RV News RVBusiness 2021 Top 10 RVs of the Year, plus 56 additional debuts and must-see units → ×

Go Back   Thor Forums > Thor Motorcoach & Motorhome > Class A Motor Coach
Click Here to Login
Thread Tools Display Modes
Old 04-10-2015, 03:12 PM   #41
Moderator Emeritus
FW28z's Avatar
Brand: Thor Motor Coach
Model: 2011 Four Winds 28Z
State: Michigan
Posts: 1,273
THOR #531
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.

The only thing that works on a RV is the owner...
FW28z is offline   Reply With Quote
Old 04-10-2015, 03:24 PM   #42
Senior Member
Brand: Thor Motor Coach
Model: 2013 31L
State: Florida
Posts: 1,989
THOR #908
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....

blw2 is offline   Reply With Quote
Old 04-10-2015, 03:43 PM   #43
Axis/Vegas Enthusiast
JamieGeek's Avatar
Brand: Thor Motor Coach
Model: Axis 24.1
State: Michigan
Posts: 9,183
THOR #1150
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.

2014 Thor Axis 24.1
2018 Chevy Bolt
blog - https://spareelectrons.wordpress.com/
JamieGeek is offline   Reply With Quote

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

» Featured Campgrounds

Reviews provided by


This website is not affiliated with or endorsed by Thor Industries or any of its affiliates. This is an independent, unofficial site.

All times are GMT. The time now is 02:47 PM.

Powered by vBulletin® Version 3.8.8
Copyright ©2000 - 2021, vBulletin Solutions, Inc.
Content Relevant URLs by vBSEO 3.6.0 PL2