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    3 min. left

    Circulation in active solar heating systems

    A solar hot water pump is used in active solar hot water systems. A solar hot water pump is designed to circulate water or a heat-transfer fluid between the storage tank and the collector. This is how the water gets exposed to the heat energy coming off the collector. A solar hot water pump is also known as a hot water circulator or a circulating pump.

    Solar Hot Water PumpImage: Grundfos Pumps LtdThere are three primary components to a solar hot water pump: the motor, the impeller and the impeller housing. The motor powers the impeller to spin within its housing, giving rise to an inward force that pushes the water or solar fluid through its plumbing passage. This way, the circulating fluid is constantly moving through the pump’s impeller housing.

    To start and operate properly, pumps need to be manually lubricated. A common type of pump that is used is the ‘wet rotor’ type which already has the impeller or rotor (the moving part of the pump) filled with liquid.

    A solar hot water pump is needed in virtually all active solar hot water systems. Sometimes, more than one pump is installed in a solar hot water system. Different solar hot water pumps have different flow rates, and this depends on their size and their ability to resist pressure. Pumps that are bigger use more energy, whereas pumps that are smaller may not be able to sufficiently circulate the water.

    A solar hot water pump can be made of different types of materials. There are iron pumps that are suitable only for use in indirect solar hot water systems, because iron rusts when it makes contact with oxygenated water. A solar hot water pump with an impeller and impeller housing that is made of bronze, stainless steel or plastic is more suitable for direct solar hot water systems, because they are corrosion-resistant and can last for years if not decades. Bronze and stainless steel pumps tend to be the more popular choices.

    A solar hot water pump can be powered either by DC (direct current) or AC (alternating current). AC powered pumps need a utility grid to get an unlimited energy supply, whereas DC pumps use a photovoltaic module to generate DC electricity to power the pump.

    As can be seen, solar hot water pumps come in different types. The type of solar hot water pump that is used depends on the type of solar hot water system.  If you are unsure which solar hot water pump is best for you, ask a solar professional today!