A combustion air proving (CAP) system for a burner assembly having a burner for providing heated air to a location, a controller, and a back plate, where outside air is fed to the burner via a conduit. The CAP system is connected to an inlet of the system. An outlet of the system is connected to the burner via the back plate. A damper within the system is translatable between open and closed positions for allowing and blocking air flow, respectively. A sensor measures an air flow parameter of air flow to the burner. The sensor communicates with the controller, which shuts down the burner if the parameter measured by the sensor meets a predetermined threshold value. An assembly installer may test for proper sensor and controller functions by translating the damper to the closed position and blocking outside air flow.