The international airports in Pennsylvania are Lehigh International Airport at Allentown, Erie International Airport at Erie, Harrisburg International Airport at Harrisburg, Philadelphia International Airport at Philadelphia,
Electric Plenum Heaters. A plenum heater is an electric resistance heating device that is installed in the plenum, which is the spot in the ductwork system where ducting and furnace join. Air is heated as it flows across electric elements and then is distributed through the existing ductwork.
A heater coil is a device used to heat water or air. Typically electric, the heater coil acts like a large resistor, and as the electric current flows through it, it begins to heat up. The resistance wire used in common household toasters is the same type of wire used in a heater coil. The amount of heat produced by the heater coil is controlled by a rheostat switch. Many appliances, such as hot water heaters, electric clothes dryers and electric ovens, all use some type of heater coil to produce heat.