Flo valve replacement

Rich_37

Does the flo valve open and close with boiler runs. The expansion tank does not fill with water and the blow off valve keeps opening under boiler operation. Rivh

Dale

blow off valve

Need a bit more info here. Assume a residential hot water boiler. However, if the pressure relief valve on a hot water boiler opens it's usually due to not enough air in the expansion tank. If the boiler has a working gauge it should show 30 psi when the blow off/pressure relief valve opens. If the tank has too much air then somehow the boiler water isn't connected to it. The tank connection should be before the flow control. The flow control valve is usually a weighted check valve that opens when the boiler pump runs, if the check valve was stuck in the closed position then the boiler burner should run until the high limit setting was reached, the relief not dumping water.