Solar Water Heater Glossary
A
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Absorber Plate: The dark-colored metal plate in the solar collector that absorbs solar radiation and transfers the heat to the fluid inside.
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Active Solar Heating System: A solar heating system that uses mechanical components such as pumps and controllers to circulate fluid.
B
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Backup Heater: A conventional electric or gas water heater used to provide hot water when solar energy is insufficient.
C
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Circulation Pump: A pump that moves the heat-transfer fluid or water through the solar collector and storage tank.
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Collector (Solar Collector): The component of a solar water heating system that captures sunlight and converts it into heat.
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Closed-Loop System: A system where the heat-transfer fluid circulates in a closed circuit, separated from the potable water.
D
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Direct System: A solar water heater system where the potable water is heated directly in the solar collector.
E
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Evacuated Tube Collector: A type of solar collector made of rows of glass tubes that are vacuum-insulated for high efficiency.
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Expansion Tank: A tank used to absorb the increase in water volume caused by heating.
F
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Flat-Plate Collector: A common type of solar collector that has a flat absorbing surface and a transparent cover.
G
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Glycol: An antifreeze fluid used in closed-loop systems to prevent freezing in colder climates.
H
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Heat Exchanger: A device that transfers heat between two fluids without mixing them.
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Heat Transfer Fluid (HTF): A liquid (often glycol-water mix) that circulates through the system to carry heat from the collector to the water storage tank.
I
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Indirect System: A system where a heat-transfer fluid, not the domestic water, passes through the collector and heats the water via a heat exchanger.
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Insulation: Material used to reduce heat loss from pipes, tanks, or collectors.
L
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Legionella: A type of bacteria that can grow in warm water systems; proper temperature regulation is essential to prevent its growth.
M
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Mixing Valve (Tempering Valve): A valve that mixes cold water with hot to ensure safe water temperature at the tap.
O
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Open-Loop System: A solar heating system in which the potable water is circulated directly through the collector.
P
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Photovoltaic Panel (PV Panel): Not part of a solar water heater but often confused; it converts sunlight into electricity, not heat.
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Pressurized System: A system where the water pressure is maintained by the supply network, offering better performance.
S
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Solar Controller: An electronic device that regulates the pump operation based on temperature differences between the collector and tank.
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Solar Fraction: The portion of total hot water heating provided by solar energy.
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Solar Storage Tank: A tank that stores the hot water heated by the solar system.
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Stratification: The layering of water in the tank by temperature, with hotter water at the top.
T
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Thermosiphon System: A passive system where water circulates naturally due to temperature differences (without a pump).
V
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Vacuum Tube: A component of evacuated tube collectors that provides excellent insulation and efficient heat capture.
Solar Water Heater Glossary