Honeywell Dual Auto By-Pass Angled (22mm) DU145 - DU145

Honeywell Dual Auto By-Pass Angled (22mm)

Manufacturers Part No: DU145

The Honeywell Dual Auto By-Pass Angled (22mm) 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 Automatic Bypass Valves (ABV’s) becomes particularly important when Heating Systems include large numbers of Thermostatic Radiator Valves (TRV’s) – such as evohome’s HR92UK Radiator Controllers.

When the HR92UK’s are open the Automatic Bypass Valve remains closed, however, as the HR92UK’s start to close, the Automatic Bypass Valve starts to open maintaining the required water flow through the boiler preventing problems such as overheating and short cycling.


  • Unique and simple adjustment mechanism
  • High capacity flow - up to 50 litres per minute
  • Wide differential pressure range 0.1 to 0.6 bar
  • 22mm compression fittings for ease of installation
  • Reduces system noise and maintains an even system pressure
  • Ensures constant flow through boiler
  • Lockable set pressure prevents inadvertent adjustment



£33.10 (ex VAT)
Brand Honeywell
Category Auto Air Vents and PRV's
Part number DU145