Problem with 'drain valves' especially ball valves.
* water gets trapped inside the ball and can freeze...split ball valve
*after installing one folks tend to NOT remove the set up to properly flush the WH Tank of sediment/scale/crud
*Atwood drain hole is on 1/2" so installation of barb fitting/ball valve chokes the drain down and doesn't allow for good flushing...drains water OK but not the crud
*and do you know what that hose/valve set up is TEMP Rated for?
Water temp/pressure COULD go as high as 210*/150PSI should the t-stats fail