Just What Is An HVAC System, Anyway?
By Shawna Thompson
Heating, ventilating, and air conditioning (HVAC) equipment can be a bit of a mystery to homeowners. You may be aware that your home has the ability to remain climate controlled at the touch of a button, but you find yourself wanting to understand more about the machinery that works so hard for you. Read on for a comprehensive definition of the components of your indoor climate control machinery.
In hot summer months, the air conditioner is the star of the climate control show. Your AC unit draws air from outside and cools and dehumidifies it as the air passes over a cold metal coil. This coil is itself an air-to-liquid heat exchanger, meaning the warm air absorbs cold from the coil, and vice-versa. Rows of tubes pass cold liquid through the coil, and flat surfaces connected to the tubes create a large cooling surface area, increasing the amount of air that can be cooled at one time. More cold surface area equals more cool air.
The cooling ability of your air conditioner depends on its efficiency at cooling and dehumidifying air. It’s important to note that factors such as outdoor temperature can affect the cooling capacity of some machinery. When cooling is inversely proportional to outdoor temperature, a machine’s ability to cool your indoor air is reduced when outdoor temperature increase. Similarly, indoor temperatures and humidity affect your machinery in much the same way. Most manufacturers of AC equipment provide a user guide that shows the efficiency change of the machinery when indoor and outdoor temperatures and humidity changes.
Alternatively, there are central HVAC units called heat pumps, which combine both the heating and cooling functions. If you heat your home with electricity, a heat pump system can be more efficient in moderate climates. Providing up to three times the heating per electrical energy it consumes.
Air conditioners and heat pumps use different components to functionally cool or heat your home’s air, but the basic principles of operation are the same. The heat pump transfers heat from the evaporator coil to air and circulates the now-heated air through your home. A heat pump’s heat coil actually extracts heat from outdoor air.
Types of Systems
Typical homes employ a “split system” HVAC, with the air condensing unit placed outside the .home, and the coil inside. And it combines the condensing unit and the coil into one outdoor unit. The best unit for you depends entirely on your home’s location and construction.