RV Hot Water Heater Malfunction

Rusted burner tube in our Atwood Hot Water Heater

We were washing dishes this morning when I heard a loud bang.  It sounded like someone dropped something really heavy on a thick wooden floor.  Not good, since nothing like this exists in our RV.  I went outside to find our water heater had decided to have a little pouty fit.  Upon further inspection, it looked like the RV dealer we bought it from replaced the LP valve (good, probably needed it) but the burner did not get replaced and was full of rust to the point where it was basically clogged and not running right.

It makes sense that we took three nights to find this issue.  The Winnebago has a clever system where the engine coolant not only goes through a heater core (to heat the cabin via the vents) but it also has a loop that goes through the hot water heater tank.  After a somewhat long trip, the water in the tank is about as hot as the engine is - around 180 degrees.  It wasn't until the RV sat for a few days (without engine heat) and the hot water heater was turned on that the problem became [audibly] apparent. 

The burner and heat exchanger tube probably filled with LP and then exploded when the ignitor finally caught.  Fortunately nothing was seriously hurt, and I disabled the system.  One of the nice folks at the front desk knew a guy I could order parts from, and a new burner is on order - he'll bring it to the KOA later today.

Taking apart the hot water heater burner