The D21-TSSR electronic controller has been designed to be a compact solution that takes 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 ‘T’ versions of controllers such as D21-T, D22-T, D21-TS and D21-TSSR are controlled by a thermistor type thermostat such as our RT (room thermostat) and DT (duct thermostat) as well as our integrated Duct Sensor.

• controlled by Thermolec’s RT, DT and integrated Duct Sensors (thermistor)
• compatible with electronic Air Flow Sensor
• works with 24 VAC control voltage
• single DC output to control up to 2 SSRs