Backdraft dampers: Set up to allow one particular-way airflow, these varieties incorporate shafts on 1 stop of each blade to avoid air from flowing back again in the alternative route. If required, a counterbalance can assist. Handbook dampers are modified by hand and are typically Utilized in older HVAC programs. https://laneuncqf.bloggactivo.com/35842368/air-control-dampers-for-hot-climates-things-to-know-before-you-buy