The Potterton air pressure switch is a safety device which checks that the fan is fully operational. It ensures that, if the fan fails within the boiler, there will not be a build up of noxious fumes with no means of extracting them safely.
Fits a number of Potterton appliances
Technical specification
TypeAir Pressure SwitchCompatible WithHE Heat Only 12 and Suprima 40 HEManufacturer Model No5112196Brand NamePotterton