Feed Check Valves are one of the most important components of boiler which control the flow of water from feed pump to the boiler and further prevents the backflow of water from boiler to pump when the boiler pressure is more than the pump pressure or when feed pump stops working. Working: During normal operation the feed valve may be lifted due to the pressure of water from the feed pump and water may be fed into the boiler. When the pump stops working, the pump pressure is less than the boiler pressure; the valve may be closed to its automatically due to the pressure of water from the boiler. It is very important to check that the non-return valve (CV) is in good condition as it is subjected to automatic upward and downward movement due to the fluctuations in the feed water pressures. The valve CV can be inspected for repair by fully closing the valve FV. If the boiler is in operation it should be seen that there is sufficient water in the boiler before such work is undertaken.