How to Adjust Home Heating Ducts

Adjusting the ductwork in a home requires patience to obtain the proper air flow in each room.


Getting the proper flow of hot or cold air to a room in your home can be problematic; common issues include the downstairs rooms being too cold and the upstairs rooms being too hot. However, don't call the furnace repairman just yet; there is a simple method for finding the perfect temperature that requires more patience than skill.

  1. Locate the register for the duct that needs adjusting. This may be on the floor or on the wall by the floor; in some older homes, it may be up toward the ceiling. The register will appear as a grate with thin slats over a hole allowing hot or cold air into the room. A small lever on the side will move brackets inside the register, allowing for more air or less air to enter the room. Adjust the register brackets to the desired air flow and repeat as necessary for each duct. This is the easiest method to adjust air flow from furnaces and air conditioners.

  2. Adjust the "balancing dampeners" for better control of the air flow coming from the duct, as well. These will be near the furnace, on the side of the duct as it moves out or upward toward the house and away from the furnace. Dampeners are controlled by either round knobs or long, thin levers that open and close a shield on the inside of the duct. If the lever is parallel to the duct, the shield is completely open for maximum airflow; if the lever is horizontal to the duct, it is closed. Knobs are usually set to open the dampener when turned clockwise; to close it when turned counterclockwise.

  3. Monitor the room where you adjusted the duct. Check the temperature in six to eight hours to see if it has cooled or heated to the desired level. If not, adjust the duct register or dampener again; check the temperature in another six to eight hours to see if there has been a change. Continue monitoring the temperature and adjusting the duct until you attain the desired airflow for the room.

  4. Tip

    You may need to adjust the duct again when the season changes and you need more or less hot or cold air.


    It could take up to a week to adjust the ductwork for the desired air flow in each room.

About the Author

Lori Lapierre


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