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 even at very low CFMs. 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. The board is factory set for either 0-10 VDC or AC/DC pulse and cannot be modified in the field. D21-PSSR controllers may be used to drive up to 2 SSRs. For driving 4 SSRs the D21-PS is required.

• 0-10V DC or AC/DC pulse input
• works with 24 VAC control voltage
• compatible with electronic Air Flow Sensor
• single DC output to control up to 2 SSRs