This valve releases steam from the boiler and opens and closes the system. These need to be kept clean by the way we explain in a maintenance video and our owner’s manual. These may clog with sediment as there is a very small passageway to allow steam to escape. As well, they can fail if they get too hot from being clogged and steam struggling to get out. When these get clogged there will be poorer steam performance and less steam escaping