In an anesthesia vaporizer for vaporizing an anesthetic agent liquid and a method of vaporizing an anesthetic agent liquid in an vaporizer, an evaporation unit evaporates the anesthetic agent, a delivery unit intermittently adds a volume of said liquid to the evaporation unit in order to evaporate at least a portion of the volume of the liquid from the evaporation unit. A heat energy storage unit includes a phase change material (PCM) and is thermally coupled to at least a portion of the evaporation unit. The PCM has a phase shift temperature that is higher than the evaporation temperature of the anesthetic agent. The PCM in the heat energy storage unit is preferably at least partly liquid at an operative temperature of the vaporizer.
