The valves are fully automatic, requiring no manual adjustment, and will not leak in the unlikely event of failure as a backup failure safety mechanism is incorporated.  Their one way valve makes them suitable for use with radiators which can cycle into negative pressure, typically loft conversion radiators or on the suction side of the pump.  The innovative Hygroseal technology (patent pending) utilises a dual-seal positive valve closure which provides an extended, leak-free life.

Installing the valves is a simple DIY job that doesn't require system draining. once the valves are installed the changing of the cartridge is a less than one minute operation