This product is the Honeywell Home 22mm Angled Auto Bypass Valve.Automatic By-pass valve.

This automatic bypass and differential pressure valve is used to maintain constant differential pressure in a heating system. It reduces flow noise in a system, particularly as thermostatic radiator valves are closing. The boiler return temperature is raised and this reduces the corrosion caused by flue gas condensation. In addition, when radiator valves are closed it also maintains flow over the temperature sensor on the boiler to ensure proper operation of external temperature compensating controls. On gas fired water heaters it guarantees a minimum flow circulation when thermostats or radiator valves are closed.

Main product features:

• Reduces system noise and maintains an even system pressure
• Ensures constant flow through boiler
• lockable set pressure prevents inadvertent adjustment
• Unique and simple adjustment mechanism
• Automatic By-pass valve