How to Find Dampers in Ductwork and Adjust Them to Control Your Home’s Airflow
This simple HVAC part is the key to a more comfortable and well-ventilated home
Dampers are small but mighty components of your HVAC system, helping direct airflow and regulate the temperature inside your house. Depending on the season, you can open and close these valve-like devices to warm or cool your home—but to do that, you have to know where they are. Below, we’ll explain how to find dampers in ductwork so you can adjust them and keep your house comfortable all year.
What Are HVAC Dampers?
"Quality ductwork will increase the efficiency of your HVAC, sometimes even by 20-30%. This is so because there is reduced air leakage due to better insulation and more optimized airflow. Because this makes your HVAC work more efficiently, it really doesn't have to work too hard to keep the desired temperature; thus, its energy consumption is lowered directly."
— Yashar Mosaferi, President of Klondike AC, Casper, WY
First things first: What is a damper? HVAC dampers (or duct dampers) are valves inside your ductwork. Like a dam, you can open and close your dampers to control how much air comes through your HVAC system.
You’ll want to open and close your dampers throughout the year to direct airflow to the parts of your home that need heating or cooling. For example, in summer, it’s best to open upstairs dampers and close downstairs ones so cool air flows upwards. In winter, it’s the opposite.
Types of HVAC Dampers
There are two categories of dampers: manual and automatic. If you have manual dampers, you’ll need to adjust them by hand whenever you need to control airflow in your home. Automatic dampers have motors to open and close automatically, so you don’t need to do it yourself. Homes with HVAC zoning systems use automatic dampers.
There are multiple types of dampers in these categories:
Butterfly flat dish dampers: These easy-to-install dampers have butterfly-shaped hinges and circular blades that open and close to control airflow. They’re best suited for round ducts.
Louver dampers: Louver dampers have slats that automatically close depending on the pressure levels in your ductwork. They work well with all duct sizes.
Blade dampers: Blade dampers have two blades that move in the same or opposite direction to control airflow.
Inlet vane dampers: Rather than directing or controlling airflow, inlet vane dampers are like small vents and help adjust the air pressure in your ducts.
How to Find Your HVAC Dampers
If you have manual dampers, it’s essential to know where they are since you’ll need to adjust them when the seasons change.
HVAC dampers are most often found in the main trunk line before and after major junctions. You can also find them at various points on multiple system ducts, with two dampers on every main line 90 degrees apart.
Next, find your HVAC system’s main trunk line, the large duct that comes from your furnace and distributes air into your home. Then, trace the main trunk line until you see a lever or handle attached to the duct. This is your damper.
Not every house has dampers, so don’t panic if you can’t find any. However, dampers are great for regulating airflow and temperature, so you might want to hire a pro to install some if you don't have them.
How to Take Care of Your Dampers and Ductwork
Your dampers play a pivotal role in keeping your house comfortable and well-ventilated, so it’s important to look after them—and the ducts that they’re in. Here are some tips for taking care of your dampers and ductwork.
Take note of any strange sounds in your ductwork. Older dampers often swing open and close, making booming or banging noises. If that’s happening at your house, bring it up with your HVAC specialist.
Stay on top of your HVAC inspections. Ideally, you should have a pro inspect your HVAC system—including your dampers—twice yearly. On average, each visit costs between $150 and $500.
Clean your ducts when necessary. If you notice excessive dirt and debris, mold and mildew, or vermin inside your ducts, it’s time to clean them. Air duct cleaning costs usually range from $270 to $490.
DIY vs. Hiring a Pro to Locate Your HVAC Dampers
You shouldn’t have much trouble locating and adjusting your dampers, but if you do, don’t hesitate to call a local duct installer. They can show you where to find your dampers, teach you how to open and close them, and ensure they’re in good working condition. If you need to replace a broken damper or install a new one, they can handle that, too.
Frequently Asked Questions
You might have dampers if you have a ducted heating and cooling system. To find out for sure, find the main trunk line on your HVAC unit, then look for levers or handles on the ductwork. Contact a local HVAC professional if you can’t find any dampers or want to install some.
You can look at the duct damper’s lever to see if it’s open or closed. If the lever is parallel to the duct, the damper is open. If it’s perpendicular, the damper is closed. Alternatively, you can hold your hand against vents throughout your home. If you feel air coming out, that damper is partially or fully open. No airflow likely means that the damper is closed.
You can test a manual damper by closing it, running your HVAC system, and checking the airflow. If air comes from your vents while the damper is closed, you could have a faulty damper. To see if an automatic damper is bad, turn on your HVAC system and monitor the airflow. You might have a damper issue if there’s not much air, the room won’t maintain temperature, or it feels drafty.