Immersion boost

Immersion boost is a control mode that temporarily energises an immersion heater to add direct electric heat, most commonly to a domestic hot water cylinder. In heat pump, cylinder and hot-water-controller documents it may appear as DHW immersion boost, manual boost or a boost button for extra hot-water demand, controller-managed immersion assistance, higher stored-water temperature or a configured pasteurisation cycle. It is not the same as the immersion heater itself, a backup heater for space heating, a cylinder thermostat, a hot-water schedule, a legionella-control design, a solar diverter or proof that the system is efficient, correctly configured, safe, compliant or able to meet every hot-water demand.