A circulating pump, used in a radiant heating system, may need repairs when it stops running, operates intermittently, runs but does not circulate water, becomes noisy or leaks. These pumps force hot water from a boiler through radiating devices such as hot water baseboards, radiators or a radiant floor heating system. The system may circulate hot water throughout multiple zones using one circulating pump and individual control valves, or each heating zone may use its own individual circulating pump.
If a circulating pump stops running, the moving parts may be damaged, jammed or frozen. If the pump is noisy, the problem may be a bearing that is beginning to fail. If a circulating pump runs but does not move water, the pump vanes or other internal parts may have become damaged. In each of these cases, a repairman should remove the circulating pump and repair or replace it.
When a circulating pump runs intermittently, the condition is typically due to a control, relay or wiring defect. An electrician should check for a loose or corroded wiring connection, a faulty control relay or a thermostat wire that is intermittently shorting.
When a circulating pump leaks, it is usually at the flanges where it mounts to the heating water distribution piping. Signs of a leak include build-up of mineral salts and corrosion at the flange. To stop the leak, a repairman should shut down the system and replace the flange gasket.