[. . . ] Combustion AIR Systems (oil) CAS-1 and CAS-2 (oil) Direct Connect The CAS-1 and CAS-2 Field Combustion Air Systems provide controlled amounts of outside air for proper combustion of oil heating appliances. [. . . ] According to NFPA 54 and NFPA 31, an engineered system such as a CAS-3 may be used to overcome the lack of air in a confined space. The CAS-3 is designed for optimum safety and includes a proving device that won't allow the burner to engage without the Fan-in-a-CanTM operating. Multiple units or additional controls are required for multiple appliance installations. The CAS-3 is equipped with a two speed control for enhanced versatility. HOW THE CAS-3 WORKS: When the thermostat calls for heat, the Fanin-a-CanTM engages and begins drawing outside air into the structure. [. . . ] The Fan-in-a-CanTM diffuses the outside air into the room near the burner. Model Fuel Application Number CAS-3 Oil Any oil heating appliance Components 4" Intake Air Hood Fan-in-a-CanTM Assembly 6" to 4" Reducer Restrictor Plate Intake Air Hood Fan-in-a-CanTM Assembly P/N 46457000 10/03 [. . . ]