I am putting a sink in the basement and running a separte vent line could be very difficult.
The sink is going to be about 3 feet from the main stack (4″), can I hook up the drain to the main stack and the vent just above it say 2ft?
I’m in Ontario, Canada, not sure if the code is different here.
Thanks
D.
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Replies
You MIGHT be able to get away with a "studor" vent, depending on local code and other issues. A "wet vent" is usually not a good idea, even if technically allowed.
Are you sure there's no vent in the plumbing above that you can tie into without too much tear-up?
Hey Dan, thanks for your reply.
The sink is going against the foundation wall next to the garage. The garage is at grade level and the only way I can think of doing this is to drill a hole in the wall to the right of the sink. This wall is lined up with the garage door. The problem I see with this is that all the utilities (gas, hydro, water, cable) come in pretty much in the exact same area where it would make sense to drill the hole, assuming I cna find a spot to drill, if I vent it at grade level doesn't that mean sewer gas will escape and everytime you go from the garage to the front door which is around the corner, you'd smell the gas from the sewer?
Thanks
D.
The studor vent (Air Admittance Valve) is a one-way valve -- it lets air in but doesn't let sewer odors out. Needs to be placed where it can be accessed for service. I think it has to be above the "flood rim", but don't know the other restrictions.
What is above this sink?
>>>The sink is going to be
>>>The sink is going to be about 3 feet from the main stack (4"), can I hook up the drain to the main stack and the vent just above it say 2ft?<<<
The answer is no. You would end up with a vent that became a drain when any upper fixtures were used.
If you can't or don't want to run a real vent do what the other post said and install a AAV.
I guess I'll have to figure out how to run a vent line otherwise I'll have to use an AAV.
Thank you all for your help.
D.
The AAV, if acceptable in your jusrisdiction, would work just fine. You might also be able to talk to the inspector to see if he would allow you dump the new trap arm for the sink into the 4" stack without venting. I would allow it in my jusridiction with the conditions you describe because it is highly unlikely that a 4" vertical stack in a residence could ever become loaded to the point where it would create enough pressure differential, positive or negative, to either siphon or burp the sink trap.
Venting
>>>talk to the inspector to see if he would allow you dump the new trap arm for the sink into the 4" stack without venting<<<
Any inspector that allowed that should be fired!
>>> it is highly unlikely that a 4" vertical stack in a residence could ever become loaded to the point where it would create enough pressure differential, positive or negative, to either siphon or burp the sink trap<<<
Thats the whole reason that you are required to have a vent on any fixture that is down stream from another fixture, in the no-vent situation it's almost guarnteed to suck the trap
"Thats the whole reason that
"Thats the whole reason that you are required to have a vent on any fixture that is down stream from another fixture, in the no-vent situation it's almost guarnteed to suck the trap"
That's not always true by any means.
You migth have heard of the Philadelphia vent system that's been used sucessfully for decades.in multi-story applications. There is a main drain stack sized for the load, and trap arms up to 10' in length are allowed to dump into the main stack with no vent, including toilet trap arms. The drain stack itself, of course, is vented at the top.
The key to making such a system work is having the drain stack be large enough to always have free air movement inside. That way, no negative or positive pressures are created in the stack that would be capable of siphoning a trap.
In the OP's situation, a 4" stack in the vertical is capable of handling 256 drainage fixture units. Even 2 full baths, kitchen and laundry would impose a load of less than 20 DFU's--and that's if they were all used simultaneously.
If you're on the UPC, check Appendix L8.0, "Single Stack Systems" ('06, and '09 editions) for verification. It's an alternate system that allows inspectors to deal more reasonably with situations that make it impractical to apply the letter of the body of the code in certain conditions.
Vents
>>>The key to making such a system work is having the drain stack be large enough to always have free air movement inside. That way, no negative or positive pressures are created in the stack that would be capable of siphoning a trap<<<
Under normal parameters there is no way you can make that stack large enough to do what you want it to do, all water falling vertical creates a negitive and positive pressure as it goes thru the pipe, the amount of DFU's would only change how fast it could occure.
In the old they ran a system called stack venting that didn't have individual vents on it, even tho it was installed in millions of houses they banned it because it had the tendency to siphon the trap seals.
I think that the system you are referng to is called a SOVENT system, if I remember they were only practical on a 8 story and up building. They are a PITA if you have to retro-fit on an existing system because you need to have an engineer design the new inter-connection.
That system also has special de-aerator and aerator fittings to get it to work. Cost prohibitive in a house
The SOVENT system is not what I meant--I am familiar with it, but that is different from the Single-Stack Vent System that is described in the UPC. SOVENT is a proprietary system; the single stack system can be built from ordinary fittings.
Stack venting works, and has been used for many decades. I have seen literally thousands of houses with a toilet dumping into a 4" stack with the tub or shower trap arm tying in below. NO problems. These same houses also have a single 2" stack that drains/vents a kitchen sink from the floor above with a floor drain tied in at the basement level--no problems.
In years past, it was common for there to be a 4" stack that ran up thru the roof, but that is rarely done in houses today. The vertical stacks are 3" or smaller for the vast majority on today's homes.
But single stack venting is alive and well--the IPC allows you to use a single 2-inch stack to drain and vent up to 4 lavs on up to 4 floors (Table 910.4).
The OP is under the National Plumbing Code of Canada. NPC. With multi story wet venting, I can't have more than 4 fixture units draining from a higher storey and any water closet has to be at the bottom of the stack. Probably not the case here.
So, to the OP, nope, you have to vent. AAV is allowed in the 2005 code, but I don't know if Ontario has adopted it yet.
The AAV was the first option I suggested to the OP, but since the AAV is not accepted in all codes or jurisdictions, I added the possibilty of his inspector approving the trap arm without an individual vent since it dumps into such an over-sized stack.
This would be a deviation from many codes in the US and Canada, but not all. However, all codes allow the code official to accept alternate materials/methods where existing conditions make it impractical to apply the letter of the code.
To me, it seems obvious that, if a method has been accepted in nationally-recognized codes and has been proven over decades, then such a method ought to be given fair consideration by code officials as an acceptable alternate.
But it all still comes down to what the individual inspector will accept--unfortunately, in the case of some inspectors who can be very close-minded when they see anything they're not used to.
Won't argue on what works or won't, but in this case, if there is a WC above the wet vented portion, it won't fly.
Would it work, probably.
I think I have a solution
OK, this might work.
There is a vent on the oposite wall. I can use this one. It will take some creative work to go around joists and I beams but I think I can get it to work without creating a high point where gas can accumulate.
It will be a PITA but I'd rather do that than risking having the inspector make me take it all appart.
Thanks for your feedback.
D.
It's not about trapping the gas, but making sure any water in the lines can drain.
That shouldn't be a problem either.