Posted by jtown on December 21, 2000 at 21:13:35:
In Reply to: Re: Circulation pump posted by David on December 21, 2000 at 07:25:56:
Wire a tag above the pump and write your service and dates on it. A relay would be in a separate box away from the pump. Most often the room thermostat calls for heat and when the boiler gets hot it starts the pump to get the heat out. Sometimes the pump starts with the burner and sometimes it is on continuously. Put a big screwdriver (or spoon if you're a cook) against the pump and having a thumb over the end of it, put your thumb's nuckle into your ear to see if the noise is coming from the pump or the box with the relay. The control switches including the thermostat are low voltage. The low voltage goes to the relay to run a solenoid that sucks in a switch to run the 120 volt to the pump. If the contacts get burned or the coil weak they can hum and not pass the 120v.