Abstract: A reusable heating device comprises a casing to be disposed vertically, the casing including a circuit element receiving chamber and a heater receiving chamber having a front opening, a lid for at least covering the front opening of the heater receiving chamber, a heater situated in the heater receiving chamber, and electric circuit means situated in the circuit element receiving chamber. The heater includes a heater segment coextensive with and disposed in the front opening and an electric heating element attached to a backside and the cover unit of the heater segment. The heater segments have U-shaped channels on a front side thereof to receive therein a Disposable Cellular Pouch through which an instillation liquid to be heated flows.