I have a 4 zone hydronic heating system. It is a 15 year old Hydrotherm HI-B series boiler with a new circulator pump.

It has been noticed that when none of the zones call for heat and the boiler is back up to temperature the pump continues to run, a waste of power since al the zone valves are closed.

The control box contains three identical relays. I purchased one replacement relay and substituted it out in all three positions but the pump continues to run. Any suggestions?:confused:

Have you traced the wires from the pump to its power source? What do you mean by'when boiler is back up to temp', Boiler should not be rising in temperature if there is no call for heat( unless your boiler is wired to be a hot boiler) Let me know some more details and I will try to help.