What is a boiler check valve?

A boiler check valve is designed to isolate steam and any other form of hot water pressure produced by the boiler water supply system so that water isn't forced back through the pumps and into the water supply. This helps to ensure a boiler system's water supply doesn't overflow.

When water from the water supply tank is pumped through a boiler system and into the water heater to be preheated before entering the boiler, the boiler check valve ensures that steam and hot water from the boiler cannot be forced back through the system and into the water supply. This is an important function to perform when the water flow to the boiler has stopped.