This Worcester Bosch fan assembly, part number 87161164740, is a crucial component for the Greenstar 25, 28, 29, and 30 HE boilers. It is responsible for injecting fresh air into the combustion chamber, ensuring efficient gas burning, and expelling noxious gases after combustion. The boiler is equipped with safety features that prevent gas flow to the main burner if the fan is not operating correctly. This product has been discontinued and replaced by part number 8716117325. It is an electronic component manufactured by Bosch under the Worcester Bosch brand.