Kitchen Island Sink Slow

[Tree Top Turkeys]

We’re at beach and it’s hot hot hot!!!
Never had this happen but after dishes the sink won’t drain. Knowing we are carful about what we put down the drain I found my Air Admittance valve under the sink. I removed it and it sprayed water out big time. Not sure how I had positive pressure on drain line unless it was just heat. These valves are pretty simple and not much to break unless it was just defective??? I wonder if the whole gray tank is vented and maybe it is messed up??? Any help appreciated.

[Rondo]

You may think this is a dumb question but have you drained BOTH gray tanks? There is one for the shower and one for the galley (kitchen sink). That drain handle is normally protruding from the frame (drivers side) either just in front of the front wheel or in between the driver side wheels.

What is the galley tank reading on the board also?

[Tree Top Turkeys]

Yes. They had been dumped. They were not completely empty. One thing I forgot to mention on post. While sink was standing with water not draining I started removing the AAV and the sink immediately drained down empty. Vapor locked I reckon. I’m going to buy a new one at Home Depo tomorrow and I hope that is the fix. I would think if the gray and black tanks were vented on roof I would think this little device wouldn’t be needed, but I’m not sure.

[rohrmann]

If the galley tank was vented to the roof, there would not be a need for the AAV. Is there a P trap under the sink, and if there is, is it clean? You might remove it to check and clean it if there is debris in it. Not sure if that will cause the problem, but this should be eliminated as a possible problem.

[RMcNeal]

I've read that these air admittance valves go bad frequently. Never had an issue with ours yet, but apparently it is common. You may need to replace it.

[Tree Top Turkeys]

Well….so far so good. Replaced with Oatley which meets most plumbing codes. Still very hot so same conditions as before. I’ve fill two sinks and both drained perfectly. Hopefully you are correct and it’s as simple as changing it out occasionally. Thanks!!!

[Tree Top Turkeys]

Still draining slow after new AAV. Does anyone know if tank has a separate vent? Bathrooms are draining just fine.