What are my options for running a vent pipe. Normally it runs from a point in the drain pipe after the trap to the roof. A roof run is impractiable so I would want to know what my other options are.
Can I run it out the side of the house? What is an autovent and can I use that? How far after the trap does the vent pipe have to be? Are there any additional venting options?
Give me some specifics and I can help you:
1 - long island, NY
2 - small sink against external wall
3 - big window in the way
4 - you bet
5 - will be getting one for some other work. the autovent I mentioned could be discribed as a air admitance valve
6 - thank you
7 - how far from the trap can a vent be?
This web site has lots of info: http://www.studor.com/
OK gotta run the disclaimer: I am not licensed to practice engineering in the state of New York. This advice is not to be taken in place of consultation with a licensed engineer or plumber.
With that out of the way-
LI, NY is governed by the 2000 International Plumbing Code (which I am familiar with, but do not have a copy here at home- some numbers will be rough and from memory)
A small lavatory will have a 1-1/4" waste line, and a 1-1/4" vent. The maximum distance between the trap and the vent riser can be no more than 2’-6" (from memory-not sure, but this is close). The proper way to run this vent would be to rise as high as possible (but no lower than the rim of the lavatory), turn horizontal to clear the window, then rise again through the roof. If this is near another existing drain (I think the maximum horizontal run of a 1-1/4" vent line is about 12’), you can tie into the existing vent line to avoid making a new roof penetration. Check in the attic for existing vent lines.
As far as air admitance valves and the 2000 IPC goes, IIRC they are allowed in an appendix that may or may not have been adopted by the State of NY. I’m not personally familiar with their use, since they are generally not allowed in the jurisdictions where I normally operate.
One concern about the AAVs is that they functionally have a mechanical trap seal. If (or should I say when?) this fails, you will have sewer gas leaking into your house. That is why they aren’t generally allowed.
“One concern about the AAVs is that they functionally have a mechanical trap seal. If (or should I say when?) this fails, you will have sewer gas leaking into your house. That is why they aren’t generally allowed.”
I don’t see this as a big problem. If they stick open you will notice it soon enough.
(The plumber who built my bathroom stubbed in a Studor vent but the dimwit neglected to actually install it, leaving us with a 1 1/4 in pipe opening into a cabinet under a sink. We figured that one out pretty quick 'cause it smelled bad off and on. We were familiar with that smell because we had lived overseas for three years in a house seemingly designed by people completely unfamiliar with the concept of vented waste lines.)
I suppose a Studor vent could be a potential problem in an apartment house or somewhere where you could potentially get large volumes of concentrated sewer gas, but it seems unlikely that there would be much of a problem using a Studor vent to vent a sink in a single family residence.
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It doesn’t have to be an apartment building or anything. An open vent line connects directly to the waste line, which connects directly to the sewer (unless there is a running trap in the building sewer, which isn’t generally required, is sometimes forbidden, and not often done).
Building officials are a pretty conservative lot, and many don’t see the benefits of AAVs to outweigh the life safety concerns. A sewer gas leak into a residence is a potentially dangerous situation. Many people either don’t have the sense to call a plumber when they smell it in their house or don’t recognize what it is*. Gases generated by the anerobic digestion of waste in the sewer system can be toxic and, in the right concentrations, explosive. Using an AAV replaces something that is inherently safe (a properly vented trap with water seal), with something that depends on moving parts that can wear out or malfunction.
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Anyway, my specific concern is that AAVs may not be legal in k2dave’s jurisdiction.
well I don’t have to worry about the smoke test since we have a cesspool.
the main trap (right before the main line exits the house) has a trap and a vent pipe that sticks out the side of the house. I was hoping I could have the vent just go outside but is appears that it still has to clear the roof line.
anyone know if I can use the AAV here?
There are no nearby vent lines to tap into 
.
Also if I am governeed by the 2000 International Plumbing Code the AAV link said that their device is acceptable for IPC which I assume is the International Plumbing code - is this correct?
They may be allowed, maybe not. Check with your local building official or a local plumber. I wouldn’t install one of these myself
Corrections to numbers above-
Max distance from trap to vent- 3-6" for 1-1/4" vent
Max developed length of 1-1/4"vent line- 30’
Are there any vents within ~25’?
I will check
with 3-6" I may just be able to sneek it around the window if the trap is angled that way too but then it will poke through a roof that ends exactly at the wall (no roof overhang) - will; that be a problem?
Could I change the drain size to get a further max distance?
The nearest vent stack it the main line vent only 12 ft away but there is no clear way to run it there. It would basically have to do an end run around the house cutting most 2x4’s supporting the house and making at least 3 turns.
This sink it going to be used mainly for filtered (RO) drinking water if that matters.
ARRRRG- the server ate my reply. I’ll summarize what I said:
From 2000 IPC:
1-1/4" trap, 1-1/4" vent: 3’6" trap to vent, 30’ max vent length
1-1/2" trap, 1-1/4" vent: 5’ trap to vent, 50’ max vent length
1-1/2" trap, 1-1/2" vent: 5’ trap to vent, 150’ max vent length
The liquid being disposed of does not make any difference (as long as it doesn’t carry too many solids).
If you have an attic, use it to make the horizontal run over to the other vent. If you don’t have an attic, run the pipe straight up through the roof, as soon as is practical.
Having no overhang makes a side wall vent possible, but it needs to be at least 10 feet horizontally from any window, door, etc. or at least 2 feet above, at least 10 feet from the property line, and at least 10 feet above the ground. It needs to be protected from birds/rodents entering and blocking. Consult a plumber.
ok I may be able to go to a 1-1/2 trap and 1-1/4 vent that 5’ makes a big difference. Anything I should know about upping the pipe size?
I was hoping I could side vent it under the window but that looks like it’s a no-no. So it looks like after the trap the pipe will run horizontal along the wall for about 4ftturn into the sheetrock on the exterior wall then straight up. I still don’t like the idea of it poking right through the roof w/o an overhang, so I was thinking of having it bend and follow the catheadral ceiling up a bit then poke through.
“Building officials are a pretty conservative lot, and many don’t see the benefits of AAVs to outweigh the life safety concerns.”
OTOH, many do. The line between “conservative” (prudent) and silly is sometimes a fuzzy one. It sounds to me like k2dave has the perfect application for an AAV. Clearly the benefits to him are large (big savings in cost, fewer holes in his walls, less threat to the structural integrity of his house, one less leak-prone perforation of his roof, and one less unsightly pipe sticking out of his house).
ScoobyTX has convinced me s/he’s conservative but has not convinced me that there is any significant safety threat. For one thing, the chance that a Studor valve will fail has got to be vastly lower than the chance that a trap will dry out. So I maintain the they are safe on theoretical grounds (for a typical residential application). But I’m even more impressed by the straight dope than by theory and I’ve NEVER heard of anyone being overcome by sewer gas in their home becuase of a leaky AAV or, for that matter for any other reason. (I have, OTOH, heard of workers overcome by sewer gas in other situations.) Has anyone here EVER heard of anyone being injured in any way be sewer gas emissions in their home?
BTW, I don’t think that ScoobyTX should assume that the English, Spanish, Mandarin, Cantonese, and Vietnamese-speaking residents of Houston are especially stupid or tolerant of bad smells just because s/he was able to blow smoke into their houses. The sewer test used smoke AND A BLOWER to produce positive pressure to blow smoke OUT of the sewer system. Normally, things are moving the other way. There shouldn’t be any significant positive pressure in the waste lines. From my experience with a vent lacking an AAV and a plumbing system seemingly lacking any proper vents, the smell is quite intermittent. Most of the time there is none. Of course, when the wind changes…).
So I got a vote for the AAV for my application. I looked over the web site again and it looks like I could have the AAV vent outside which is possible (it would be right below the window). If the AAV fails then any gas would be outside right under a window and about 5 feet above ground level. I know ScoobyTX said that a vent pipe must be 10 ft above ground (along with other things) but what about an exterior AAV?
Also if I don’t trust AAV would this make any sense (and is it permitted):
installing the sink w/ the AAV.
running the drain lint near the main waste line.
installing a trap right before the main waste line then into it.
This way if the AAV did fail there would still be another trap to stop all those nasty gases.
whoops that was not an outside venting AAV, just a wall vent.
k2dave, I’m not sure if I understand the alternative you are proposing, but it sounds like you are talking about installing the AAV between the drain and the trap. This will not work. The main purpose of the vent is to allow air into the line to prevent the trap seal water from siphoning out of the trap. If the AAV is between the drain and the trap, it will do nothing- the drain is already open to the atmosphere.
With a conventional vent- if it is not connected to an existing vent and is run through the roof by itself, it would be best to do this at the wall/edge of the roof. It will be much easier to flash this penetration (and if it did leak, it would affect less area than a leak higher up the roof).
Like I said before- consult a plumber familiar with the jurisdiction.
The IRC allows "autovents,: These must be open to a well-ventilated area (i,e, you can’t hide them in walls), The UPC does not allow them at all, unless “the local authority” grants a special waiver. Otherwise, you must resort to “back vent” or “revent” assemblies. Various options are available. Cjeck with your local code enforcement agency.
I used to be a plumber before I became a physician, and I supported myself through med school in that trade. It was over 15 years ago, but I still recall the codes fairly well. But these have surely changed over the years, hence my caveat.
ScoobyTX no i was suggesting having drain>trap>AAV/drain pipe (long run here) then another trap right before the tie in to the main waste pipe.
That would stop sewer gasses from entering the house if the AAV failed.
That said I got some pretty good advice here.