This thermostat can be used as a 1 or 2-stage duct stat with the DS600 sensor.

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-PSSR electronic controller has been designed to be a compact solution 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...