An ozone generating apparatus is provided which includes a pair of electrodes for producing a discharge by the application of an ac voltage therebetween, and at least one dielectric provided between the pair of electrodes. A respective air tube is pulled through each vent of the ductwork, directly or by an intermediate line, by a parachute which is sucked from the vent to the plenum by a blower attached to the plenum or to a primary trunk of the ductwork. Transition characteristics are also received. The hall effect device is configured to generate an output signal indicative of a latch condition of the mechanical engagement system as applied to the sensor assembly.