The Vaillant pressure sensing venturi is the device that pushes fresh air into the combustion chamber and allows the gas to be burned correctly. It also removes the remaining burnt gas after the combustion process is complete. The boiler has safety parameters in place to make sure no gas can be passed through to the main burner if the fan has ceased functioning.
Fits multiple appliances
Technical specification
Manufacturer Model No0020135122Brand NameVaillantCompatible WithVU 126/5-5 R1 and VU 156/5-5 R2