Using solar collectors the solar thermal system uses the free energy from the sun to heat water that is pumped through it, which in turn heats the water in a tank that is used for domestic hot water.
The water in the system will contain an anti-freeze solution to prevent freezing or the need to drain the system during winter. In fact the system is capable of delivering a proportion of your hot water during the sunny winter days. However the solar thermal system works best in the summer months, when it would usually provide you with all your domestic hot water needs.
A typical system consists of a solar collector, difference temperature controller, circulation pump, expansion vessel, solar hot water tank, flow regulator and all the necessary pipe work, insulation and fittings.
The difference temperature controller constantly monitors the temperature of the water in the solar collector and that of the hot water tank. As the sun heats the solar collector a temperature difference occurs between it and the hot water tank. The controller uses a preset temperature difference to determine when to start the circulation pump. Once the pump has been signalled to start a flow of sun heated water is circulated through the system, which by a means of heat transfer heats the water in the hot water tank. When the temperature of the hot water tank reaches the preset parameter, the controller signals the pump to stop. This cycle can be repeated many times throughout the day.
During the days when there is little or no sun the water in the hot water tank is heated by the existing immersion heater and or the central heating system so the house always has a supply of hot water.
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