The Elta 018-RH70/40 – 21-3TP is a rectangular electric heater designed for duct installation, offering a heating capacity of 21kW and operating on a 3‑phase power supply. Its compact 700mm x 400mm frame is constructed from Aluzinc-coated steel for superior durability and corrosion resistance. The unit is equipped with two safety thermostats to protect against overheating and uses screw terminals for easy and reliable electrical connections. A built-in potentiometer allows precise temperature adjustment. To ensure proper airflow, it includes a differential pressure switch and a sensor for minimum air velocity. A supply air temperature sensor is also provided to help maintain stable and efficient operation.