The 4 Types Of Dampers: Advantages And Disadvantages

Types Of Dampers

Dampers are used in HVAC (Heating, Ventilation, and Air Conditioning) systems to help control indoor temperatures.

It is in the ductwork, which is in charge of the airflow and distributes it to certain home areas. There are many different types of dampers, and it’s critical to choose the correct one for the job at hand.

How many types of dampers are there in HVAC? There are four types of dampers for HVAC systems. These are the Zone Control Dampers, Back Draft, Economizer, and Face and Bypass. These four types of HVAC dampers work in different ways, but all aim to circulate the best air quality.

Despite their identical appearance, dampers come in several shapes and sizes, which each has a unique function. The following are four types of dampers commonly found in HVAC systems.

Zone Control Dampers

The technique of cooling and heating separate areas using varying temperature settings is known as HVAC zoning.

You can, for example, create a multi-zoned environment in your home. You can set the master bedroom to a different temperature than the living room or kitchen.

You can have many zones in your home while only using one HVAC system with zone dampers. Each zone has its thermostat, which used to necessitate a separate HVAC system.

Multiple thermostats are still in the system, which controls heating and cooling via dampers located in the ductwork.

Open the damper to that zone when a room requires additional air to increase or reduce the temperature. The HVAC system continues to work if the 1st zone temperature reaches its limit but not in zone 2.

However, you have to close the dampers to keep the temperature in zone 1 while zone 2 cools.

Advantages Of Zone Control Dampers

1. Unused Rooms Will No Longer Be Heated Or Cooled

Bye-bye to squandered energy. The top advantage of zonal HVAC is that you have complete control over the distribution of conditioned air. Zone controllers shift duct dampers, preventing airflow to undesirable areas.

You may get some of this functionality by having numerous thermostats. However, this method isn’t feasible when dealing with multiple climate zones.

2. Reduced Maintenance

It is another benefit of reducing the number of rooms your heating and cooling devices must serve all at once. Your HVAC system doesn’t need to work as hard as it did before if you reduce the demand for conditioned air.

3. There Will Be No More Temperature Fights

It isn’t unusual for family members to disagree about thermostat settings. All of your home’s occupants may live in peace while enjoying their distinct air temperature preferences, thanks to zoned HVAC.

Disadvantages Of Zone Control Dampers

HVAC zoning is a fantastic idea and a significant improvement over your current system. It increases efficiency and helps you save money on your energy expenses each month. So, there are a few disadvantages to be aware of.

First, zoning might be a costly first investment. Upgrading to a dual-zone system might cost anywhere from $2,000 to $15,000. Of course, the cost will vary by some factors.

  • The total number of zones
  • The equipment required
  • Labor prices in your area,
  • If old HVAC parts need replacements.

Second, if your system does not have proper construction, expect a loss in all efficiency. A poorly planned and implemented system might cause your monthly expenditures to rise.

If you have the system properly built and installed, the system will pay itself in annual energy and utility savings. It is especially true if you elect to invest in the upfront costs and fees.

Back Draft Dampers

A is also known as a gravity damper. It is a piece of equipment that allows air to flow in one direction while stopping air from flowing in the opposite direction. This process is preventing any backdraft.

Backdraft dampers are popular in heating, ventilation, and air conditioning (HVAC) systems to help with exhaust or intake. A backdraft damper reduces energy loss in a building while simultaneously maintaining a constant pressure in the space.

Backdraft dampers can be mounted vertically and horizontally. However, the mounting direction changes the type of damper that contractors must install.

A motorized backdraft damper can be installed horizontally or vertically by a contractor. It will give the contractor more versatility in the design of the space.

If the HVAC damper is gravity operated, the contractor must install the damper vertically. It will help gravity move the flaps open and close.

Advantage Of  Backdraft Dampers

1. Less Noise

The majority of backdraft dampers on the market are simple to install. With no effort and time, you may easily install one in your vent system.

The damper is a convenient home item since it performs its function silently. It saves you money because you won’t have to hire a professional to conduct the installation.

2. Wide Selection

The dampers come in several sizes, making it simple to pick the right one for your duct system. The backdraft damper is well-made, ensuring years of reliable service.

The springs, metal gauge, and other components are all well-made, resulting in a solid unit. The damper is hard to distort or break.

3. Flexible Ventilation

Backdraft dampers are a flexible household ventilation component. They successfully keep cold air from penetrating the house, especially when it’s freezing outdoors.

The damper’s vent motor is the best feature for boosting household ventilation. It adjusts the vent motor to a higher level of cooking scents that become unpleasant, and household air becomes suffocating.

This HVAC damper is also one of the best in equalizing pressure in various areas of the home.

The backdraft of air is a common concern with the numerous heating options offered in most homes. The damper aids in the release of hot air from the house’s various heating sources while also avoiding a backdraft.

It’s a handy feature for boosting air movement in places like the chimney, attic, laundry room, or furnace room, where the air might get stuffy.

Indoor air can become stale or musty after a while, especially if the house has been vacant. It could happen if nobody is inside while you are away on vacation. Or maybe you have a few rooms in your home that you rarely use.

The damper does a great job of freshening up stagnant air while also preventing outside air from flowing back into the house.

Disadvantages Of  Backdraft Damper

A backdraft damper is excellent for keeping cold air outside during the winter. However, it does not provide control over whether or not cold air escapes during the summer.

A contractor must also incorporate a damper into the ventilation system. You’ll need to replace your backdraft damper if you need to change your home or office ventilation system.

Economizer Dampers

If you wish to save money on energy in your building, an HVAC economizer might be the way to go. Saving energy is a must for most facility managers and building owners, and improving your HVAC system is a great way to see a reduction in overall energy usage.

The outdoor air is drawn in by an HVAC economizer. It is only if the air temperature is lower than the set temperature and the humidity in the building is lower than the set percentage.

This action cuts down on the amount of time your air conditioning unit is on. It will also reduce your unit’s energy use, cutting your power expenses.

Dampers within the economizer govern the air drawn in, recirculated, and evacuated air from the structure. The system also includes logic processors and sensors for external temperature regulation.

These functions will determine whether or not you need to use the economizer due to the weather.

Actuators control the dampers in the system, which open and close them. When the outside air reaches the desired temperature and humidity, the damper will open, and the compressors will turn off.

If the outside temperature is too hot for cooling, the damper will close, limiting ventilation. The return opens as the exhaust fan closes. Finally, the compressors in the unit turn back on to begin the mechanical cooling process.

The three main types of HVAC Economizers:

  • Dry Bulb – The Dry Bulb option only monitors the ambient temperature and ignores humidity. Installing and maintaining this approach is less expensive.
  • Single Enthalpy (Wet Bulb) – Wet Bulb measures the quantity of energy in the air, such as heat and humidity.
  • Differential Enthalpy – With the Differential Enthalpy option, two sensors are in place. Outside, the enthalpy is measured.

Advantages Of Economizer Dampers

1. Improves the Indoor Air Quality

Adding an economizer has many benefits. The most obvious advantage of having an economizer is that it improves interior air quality by improving ventilation.

Consider how some old schools, structures, and some modern ones, fail to emphasize ventilation during construction. An economizer can significantly improve air quality by taking the fresh air in and expelling stale air from a structure.

2. Your HVAC System Will Be Less Stressed

An economizer also minimizes the burden on your HVAC system. As a result, this device can help your HVAC equipment last longer.

Furthermore, because your HVAC equipment is not subjected to as much wear and tear, it requires less maintenance. Your HVAC system will last for a longer time because it will require less maintenance and failures.

3. Easy To Install

An economizer is sometimes already incorporated into HVAC equipment. If your HVAC system does not have an economizer, an HVAC professional can easily install one.

Fortunately, installing an economizer is straightforward, and it doesn’t take up lots of space because these devices are reasonably sized. Furthermore, installing an economizer does not necessitate extensive mechanical or structural work.

4. Cost-Effective: Savings On Energy Bills

Is your building’s energy bill out of hand, particularly during the summer? If this is the case, an economizer can help you save money on electricity.

Consider how an economizer might pull in outside air to provide free cooling for your building. Mechanical refrigeration is reduced by bringing cool outside air into your building. Employing an economizer can save your energy bill by as much as 24 to 35 percent.

Disadvantages Of Economizer Dampers

This system needs return or exhaust fans with higher return air static pressure. Without it, it will not adequately exhaust building air. Without exhaust, the unit cannot bring in outside air, too.

Another issue is the humidity control issues. It may develop if the unit’s leaving air temperature is also reset during the airside economizer cycle. Plus, the fan may use more energy.

It may need humidification during the winter, and there may be a need for more or larger air intake louvers, ducts, or shafts.

Face Bypass Dampers

Face and bypass dampers are conventional control dampers. These are stacked on top of the other (FBV), next to each other (FBH). They can also sit at right angles to each other (FBR).

For simultaneous blade action, the units are in pairs. It forces one damper to open while the other closes. HVAC dampers higher than the maximum single section sizes are equal to single section dampers.

It means that the first section sizes are listed on the damper specification sheet and can be operated in many ways. For multiple section coupling, it commonly needs a jackshaft.

Advantages Of Face Bypass Dampers

A modulating cooling coil is inserted between the film box and the coil section. It adds building air through a mixing box part for ventilation and room pressure adjustment. Also, it needs an extra section installation between the film box and the coil section.

This Face and Bypass part features a set of cross-linked dampers. It flows all of the air through the coil or diverts as much as is required around it.

When portions of the air are modulated around the coil, the airpath will have the same pressure drop as the coil. This process will ensure that the overall discharge air volume does not change.

When dehumidification is required, the temperature of the cooling coil is reduced to remove the moisture. To keep the discharge temperature needed to maintain room temperature, a part of the entering air bypasses the cooling coil.

Disadvantages Of Face Bypass Dampers

The dehumidification cycle is the biggest concern with this type of damper. It sometimes limits the amount of air traveling through the cooling coil to small amounts. As a result, it could not work under extreme conditions, which will need attending to.

Furthermore, the face and bypass dampers would reverse and modulate back open to the coil in this case. The duct temperature would begin to drop.

Also, the reheat valve would be modulated by the duct temperature control loop. As the need for dehumidification decreases, the entire procedure reverses.

Selecting The Best Damper For Your Unit

Dampers are a crucial component of HVAC systems and choosing the proper ones for long-term performance. Here’s all you should know about selecting the correct damper.

The Basics

Dampers regulate airflow in specific areas of an HVAC system. You may require them to open and close, as well as modulate for varying airflow.

You can install them in ducts, on the wall, or as part of air handling equipment. Smoke dampers are specialized dampers that prevent smoke from spreading via ductwork and air transfer apertures.

Dampers are made of metal (aluminum or steel) and have a frame and movable blades. The amount of air that may flow through these blades varies by their position.

Dampers can have HVAC blades that are parallel or opposing. In open/close applications, parallel blade dampers are preferable, while opposing blade dampers are better for modulating airflow.

Sizing And Selecting A Damper

The equation for sizing a damper starts with the maximum airflow through the damper:

  • Airflow = Velocity x Cross-sectional area.

The cross-sectional area of a damper is the free area. It is the area where air can flow when the damper is fully opened.

Manufacturers display this data in graphs. Use these charts to determine the height and width of your damper once you’ve calculated your free area for a specific velocity.

The fan must overcome the damper pressure drop to guarantee that the dampers do not cause airflow problems. To lessen the pressure drop, you may need to oversize your HVAC damper, depending on the situation.

The application determines which velocity to use when sizing the damper. To prevent rain from entering, reduce the intake velocity to 450-500 feet per minute (fpm). Exhaust velocities can reach 1200 feet per minute.

When choosing a damper, you must also consider whether the blades should be weather-sealed or insulated. Intake and exhaust dampers that are exposed to the elements should use weather-sealed and insulated dampers.


Dampers can be automatic or manual, and with the rise in building automation, it’s more vital than ever to get the controls correct. Actuators play a role in this.

Actuators serve as the link between the control system and the mechanical system. They are essential for precise control.

Actuators often get 80 percent or more direct digital control (DDC) outputs in the HVAC system. Incorrect damper or actuator sizing cannot be compensated for by a controller.


There are several types of dampers, each of which serves a specific purpose. All of these dampers may be required to function together in your HVAC system. In fact, you’ll probably utilize all of these dampers.

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