HVAC Damper Basics Manual Dampers VS. Automatic Dampers

Fixing Your HVAC Damper

Many people don’t know about HVAC dampers and still have no idea how to keep their homes comfortable all year round.

According to many HVAC technicians, this is valid as this is considered to be one of the less popular parts of the heating and cooling system.

The more popular ones include the coils, compressor, air filters, vents, etc. However, many homeowners still do not know about dampers and their role in regulating temperature in your indoor living spaces.

How do I fix my HVAC damper? To fix your HVAC damper, you need to have a licensed HVAC technician who will look into it. Of course, do-It-Yourself is also a possible route, but it can be less hassle when a professional take care of your HVAC damper.

This article will tackle heating, ventilation, and air conditioning damper basics and the proper ways of handling its maintenance.

HVAC Damper Basics

When it comes to getting the most cost-effective performance from many HVAC systems, many homeowners and businesses strive to achieve this. In addition, many industries are trying to maintain control over the distribution of warm or cool air via the installation of HVAC dampers.

These HVAC dampers are responsible for overseeing the airflow throughout your system.

They are the ones responsible for controlling the amount of heated or cooled air that passes through your HVAC duct system towards your network.

An HVAC damper serves as a valve or plate that can perform a function similar to a traffic cop in a major street or intersection. It also acts in tandem with your thermostat to deliver the right amount of air that generally flows through the system.

HVAC dampers allow for specific control over zone heating and cooling, and using this component can result in significant cost savings.

It is primarily because the responsibility for heating or cooling a room will heavily rely on more than just the thermostat.

In addition, it means that it can permit your central HVAC system to provide temperate air for rooms in use without wasting it in an empty area. It can also allow operators to either limit or completely shut off airflow to new zones. 

Manual Dampers VS. Automatic Dampers

HVAC dampers can be split into two general types, which can be either automatic or manual dampers. Each of these systems brings unique benefits to many HVAC applications, and here are some of their fundamental differences:

Manual Dampers

Most of its levers are located outside of air vents for many manual damper systems, and the duct controls the damper plates or valves. Most manual dampers are pretty straightforward in terms of design, and they allow operators to control the airflow throughout the system intuitively. They also tend to be relatively durable, and the maintenance is free, but not all of them are on the positive side.

Manual dampers lack precision compared to automatic dampers, and they also cannot be operated remotely. This can create difficulties in facilities that mount their HVAC systems on or near every ceiling. Many providers produce a broad range of manual dampers for different installations and OEM replacement. Here are some of the most popular ones you can check out in the market:

  1. Volume dampers can be either gasket or non-gasket, and they consist of collared dampers.

  2. Some cable-controlled volume dampers can provide damper control. It uses a rotary-to-linear mechanical actuator-assembly system for precise and dependable calibration.

  3. You can also check the barometric bypass dampers, preventing damage to many duct systems by bypassing static duct pressure when ducts start to open and close.

  4. Lastly is the manual damper tube assemblies which can offer various standard damper tubes for assembly configurations.

Automatic Dampers

Automatic dampers use small motors that can open and close the damping plates and their valves. The only difference between automatic and manual dampers is that automatic systems can be controlled remotely and can self-regulate in many changing climate environments and conditions.

For example, many operators use a thermostat to designate the desired temperature in various zones. The thermostat will then calculate the precise air temperature and airflow that can achieve the desired conditions.

As a result, many automatic dampers can provide more precise internal climate conditions compared to manual dampers.

They can also be programmed remotely without the hassle of checking the damper physically. As a result, many providers build a wide variety of automatic dampers and systems that meet the needs of their customers. Here are some of them:

  1. Motorized round-tube and collar dampers can offer a variety of types and rectangular collar dampers. It can be helpful for new installations or to replace the old ones in your house or commercial buildings.

  2. There is a modulating damper system that can use a thermostat for airflow and zone control.

  3. Wired zone-control systems are the kind of systems that can automatically adjust the heating or cooling of the areas that need to have greater or lesser airflow.

  4. If there is wired zone-control, there are also wireless zone-control systems that are built to retrofit manual dampers with some motorized remote-control systems.

Custom HVAC Damper Capabilities

Whether you prefer manual or automatic dampers, some providers offer a zone-control system. It is because it provides a broader range of applications in many industries worldwide. In addition to manufacturing a standard system, some providers offer customized HVAC zone-control systems, and it includes the following:

  1. Some custom HVAC dampers are made from galvanized stainless steel, aluminum, plastics, and some other UL-approved materials when coming to materials.

  2. For many damper types, you can choose either a round tube or a collar tube. In addition, there are some which are rectangular, blade, shutter, or radial dampers depending on your specifications.

  3. Some dampers can be customized using manual, wired-zone control, or even wireless zone control capabilities in terms of control methods.

  4. Lead times can be quoted on a job-by-job basis, but most projects usually require ten days. Some providers can do emergency or rush-order as needed but be mindful that it comes with a higher price range.

  5. Many providers offer a broad range of additional manufacturing capabilities like accessories, OEM replacement, assembly, punching, riveting, tooling, barcoding, and packaging for a customized HVAC damper.

Types Of Dampers In HVAC

HVAC system dampers are commonly known as duct dampers or volume balancing dampers. It is a movable plate situated in the ductwork that can regulate airflow and redirect it to specific places.

The usage of dampers can be typically seen in many zoning or zone control systems, an essential part of those industries. It is where gases and liquids are moved through different pipes and ducts to control the flow of materials.

Many air control dampers are available in various sizes and shapes like square, circular, rectangular, and backdraft. In addition, many damper locations, the ducting structure, and its purpose altogether determine its type.

Therefore, when it comes to dampers for HVAC application, you can find many variations, and you can operate them through different means. It includes manual, mechanical, and automatic methods, and some damper types are the following:

Butterfly Flat Dish Damper

Butterfly flat dish damper is known to be designed for high efficiency that has less maintenance. It usually uses a hinge built to fill up the duct when properly lined to restrict airflow accurately. This kind of damper can completely stop the airflow and is also available with multiple blades when necessary.

Another vital thing to notice is that they can prevent backdraft by only enabling the air to flow in a single direction. This makes it a better option for fire prevention and heating application. The application can cover Oxidizers, Baghouses, Scrubbers, Heaters, Precipitators, etc.

Blade Dampers

Blade dampers are originally made of thin metal plates to regulate airflow inside the air handling equipment properly. In addition, there is the presence of blade dampers that contain blades that move in an opposite direction.

Blade dampers are designed for great metering and control of the HVAC systems, and they are equipped with greater strength, superior sealing capacity, and usually produce less noise.

Guillotine Dampers

Guillotine dampers are known for their capability to have the best Seal possible, and they are usually kept in place to block the airflow completely.

However, they can also be used at any place where the proper isolation is required during their regular maintenance or entry to a specific duct behind the required media source.

Louver Dampers

Louver dampers are mainly used For the quick response time and vital air blocking properties. This kind of damper usually uses flat blades on hinges to fill the size of the duct, and they are one of the most frequently used HVAC dampers.

Inlet Vane Dampers

If you deal with Inlet vane dampers, these are mainly used on fan inlet applications that usually provide a better flow of the materials and pressure control.

Their usage can sometimes be seen in many HVC settings where a facility needs full regulation for ventilation. These dampers have multiple blades designed around a central hub, improving the fan’s performance.

It can be done by introducing a swirl into the fan inlet, offering an excellent control method.

The Work Of An HVAC Damper

Multiple components function together to make your home’s HVAC system work. When they are correctly working altogether, your home is expected to be in an excellent state as far as its heating and air conditioner go.

One set of HVAC systems that can help your system meet your indoor space temperature needs is damp.

The most helpful start to understanding how it works is first by mentioning what they are. They are the ones responsible for helping regulate the temperature around your commercial buildings or your personal home.

They serve as valves that decide how much heated or cooled air is required to feed into different areas of your ductwork. It is also responsible for lowering and raising the zone’s temperature to its desired number.

The Operation Of HVAC Dampers

When it comes to how an HVAC damper operates, this question may seem like a repetitive question on how an HVAC works.

But it’s slightly different because it covers the actual mechanism that is behind the dampers. So the function of manual and motorized dampers varies depending on the type of damper you have.

HVAC dampers come in two types, and this is manual and motorized. Manual dampers work by the homeowner twisting a screw to regulate the airflow that goes into specific areas.

On the other hand, motorized damper functions on its own, and motorized dampers are more convenient for homeowners with a programmed HVAC zoning system.

They work consistently with the whole HVAC system and follow the home’s heating and cooling that the owner expressly sets.

Adjusting The HVAC Dampers

The first step is to find your dampers, and this can sometimes be challenging for many homeowners. For example, older homes might have dampers, but some drywall already blocked them after many renovation projects.

So you might need to check the old blueprints to see where the dampers will be. If you cannot find it or tear the wall down to reach it, you might have to resign yourself to adjusting the vents properly.

You should also be aware that there are homes that do not have the balancing damper, and sometimes it is more cost-efficient to remove this from the whole system.

Then again, some more considerate contractors put a vent in the access panel that is covering it. This covering is usually the part of the duct system with a damper while still keeping it accessible.

You can easily shine a light through the vents to try and find it, and once you find the damper, it will get easier from there.

Adjusting the balancing damper is like turning a lever to open and close it, and to be able to achieve that, you need to make sure you are really adjusting the dampers.

You do not want to change the wrong part of the HVAC system, so you need to label the balancing dampers. Make sure you have all the information where it leads, like kitchen, bedroom, and others.

At the same time, this might be tedious for many since they have to open and close their dampers.

Tips When Adjusting The HVAC Dampers

Once you can identify what dampers are for and what effect they will be in different parts of the room, it is time to figure out how to maintain them properly.

First, you need to make sure that you know what to do to make hot or cold airflow in a particular room properly. Again, labeling might be your best route, but there are two essential rules that you need to remember here.

The first is that cold air sinks and hot air floats will heavily affect your indoor spaces’ distribution of cold or hot air. This can only mean that the attic will be the hottest part of the house while your basement will be cold.

Many experts recommend closing the dampers that usually lead to the lower levels of your house. But, unfortunately, it will eventually find its way down, especially if you are cooling your home.

If you want to heat your home, you can do the opposite of what is mentioned above. When the AC is off and fires up your furnace, you want to adjust the dampers to have less airflow in the upper floors.

Eventually, the heat will rise, and the right temperature will be distributed well all over your house.

If this is your first time implementing this to your new home, it might take a couple of days to determine the correct adjustments.

Please do not change your dampers immediately because usually, it will take a few days for the right temperature to kick in. Instead, see if the rooms you want to be hotter or colder turn out as you want them to.

Seasonal Adjustments

So far, the tips provided above that refer to the adjustment will only work during the summer and winter seasons. If you have this mastered, you need to put the exact labels on the damper to know it quickly. This way, adjusting them in the future will be much easier as it’s just one move away.

Summer and winter are not the only seasons that you will face every year. You might be wondering what should be the correct settings for your dampers during the spring and fall season.

The answer is that you need to adjust the dampers when the season changes. It can be helpful to put on some alerts in your calendar so you will be reminded to make the necessary changes.

This will help your indoor spaces to adjust quickly when it gets cold or hot, and if you label your dampers correctly, you won’t be confused as to how you should change them. This can also be applicable even if you change houses as your new owner appreciates your efforts.

Signs That Your HVAC Damper Needs To Be Replaced

Adjustment is essential when it comes to your HVAC dampers, especially during the change of the season. It is also essential to have it looked at now and then to ensure your dampers work efficiently.

The easiest route to determine that something is wrong with your damper is to check whether it is working. It is a straightforward process that you do not need any technician for:

  1. The first thing in the business is to know which zone your damper will affect, and this can be done by following the ductwork from the damper.

    Next, you can see which area of the house the airflow will affect. You need to have access to these registers so you can see them comfortably.

  2. The next thing to figure out is whether your damper is manual or automatic, and by the time you encounter a problem, you should know it. A manual damper should have a handle for adjustments to the ductwork. On the other hand, the automatic damper has motor control, and it can be easily compared to one another.

  3. Get your HVAC blowing and check the vents properly. If your damper is open and the air flows out of the register, this is a positive sign.

    However, you are not in the clear yer as you need to close the damper and see if the airflow is stopped. If it is, you have nothing to worry about, and you can go about your day.

  4. Next is to check if your thermostat is still working correctly. You need to turn it on when you use it and then turn it off and check if it follows your desired instruction.

    If it happens to malfunction, you can quickly solve this by replacing your batteries, but you might need a new thermostat if it does not restore its function.

  5. Always check the thermostat’s calibration, and the essential component of the thermostat is its internal thermometer. Over long periods, these can stop working correctly and check it. However, you can get a cheap thermometer from the store and put it right on your thermostat.

    Then, leave it for a while until the room is cooled or heated, and when the HVAC stops blowing air, you can check to see if the room is at the right temperature.

How To Replace HVAC Dampers

Once you can see the signs and the quick troubleshoot and solution didn’t work, you might need to fix your HVAC damper and replace it.

Manual balancing dampers are usually found in round HVAC ducts ranging from 4 to 10 inches in size. Right after installation, these simple galvanized sheet-metal circles pivot on two pins inserted in a small hole.

For example, you can drill in the start collar of a supply duct or the sides of a register can.

This process needs complete control of the material with a bar called an adjustment handle. You can try to upgrade to fancier dampers such as automated balancers with integrated electronics.

However, it would be best to be an HVAC apprentice for at least hours to replace dampers. For this reason, it is best to ask a professional to do it for you.

Here are some steps that a professional HVAC technician will do to be able to fix your HVAC damper:

  1. The first thing that they will do is access the basement ductwork to locate your existing dampers. Next, they will check to see if the first section of ductwork is near the damper and supports it.

  2. They will score the duct tape or foil at each side of the damper using a utility knife, and one end will connect to the register boot or plenum collar.

    The other will be to a duct section or possibly an elbow. Then they will remove the sheet metal screws through the scoring in the tape. If the tape is initially on the loose end and peeling, they will pull off the tape and then unfasten the screws.

  3. The next step is to pull the nearest duct section out of the damper. It needs to be let its hand suspended for safety purposes. Then they will remove the old damper that is broken and set it aside.

  4. Following that is the brushing of the crimped edge of the damper using a mastic. Again, this is recommended as you can achieve far superior protection against air leaks compared to duct tape.

  5. Slide the new damper’s crimped side into the register boot or in the cramped end of your rigid. The crimped end must be pointing away from the furnace. It is so the air will go past the seam without the fear of any leakage.

  6. Press the un-crimped side of the damper to the other side of the duct run. It will be either a start collar or the crimped end of the duct run.

  7. Secure both ends of the damper using three sheets of metal screws or more if you have larger diameter dampers.

  8. Lastly, they will try to paint the tight joints with additional mastic and then ember fiberglass mesh tape in the coating. You can paint another coat of mastic on your tape as well as the seams of the damper itself.


To summarize, dampers are known to be long-lasting. As a matter of fact, they can be quite a sturdy investment. But when it ceases to work, you need to fix and replace them.

It is not the most expensive type of HVAC repair, but it will run fairways and can at least reach triple digits. Many professional technicians will be able to get this job without any hassle.

It might be within the range of a dedicated DIY amateur process, but it will be easier to finish by a professional.

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