Air duct heater is mainly used for heating the air in the air duct, the specification points at low temperature, medium temperature, high temperature three forms, have in common is adopted in the structure with steel plate to support electricity heat pipe to reduce the vibration of the fan stops heating tube, overtemperature control devices are fitted in the junction box.Type low temperature can be directly installed on the air duct and the medium temperature, high temperature, due to the different structure of the channel walls and the heater junction box with 100 mm thick insulation materials, on the one hand, reduce the external heat dissipation of the whole passage, on the other hand also decreased after the temperature within the XianQiang.