DU146 Automatic Bypass Valve

The DU146 Automatic Bypass Valve controls flow of water through a bypass circuit which is typically installed between flow and return pipework on a large system or branch of a district heating system. Building Regulation advice states that if a bypass is installed, an Automatic Bypass Valve must be fitted.


The DU146 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.



  • Integral pressure indicator for simple setting up
  • Wide differential pressure range 0.05 to 0.5 bar
  • Lockable set point adjustment
  • Reduces system noise and maintains an even system pressure
  • Ensures constant flow through boiler or branch of large heating system
  • Lockable set pressure prevents inadvertent adjustment



  • DU146M High duty construction suitable for district heat schemes