The first step in designing an air heater is to determine the temperature and airflow needed to adequately meet the desired results. Next evaluate your system by answering the following questions:

• What voltages are available at the process location?
  
• Will the wiring and circuit breakers be able to handle the load of the heater?
  
• How tightly must the exhaust temperature be maintained?

Giving these questions careful consideration in the design stages will ensure that you develop an efficient, effective system.

In air heater design, the proper selection of power output is based on variables gleaned from the questions above. A simple equation to use when looking at system requirements is:

W  =  Flow Rate (scfm)  x  ΔT  x  0.3165

In other words, the wattage output of the heater is proportional to the flow rate in standard cubic feet per minute, the temperature rise required in degrees Fahrenheit, and a laboratory-calculated constant.

It is important to note that this equation was developed with air or nitrogen selected for the thermal fluid. If this equation is properly applied, the heater will generate a temperature output that is close to desired results if no controller is utilized.