Duct Heater Selection Guide: Power, Size, and Material

air duct heater

Duct heaters are crucial in numerous heating applications, providing warmth and comfort in residential, commercial, and industrial settings. These heating devices are designed to integrate seamlessly into HVAC (Heating, Ventilation, and Air Conditioning) systems, allowing for efficient and controlled air heating within the ductwork. Duct heaters are commonly used in heating systems where a centralized heat source is required to maintain optimal indoor temperatures.

In residential applications, duct heaters contribute to the overall comfort of homes by ensuring warm air is distributed evenly throughout living spaces. They are typically found in forced-air heating systems, where heated air is pushed through ducts and released into different rooms. Homeowners can achieve a consistent and cozy atmosphere by integrating duct heaters into such scenarios, regardless of external weather conditions.

Similarly, duct heaters are employed in commercial buildings to maintain comfortable indoor environments for employees, customers, and visitors. These heaters are widely used in offices, retail spaces, educational institutions, and healthcare facilities, where precise temperature control is essential for productivity, customer satisfaction, and well-being. Duct heaters are often a crucial component of larger HVAC systems, working with air handlers and ductwork to provide the necessary heat.

air duct heater

Understanding Duct Heaters


What duct heaters are

Duct heaters are specialized heating devices integrated into HVAC systems to heat the air flowing through ductwork. They serve the essential purpose of raising the temperature of the air before it is distributed throughout a building or space. Duct heaters are typically installed within the ductwork, either directly or near the airflow, ensuring efficient heating and temperature control.

Incorporating duct heaters into heating systems makes it possible to maintain desired indoor temperatures regardless of external weather conditions. These heaters allow for precise control over the heat introduced into the airflow, enabling comfortable residential, commercial, and industrial environments.

Click here to learn more about it.


Different types of duct heaters

Various types of duct heaters are available, each with its characteristics and suitability for different applications. The two primary types are electric duct heaters and gas-fired duct heaters.

  1. Electric Duct Heaters. Electric duct heaters are the most common type and operate using electrical resistance heating elements. These heating elements, typically made of alloys such as nickel-chromium, are energized by an electric power source, generating heat through the resistance to electric current flow. Electric duct heaters offer precise temperature control, rapid response time, and relatively easy installation. They are predominantly used in residential, commercial, and industrial applications where electricity is readily available.

2. Gas-Fired Duct Heaters. Gas-fired duct heaters utilize a combustion process to generate heat. They are equipped with a gas burner assembly that ignites a mixture of fuel (natural gas, propane, or oil) and air, producing a flame. Heat is transferred from the love to the surrounding air, then distributed through the ductwork. Gas-fired duct heaters are known for their high heating capacities, making them suitable for larger spaces or industrial applications requiring substantial heat output.


Components and functions of duct heaters

Duct heaters comprise several vital components that provide efficient heating within HVAC systems.

  1. Heating Elements: The heating elements, commonly coiled or rod-shaped resistive wires, are the primary components responsible for generating heat. Electric current passing through these elements encounters resistance, converting electrical energy into heat energy.
  2. Control Panel: The control panel houses the necessary controls, switches, and safety features for operating and monitoring the duct heater. It allows users to adjust temperature settings, set operating modes, and ensure safety measures are in place.
  3. Airflow Sensor: An airflow sensor is often incorporated into duct heaters to detect the presence and velocity of airflow. This sensor ensures that the heating elements are only energized with adequate airflow, preventing overheating and potential damage.
  4. Safety Features: Duct heaters have various safety features to prevent overheating, electrical malfunctions, or fire hazards. These features may include thermal cutouts, limit switches, and overcurrent protection devices, which help safeguard the heater and the surrounding environment.

The functioning of a duct heater involves the controlled passage of air over the heating elements. When the heater is activated, the heating elements generate heat, which is transferred to the passing airflow. The heated air is distributed throughout the ductwork, raising the temperature within the building or space. Precise control mechanisms ensure that the desired temperature is maintained consistently.

Understanding the different types of duct heaters and their components allows for informed decision-making during the selection process, considering factors such as energy efficiency, heating capacity, and compatibility with the existing HVAC system.

Why it is crucial to choose an air duct heater

Selecting the appropriate power, size, and material for duct heaters is vital to ensure efficient and effective heating performance. These factors significantly impact the heater’s functionality, energy consumption, longevity, and overall performance.


  1. Power: Choosing the correct power output is crucial to meet the heating requirements of the space. Undersized heaters may need help to generate sufficient heat, resulting in inadequate warming, while oversized heaters may lead to energy wastage and higher operating costs. By accurately assessing the system’s heating load and heat loss/gain, selecting a duct heater with the optimal wattage or BTU (British Thermal Unit) output is possible, ensuring efficient and cost-effective heating.
  2. Size: Proper sizing of duct heaters is essential to ensure compatibility with the available space within the duct system. Large heaters may not fit or cause airflow disruptions, while undersized heaters might not provide the necessary heat output. By considering factors such as the dimensions of the ductwork, airflow velocity, and pressure drop effects, one can select a duct heater that fits seamlessly into the existing system while maintaining optimal airflow and efficiency.
  3. Material: The choice of materials for duct heaters is critical to their performance, durability, and compatibility with the intended application. Different materials offer varying resistance levels to heat, corrosion, and chemical exposure. For instance, stainless steel may be preferred in corrosive environments, while galvanized steel or aluminum could be suitable for general heating applications. Selecting the right material ensures the heater’s longevity, efficient heat transfer, and ability to withstand the specific environmental conditions it will encounter.


Considering these factors during the selection process, one can optimize the performance and longevity of duct heaters, ultimately leading to energy efficiency, cost savings, and enhanced comfort in residential, commercial, and industrial spaces.


How to Choose the duct heater?

Power Considerations for Duct Heaters

  1. Factors to consider when determining the required power output

When selecting a duct heater, it is crucial to decide on the appropriate power output to meet the heating requirements of the specific application. Several factors should be taken into consideration during this process:

Heating load calculations based on the specific application. The heating load calculation involves assessing the heat energy required to achieve and maintain the desired indoor temperature. Factors such as the size of the space, insulation levels, outdoor temperature, and ventilation rate should be considered. Conducting a thorough heating load calculation provides a baseline for determining the necessary power output of the duct heater.

It understands the heat loss/gain of the system. Heat loss refers to the amount of heat that escapes from the building or space, while heat gain refers to heat from external sources. Evaluating the heat loss and growth of the system allows for a more accurate estimation of the power requirements. Insulation quality, air leakage, windows, and occupancy levels influence heat loss and gain.

2.  Choosing the appropriate wattage or BTU output based on power requirements

Once the heating load and heat loss/gain are determined, choosing the appropriate wattage or BTU output for the duct heater is essential. This involves matching the heater’s power output to the calculated heating requirements.

For electric duct heaters, wattage is the primary unit of measurement, indicating the amount of electrical power consumed by the heater. The wattage requirement depends on the desired temperature rise, airflow rate, and system heat loss. Selecting a duct heater with a wattage rating that aligns with the calculated heating load is essential.

Gas-fired duct heaters are typically rated in BTUs (British Thermal Units), which represent the amount or level of heat energy required to raise the temperature of one pound of water by one degree Fahrenheit. The BTU rating should be determined based on the heating load calculations, considering factors such as the gas supply pressure, combustion efficiency, and desired temperature rise.


3. Importance of proper power sizing for efficient heating and energy savings

Proper power sizing is crucial for ensuring efficient heating and achieving energy savings. Undersized duct heaters may need help to meet the heating demands of the space, resulting in insufficient warmth and potentially overworking the heater. Conversely, oversized heaters may consume excess energy and lead to unnecessary heating costs.

By accurately matching the power output of the duct heater to the heating requirements, optimal energy efficiency can be achieved. The heater operates at its intended capacity, providing heat without wastage. Proper power sizing ensures comfortable and consistent heating and contributes to cost savings and reduced environmental impact.

Furthermore, efficient power sizing helps prevent premature wear and tear of the heater components, prolonging the lifespan of the equipment. It minimizes the likelihood of overheating or overloading, promoting safe and reliable operation.

In summary, considering the heating load, heat loss/gain, and selecting the appropriate power output for the duct heater is vital for achieving efficient and effective heating. Proper power sizing leads to energy savings, improved comfort, and extended equipment lifespan.


Size Selection for Duct Heaters

  1. Determining the appropriate physical dimensions of the duct heater

When selecting a duct heater, it is crucial to consider the physical dimensions to ensure proper integration and functionality within the HVAC system. The following factors should be taken into account.

Heater Length and Width. Assess the space within the duct system to determine the maximum allowable dimensions for the duct heater. Consider factors such as the dimensions of the ductwork, clearances required for installation, and any obstructions that may limit the size of the heater.

Heater Depth. The depth of the duct heater is significant to ensure proper airflow and avoid restrictions within the duct system. Consider the space between the duct walls or other components that may affect the depth of the heater.

size of the air duct heater

2. Evaluating the available space within the duct system for installation

The open space within the duct system is a critical factor in selecting the size of the duct heater. Evaluate the following aspects to ensure proper installation.

Duct Size. Consider the dimensions of the existing ductwork, including the height, width, and depth. The duct heater should align with the dimensions of the duct to facilitate seamless integration.

Clearances. Determine the permissions required for the installation of the duct heater. This includes sufficient space for electrical connections, access for maintenance, and any safety regulations or codes that specify minimum clearances.


3. Considering airflow velocity and pressure drop effects on sizing

The airflow velocity and pressure drop within the duct system can impact the size selection of the duct heater. Consider the following factors:

Airflow Velocity. Evaluate the airflow velocity within the ductwork. Ensure that the duct heater’s size is appropriate for the volume of air passing through the system. Higher airflow velocities may require larger duct heaters to maintain effective heating.

Pressure Drop. Consider the pressure drop caused by installing the duct heater. Pressure drop refers to reducing air pressure as it flows through the heater. Choosing a duct heater that minimizes pressure drop is important to avoid hindering the overall HVAC system performance.


4. Ensuring compatibility with existing ductwork and HVAC system

Compatibility with the existing ductwork and HVAC system is crucial for successfully integrating the duct heater. Consider the following factors:

Ductwork Connections. Ensure the duct heater has compatible connections that align with the existing ductwork. This includes matching the diameter and shape of the inlet and outlet connections for a seamless fit.

HVAC System Capacity. Evaluate the capacity and specifications of the HVAC system to ensure that the selected duct heater is compatible with the system’s heating load requirements and can be adequately supported.

By considering the physical dimensions, available space, airflow velocity, pressure drop effects, and compatibility with the existing ductwork and HVAC system, one can select a duct heater that fits appropriately and operates efficiently within the heating system. Proper size selection ensures optimal airflow, heating performance, and system compatibility, contributing to the overall effectiveness and longevity of the HVAC system.


Material Selection for Duct Heaters

1. common materials used in duct heater construction.

Duct heaters are constructed using various materials, each chosen for its specific properties and suitability for different applications. The following materials are commonly used in duct heater construction.

Stainless Steel. Stainless steel is a widely known choice due to its excellent corrosion resistance properties. It is highly resistant to rust, oxidation, and chemical exposure, making it suitable for applications where the duct heater may be exposed to corrosive environments or high humidity levels.

Galvanized Steel. Galvanized steel is coated with a layer of zinc, providing a protective barrier against corrosion. It offers good durability and resistance to environmental elements, making it suitable for general heating applications.

Incoloy. Incoloy is a nickel-chromium-based alloy that provides high-temperature strength and excellent resistance to corrosion and oxidation. It is commonly used in duct heaters that operate at elevated temperatures or in environments with corrosive gases or chemicals.

Ceramic. Ceramic materials are known for their excellent thermal insulation properties. They can withstand high temperatures, providing efficient heat transfer while minimizing heat loss to the surrounding environment. Ceramic materials are often used in insulation elements or as insulating supports in duct heaters.

air duct heater

2. Factors to consider when selecting materials

When selecting materials for duct heaters, several factors should be considered to ensure optimal performance and longevity:

Compatibility with the intended application. Evaluate the environmental conditions and potential exposure to corrosive gases, chemicals, or moisture. Choose materials with high corrosion resistance to ensure the duct heater can withstand the specific application’s demands.

Heat transfer efficiency and insulation properties. Consider the material’s ability to transfer heat effectively and efficiently. Look for fabrics that promote good heat transfer while minimizing heat loss to maximize energy efficiency. Additionally, materials with good insulation properties help retain heat within the duct heater, reducing heat loss during operation.

Durability and maintenance requirements. Assess the material’s durability and its ability to withstand mechanical stress, thermal cycling, and potential wear and tear. Additionally, consider the maintenance requirements associated with the material, such as cleaning, corrosion prevention, or surface treatments.


3. Examples of suitable materials based on different scenarios

Stainless Steel. Stainless steel is an excellent choice for duct heaters installed in environments with high humidity, corrosive gases, or chemicals. It provides superior corrosion resistance, ensuring the longevity and reliability of the heater.

Galvanized Steel. Galvanized steel is suitable for general heating applications where corrosion resistance is required, but exposure to corrosive elements is relatively low. It is durable and commonly used in residential and commercial duct heaters.

Incoloy. Incoloy is ideal for high-temperature applications or environments with corrosive gases or chemicals. It provides excellent corrosion resistance and high-temperature strength, making it suitable for industrial processes or specialized heating requirements.

Ceramic. Ceramic materials are often used for insulation components in duct heaters. They provide excellent thermal insulation properties, reducing heat loss and improving energy efficiency. Ceramic insulation elements help maintain high temperatures within the heater while protecting the surrounding components.

It is essential to consult with manufacturers, suppliers, or industry experts to determine the most suitable materials based on the specific application requirements and environmental conditions. Their expertise can help ensure the selection of materials that offer the best performance, longevity, and compatibility with the intended application of the duct heater.



Duct heaters are essential components in HVAC systems, responsible for raising the temperature of air flowing through the ductwork for comfortable indoor environments.

Selecting the right power, size, and material for duct heaters is crucial for achieving efficient heating and optimal system performance.


Hasteco has many years of coil heater experience; contact us to get a quote.

Sales representive Luke


As the devoted CEO of Hasteco, I've spent countless years nurturing my passion for heating elements. Warmly inviting you to connect & collaborate for cozy, tailor-made solutions. Get in touch!

Get a Free Quote

Table of Contents

On Key

Related Posts

Get the free quote