Why An HVAC Damper Should Never Be Totally Open Or Closed

HVAC Damper

Knowing how to adjust your HVAC dampers is the best method to control the temperature in your home. Your damper settings determine how much air each of your rooms receives. And because of that, you must adjust your HVAC damper regularly.

Should an HVAC damper be open or closed? An HVAC damper should never be entirely closed or opened. Begin by making small changes in each room. If a room is scorching, open the damper a little more to allow more air to circulate through it.

When making adjustments to your HVAC damper, you have to be very careful. One false move in one room could affect the air quality in the other rooms. The following overview will allow you to understand more about adjusting dampers and air balance.

What Is A Damper?

A damper is a type of valve or plate that controls the flow of air in many systems. Ducts, VAV boxes, chimneys, and other types of air handling equipment are the most common places to find them.

Dampers serve many purposes, especially in HVAC systems. It helps control the temperature of each room in a house. Dampers shut off the flue in chimneys. It keeps the weather and animals out while allowing warm or cool air into the indoors.

There are two damper controls: manual and automatic. Manual dampers handle the outside ducts, while automatic dampers continuously adjust airflow and are controlled by thermostats or building automation systems. It uses either electric motors or pneumatic motors.

When you press a button on an automatic damper, it opens when you need it. If you are not familiar with them, manual ones can be a little more difficult to use.

Different Types Of Dampers

Control Dampers

Control dampers are fitted at various points along with the ductwork to manage airflow through the system. These dampers can also be modified for usage in heating and cooling air mixing zones.

Control dampers will fully open or fully close their blades multiple times throughout the day. This process completes its purpose. To control the blade movements, you can use a range of different actuators.

Balancing Dampers

Air pressure imbalances can cause subtle annoyances for inhabitants. It can cause slamming doors or odd gusts of air, but it can also cause worse system difficulties. To manage air pressure in rooms connected to the ductwork, fit balancing dampers.

A space that is unevenly heated or cooled can be more difficult to heat or cool. It puts additional strain on the air handling devices.

Technicians modify balancing dampers by measuring the air pressure in a room while adjusting the angle of the damper blades.

The blades of the balancing damper are locked in position to maintain the required air pressure after determining the correct air pressure. You can unlock it in the future if you need to make changes.

Backdraft Dampers

Backdraft Dampers (366) are put in specific locations of the ductwork to limit airflow to only one direction. Insert shafts on one end of each blade in these dampers. Transform the damper blade into a flap that only opens when air flows in the proper direction.

If no air passes through or if air begins to flow in the opposite direction, backdraft damper blades will close. You can add a counterweight on backdraft dampers to help or hinder the opening operation. These dampers do not have actuators.

Multi-Zone Dampers

Single-buildings and small-scale buildings with single air handling use multi-zone dampers. These dampers are massive assemblies of many dampers – each has a link to a different zone.

  • Multi-zone dampers control the flow of air throughout the system by connecting to multiple ducts.
  • Multi-zone dampers use multiple actuators; each controls a different zone.
  • Sellers sell multi-zone dampers as a package with the air handling unit.

Industrial Dampers

The design of industrial dampers aims to endure high air pressures and constant temperatures of more than 250 degrees Fahrenheit.

To withstand extreme conditions, they have thick gauge materials, primarily steel. All components are welded in the perfect place to ensure optimal longevity.

The power plant industries can usually see these dampers and other sites that demand high amounts of airflows. Industrial dampers are the most robust dampers available.

Benefits Of An HVAC Damper

Individual room temperatures can be customized using dampers while the central HVAC unit remains in a single setting. An HVAC damper is especially handy if you have older relatives who feel too chilly or too hot in conditions you find comfortable.

Dampers allow the inhabitant of a room to alter the temperature without impacting the rest of the house. For the elderly, comfortable temperatures offer some real health benefits, so this is a must-have piece of equipment if you plan to live in one place with elders.

Another advantage of incorporating dampers in your HVAC system is the potential cost savings. When opposed to individual window-mounted or split-type units per room, a centralized HVAC system consumes significantly less energy.

Completely closing the dampers can be used to close off spare rooms or other locations that require little or no cooling.

How To Determine Whether Or Not An HVAC Damper Is Open or Closed

It can be hard to tell if a damper is open or closed if you are unfamiliar with HVAC systems. However, if you understand what to look for, the process is not nearly as complicated as you think it will be.

All you need to do now is locate the damper and examine its position.

Locating The Damper

You can usually find HVAC dampers in the main supply trunks of most residences. The supply trunks are the ductwork components, depending on the season, blow warm or cold air.

How many dampers do you require? Every house is unique. Some are devoid of dampers. Most homes, hopefully, have an HVAC damper in each supply duct. A supply duct from your furnace may run to the right of your residence. The other one may run to the left.

You can usually find a damper in the supply duct leading to your upstairs. If your ductwork is exposed, inspect all of the runs to see which ones have dampers. Some homes include dampers in each run, which helps to balance the air.

Determining An Open Or Closed Damper

Manufacturers use sheet metal for HVAC dampers. Sheet metal dampers are part of the little wing nut. A flat point in the center of the bolt that runs through the wing nut indicates the damper position.

Look at it and notice if it has been smashed in a particular way. If so, then you will know the damper is in that position. You can see it attached to the section you can turn when you rotate it.

It moves in the same direction when you turn the wing nut. If it is horizontal when you look at it, it is open. How much air passing through the duct will be reduced if you turn it at an angle.

Checking If Dampers Are Open Or Closed

If you are staring at horizontally running ductwork above your head and the small wing is horizontal, it is open. It is also an open damper if you look at a duct coming from the furnace and running straight up like it is going upstairs.

It is also open if the wing is facing the same way as the duct. The damper is closed if the wing is in the opposite or vertical orientation to the ductwork.

Adjusting Your HVAC Dampers

Follow these procedures to adjust your HVAC dampers correctly:

  1. Turn your fan to the on position – Adjust your thermostat so that the system operates while you complete these steps if you do not have a fan setting.

  2. Open every damper all the way – Typically, this entails twisting the lever in the same direction as the duct.

  3. Open every register in your home – The air is now flowing freely throughout the entire system.

  4. Determine which duct serves which rooms – Follow every duct as far as you can from your unit before it disappears. It will give you an idea of which rooms it can accommodate.

    Then, one by one, close the damper on each duct and check which rooms are effected. You can tell since there will be little to no airflow with the registers wide open.

  5. Make initial adjustments – Time to start adjusting your dampers now that you know which duct serves which rooms. Remember that the damper lever is open when it is facing in the same direction as the duct.

    The closer the lever is to be perpendicular to the air duct, the less air goes through. Time to adjust your dampers to maximize your heat as we approach the cold weather season.

Hot air rises, as you may recall from second-grade science lessons. Because warm air rises naturally, you will want to adjust your dampers to give less ventilation upstairs and more airflow downstairs.

During the summer, you will want to do the reverse. If you live in a one-story house, adjust the dampers to provide more warm/cool air to the rooms. Turn your system back to auto after initial tweaks and let it do its job.

  1. Monitor and adjust again – Allow your system to operate for a few days before assessing the level of comfort in each room. If required, re-adjust the dampers, wait a few days, and evaluate your progress. Rinse and repeat until each room is at ease. Also, you must do tiny tweaks.

When some people get home to a coolish house in the winter, they crank up the thermostat to 87 degrees. Do they hope to speed up the process? It isn’t going to happen. Don’t be that man.

Also, don’t close all of your dampers entirely, or you’ll be unsatisfied with the results. More little modifications will save you time and frustration in the long run.

  1. Label the damper position – Mark the position of the damper on the duct after balancing the HVAC system to your maximum comfort level. That way, you won’t have to repeat the experiment the following year.

  2. Adjust your dampers again after switching from heat to air conditioning – Never succumb to the temptation of simply reversing your dampers in cold weather and calling it a day.

    In both the summer and winter, you may find that you prefer closing some dampers. So, make your initial tweaks, watch them, and make adjustments as needed until you’re satisfied. Then, on the duct, mark your summer damper position.

Air Balancing

To transfer air through a house, most household and commercial HVAC systems employ a series of ducts. Many things are happening simultaneously in a fully operating HVAC system.

The heat pump is running smoothly, and the air is circulating freely. Also, the dampers are allowing a specific amount of air to flow through each vent.

Yet, the most crucial aspect of any HVAC system’s flawless operation is ensuring proper air distribution for each room. Adjusting dampers and analyzing air passages can guarantee that one area does not remain toasty warm while another remains frigid.

How To Increase Air Flow In Air Duct With HVAC Damper

So, how do experienced HVAC professionals boost or reduce airflow in your home to reach the optimum balance? They:

  1. Raise or reduce total airflow output, change the system’s blower fan speed.
  2. Examine the ductwork for any signs of damage or weakening. The most common cause of unbalanced air in residential houses is duct design or installation issues.
  3. Ensure that each area receives enough air, add or remove supply, and return ducts.
  4. Seal or insulate accessible under-insulated ducts.
  5. Install dampers in the air ducts to direct the airflow from the HVAC unit. It will distribute the desired amount to each room. Some air ducts already have dampers, which you can adjust easily.
  6. Change the air cleaner/filtration unit’s settings.


Adjusting your dampers requires some patience and time. But it’s well worth it in the long run if you want to maximize your unit’s efficiency.

Knowing the correct opening and closing of the damper will give you comfortable air all year long. Schedule a service call to specialists near you if changing your dampers doesn’t alleviate your heating and cooling discrepancies.

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