It might have to do with the 120 volt power supply, not in most RV's while dry camping, and the lack of ability to run the system on a cold night. Many will turn on at 35F to keep it above freezing.
You can plan on installing a drain adjacent to the unit to completely drain the water heater before driving on a freezing day. Even driving will bring a lot of outside air through the heater, completly freezing the water solid on a 30F day. This can burst the pipes, and of course freeze damage is not a "Warranty defect". Also if the unit does try to cycle on while in a moving RV - who knows where the flames will go or get pushed by wind? So if it has not been tested, I would not allow it to go into a RV if I was the designer.
Maybe they have tested them, and the compartment got to warm around the heater while driving the test RV.
Fred.
Money can't buy happiness but somehow it's more comfortable to cry in a
Porsche or Country Coach!
If there's a WILL, I want to be in it!
I havn't been everywhere, but it's on my list.
Kangen.com Alkaline waterEscapees.com