A pressure differential switch is used to prevent a heater from operating if there is no airflow across the heating elements. The switch is provided with a pitot tube to be installed into the duct, which makes it sensitive to velocity pressure as well as to static pressure. In ap...

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...

The D21-TS 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...