Solar Heating

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Solar Heating – Queensland

Solar heating is the process by which a device more simply known as the solar water heater provides hot water for bathing, washing, cleaning and other domestic purposes. The solar heating collector is generally installed at a terrace or someplace where plenty of sunlight is available.  This collector is responsible for heating up of the water and this heated water is now stored in a heat insulated tank which can be gradually used up for future requirements.


Working Principle– A solar heating assemblage basically consists of one or more solar collector based upon the usage and an insulated tank to store the hot water. The working principle is quite simple as the water in the solar collector gets heated up during the day time and the water to the solar collector is generally pumped up or is automatically transferred by thermosiphoning.

  • [N.B.-Thermosiphoning is a very simple yet effective physical effect where basic processes like heat exchange and natural convections are utilized to heat up fluids without the help of any mechanical pump. The mode of circulation in a thermosyphon can either be an open loop where the water in the holding tank is passed in a single direction by the help of a heated transfer tube that is usually mounted at the bottom of the tank to a distribution point which is usually situated at the top of the originating tank. Again there can also be a closed loop system where return of hot water can be redirected back to the originating container. Overall the choice of installation depends purely on the customer’s wishes and the usage of the assemblage.  The convective property of water basically moves it when heated as it expands when heated and becomes less dense and the heavier cooler water now settles down to the bottom of the loop. Convection works in synchronisation with gravity here as the lighter and warmer water moves up the loop, the heavier cooler water moves down the loop into the collector and hence there is a cycle of heating. Ideally there is very little wastage of energy here because a good thermosyphon causes minimal hydraulic resistance.]

Types of Solar Heating systems available – There are basically two types of solar heating systems available in the market namely the Flat Plate Collectors (FPC) and the other is the Evacuated Tube Collector (ETC). The FPC systems are basically made of metals while the ETC assemblages are made of glass which is fragile by nature. Hence FPC belongs to the more long lasting genre. Heat exchanger and pump both are optional. Without pump system assemblages work on thermosiphoning while the ones with the presence of pump are known as forced circulation systems.

ETC based assemblages are comparatively cheaper to FPCs. In fact they deliver better performance in the colder regions and are able to cope with sub zero conditions much easily. FPC assemblages however do also perform well in sub zero conditions with the additional installation of anti freeze but again this further increases the cost.

Systems that work on the Thermosiphoning principle are quite simple and are way cheaper than the forced pumping options. This system is very suitable for domestic and small institutional uses but conditions apply that the water does not have too much chlorine in its content. Forced circulation systems are generally preferred in industries and large establishments.

FPC systems work better in hard water heating provided there is additional heat exchanger is also installed as this shall be preventing the scale deposition in the copper tubes of solar collectors .  ETC based systems do not block the flow of water due to scaling but however performance may go down. But again the salt depositions on the inner surface of the glass tubes may however be cleaned easily once a year.

Thanking you for reading this article on Solar Heating.


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