Hi,
My kitchen sink (double sided) drains real slow or at times not at all. When we bought the house it had 2 traps in the line and would not drain at all. I changed it to only one trap and it now drains real slow or at times not at all. The lines are clear as far as 25 feet on the auger snake that I have. The pipe enters the wall and goes the into crawl space between the walls. There doesn't seem to be a vent on the roof.all other drains work just fine.the kitchen drain is the furthest from the exit to the main line. Any ideas?

hi,
my kitchen sink (double sided) drains real slow or at times not at all. when we bought the house it had 2 traps in the line and would not drain at all. i changed it to only one trap and it now drains real slow or at times not at all. the lines are clear as far as 25 feet on the auger snake that i have. the pipe enters the wall and goes the into crawl space between the walls. ther doesnt seem to be a vent on the roof.all other drains work just fine.the kitchen drain is the furthest from the exit to the main line. any ideas?

From the way you describe yiour drainage it's no wonder you have a problem. You have described a illegal "S" trap. Clear for 25 feet huh? Would you be surprised to learn that you shouldn't be able to run your snake in over about 10 feet from under the cabinet before it hits a sanitary tee and the vent. Oh! That's right! You don't have a vent do you? That's one of your main problems. I'll most likely find more after you tell me the pipe size and how far it runs horizontally. Do you have a disposal in the sink? I hope not because that will be another trouble spot. The first thing I would do is to vent your drain line. The easiest way would be to install a AAV,( Air Admittance Valve) back of a "P" trap(see image) and then 90 down to the drain line in the crawl space. I'll tell you more when you give me the pipe size in the crawl space. Regards, Tom

Tom thank you for the quick response:the pipe size in the crawl space goes from 3" to the 4" main line, under the sink it goes from 1 1/2" to 2" into the wall.from the sink to the wall is about 3 feet and it 90s down to the crawl space from there.I put a p trap in already and that's when it strated to drain slowly instead of not at all.I willput in an aav in the morning and let you know if that helped.should I put the aav on after the trap as it enters the wall or is there a better spot? My best regards, Dave