Heating and Ventilation (HVAC) System Controls

Air Registers and Duct Dampers

To control your heating and air conditioning air flow, you may adjust the floor and ceiling registers OR the damper levers on the ducts in the utility closet.  You have two choices and it is a matter of personal comfort and convenience as long as you maintain a consistent air flow.  It can take 24 hours for the HVAC system to balance itself after you make any major changes to the damper controls although you will feel the air flow (cool or heat) within a few minutes.  Click here to go to the Photo Gallery and find the album entitled "Duct Damper Levers" for further instructions and photos.


Adjust the DAMPER CONTROLS and leave the registers in one position year round:


1.  Set your registers in one position, optimally 1/4 to 3/4 open at all times.


2.  Adjust your two damper levers to either the Open or Closed position, depending on the season of the year.  The levers are located on the duct work in the utility closet near the ceiling.  One is usually easy to spot, but the other one is often hidden and not easily accessible - I've attached a bent wire coat hanger through the loop of my less accessible control so I can just pull it down or push it up with ease. Hopefully there are markings on your duct work near the levers to tell you which position is Open and which is Closed.  One damper lever might be also marked for 1st and 2nd floor, the other for 3rd floor. When one lever is in the Open position, the other should be in the Closed position.


3.  In summer, move the 3rd floor damper lever to the Open position and the 1st and 2nd floor damper lever to the Closed position.


4.  In winter, move the 3rd floor damper lever to the Closed position and the 1st and 2nd floor damper to the Open position.


For convenience, you can mark the Open and Closed positions of each damper as "Summer" and "Winter" to direct the air flow to the proper floor.  You may have to test which one controls which floors by closing one damper all the way and leaving the other one open, then turning your thermostat way down (for Air Conditioning) or way up (for Heating), then check the registers on each floor to see the volume of air coming out. 


It is acceptable to position the dampers anywhere between Open and Closed positions, but the most effective method for a balanced system is fully open or closed.


Adjust individual REGISTERS and leave the damper controls in one position year round:


Set both of your dampers to a middle position between OPEN and CLOSE, and then adjust your registers individually.