Caleffi Solar SolarCon Indirect Hot Water Storage Tanks
The Caleffi solar water heater has either one or two internal coils and a backup electric heating element in the single coil units. A heating medium is passed through the solar panels and internal coil as long as there is an adequate temperature difference between the heating medium and stored water in the tank. The internal coil is located as close to the bottom to facilitate the transfer of heat even at lower solar panel temperatures.
During periods of water flow through the water heater. Hot water is drawn from the top of the heater and cold water comes into the bottom of the tank (by a dip tube or bottom inlet). With single coil hot water storage tanks, if the hot water demand should exceed the solar heat input or there is an insufficient temperature difference between the heating medium and stored water, the heating element thermostat will activate the electrical heating element for backup heat. On double coil tanks, the upper tank is connected to the boiler for backup heat.