Venting a Bar Sink

I'm installing a bar sink in a remodel project. The bar sink will be located in the basement. I plan to drain the sink into a sealed pit that contains an ejector pump that empties into the sanitary line. The sealed pit is vented. My question is this: will my installation comply with the UPC if I install a sanitary-Tee in the vent pipe and drain the sink through this Tee into the pit?

I was told by an architect that this would cause the sink to be "wet vented." The sink is located about 8 feet from the sealed pit.

darmstro said:

Will my installation [work correctly] ... if I install a sanitary-Tee in the vent pipe and drain the sink through this Tee into the pit?

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I do not know about "UPC", but I do know that is not a good idea. In my way of understanding things, you would be better off draining that sink into its own pipe going into the cover of the pit and running a vent line for the sink into the area of your proposed tee. Otherwise, your sink drain could prove to be the path of least resistance for a vent line whenever the pump discharges the content of the pit.

sink

It is a wet vent for the pump, and there is no "path of least resistance" when the pump runs. The bad thing about doing this is if your pump cover has to be completely removed to service the pump. If so, the sink will have to be disconnected every time it happens.

hj said:

... there is no "path of least resistance" when the pump runs.

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What I was saying there is that if the sink simply drained into the sump's vent as the poster had first asked about, the vacuum in the sump when the pump runs might/could(?) try to pull air through the sink's trap, either rather than or even along with pulling air through its own more-resistant (longer and with warm air rising) vent line.

vent

It would never happen, regardless of how small the vent line was, and certainly not with the size vent that is on the sump pit.

hj said:

It would never happen ...

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If that is truly so, and with code issues aside, the bar sink's trap and short run to the sump's vent line should work just fine without having a vent of its own! But, I would probably oversize that line just to be sure the discharge from the bar sink does not siphon its own trap.

While still pondering the question of “path of least resistance” and venting, it just struck me that I have some plumbing that is nearly identical to the initial question in this thread:

darmstro said:

I'm installing a bar sink in a remodel project. The bar sink will be located in the basement. I plan to drain the sink into a sealed pit that contains an ejector pump that empties into the sanitary line. The sealed pit is vented. My question is this: will my installation comply with the UPC if I install a sanitary-Tee in the vent pipe and drain the sink through this Tee into the pit?

I was told by an architect that this would cause the sink to be "wet vented." The sink is located about 8 feet from the sealed pit.

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My open-top (like the bar sink would be) gray-water sump is about six (rather than eight) feet away from my sewage sump, and in my gray-water sump I have an 1-1/2” overflow pipe and trap (like the sink would have) that runs under the floor and over into my sewage sump. (That configuration allows for my sewage pump to serve as a backup for my gray-water pump.)

The 2” vent for my sewage sump runs over (diagonally) and up for a total of about sixteen feet to where it connects to my 3” vent going yet another twelve feet to get through the roof, and the water in the overflow trap in my gray-water sump actually does move at least a little each time the sewage pump starts ... thereby proving at least a momentary “path of least resistance” even in a properly- and well-vented system.

Darmstro: What do you know about the overall configuration and size of the vent for your ejector pump?

As it makes its way out of the sewage sump, the vent is 1-1/2" for the first four feet then it becomes 2" for the balance of the run that I can see in the basement. After that it takes a turn upward into a first floor wall for the run towards the roof (and I believe becomes 3" in a 6" deep service wall behind the powder room on the first floor). I had planned to insert the Tee 9" above the sump in the 1-1/2" section.

leejosepho said:

If that is truly so, and with code issues aside, the bar sink's trap and short run to the sump's vent line should work just fine without having a vent of its own! But, I would probably oversize that line just to be sure the discharge from the bar sink does not siphon its own trap.

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Now, take the pebble from his hand....

darmstro said:

As it makes its way out of the sewage sump, the vent is 1-1/2" for the first four feet then it becomes 2" for the balance of the run that I can see in the basement. After that it takes a turn upward into a first floor wall for the run towards the roof (and I believe becomes 3" in a 6" deep service wall behind the powder room on the first floor). I had planned to insert the Tee 9" above the sump in the 1-1/2" section.

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As learned and drawn from everything relevant that has been posted here:

It sounds to me like that will work ... but you might want to use 2" PVC for the sink drain and add one of those pop-up AAVs under the sink just to be sure. Using 2" pipe makes it impossible for the drainage from that small sink to siphon its own trap, and adding the AAV helps protect that trap from being siphoned in some other way in the absence of a regular vent.

Thanks, Senior Members! I'll do the install and report back later on the results.

I did it the way you're proposing and it works fine for me. I used an AAV (studor) on the bar sink.

My rationale was that when the bar sink is on,the 4" drain inlet to the pit serves as the pump vent. For the pump to NOT have at least one path to the roof, someone would have to take a shower, flush a toilet, and have the bathroom sink on all at the same time someone was using the bar sink.

In addition, my bar sink drain is 1.5", which is smaller than the 2" vent line on the pit. So, there's little risk of completely blocking the air flow even if all these things happened.

Don't know if it's UPC, but it passed my town's code and works like a champ for me. I was surprised they let me use a sanitary tee, though.