On the Dutch Star and below, the engine coolant heats your hot water via the Oasis unit while driving. Even though I don't have the diesel burner or electric burners running, my Oasis unit is turned ON before each trip. I've never checked to see if the unit heats water, via the coolant, when the system is shut down.
On the Mountainaire and above, the Oasis system can be used to warm your coolant in cold weather via an additional pump added to the Oasis system on the higher end coaches. The pump can be added to a Dutch Star for about $125.00.
