Pressure vessels with an enamel-coated inner surface transfer the heat from the heating fluids coming from two different heat sources to the hygienic water prepared inside the enamel-coated body using built-in heat exchangers (coils), producing hot and hygienic water. In RUSH double-coil hot water heaters, the large-surface-area heat exchanger (coil) uses hot water from boilers or cascade systems, while the lower heat exchanger can use heating fluid from solar energy systems. A closed circuit is created and circulation is provided by a pump. Thermostat inputs on the device allow for temperature control. Based on measurements from these inputs, flow is controlled by the pump. The inlet temperature and pump speed are adjusted according to the targeted heating time to ensure maximum efficiency. Higher temperatures can be achieved more quickly thanks to the backup electric heater input on the device.
