HVAC 101

HVAC 101

Posted by
Ed Miller on Mon, Sep 23, 2013

As the seasons change, we tend to take one of the most important parts of our home for granted – the Heating, Ventilation, and Air Conditioning systems, or HVAC, that maintain a comfortable climate. They keep our households warm in winter and cool in the humid height of a Jacksonville summer. It is important to understand the basics of HVAC in order to choose and maintain the best systems for your home.

Basic Functions and Components


Heating, Ventilation, and Air Conditioning systems are mechanical air handling systems, from window AC units to central air. They bring outdoor air into our homes, filter, circulate, and release it outdoors. An HVAC system’s main purposes are to provide (1) a comfortable home climate through heating and cooling, and (2) Indoor Air Quality (IAQ) through air ventilation and filtration.

On a very basic level, your HVAC system includes four elements: an outside air intake, air handling unit, air distribution system, and an exhaust system.

  • Outside air moves in through the air intake and on to the air handling unit (AHU), which includes your cooling coils, the blower, and filters, among other equipment.
  • There, the air is filtered to remove mold, allergens, dust, and other particulates before being heated or cooled, depending on the season.
  • The air is then circulated throughout your home through the ducts and registers of the air distribution system.
  • The fiberglass or metal ducts run below or in the attic of a house. Supply ducts carry the air into rooms, with both main supply trunks and smaller side branches, while return ducts draw the air back out and should be as close to the AHU or furnace as possible.
  • Depending on the system, the air may be recycled through the air handling unit along with newly supplied air, but eventually, it will be released as exhaust.

Types of HVAC Systems

Most HVAC systems involve a great deal more equipment, too, from your thermostat to your home’s insulation, filters and grills, and much more, but there are only three basic types.

  1. In a split system, the furnace combusts gas to create heat and warm air that is blown into the rest of the house. In the summer, the furnace blower also circulates air that has been cooled after passing over the indoor coil above the furnace. Furnaces are rated according to their fuel efficiency, as the Annual Fuel Utilization ratio (AFUE), while air conditioners are rated by their total cooling ability, or Season Energy Efficiency Ratio (SEER) for central air units. The higher the ratings, the greater the efficiency, and the lower the cost.
  2. Heat pumps rely on electricity to transfer heat between two reservoirs. In warmer months, this system pulls heat from inside out, while in colder months, it pulls outdoor heat inside. This kind of system is less useful in colder climates, but even when combined with a furnace system, a heat pump can help to lower your utility bills. They are rated according to their Heating Season Performance Factor (HSPF), with higher ratings for greater efficiency generally falling between 7 and 9.4 in the United States.
  3. Packaged systems combine heating and cooling, and they generally sit on the ground or on the rooftop of one’s home. They tend to include three different types: packaged heat pumps that both cool and heat, packed air conditioning units that mainly cool but can heat via electrical strip heating, and gas-electric units with both air conditioning and a gas-fueled furnace.

Installation and Service

When looking for a new HVAC system or upgrading an old one, the first step is to have a detailed inspection of your home done to determine what system will work best for your home. In the process, be sure that you choose the best installation contractor and that your installation considers the size and age of your home, as well as the number of rooms and local climate and utility costs.

Most importantly, remember that maintaining your HVAC system is just as important as choosing the right system and a trustworthy installer. Enroll in a maintenance plan to keep your system running well and so lengthen its lifespan. At the same time, educate yourself, and stay up to date on recent technological developments. Doing so will help you decide what upgrades or even different systems will work best over time.


Air Filter,


Air Conditioning

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