Kitchen Island

[Steve89GTA]

Hi guys
Roughing in kitchen plumbing (reno). Current sink is on an exterior wall, 1.5 inch abs vent coming down and feeding sink drain...from there it flows across to the center bearing wall where it joins the 4" abs pipe (about 13.5 feet across. The new island sink will replace the existing exterior wall sink. The island sink will be located between the exterior wall (current sink location) and center bearing wall (where 4" pipe is). So, how to properly vent sink...dishwasher will be in island as well.
First thought, carry existing vent in ext wall across (basement ceiling is exposed) and connect to sink drain (after trap?) with y abs fitting, continue on to 4" drain using existing pipe.
Distance from island sink to 4" pipe is around 6-7 feet or so. I've read that a 6' or less run from 4" main does not even require a vent (Canadian plumbing code) but I want to be sure of no issues and don't mind extending the existing vent line to the island as described. Let me know your thoughts and many thx in advance!

 

[hj]

Unless your trap is going to be in the basement, what you are describing does not work. You are trying to use the distance from the main line to "justify" doing something, but that ALSO depends on HOW the piping is being done. It is NOT an absolute permission to do it.

 

[Sponsor]

 

[Steve89GTA]

Thanks for the response. The trap right now is in the basement ceiling for the sink. Not ideal I know. So the island being vented by the main is not applicable?

 

[Terry]

You would be better off installing an AAV to prevent the trap from siphoning.
A trap below the floor is not allowed most places. They do in Canada,

 

[Steve89GTA]

Thanks Terry! This site is really great, you helped me with a basement bathroom job 5-6 years ago which came out awesome. I have a plumber looking at it today, likely he will recommend AAV as well...alternative I guess would be the loop?

 

[JohnfrWhipple]

Why not install a cheater vent under the sink in the Island?

Something like this but higher up.

Works in Canada! But our water is finer...... lol we can use 1.5" pipes for showers because ours flows faster! ha

 

[hj]

Your picture MIGHT be an improvement if it did not show a 3/4 "S" trap, instead of a "P" trap.

 

[Terry]

Your picture MIGHT be an improvement if it did not show a 3/4 "S" trap, instead of a "P" trap.

Yes, why not at least the proper santee there instead of the wye fitting?

 

[JohnfrWhipple]

Your picture MIGHT be an improvement if it did not show a 3/4 "S" trap, instead of a "P" trap.

LOL - I googled Cheater Vents and found that photo.

Excellent catch HJ. I knew you or Terry would pick it apart if it was not right.

 

[JohnfrWhipple]

....

That's how we see it. Up high like that.

 

[Steve89GTA]

Thanks all. will be doing an AAV.