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 plenum chamber is a pressurised housing containing a gas or fluid (typically air) at positive pressure (pressure higher than surroundings).hese gave rise to the notion of 17th century 'plenum' as the opposite of vacuum, and all things being either Plenum or Vacuum. By the 19th century, the development of mechanical fans and industrial machinery had provided another, more technical use.