A heat storage unit (2) includes a body having a passage (12) formed therein through which a flowable product passes. A heatable element (10) is incorporated within the body of the heat storage unit (2) in thermal communication with the passage (12). Meanwhile, a heat-retentive material (8) is in thermal communication with the heatable element (10). The heatable element (10) includes either a magnetically-compatible material or a microwave-compatible material that is heated by locating the heatable element in a field (F) generated by a charging device (6), for example.