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Circulator Pumps

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A circulator pump is used to circulate gases, liquids or slurries in a circuit. Most often, these pumps are found circulating water in a hydronic heating or cooling system. The circulator's job is to move hot water from the boiler to the radiators, and then return the cooled water for another injection of heat.

Types Of Circulator Pumps

While the function of circulator pumps is generally the same, there are many different kinds. Among the designs are bronze sweat end pumps, stainless steel/bronze circulator pumps, cast iron pumps, pre-wired models and in-line pumps. Circulator pumps also vary based on horsepower, flow range (expressed in gallons per minute), head range (expressed in submersible feet of depth), motor type, and the maximum and minimum liquid temperatures they can be used in.

Replacing A Circulator Pump

The actual removal and reattachment of the pump is easy but is hardly the only task in adequately replacing the pump. To remove the old pump, the boiler should be turned off, as should the electrical supply to the boiler and pump. The circulating pump terminal cover should be removed, and the voltage at the terminals checked with a meter-reader to verify zero voltage. Note the wire colors and their respective terminal attachments, as well as the water flow direction, which is normally signified by a logo on the base of the pump. The electrical wires may then be removed as well as the vent plug. This step could lead to water spillage, which is why towels or a bowl should be on hand for cleanup/prevention. The pair of union nuts holding the pump in place can be removed, freeing the pump. The system should then be flushed and protected to ensure cleanliness and to guard against corrosion. The positioning of the pump should be checked, making sure it's proper given the piping setup. For example, if installed in vertical pipe work, the pump installed should pump up. Only then should the new pump be installed.

Who Makes Circulator Pumps?

Among the largest of circulator pump manufacturers are:

  • Grundfos
  • Laing
  • Taco

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