They may be put in while in the HVAC ductwork and are brought on to close whenever they sense smoke. Smoke dampers are usually made of aluminum and have a motorized actuator that closes the damper. Backdraft dampers are either gravity or motorized. Gravity backdraft dampers use the force of https://israelzrhui.blogdemls.com/36609493/air-control-dampers-for-hot-climates-can-be-fun-for-anyone