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...

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...

It offers additional protection against overheating. It is standard on heaters of 30 KW and less and not in excess of 300 volts, and optional on all others. This switch must be manually reset to make the heater operational.