The water heater can be adjusted. There is a shutter that you can move to change the amount of air mixed into the LP.
On the burner tube that comes off the gas valve look for the slotted round fitting. There should be a screw. Loosen the screw while the heater is running and slide the shutter in or out. You will hear the noise the burner makes change. The flame should be mostly blue with a small orange tip. If you run it too quiet it will soot.
WBCCI #5501 AIR # 49
1978 Argosy 28 foot Motorhome
Wise men talk because they have something to say; fools, because they have to say something. -- Plato