![]() Ambient air is directed between the combustion chamber and the outer shroud. The exhaust from combustion is funneled overboard. The correct amount of fuel and air are ignited in the air-tight inner chamber. The source of heat in this case is an independent combustion chamber located inside the cylindrical outer shroud of the heater unit. The most up to date units have electronic ignition and temperature control switches.Ĭombustion heaters are similar to exhaust shroud heaters in that ambient air is heated and sent to the cabin. Most are similar to the description that follows. Combustion heaters are manufactured by a few different companies that supply the aviation industry. It is a heat source independent from the aircraft’s engine(s), although it does use fuel from the aircraft’s main fuel system. However, their use on the ground when powered by a ground electrical power source preheats the cabin before passengers board and does not tax the electrical system.Ĭombustion HeatersAn aircraft combustion heater is used on many small to medium sized aircraft. For this reason, they are not very common. Electric heating element heaters require a significant amount of the aircraft’s generator output, which is better dedicated to the operation of other electrical devices. Other floor or sidewall elements simply radiate heat to warm the cabin. A fan to blow air over the elements and into the cabin is used to transfer the heat. Electricity flowing through a heating element makes the element warm. All of these bleed air heating systems are simple and function well, as long as the valves, ducting, and controls are in operational condition.Įlectric Heating SystemsOccasionally, an electric heating device is used to heat the aircraft. One STC’d bleed air heat system uses mini-ejectors in helicopter cabins to combine bleed air with cabin air. Mixing air valves, flow control valves, shutoff valves, and other various control valves are controlled by switches in the cockpit. The mixing of air can be done in a variety of ways. The bleed air is mixed with ambient air, or cabin return air, and distributed throughout the aircraft via ducting. Some turbine-powered aircraft not equipped with air cycle systems still make use of engine compressor bleed air to heat the cabin. Aircraft not equipped with air cycle air conditioning may be heated by one of a few possible methods. This is discussed in the section that covers air cycle air conditioning in this site. Pressurized aircraft that use air cycle air conditioning systems mix bleed air with cold air produced by the air cycle machine expansion turbine to obtain warm air for the cabin. Combined with seasonally cold temperatures, this makes heating the cabin more than just a luxury. Bleed Air SystemsTemperatures at high altitudes in which aircraft operate can be well below 0 ☏.
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