A Balancing Act: Adjusting Airflow From Your AC

If you have central air, you may have noticed that some rooms remain hotter than others when you are running the air conditioning. There are many factors, such as the number and location of windows in the room or the presence of a frequently used outside door, that can affect how well your AC cools a room. Tweaking the airflow in your duct work to compensate for these factors will keep you and your family more comfortable and help to even out the temperature in your home.

  1. Open all the registers or wall grills in your home. Typically, each room contains one or more grills that can be adjusted via a knob or dial. These are convenient for closing off the airflow to a room for a short period, but should not be relied on as your main means of controlling the airflow in your home. The dials on grills are easily reset when kids play with them or they are bumped while vacuuming or performing other household duties.

  2. Locate the balancing dampers in your duct work. These should be located near the furnace at the beginning of each branch of the duct work. A lever or knob controls the damper inside the duct work. When the lever is positioned across the duct work, it indicates the damper is closed. When the lever is positioned so it runs along the length of the pipe, the damper is fully open.

  3. Open all the balancing dampers. This allows air to flow freely from your unit to the various parts of the house. You may need to adjust the dampers to allow more or less air to flow through that line later, but for now, you want air to flow evenly through all the duct work to all areas of your home.

  4. Observe the temperature in all areas of the house for the next two or three days. This will give you a good starting point for adjusting the airflow to manage the temperature in each room.

  5. Note areas of the home that do not cool properly.

  6. Identify the dampers for the branches of duct work that lead to areas of your home that are currently the coolest when the AC is running.

  7. Partially close these dampers. This will block some of the air flowing to the rooms that are cooled the most and allow a greater portion of cool air to flow to the areas of your home that need more cooling.

  8. Observe the temperature and comfort of your home for a day or two, noting areas that continue to feel too warm (or too cool) for your comfort.

  9. Readjust the balancing dampers to direct more or less cool air to specific parts of your home.

  10. Mark the settings on the duct work and label them as summer settings. This will allow you to reset your dampers to match your cooling needs after the heating season passes.

  11. Follow the same procedure for adjusting the dampers for proper airflow during the heating season. Remember, when it comes to adjusting for warm air, you will need to partially close the duct work to the warmest areas of you home to force warm air to the cooler areas.

Most central air or HVAC systems have balancing dampers. If your system does not have balancing dampers, your local HVAC serviceman can install them for you. Although they will set them according to their professional judgment, you may need to tweak them to meet your specific needs. Leaky windows and doors, outside temperatures, the location of your rooms and kids running in and out to play all affect the inside temperature of individual rooms. Click for more information on how to provide better consistent air flow throughout your home.