What did I do wrong? Slow drain...

Hi all,

I just installed a new bathroom sink in my basement. There was an existing sink on an adjacent wall, during remodeling I moved the sink by extending the pipes. After I had it all hooked up, the drain was draining extremely slow. If you look at the picture below.....when I loosen this screw (indicated by the red arrow) and allow air to get into the drain pipe, the sink drains fine.

I have installed an AAV because there was no existing vent pipe, although I'm only about 4 feet from the main stack, and I did not have any drainage issues in the old sink. The drain is 1 1/2" pipe.

What did I do wrong? The drain does not leak, is it okay to leave it this way?


Thank you for the help!

Bryce

You are misdiagnosing the problem and cure. You are NOT letting air into the pipe, you are letting air OUT. The air is being trapped between the water in the sink and the water in the trap, for some reason.

Usually it escapes through the overflow passage in the sink but you may have a sink without an overflow drain opening.

Thanks for the reply.

You are correct, this sink does not have an overflow drain. So how do I remedy the problem correctly?


Thanks,
Bryce

If there are no holes in the sink itself you need to get a drain for a vessel sink (I don't know what you have on there) which should help but, it's never going to drain as well as the old one.

If you have a grid drain, it is likely the holes are too small.

Try adjusting the pop up drain so that it go's up higher when you push it, or remove it and use a regular plug.

The pop-up assembly has to lift higher so the air can escape even with the water over it. Some drains can do it easily, by removing the pop-up plug, rotating it 180 degrees, and then reinstalling it.