2014 Hurricane 34e - Problems again

[FW28z]

Well I learned something today. I went out and checked my coach, and sure enough, I have a cheater vent behind both sinks, similar to the schematic that BLW2 showed.

I am rather surprised though, as the drains are pretty much a straight shot to the tanks. Me thinks its perhaps another example of guesswork engineering.

[blw2]

I'll bet you're right on that !...
I call it
"Star Trek Engineering.... Going where no man has gone before"

I'm not a plumber, but I've worked with piping and pumping systems for a good bit of my career. My "gut" tells me that my lav sink drain is a short enough run to the tank, along with a small enough flow rate, that I'd likely be ok without the air admittance device. Although there may be issues if say, dumping a pot full of water in the sink, especially given the horizontal run...... So, not great but maybe ok....
...but my kitchen sink is such a long run to the tank that it would likely be problematic without it.

If my problem continues, I think I'll remove the lav valve and plug it to see what happens. If I think about it, maybe I'll throw a 1-1/2in NPT plug into my RV project box so that I'll have one handy on my next trip....

[JamieGeek]

Our Axis also has these valves on both sinks and, in my case, both tanks vent through the same roof vent--I posted that diagram earlier. Our kitchen sink has a long run to the drain and the way they plumbed the bathroom sink turned that into a long run as well.

As mentioned: just another maintainance item to keep an eye on.