The DU145 Automatic Bypass Valve controls flow of water through a bypass circuit which is installed between flow and return pipework, typically at or near the boiler

• Building Regulation advice states that if a bypass is installed, an Automatic Bypass Valve must be fitted
• The DU145 saves energy by only allowing flow through the bypass when needed i.e. when flow through the system is reduced when zone valves or radiator thermostats are closing
• The use of an ABV is recommended by the UK government as Best Practice in the CHeSS (Central Heating System Specifications) guide to central heating systems