Mounted inline in an HVAC system Electric Duct Heaters heat air as it passes over an electrically heated coil. The units can be actuated remotely by connecting them to the Building Management System or locally via temperature sensor.Mounted inline in an HVAC system Electric Duct Heaters heat air as it passes over an electrically heated coil. The units can be actuated remotely by connecting them to the Building Management System or locally via temperature sensor.