Titus D21-PS Relay Proportional Signal controller is 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 elements even at very low CFM's. With normal airflow the controller will operate at full power. When the airflow drops below the minimum airflow, the controller will still operate but at reduced power. It will also safely shut down the heater in case of a total loss of airflow.

The ‘P’ versions of controllers such as D21-P, D22-P and D21-PS operate with an input signal of 0 - 10 VDC or AC/DC pulse. It is also possible to adapt the wiring to use a simple ON/OFF contact to turn the controller full on and off.