Abstract: An active stairwell compensation system includes air injection points at different elevations in a stairwell; a fan for providing airflow to the air injection points; sensors; air injection dampers; and a controller in data communication with the fan, the sensors, and the air injection dampers. At least some of the sensors are located inside the stairwell, and at least some of the sensors are located outside the stairwell. A respective air injection damper is located between each air injection point and the fan. The controller has programming to utilize data from the sensors to adjust an amount of air provided by the fan and independently adjust the air injection dampers to maintain a desirable amount of air pressure at the air injection points. The desirable amount of air pressure is selected to prevent smoke from entering the stairwell while allowing stairwell doors to open for egress.

Abstract: Reversible draft controllers and exhaust systems incorporating reversible draft controllers are disclosed. One system for controlling draft in a chimney includes a sensor for determining condition data, an axial fan blade, an electronically commutated motor (ECM), and a controller. The ECM is configured to rotate the fan blade in a first direction to increase draft in the chimney and in a second, opposite direction to decrease draft. The controller has a processor and a program of instructions executable by the processor to perform steps for controlling draft in the chimney with the fan blade. The steps include: comparing condition data from the sensor to set point data to determine if an intervention is required; addressing insufficient draft by actuating the ECM to rotate the axial fan blade in the first direction; and addressing excessive draft by actuating the ECM to rotate the fan blade in the second direction.