Air Heater Basics Part One: Air Heaters Defined

At its most basic level, an air heater works by passing air across a heated element to elevate the temperature of the air. That hot air can then be used for a variety of applications ranging from heating a space to drying parts and coatings, or from de-flashing plastic components to heating parts in a manufacturing process.
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Every air heater is comprised of two main components: 

1. A source of air flow
   The source of air can be a fan, blower, or air compressor. The best source depends on the application and the type of heater. For example, a space heater does not need high velocity or specifically focused air, so a fan is used. In a more industrial application where a great deal of heat must be transferred in a focused stream an industrial blower or compressed air is usually used.
2. A heating element
   For simplicity, the scope of this article series will be limited to electric heaters. This type of heater has an element that is normally a coil of wire with a high resistivity. By passing an electrical current through the wire, heat is produced. The configuration of the resistance wire is dependent on the purpose of the heater. The element should not be powered without air flow, or it may overheat and burn out.

Relationship between Volume of Air Flow and Temperature

There is a direct relationship between volume of air flow and temperature. For a constant heating power in kW, an increase in volume of air flow results in a decrease in the output temperature. Energy is required to increase the temperature of any solid, liquid or gas and the amount required is directly related to the mass of the material being heated. As the volume of flow increases, the mass of air to be heated also increases. There is a lower limit to volume of air flow for any heater, where temperature rises to the point where the components are damaged.
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See our article on Sizing your Heater and Blower: The Relationship between Air Flow and Temperature for more information.  
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​Many people make the mistake of choosing a heater/blower combination from a catalogue based on maximum flow or temperature values; in reality, there are many factors that influence the correct equipment choice. When you contact your heater supplier they should ask for details of your application to be sure you are choosing the appropriate equipment. If they don’t, we suggest you consider finding an alternate supplier who can ensure that the equipment you purchase is right for your application. 

Continue reading: Air Heater Basics Part Two: Elements