The Field Controls 46266306 7" Fan-In-A-Drum CAS-7 is a combustion air supply component designed for compatible gas-fired boilers, furnaces, and commercial heating equipment with firing capacities up to 1.8 MBTU. It uses a powered fan to deliver controlled fresh air into the combustion chamber, supporting proper fuel burning and ventilation. This assembly helps maintain adequate combu... https://www.partshnc.com/46266306-field-controls-cas-7-7-faninadrum-18mbtu