An anesthesia vaporizer system includes a vaporizer reservoir forming a sump chamber containing a liquid anesthetic agent, a piston that forms a first chamber on a first side of the piston. The vaporizer reservoir has a fill port configured to receive a refill container containing liquid anesthetic agent and to permit flow into the first chamber. A motor moves the piston between a first position and a second position, wherein the volume of the first chamber increases as the piston moves from the first position towards the second position. The liquid anesthetic agent is thereby drawn from the refill container into the first chamber. A transfer valve is configured to permit the liquid anesthetic agent to flow from the first chamber into the sump chamber. An outlet port delivers the liquid anesthetic agent from the sump chamber into a vaporizing system that vaporizes it for delivery to a patient.