Industries such as shrink fitting, plastics and welding, drying, laminating, sealing, packaging and automotive industries use air heaters to heat, dry and reduce atmospheric humidity. These kinds of heaters are used not only in industrial settings but also in homes as furnaces or as portable air heaters placed in a single room. Air heaters can also be found as components of climate control systems in offices, institutions, stores and in many other contexts.
Air heaters work by two different methods: gravity and forced air. With the gravitational method, cool air enters the heaters through the cold air ducts. As the cool air passes through the heating elements, the air warms and then rises from the heater through a large supply duct. The cool air re-enters the furnace through the cold supply ducts; and all the while the weight difference between the cool and warm air keeps the air circulating. With the forced air method, warm air is forced through a supply duct by a blower; it enters the room through registers or diffusers and then returns via a cold air duct to the heater, where it is filtered of dust and dirt particles, reheated and recirculated. Both methods require heating elements such as coils or wires to warm the air.
A cost effective solution to electric air heaters are solar powered air heaters. Solar heaters are panels that are placed on roofs, walls or windows; they are heated by solar radiation and disperse the heated air through the ducts. A blower placed in the room circulates the air, while a damper keeps the room air from flowing back into the panel. Solar air heaters, aside from the initial installation cost, are very cost effective in the long run because they run on solar energy.