An HVAC engineer is trying to figure out where a system isn't functioning properly. She is looking at the
control sequence. Which is the last event to happen in this sequence?
A. When the room temperature drops below the setpoint, the room thermostat demands heat and closes a switch
to start the burner.
B. When the air temperature within the bonnet reaches the setpoint of the bonnet controller, the blower motor is
energized.
C. Heated air from the furnace is delivered through ductwork to occupied spaces within the building.
D. The generation of heat within the heat exchanger results in a rapid rise in air temperature within the bonnet. The
blower isn't operating yet.