American Society of Sanitation Engineers support their use.

I also thought there was some code requirement for a single vent stack at the top...

 

[ODB_PE]

Oh, forgot to mention this: while I was renovating my house, an ME buddy of mine recommended that I connect as many of the vent pipes together in the attic as I could, to minimize the number of penetrations. So if you're consideiring roof repairs, you could try to do that while you're at it. I didn't, because by the time he told me this, my contractor had already done the roof.

I thought about this too. Ov course, theoretically you need to worry about maintaining a slope in horizontal runs and providing an larger pipe section for the main trunk - plus right now my attic is probably sitting at about 130 degrees most of the day, so i'd like to minimize my time up there.

These AAVs are pretty cool - from the info sheet:

"Vent at the source. Eliminates a vent pipe through the roof. Allows air into plumbing system while containing foul odors."

and also...

"The Oatey Sure-Vent Air Admittance Valves have been developed based upon the philosophy that all plumbing drainage systems require at least one primary or main vent. They are intended as an alternative to secondary vents that extend through the roof. oatey recommends that at least one primary or main vent be vented to the open air. Always consult local plumbing codes prior to installing an air admittance valve"

http://www.oatey.com/Plumber/Shared/Produc...ve+160+DFU.html

 

[Dleg]

That's the point behind air admittance valves...

Well, yeah... but you MUST have at least one vent for gas to escape from, especially if you're on a septic tank. The design of all septic tanks I have ever seen depends on it. Otherwise, the gas has nowhere to go, and you've got big trouble.

 

[IlPadrino]

Well, yeah... but you MUST have at least one vent for gas to escape from, especially if you're on a septic tank. The design of all septic tanks I have ever seen depends on it. Otherwise, the gas has nowhere to go, and you've got big trouble.

If that's true (are you saying it's a code requirement?) then what good are AAVs? But I guess it makes sense that airtight septic tank gases have to go somewhere. Now you've got me thinking...

 

[Dleg]

That is true. Trust me, I work for the government, and I am here to help you! I don't know plumbing code, but I would bet that it is a requirement in the code. I regulate septic system design and construction (among other things)for an environmental agency, which means that our authority pretty much stops where the "plumbing" system starts, but every septic system regulation and design guidance I have ever seen (which is a lot) requires an open vent to the atmosphere through a roof stack. We do regulate and check for at least that.

At any rate, even if you are on sewer, gases WILL migrate into your building sewer, so I would be very hesitant to put any vents inside an enclosed, unmonitored space, no matter what the design of the vent is. It's just too big of a risk, in my mind, but then again I don't design building plumbing systems.

 

[Sschell]

^I think the point is you only need one vent through the roof, and the rest are vacuum breakers, shich can hang out in the attic, because they never vent (they only suck, they don't blow).

 

[Dleg]

Wikipedia to the rescue

Air admittance valves (AAVs) are pressure-activated, one-way mechanical vents, used in a plumbing system to eliminate the need for conventional pipe venting and roof penetrations. A discharge of wastewater causes the AAV to open, releasing the vacuum and allowing air to enter plumbing vent pipe for proper drainage. Otherwise, the valve remains closed, preventing the escape of sewer gas and maintaining the trap seal. Using AAVs can significantly reduce the amount of venting materials needed in a plumbing system, increase plumbing labor efficiency, allow greater flexibility in the layout of plumbing fixtures, and reduce long-term roof maintenance problems associated with conventional vent stack roofing penetrations.
While some state and local building departments prohibit AAVs, the International Residential and International Plumbing Codes allow it to be used in place of a vent-through-the-roof. AAV's are certified to reliably open and close a minimum of 500,000 times, (approximately 30 years of use) with no emanation of sewer gas; and some manufacturers claim their units are tested for up to 1.5 million cycles, or at least 80 years of use. Air Admittance Valves have been effectively used in Europe for more than two decades. U.S. manufacturers offer warranties that range from 20 years to lifetime.

Still, I would think that at least one vent stack through the roof would be required if you were on a septic system, since it requires venting of gases, but apparenlty, in many places, you can get by solely with AAVs in your attic, if you're connected to a swere system.

 

[Dleg]

Found this on another web page:

Although Air Admittance Valves can eliminate the need for multiple roof vents, one fresh air vent per structure is required in the United States, especially when used with a septic system.

That's rather important info to be buried so far in the pages about AAVs. I guess the local permitting people are supposed to catch that important little detail.

 

[ODB_PE]

I'm fairly certain I have one main 4-inch stack that I will leave alone, and I think I will be able to eliminate 4 of the secondary holes through my roof. I'm going to go for it.

I'll take pictures.

 

[PinoyCE]

the vent to your roof is helping the water closet to flush down if your on septic tank.