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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There are many different sizes, shapes, and configurations of heaters which vary in complexity. This article will focus on the difference between a Hot Air Blower and an Air Heater
Hot Air Blowers
Some heaters on the market package both the air source and heating element into a single tool. These can range from small hand tools with 400W elements to large industrial units with 10kW elements and everything in between. These have the obvious appeal of simplicity and, sometimes, compact design. For some applications these are ideal but in many situations a system designer requires the flexibility of specifying both the heater and air source separately in order to achieve the best possible results.
Many air heaters provide the heating component only and require an external source of supply air. While this adds a layer of complexity to the heat system design, it also gives the system designer a greater degree of freedom. A heat system can be developed which will provide the exact kilowatts required to deliver the correct volume of air at the correct temperature for the application. This type of “perfect fit” is often not possible with an off the shelf Hot Air Blower.
Choosing the Right Heater
There are several decisions a heat system designer must make in choosing the right air heater.
1. High or Low Volume Air Flow
The application will generally point towards either a high flow (open element) or low flow (fully supported element). A few examples are:
2. On-board Thermocouple
Industrial heaters can be found both with and without an on-board thermocouple. It’s important to give careful consideration to an application’s control needs to avoid paying for more sophistication than is required. You may choose to omit an on-board thermocouple when selecting a heater if:
3. On-board Temperature Controls
As with the on-board thermocouple, there are sophisticated heaters that also have on-board temperature controls. On-board temperature controls are almost always paired with feedback from an on-board thermocouple. Although the heater itself may be more expensive than one without this capability, there are situations where it is more economical because closed-loop control is possible without any external control components. There are also times when it does not make sense to have this capability, such as:
4. Compatibility with Air Sources
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 Five: Sizing a Heater and Blower