View Full Version : Kitchen Drain Airlock?
PMPNX5
Aug 24, 2007, 09:04 AM
I have an old farmhouse where under the sink there are two separate 1.5" copper pipes for the drain each going down through the floor and meeting at the old barrell type trap. I replaced the counter and put in a new sink, valves, drain pipes down to the trap, but left the barrell trap. I routed the two drains from the double basin sink both into the drain on the left, and turned the one on the right into the drain for the washing machine. I also put in an S-trap on the sink after the two drains from the double basin sink join together. The sink will drain for about 5-7 seconds then begins to backup in both sinks. It will drain extremely slow until I loosen one of the joints and then it goes like crazy (like it should). Could this be due to having the two traps, and nowhere for the air to go that's trapped in between them? Please Help. Thanks in advance.
speedball1
Aug 24, 2007, 11:35 AM
Airlocks are a "given" in a unvented drainage system. At the very least change the traps to "P' traps and vent them with AAV's( Air Admittance Valves) Good luck, tom
PMPNX5
Aug 24, 2007, 11:51 AM
But the p-trap would be for a wall drain, I would have to eliminate the upper trap all together and just use the orig. barrell trap wouldn't I?
biggsie
Aug 24, 2007, 12:06 PM
I had a problem with a kitchen sink draining, and thought of venting the drain it
To outside..
Just pipe in pvc line out and up to vent drain outside, making sure to seal out
Rain water around pipe... at entry hole
speedball1
Aug 24, 2007, 12:18 PM
But the p-trap would be for a wall drain, I would have to eliminate the upper trap all together and just use the orig. barrell trap wouldn't I?
OK, new game plan. Install a AAV on the dischage line of the barrel trap and vent the sink that way. Regards, Tom
PMPNX5
Aug 24, 2007, 12:42 PM
Thanks. I'll give it a shot.
biggsie
Aug 24, 2007, 05:36 PM
Agree with speedball1 --- air admittance valve -- 2 good pictures of their uses
OATEY: Sure-Vent® Air Admittance Valves (http://www.oatey.com/aav_public/why_vent.html)
NSF Tests Air Admittance Valves (http://www.nsf.org/business/newsroom/plumbing98-1/air.html)
Second link shows AAV under a sink -- looks easy to install