Hydronic Circulator Pumps

Circulator Pumps Play an Important Role in Closed Hot Water Home Heating

By Mark J. Donovan




Hydronic circulator pumps are commonly used in closed hot water home heating systems. Hydronic circulator pumps circulate the hot water through the heating system and work in conjunction with the boiler, hydronic zone valves, and thermostats to heat/cool your home.

Hydronic circulator pumps used for residential use are small centrifugal type pumps that are electrically powered. They are typically made out of cast iron. You can locate them usually near the boiler and in series with the hot water piping.

Hydronic circulator pumps are sealed units with an internal motor, bearings and impeller, thus making them less prone to leakage and breakdown.

They are typically installed in series with the boiler, hydronic zone valve and hot water heating. When the thermostat indicates that heat is required, the zone valve is opened, the circulating pump is activated and hot water is circulated through the hot water heating system. As the water cools the boiler turns on and reheats the water in the closed loop hot water heating system.

Besides being used for home heating systems, a hydronic circulator pump is also frequently used for supplying on-demand hot water for the home’s domestic hot water needs. The circulator pump continuously provides hot water through the home hot water supply lines so that when a hot water faucet is turned on, hot water is immediately available. The advantage of this is that you don’t waste water, but the disadvantage is that you waste energy by constantly heating water that may be rarely used.

If you consider using a circulator pump for your home’s hot water system, then you may want to insulate your hot water supply pipes or put the system on a timer so that you mitigate the waste of energy.

Hydronic Circulator Pump

A circulator pumps performance is measured by its flow performance. The flow performance is a function of the flow-rate (number of gallons/liters of water that can be pushed through the system per minute), and the circulator pumps head pressure.

A circulator pumps head pressure rating is the maximum vertical height the pump can lift the water. Consequently if you have a large hot water system design that needs to go up two floor levels (e.g. from the basement to the second floor of a home) you will need a circulator pump that can support a higher flow performance with a high head pressure.

As with everything in nature, hydronic circulator pumps eventually break down. When they do, the motor usually seizes and hot water fails to circulate. When this situation occurs, call a plumber as this is a repair project that is quite extensive and should not be handled by a homeowner.



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