Ultimately though, the mystique surrounding our HVAC systems, which are among the most essential of all appliances and systems in our homes, can easily evaporate by our coming to understand just a bit about what these systems consist of, and how they use the air around us to help us control our environment.
How HVAC Systems Work
All HVAC systems are really just our old friend physics working in well-orchestrated conjunction with some clever machinery that helps us better manipulate the air around us by making good use of a few key elements.
All types of HVAC systems, regardless of what purpose we are using them for, rely on channels through which air can be moved. Without ducts, or other means of moving air, heated air would still rise, and cooled air would hang around, but neither would disperse throughout our homes, and no air would be circulated for outside our homes to in, or vice-versa as no transference or hot or cold air could take place, an exchange that must occur if any HVAC system is to function properly.
Heating or Cooling Elements
Furnaces, whether gas or oil-powered, make use of heat exchangers which are responsible for heating the air to our desired temperature. Air conditioners use coolant inside of an evaporator coil to chill the air that is circulated within the unit from the inside of our homes, and condenser coils to push hot air outside.
If ductwork is the veins of our HVAC systems, and heating and cooling elements their hearts, then thermostats are the real brains of the operation. Thermostats help us to use our HVAC systems to not only control our environment but prevent damage that can occur to our homes when conditions would otherwise become too hot or too cold (think of frozen pipes in the winter). Thermostats work by utilizing their bimetallic element, which contracts or expands when the temperature changes within your home.
HVAC System Types
While most HVAC systems make use of the elements above, how they make use of them can differ slightly depending upon their arrangement in your home. Of these arrangements, there are three that are the most common.
Forced Air Systems
Forced air systems take hot or cold air and force it through our ventilation systems using a blower. Blower motors have a finite life expectancy of approximately 10 years at the minimum, and 20 years at maximum, so you can expect each blower motor to last about 15.
Gravity systems rely on the rule of thermodynamics that hot air rises while cool air sinks, meaning these systems are typically housed in basements. When turned on, heat rises through our ventilation system, and the cool air sinks. Gravity systems cannot be used in conjunction with air conditioning systems, so they can be used only for heating our homes.
Similar to other types of HVAC systems, radiant systems use the infrastructure of our homes, in this case, a series of pipes installed specifically to radiate heat, to move heat around so that it is distributed evenly. Like gravity systems, they cannot be used in conjunction with air conditioning systems.