Duct heater is used to heat moving gas streams. They are installed in the middle of a moving air / gas stream in order to heat the air as it moves through the heater.
Multi-Zone or Dual Duct Heaters – These heater is designed for installation inside multi-zone or dual duct air conditioning equipment, where the airflow is highly variable and unevenly distributed. These heaters use coils derated to approximately 25 watts per square inch (3.8 watts per square cm) of wire surface
area (approximately one half normal watt density). Low density coils run cooler and thus provide longer life under these stringent operating conditions. These heaters are supplied with fully proportional SCR control or with many heating stages to insure that no more heat is being supplied than is absolutely necessary. Each heater stage is spread over the entire face area to take advantage of all available airflow. A perforated pressure plate is factory-installed on the air inlet side of the heater to make the airflow as uniform as possible. Linear limit thermal cutouts
protect against serious overheating anywhere along the length of the heater. When the heater must be installed entirely within the unit, only thermal cutouts are built into the heater, a remote panel is required for controls. When the
terminal box can be external, heaters are available with a wide range of built-in controls.