Adjusting air flow in your ducts

June 5, 2012

     Some rooms need more airflow than others, and sometimes there is a temperature disparity between rooms and/or levels in your home. Adjusting the air flow rate in the duct can help to alleviate these issues. This can be done by adjusting what are called dampers in the system. There are basically three types of dampers - Face, Branch, and Main dampers. Face dampers are the ones that are on the face of the register itself. These can be used to regulate airflow if needed, but this is not the most desired method. 
     The second are the small levers located on the round branch ducts. These levers can be adjusted to regulate air flow closer to the source. If the lever is parallel to the pipe, the damper is open. If the lever is perpendicular to the pipe the damper is shut, and there is a varying degree of settings in between. These are the best dampers to use to regulate the air into individual rooms.
     Main dampers are the dampers that are located in the larger main trunk lines. Not all systems have these, but if installed it gives the home owner another avenue of adjusting airflow if needed. An example of this would be regulating the airflow out of either side of a tee fitting, and the levers themselves are often similar to branch dampers.
     Remember bathrooms need less incoming air than other rooms, and second floor rooms may need more. By using the dampers to limit or increase airflow you may be able to increase comfort levels in the home overall.
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Comments (2) - Post a Comment
Good to know. Does the same rule apply to adjusting the large levers on main trunk line? So when they are perpendicular to the trunk, the air flow is stopped?
My levers read open and shut. I will try to adjust them to the parallel position, as the 2nd floor is hardly getting any air flow. The "parallel" position of the large levers is right between "open", or "shut".
martha roessner at 1:42pm EDT - June 18, 2014
Yes, the levers need to be parallel with the duct in order for them to be open. Slight adjustments are sometimes made in in main trunks in order to force more air to certain sides or floors of the house. Minor adjustments should be made, then monitored for a couple of days. Further adjustments can be made as needed until optimum conditions are met.
Eric Morrow at 10:49am EDT - June 19, 2014

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