A heater-cooler apparatus of an extracorporeal perfusion system comprising at least one fluid circuit 102, 104 providing a supply of a heat transfer fluid to the perfusion system, a cold storage unit, and a refrigeration unit for charging the cold storage unit. Wherein the cold storage unit comprises a chamber containing a liquid that freezes at a temperature above that to which the heat transfer fluid is cooled by the refrigeration unit, and an array of tubes through which the heat transfer fluid is conveyed. The array of tubes extending through the chamber. The apparatus may comprise one or more heaters. The heat transfer fluid may be a biocidal fluid such as glucose. The cold storage unit may comprise a non-water-based phase change material. A method for the heater-cooler apparatus is also provided. A heater cooler apparatus comprising a first and second device requiring temperature control, a thermal generator unit, hot and cold fluid circuits, first and second off-takes and first and second intermediate heat exchangers is also provided along with a corresponding method.
