A temperature control unit – or TCU – gives precise temperature control to a process. The device can heat – or heat & cool – at very high temperatures and handle rapid changes in temperature. TCUs incorporate a pump, heater, a cooling method, and a controller. The required temperature set point is input into the controller. The pump circulates fluid to the process and back to the unit. This fluid is normally water but can be oil, depending on temperatures involved. Whilst the fluid is circulated, the controller constantly monitors return temperature. If this temperature drops, the unit’s heater will activate. If the return temperature increases, the unit will swap to cooling mode.