When camping last week with our 2015 bunkhouse I noticed that one of these valves was constantly dripping (even spraying as time went on). I figured out that it was a drain for the hot water lines (and would eventually stop leaking when the lines weren't charged by city pressure or pump), so I was able to effectively ignore it until I got back home.
On the way home I called our dealer, and they thought that in order to address it they would have to cut an access panel and/or tear apart the belly to get at it, and they couldn't even look at it for three weeks. Well, that wasn't soon enough for me since we will need to use the trailer before then to travel to a weeding, so I elected to try and tackle it myself.
The first thing to note about the valves on my trailer was that you cannot spin them off the fitting, as there isn't enough clearance. The lever would stop against the fresh water belly shroud once you turned the entire petcock a bit more than 1/2 way over to unthread it. I figured out that if I removed the handle held on by a hex screw, I was able to just get enough clearance (with a bit of belly scratching) to spin off the entire petcock.
Once I had the valve off the trailer, I noticed that the brass fitting itself was cracked. Given the tight clearance to spin the petcock on the exposed threads, I couldn't find a low enough profile valve at the local hardware store to replace it, so I ended up ordering one from Amazon and just putting a 1/4" brass cap on it for the time being. Now, for the first time ever, the lines hold a full pressure charge overnight - previously the pump would run every 10 mins or so quickly to keep pressure in the lines. This leads me to believe that this fitting has been cracked since we took delivery of the trailer (back in January), and has slowly gotten worse.
Yesterday I did receive the new petcock from Amazon, but as I have a working system now I'm not in a rush to reinstall it until it gets closer to winter time.
If y'all are interested in what I ended up ordering to replace it, I went with this from Amazon, which is low profile and has a removable lever if I need additional clearance to install it: http://www.amazon.com/gp/product/B00...ilpage_o01_s00
I hope this information helps others - I wasn't able to find anything helpful in the manual.