The D21-PS electronic controller has been designed to take full advantage of our patented Air-Flow Sensor which modulates the heater’s capacity according to the quantity of air flowing through the heater by responding to the radiant heat of the elements even at very low CFMs. Wit...

Safety feature, monitors the quantity of air flowing through the heater, adjusts the heater’s capacity to match the air flow available and shuts the heater down in case of a total loss of air. This feature is available only on heaters equipped with full SCR.

Pilot lights are mounted on the control box to indicate that either a function of the heater is operating or a failure condition is present. The most commonly specified pilot lights functions are: power on, heating on, no airflow, overheating, stages on. The pilot lights' functio...