In a heating system, a circulating pump is a device used to circulate hot water or steam throughout the system. It helps to distribute heat evenly to different areas of a building, such as radiators, baseboard heaters, or underfloor heating systems.

When the heating system is activated, the circulating pump is turned on, and it begins to pump hot water or steam through the pipes to the various heating components. This circulation process ensures that all parts of the building receive the desired amount of heat, maintaining a comfortable indoor temperature. Without a circulating pump, the heated water or steam might remain stagnant in the boiler or not reach all areas of the building efficiently.