What Is a Circulator Pump?

Alex Newth
Alex Newth
Man with a drill
Man with a drill

A circulator pump is a pump used in closed circuit environments, typically to pump water, though it also can pump gases and slurries. These pumps are used in homes and large buildings for hydronic heating and cooling, in which water is used to lower or raise temperatures to a satisfactory level. Depending on the size of the circulator pump, the motor needed to push the water is either internal or external, with external motors being much more powerful. If used for hydronics, the pump is made from cast iron, while pumps used in drinking water systems are made from bronze.

Circulator pumps are made to push gas, liquid or slurry through a closed circuit, or a circuit that is constantly rotating. These pumps are found paired with water systems for drinking or temperature adjustment, or with large equipment. Water is the most common material to be paired with a circulator pump, with slurries being the second.

Large machines and equipment pieces that are constantly running build up a high amount of heat. If the heat is not reduced quickly and constantly, then the equipment can break, melt or cause damage to the surface on which it is working. By circulating either water or a slurry over the heated parts, the heat will be transferred away from the equipment and into the water or slurry. A circulator pump will continually circulate the same liquid, so a relatively small amount of water or slurry is needed for this application.

More often, circulator pumps are used in hydronics. This is a system in which water is either heated or cooled and passed around the house to raise or lower the temperature. The earliest form of hydronics is the radiator system. To push the water around the circuit, the circulating pump needs to have a motor.

Small household pumps have internal motors, while larger spaces need an external motor. The internal motor is weak but keeps the pump watertight, because the pump does not need to interact with anything outside itself. External motors are needed for large applications; otherwise the water cannot circulate through the circuit, but these systems are more difficult to maintain.

A circulator pump will be made of either cast iron or bronze. When used in hydronics, and in any application in which the water only regulates temperature, cast iron is used. Bronze pumps are used for water consumption, and these pumps are used to keep a constant circuit of heated or cooled water, so users do not have to run the water at a sink for several seconds to change the water’s temperature.

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