Shower drain very slow

[wnishimoto]

I am having a problem with my Georgetown 270S shower drain when we dry dock even on the first day. The water backs up in the pan and the sink drain seems a little slow however if I pull the grey tank lever to open the tank then the drain works fine. Any suggestions?

[Rich5117]

You may have a clogged vent or a sticking air admittance valve

[wnishimoto]

The service department changed the air vent in the wall next to the toilet however the problem is still the same. What is an air valve?

[Rich5117]

The air admittance valve helps air enter your drain line so as not to create a vacuum condition, when it is to far from a normal roof vent. It also has a spring loaded flapper that closes and will not let gasses back into the RV. If you can access the valve they normally screw off or out of the connecting pipe. I would remove this and see if the problem is still there.

I tend to think though, that this is going to be a tank vent problem. When water flows into the tank it will displace air which is pushed up and out the roof vent. When you are pulling the gray tank valve you are allowing the tank to breath and get rid of the excess air, which is allowing it to drain.

Many people have found wasp nest under the roof tank caps that have caused issues. While it is unlikely the vent may be clogged by waste from the tank and may need flushed to clear it.

Let us know how things go.

[wnishimoto]

I agree with your analysis and will pass it on to the service manager at Wagon Trail in Las Vegas. Thank you.