why is there a vent under bathroom sink?

[GT4Point6]

2013 Sundance SD 3000 MK.
I have a vent under the bathroom sink off the drain line below the trap. When u open the cabinet under the sink, it stinks.
Should this vent valve be inside the rv?
I use my RV full time, grey water lines are always open.

Why is there a vent inside the RV?
Is it possible it is stuck and needs replaced?

Off for the weekend, can get pics next week.

TIA,
Kevin

 

[hoefler]

If you are getting an odor under the sink, the Studer valve is bad. It is on top of the Tee. You can buy one at any hardware store for about $3, replace it.

 

[Garypowell]

Also check all of the other connections. I recently had the same problem but smell did not go away until I rebuilt the sink drain. It only had gasket and not sealant.

 

[JohnDar]

It's an air admittance valve to allow the water to drain easily. Normally, it only "opens" when water flows through the drain. But, they have been known to stick, allowing odors to get into the coach. As mentioned, relatively simple fix.


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[GT4Point6]

Thanks all for the help. Replacing the valve and checking the other connections this weekend.

 

[vangoes]

I have found that when running the a/c, it sometimes creates enough vacuum to cause the valve to open emitting odors. I replaced the valve and it did not help. I finally took it off and put a plug in. Whalla.....no more odors and everything drains as normal. I'm not sure why its there to start with as the tank is vented to the outside through the roof.

 

[Bohemian]

It's there because it is required in housing codes. All drain lines must be vented (at least in most places). Water in a drain line can cause a vapor lock if not vented. If you have no problem, great. Just remember in the future if you develop a problem.

I have found that when running the a/c, it sometimes creates enough vacuum to cause the valve to open emitting odors. I replaced the valve and it did not help. I finally took it off and put a plug in. Whalla.....no more odors and everything drains as normal. I'm not sure why its there to start with as the tank is vented to the outside through the roof.