September 14, 2013

HVAC: Condensing Furnace

Furnace Diagram
A furnace provides heat through the exchange of heat through a intermediary fluid movement such as air, steam or hot water. A furnace can use different fuel including natural gas, LPG, oil, coal or wood. Combustion furnaces always need to be vented outside. Condensing furnaces are essentially high-efficiency furnaces with a AFUE (Annual Fuel Utilization Efficiency) starting at 90% or greater, verses mid-efficiency furnaces with a AFUE in the 80's. This difference in efficiency is the result of heat lost to the flue, or the loss of of some of the heat produced during combustion.