[dagkrauzog]

Hi,

I have a double laundry sink draining very slowly. The plumbing is attached to the sink and the floor drain with rubber couplings. I removed everything. Pipes and trap are clear. I can pour water rapidly down the floor drain with no problem. I even snaked it 25 feet and found no problems. Hooked it all back up and when the water runs it backs up into both sinks and takes forever to drain.

Thank you.

[mygirlsdad77]

Lack of vent. Has it always done this, or did it just start? Can you post some pictures of your drain setup. We will do our best to help solve your problem.

[dagkrauzog]

Thank you for the response. Here is a photo. It just started happening. The only thing that has changed is the top coupler was added (after the problem began). It used to just have the pipe covering the threadless flange coming off the sink.

[mygirlsdad77]

Try removing the bottom coupler and just letting the sink drain into the floor drain. Let me know if the floor drain will take all of the water then. What I'm looking for is to achieve an air gap between sink drain and floor drain. If this works, you will need to add an aav vent and redo your trap assembly.

[dagkrauzog]

I removed the coupler and it drained just fine. Ironically after reattaching the whole system drained better. This pipe is only about five feet from the vent pipe that runs next to the downstairs bathroom and I assume it ties in. However, if adding a vent right there will always ensure a quick drain then I'll add it. Also, I'd like to eliminate the bottom coupler altogether by removing the floor pipe (threadless on top). Can I screw PVC directly into the drain or should this be metal where it meets the floor?

Thank you.

[hkstroud]

What's that round cylinder device. Doesn't look like a bottle trap since you have a trap. Is it some kind of filter device. I only ask because you said that this a laundry sink. Sink could be used as washing machine drain amd water has lint in it.

[dagkrauzog]

The black coupler connects the drain pipe the plumbing (the top of the pipe is threadless). All the lint is captured at the drain hose with wire mesh. Everything is clear of lint.

[hkstroud]

OK, but what is the round cylinder thing?

[dagkrauzog]

If you mean the large round cylinder in the middle, that's the trap.

[mygirlsdad77]

You can use a pvc male adapter to thread into floor drain. Since it drained fine when bottom coupler was removed, I think you will be best off to install a vent. Let us know how things work out.

[dagkrauzog]

Vent installed! It took a bit of architecture but I got the vent above the sink. Plumbing guy at hardware store suggested I leave the pipe in the floor. The couplers made the PVC gluing a bit easier too. Works great. Thank You mygirlsdad77.

[mygirlsdad77]

Glad you got it done. Good job.