An evaporator (10) includes a housing (100, 200), a bottle (400) containing a substance to be evaporated, a wick (500) protruding from the bottle (400), a rotatable plug deck (300) for providing electricity to the evaporator (10), a heating device (250) disposed within the housing (100,200), and an adjuster (600) within the housing (100, 200) for displacing the wick (500) toward or away from the heating device (250). The adjuster (600) includes a retaining mechanism (650) that retains the adjuster (600) in a selected one of a plurality of discreet adjustment settings. The plug deck 300 includes a locking mechanism (340, 342) that retains the plug deck (300) in a selected one of a plurality of discrete positions.