Stabilize Fresh Air Temperatures with Electric Duct Heaters


Electric duct heaters are a convenient, affordable and effective way to provide heat to a room or ventilation duct system. Professional HVAC contractors have used these devices in residential, commercial and industrial HVAC systems for many years.

Common Applications for Electric Duct Heaters

The main idea behind heating with an electric duct heater is adding heat to the air inside the duct in an efficient manner. Electric duct heaters can be used in a broad range of applications, some of the most popular of which are:

  • Forced Air Furnaces
  • Heat Recovery Ventilation
  • Tempering outdoor air
  • Makeup Air

When choosing an electric duct heater for your home or workplace, you’ll want to keep the specific application in mind when deciding the model you need.

Types of Heating Elements

Electric Duct Heaters typically use one of two types of heating elements:

  • Tubular elements are ideal in situations when the air in the duct may contain particulates or contaminants. This makes them popular in industrial applications.
  • Open Coil elements are more efficient and less expensive than tubular elements. They are used in HVAC systems where the air has already been filtered. These heating elements are typically made of a nickel chrome composite— they require less airflow than tubular elements, typically resulting in a longer operating life.

Modulating Operation Keeps Costs Low

Electric duct heaters are either designed to be staged on/off or modulating. Of these two, modulation is the best way to control duct temperatures.

On/off design is typically chosen when a duct heater is controlled by a wall thermostat and used to maintain temperature in a room.  Modulation is best when a heater is used to maintain a set temperature in the duct and is controlled by a duct thermostat.  Modulating control uses just the right amount of heat to maintain the temperature set by the duct thermostat, saving energy and improving comfort.

Duct thermostats can control temperatures using electric, electronic and pneumatic controllers. Large systems may even benefit from a sophisticated Direct Digital Control (DDC) system. Electric duct heaters are designed to interface with any of these options and are available in virtually any size, power handling and voltage.

Quality Duct Heaters Eliminate Air Flow Safety Concerns

Both open-coil and tubular heating elements require air flow to transfer the heat from the elements to the air in the duct. If the air flow stops for any reason, temperature in the duct can rise to dangerous levels.

This is the reason companies like Thermolec install automatic thermal cut-off features as well as manual resetting thermal cut-offs. Air flow can be stifled by obstacles and debris without warning, making redundant safety features like these critically important.

Three-Step Guide to Selecting the Right Heater For Your System

For a standard HVAC system, selecting a heater is straightforward once the basics of electric duct heater operation are understood. It comes down to three steps:

  • First, determine the heater capacity (kW) and voltage/phase needed. This can be done through a simple proportion equation found here.
  • Second, measure duct dimensions and select the appropriately sized heater.
  • Third, determine whether you want a modulating or a staged duct heater, and what other accessories you may wish to include. Examples of common accessories include thermostat controls and disconnect switches.

With this information in hand, you’ll be ready to choose between the various affordable, high-performance electric duct heaters on the market.



EP Sales maintains a large inventory of Thermolec and Greentek products and parts to service the needs of our customers.