Why is my condensate tank pump coming when the boiler is not running

Erock7625

Hello, I have a Weil McLain LGB-6 steam boiler with a big condensate tank and pump next to it. The pump cycles on every 8 minutes like clockwork for about 5 seconds even when the boiler has been off for a long time. Right now the last time the boiler has run was about 8 hours ago but the pump still periodically comes on. As I understand it the pump will only activate via a float in the boiler when the water level gets to a certain point. So why would it come on when the boiler isn't running. I do not see any visible signs of leaks.

EBEBRATT-Ed

You probably have a bad check valve in the boiler feed pipe between the pump and the boiler. Even though the boiler is off some water is leaking from the boiler back into the condensate tank. The check valve is supposed to stop this backflow and its probably leaking by. When the water level in the boiler drops the control on the boiler starts the pump to replenish the boiler as it is supposed to do.

I can see the check valve in the picture. Coming off the pump you have a ball valve then a union then the pipe turns up into the check valve.

109A_5