We’re going to start another blog series, this one will focus on different heating and cooling options.  The most common idea people have when they think about heating and cooling is the conventional ducted system, but most still don’t fully understand this.  So I’m going to try to explain it in Laymen’s terms.  I will also go over less traditional forms of heating and cooling like ductless systems, heat pumps/air handlers, radiant, and geothermal in separate blog posts.

Let’s dive right in!  So the conventional method requires ductwork.  The ductwork provides a way to distribute air.  The airflows it is responsible for is supply air, return air and exhaust air.  Simply put, the ductwork is the “V” in HVAC.  It ventilates your home.  It is important because it ensures the air quality in your home as well as the thermal temperature.

Let’s focus, first, on the furnace.  The furnace can be on it’s own (unlike the condenser which needs to be coupled with a furnace).  The ductwork connects to the furnace, 1 part connects to the heat exchanger and 1 part at the blower.  Like I mentioned before, there’s the supply, the return and the exhaust.  The return takes in cold air, the blower pushes the cold air passed the heat exchanger and out the supply.  The cold air gets heated when it is blown passed the heat exchanger. The heat exchanger is where the combustion happens.  Combustion creates toxic gases, which are expelled through the flue pipe, or the exhaust.  Let me just add that the combustion is happening within the heat exchanger, this process heats the outside of the heat exchanger, which then heats the air that is passing by, that heated air is then pushed out the supply by the blower and distributed throughout the house.  That’s as simple as we can put it.


Things get a little more complicated once you tie in the air conditioning.  When you add cooling, you also add an evaporator coil, freon lines, condenser, fan and compressor.  The process, however, is fairly similar to the furnace.  The blower pulls in hot air, blows it passed the evaporator coil and out the supply and then distributed throughout the house.  Like with the heat exchanger, the coils are cooled by a process that is happening within the coils, but because the coils are so cold, it is able to cool the air passing by, and thus the rest of the house.  The evaporator coil is cooled by freon being pumped into the copper tubes, the process of the liquid freon evaporating into a gaseous state cools the coils and the gas released is a higher temperature.  That hotter gas is removed through the freon lines and pumped through the outdoor compressor to turn it into a liquid again, which is then returned back to the evaporator coil.  This process creates more heat, which the fan then expels through the condenser.


That is how the conventional duct system works.  This is the watered down version, it is actually way more complicated than I’m making it seem, but this gives the typical homeowner/tenant an idea of what’s going on behind the scenes.  To learn about ductless, heat pumps/air handlers, radiant and geothermal, stay tuned for the blog posts to come.  To get real time updates, follow us on Twitter and like our page on Facebook.