A sterilizer for sterilizing instruments and devices disposed therein. The sterilizer includes a vessel that has an inner wall and an outer wall. The inner wall defines a sterilization chamber. The outer wall is spaced from the inner wall to define a cavity surrounding the sterilization chamber. A heating element for vaporizing a fluid is disposed in a lower portion of the cavity. A fluid circuit is fluidly connected to the vessel to convey fluid to the cavity, to convey steam from the cavity to the sterilization chamber and to exhaust steam from the sterilization chamber. The fluid circuit includes a conduit that fluidly connects the sterilization chamber to the cavity. A valve is disposed in the conduit for controlling the flow of steam from the cavity to the sterilization chamber. A boiler pump is provided for conveying fluid to the cavity of the vessel.