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Slow Drain in Kitchen

Posted: Tue Jul 09, 2019 7:18 am
by sly12
I've updated kitchen sink drain from 1 1/4" to 1 1/2"-but when one crumb cut is in,(double sink) the other side drains very slow-(someone said you need drain vent)they never did this before I changed to bigger size,so why now???

Re: Slow Drain in Kitchen

Posted: Tue Jul 09, 2019 9:50 am
by Shannon
How much of this drain pipe did you change? right to the main stack? Is there any venting on that line now? How far does this drain travel until it gets to main stack?

Re: Slow Drain in Kitchen

Posted: Wed Jul 10, 2019 9:25 am
by sly12
changed about 4 ft.from bottom of sinks to main line ( which was already 1 1/2'') there is venting on main line-travels a total of about 6' to main line - and the vent is only about 2-3' away (the old drain was the 1 1/4" kit you buy at Hardware store)

Re: Slow Drain in Kitchen

Posted: Wed Jul 10, 2019 9:22 pm
by Shannon
And this was a double sink before and had no problem with 1-1/4" drain?
My guess is that the vent is too small for the extra water being drained since the drain line is all 1-1/2" now. There should be a 2" or bigger vent stack.
The only way around this now is to install AAV under the sink. Its basically a vent that opens when water is flowing out but closes after and also does not allow water to flow backwards though it. There are cheaper types but they are really not legal.
This is an AAV
AAV plumbing vent.png
AAV plumbing vent.png (183.31 KiB) Viewed 131 times
This is a cheater that really should not be used
cheater vent.png
cheater vent.png (24.58 KiB) Viewed 131 times

Re: Slow Drain in Kitchen

Posted: Thu Jul 11, 2019 4:45 am
by sly12
Oh I forgot another thing with both crumb cups out it flows perfect/vent stack is 2 1/2"-and yes it was double before,flowed perfect with one or both cups out...Thanks a bunch-I guess will try venting

Re: Slow Drain in Kitchen

Posted: Thu Jul 11, 2019 7:02 am
by Shannon
Maybe can you post a picture of the plumbing below the sink. I doubt there is any problem but ill have a look.

Re: Slow Drain in Kitchen

Posted: Fri Jul 19, 2019 9:29 pm
by MrNickWoodward,
Hello i am new here this site. i need your suggestion