Product Information: The air pressure switch enacts safety protocols to check the fan is working correctly. It ensures that, if the fan fails within the boiler, there would not be a build up of toxic fumes with no means of venting them. The PCB closely monitors the air pressure switch to make sure it is fully functional before the unit is fired up, preventing the appliance from starting without one of its key safety mechanisms.
This part is listed against 2 boilers on our website, The ARISTON SX 20 MFFI CE from serial no and the ARISTON SX 20 MFFI CE from serial no.