Air Admittance Valve (s)

[Ebjy3]

We recently purchased a used 2014 Montana 3400RL. Our first 5th wheel and we are loving so far. Been slowly working thru some learning and minor repairs. Thanks to MOC, I was able to locate and replace the Air Admittance Valve located behind the galley sink to help with some odors. We are still experiencing some occasional odor that seems to be coming more from shower and bedroom sink area. I don't see an Air Admittance Valve anywhere to replace. Not even sure there is one. Hoping for some advice on what to look for or how to resolve.

[Carl n Susan]

Are you plumbed for a washer dryer? Do you have a washer dryer installed? If no washer/dryer then the problem is most likely stagnate water in the water lines feeding the washer.

Flush out the lines and the smell will disappear.

[DQDick]

If that doesn't solve the problem, the next thing to try is check the Hepvo valve. Many, if not all, Montanas have at least one under the shower in the drain line usually found along the drain line on the ceiling of the basement either behind the wall or before the wall. On our rigs it's been one place or the other but we have had it either place. What it is (look it up on Amazon to see what it looks like) is a substitute for a P trap where they didn't want to put a P trap. The issue is it has a membrane inside that keeps sewer smell from coming back into the rig, but if you don't take out the drain cover in the shower and replace it with a screen that will catch the hair etc the hair will clog up the Hepvo valve then someone sticks something down the drain thinking they'll poke a hole in the clog and instead they poke a hole in the membrane. You can remove the Hepvo valve and clean the membrane with a soft brush, but I'm lazy and prefer to catch the hair before it gets there.

[Ebjy3]

Thanks for the tip. I have flushed both the hot/cold water line. We will see how it goes.

Any thoughts on the drain pipe? I saw a notice that it drains direct to sewer line and not to tank. I have a valve directly on my sewer line and it is closed except when draining tanks. The drain is capped. Any thoughts on need to flush this as well?

[DQDick]

Couldn't hurt. There could be a p trap on the line or a low spot somewhere.