Blower for generating static pressure

A blower fan assembly for removing combusted by-products and flue gas from a furnace is presented. The blower fan assembly includes a housing with a cavity for receiving a blower fan. The housing is secured over an opening in a furnace so that when the blower fan rotates, flue gas is drawn from the furnace to an exhaust conduit outside the building in which the furnace is received. The blower fan includes a fan ring connected to a fan disc by a plurality of vanes which are parallel with the axis of rotation. A motor, mounted to the housing, rotates the fan disc. The blower fan draws air in through the fan ring, through the plurality of vanes and out through the exhaust conduit. A static pressure tap is located in the housing and is connected to a pressure sensor which measures the static pressure generated by the blower fan as it rotates. By employing a plurality of pressure openings in the fan disc, a predictable range of static pressures can be generated within the cavity which allows the pressure sensor to monitor whether the blower fan assembly is working properly. Thus, if the pressure sensor determines that the blower fan is not working, the furnace is turned off. This precludes generation of flue gas that might accumulate in the building receiving the furnace. By adjusting the number of pressure openings, the blower fan assembly can be designed so that the static pressure tap is in only one location and does not have to be placed in different locations for each particular use of the blower fan assembly with a particular furnace.