What is a Range Hood Damper and How Does It Work?

September 04, 2023 8 min read

The range hood in your kitchen is important for keeping the air clean and healthy. But did you know that a small part called the damper helps the range hood do its job? This nifty device ensures air flows in and out of the range hood without issues. The range hood damper functions like a valve for controlling airflow. While it may not be the most obvious component, it plays a vital role in keeping the air clean.


We will cover the core parts and features of a range hood damper. You will learn what a range hood damper is, how it works, and the different types of range hood dampers. If you want to replace an old damper or learn more about dampers, this is for you. Read on to learn everything about range hood dampers.

What is a Range Hood Damper?

A range hood damper, also known as a draft regulator, is a valve or plate located within the ductwork of a range hood. It controls airflow direction, allowing air to move through the range hood ductwork. It opens when the hood is venting, allowing air to flow out, and closes when it is off. This removes pollutants and stops dust and debris from returning to the kitchen. Dampers can also play a role in reducing noise from range hood systems. Maintaining steady airflow and reducing turbulence in ducts helps create a quieter environment.

The key components of a range hood damper include the flaps, hinge, spring, seals, and mounting brackets. The  flaps are the primary moving parts, opening and closing to control airflow. The  hinge allows the flaps to pivot smoothly, so they respond quickly to changes in air pressure. A  spring keeps the flap closed when the range hood is off, maintaining a proper seal. The  mounting bracket secures the damper within the duct system, holding it firmly in place during operation. To ensure airtightness,  seals  line the edges of the damper, preventing leaks when the flap is closed.

HOW DOES A RANGE HOOD DAMPER WORK?

The primary role of the damper is to control the direction of air movement. It does this based on air pressure changes in the range hood duct. The damper can open and close using springs and pivots sensitive to air pressure changes. When the fan is turned on, the increased air pressure in the duct causes the damper to open. When the fan is turned off, the decreased air pressure allows the damper to close.

This means the basic operation of the range hood damper is this:

The damper flap swings open under positive pressure (when the fan is on) and closes when the pressure drops (when the fan is off).

Learn more about range hood airflow and understand the science behind it.

TYPES OF RANGE HOOD DAMPERS

Dampers can be classified based on their application and mechanisms. The main types of range hood dampers are:

1. GRAVITY DAMPERS

A gravity damper is a type of range hood damper that operates using gravity to open and close. It controls airflow in ventilation systems, letting air escape while stopping backdrafts.

Gravity dampers are made of lightweight materials, like aluminum or galvanized steel. They have a simple design of a flap attached to a hinge. When the range hood fan is turned on, the increased air pressure causes the flap to swing open, allowing air to flow out. When the fan is off, gravity pulls the flap closed, sealing off the duct and preventing outside air. They are designed to be installed in a horizontal duct run.

They are easy to install with little maintenance, making them a cost-effective option. However, gravity dampers have limitations in terms of air control. They are less effective in preventing backdrafts and can sometimes be noisy when the flap swings open and shut. They are also not durable in ducts with high pressure and strong airflow.

2. BUTTERFLY DAMPERS

A butterfly damper is a range hood damper that uses a set of blades resembling butterfly wings to regulate airflow. It is also made with aluminum or galvanized steel and can be manual or motorized.

When the range hood fan is turned on, the butterfly damper opens to allow air to flow out of the kitchen. When the fan is turned off, the damper blades close, preventing air from flowing back into the kitchen. The blades can be adjusted to control the air flowing through the ductwork.

Butterfly dampers are popular for those who want greater control over their ventilation system. They are suitable for applications that need precise airflow control, like in commercial kitchens. Motorized versions can be controlled with a switch or remote control.

3. BACKDRAFT DAMPERS

A backdraft damper is a special range hood damper that stops cold air from outside from flowing back into the kitchen. This type of damper is installed at the point where the range hood ductwork exits the building.

Backdraft dampers use a one-way flap that allows air to flow out of the kitchen. The flap is spring-loaded and held closed by the air pressure inside the ductwork. When the range hood fan is turned on, the airflow pressure opens the flap, allowing air to escape. The flap closes again when the fan is off, preventing outside air from entering the kitchen.

The range hood backdraft damper stops outdoor pollutants like dust and allergens from entering the kitchen. They also protect against wind-induced downdrafts, which can cause smoke and fumes to backflow into the kitchen.

Backdraft dampers are commonly used in kitchen ventilation systems in areas prone to high winds. They are also used in industrial areas or where outdoor pollutants are common.

4. Control Dampers

A control damper is a range hood damper used to regulate the volume of air flowing through a kitchen ventilation system. It is a more advanced version of the gravity and butterfly dampers. It is common in larger commercial kitchen ventilation systems.

Control dampers use a set of blades to adjust the amount of air that passes through the ductwork. The blades are attached to a motor or actuator, which opens or closes them, letting the user adjust the airflow as needed. Control dampers offer two operation options: manual or automatic. It is used with a wall or roof cap to ensure optimal airflow and good air quality in the kitchen. Some models can be integrated with a building automation system, enabling remote control.

They have precise air control, which can help maintain consistent indoor air quality. They are also easy to install and maintain. However, they are more expensive than gravity dampers and butterfly dampers. They are often installed where the range hood connects with the central ductwork.

5. BALANCING DAMPERS

Balancing dampers are used in ventilation systems with multiple exhaust hoods and ductwork. They are used to regulate and equalize airflow between different areas or rooms. They are often installed at the branch points where the ductwork divides into smaller sections. They work best at points in the ductwork leading to various rooms.

Balancing dampers are designed to adjust the amount of airflow in a duct system. They help ensure that each connected kitchen area receives the appropriate air. This prevents some areas from being over-ventilated while others are under-ventilated.

Balancing dampers can be manually operated or have automatic controls that respond to changes in air pressure. This allows for dynamic adjustments based on real-time conditions within the building. Balancing dampers are designed to prevent excessive pressure in any one section of the duct system. It helps maintain consistent temperatures and air quality in all rooms.

6. SHUT OFF DAMPERS

Shut-off dampers are a type of range hood damper that can completely shut off the airflow in a kitchen ventilation system. These dampers are usually used in emergencies or when maintenance needs to be performed on the system.

Shut-off dampers use a rotated blade or disc to block or allow airflow. They are often motorized and controlled by a switch or automated system.

The main advantage of shut-off dampers is their ability to quickly and effectively stop airflow. This can be important in a fire or other emergency. However, they can also be expensive to install and maintain and may not be necessary for all kitchen ventilation systems.

Shut-off dampers are used in commercial vent systems that have fire suppression units. They may also be used in residential systems for added safety measures.

Learn more about residential kitchen hood code requirements

HOW TO CHOOSE THE RIGHT RANGE HOOD DAMPER

A range hood damper is a crucial part of your kitchen ventilation system. It ensures the smooth removal of smoke, fumes, and moisture. To select the perfect damper, consider the following key factors:

1. Assess Your Damper Functionality

The functionality of dampers is a critical aspect to consider when selecting the right one for your ventilation system. Dampers serve various purposes, with some even performing multiple roles. Understanding these can help you choose the most suitable type for your kitchen needs. Check if the damper's main function will be to prevent backdrafts, control airflow, or provide balance. Assessing how you want your damper to function will ensure you choose the right one.

2. Match the Damper to the Ductwork Size and Shape

The damper’s size must align with the ductwork for proper airflow. Ensure the damper matches the dimensions and shape of your ductwork. This ensures a proper fit that allows for optimal airflow without restrictions. A damper that is too small can cause back pressure, while one that is too large may lead to air leaks.

Dampers come in various shapes, including round, rectangular, and square. The shape should correspond to the duct shape to maintain airflow efficiency. Round dampers are ideal for spiral ductwork, while rectangular dampers are better suited for traditional rectangular ducts.

3. Check the Maximum Pressure Rating of the Damper

Each damper model is designed to operate within specific pressure limits. This value is typically expressed in Pascals (Pa) or inches of water gauge (in. wg). This rating shows the maximum static pressure a damper can withstand without affecting how well it works. Check that the damper can handle the pressure exerted by your range hood or HVAC system. This is crucial for maintaining performance and preventing damage. Operating a damper beyond its maximum pressure rating can lead to malfunction, damage, or complete failure.

4. Consider the Air Volume (CFM Rating) of the Range Hood

Range hoods are rated by air volume, measured in  cubic feet per minute (CFM). Select a damper rated to handle the fan's maximum CFM. If the damper cannot match or exceed the range hood's CFM, it may restrict airflow and impair performance. Ensure it can operate effectively without damage at these speeds. A higher CFM results in increased dynamic pressures, which must be accounted for when selecting a damper.

5. Account for Pressure Drops and Leakage With Damper Use

Pressure drops and leakage in any venting system affect efficiency and energy consumption. It refers to air pressure reduction when air passes through dampers, filters, or other obstructions. It is a measure of the resistance that air encounters along its path. The size and configuration of the damper itself can affect pressure drop. Consider how much pressure drop the damper causes. Look for dampers designed to cut leakage when closed. Smaller dampers create more resistance because they often have less free area for air to pass.

6. Durability and Insulation of the Damper Unit

Your damper unit should be able to resist wear and pressure without losing much of its performance. Materials like galvanized steel, aluminum, or stainless steel are major damper materials. They provide strength and resistance to corrosion, moisture, and temperature fluctuations. This contributes to the longevity of the damper. Durable dampers require less frequent replacement and repair, lowering maintenance costs. This reliability is crucial for minimizing downtime in both residential and industrial applications.

FINAL THOUGHTS

A range hood damper is a very nifty device that offers an inexpensive solution to the problematic downside of external venting. Most dampers help maintain the best airflow in the kitchen area. You can vent your kitchen without worrying about backdraft, polluted air, or pathogens finding their way back in.