A Glossary of Common HVAC Terms

Maintaining optimal home comfort in the Metro Atlanta Area requires a clear understanding of your HVAC system. From scorching, humid summers to brisk winters, your heating, ventilation, and air conditioning equipment works tirelessly year-round. This guide breaks down the essential HVAC concepts and components, specifically tailored to the unique climate demands of homes in our region. Learn how to maximize your home's efficiency, enhance indoor air quality, and understand the critical elements that keep your family comfortable – and remember, Empire is always ready to provide expert service and solutions for all your comfort needs.

Core HVAC Concepts

HVAC System: Your HVAC system is essential for managing the distinct seasonal changes experienced by homes here, from hot, humid summers to mild but sometimes freezing winters. It precisely controls temperature, humidity, and air quality, ensuring year-round comfort. HVAC stands for Heating Ventilation Air Conditioning system and includes many components like the condenser, air handler, furnace, ductwork, filters, humidifier, outside air ducting, Energy Recovery Ventilator and all the air quality and accessory items that work together to make a complete system.
BTU (British Thermal Unit): This measure of heat energy is crucial when sizing heating and cooling equipment for the diverse climate. A correctly sized unit with the right BTU rating is essential to efficiently handle both summer heat waves and winter chills without oversizing (wasting energy) or undersizing (failing to keep up).
SEER (Seasonal Energy Efficiency Ratio) aka SEER2: In 2023 the DOE raised the minimum efficiency of air conditioners to 15 SEER for the southeast. This eliminated the less expensive units allowed to be manufactured or sold in the USA.
EER (Energy Efficiency Ratio): This rating is particularly valuable here, as it measures air conditioning efficiency at a specific high temperature (usually 95°F). EER tells you how efficiently your system will perform during those notoriously sweltering summer days when your AC is working its hardest. Higher numbers indicate better efficiency under peak demand.
HSPF (Heating Seasonal Performance Factor): For homes in the Metro Atlanta Area, where heat pumps are a very common and efficient heating solution, a higher HSPF rating is key. It indicates how efficiently your heat pump will convert electricity into heat during the milder but still significant heating season, leading to lower winter utility costs.
Thermostat: A smart or programmable thermostat is highly recommended for homeowners in this region. It allows for efficient temperature management throughout the fluctuating seasons, enabling you to set back temperatures when away and pre-cool or pre-heat your home before you arrive, optimizing energy use for the variable weather.
CFM (Cubic Feet per Minute): Proper CFM is vital in the humid climate of the Metro Atlanta Area. Adequate airflow ensures that conditioned air reaches all areas of your home effectively, aiding in both cooling and, critically, dehumidification to combat that sticky summer feeling.
Dehumidification: This is a non-negotiable concept for homes in this region. Removing excess moisture from the air is essential not only for comfort (making 78°F feel like 72°F) but also for preventing mold and mildew growth, which can be rampant in the humid environment.
Latent Heat: Understanding latent heat is crucial here. The "hidden heat" in moisture significantly impacts how humid your home feels. Effective HVAC systems in the Metro Atlanta Area are designed to remove this latent heat, keeping your home cool and dry, even on the most muggy days.
AFUE (Annual Fuel Utilization Efficiency): While heat pumps are popular, many homes in the Metro Atlanta Area still rely on furnaces, especially for auxiliary heat during colder snaps. An AFUE rating demonstrates how efficiently your furnace converts fuel (often natural gas in the region) into heat. A higher AFUE means less wasted fuel and lower heating bills during the winter months.

System Components Specific to Homes in the Metro Atlanta Area

Air Conditioner: The workhorse of summers here, an air conditioner removes heat and moisture from indoor air. Due to the prolonged hot and humid conditions, proper sizing and regular maintenance are critical for its efficiency and longevity. Empire specializes in reliable AC installation and service.
Air Balance (Whole Home & Single Room): Given the common two-story layouts and sometimes sprawling ranch homes in the Metro Atlanta Area, ensuring proper air balance across different rooms and levels is essential. This service, often done during HVAC system replacement, ensures even cooling and heating, preventing hot or cold spots common in multi-level residences. We can perform detailed air balance for your home.
Air Duct: Many older homes in the Metro Atlanta Area may have outdated or leaky ductwork, leading to significant energy loss. Having the proper amount and size of air duct is critically important to proper system performance. A qualified HVAC company can help plug leaks, add or repair broken ductwork.
Air Filter: With the pollen seasons (spring and fall) and general outdoor allergens in the Metro Atlanta Area, selecting the right air filter and replacing it monthly is vital for maintaining indoor air quality and protecting your HVAC system. Typical air ducts are the 1-inch size.
Media Filter: For residents concerned about allergies, dust, and general air quality due to urban pollution or nearby construction, a media filter installed in the duct system offers superior filtration, capturing finer particles and significantly improving the air you breathe. Typically 3 to 5” wide provides a greatly extended surface for filtration. These filters can often go 3 to 12 months between replacements.
Air Flow Meter: An air flow meter or anemometer is a valuable tool used by technicians for diagnosing comfort issues in homes here, especially in rooms that feel consistently too warm during the summer. It helps confirm if sufficient cooled air is reaching those areas.
Air Handler: In the Metro Atlanta Area, where electric HVAC systems are common, the air handler is the indoor component containing the evaporator coil, heater, and blower. Its efficient operation is key to both cooling and heating cycles.
Air Register: ( Supply Air Registers blow air and Return air Grills pull air back to the air handler) The strategic placement and sizing of air registers are critical in homes across the region to effectively distribute conditioned air, especially important in rooms with large windows that absorb a lot of summer heat.
Blower & Blower Components: The blower is constantly working to circulate conditioned air. An efficient blower (like one with an ECM) is essential for consistent airflow, especially for humidity control during the long, humid summers.
Capacitor: A frequent culprit for AC breakdowns in the Metro Atlanta Area, especially during intense summer heat. A failing capacitor can prevent your outdoor unit from starting, leading to uncomfortable indoor temperatures.
Collar: Essential for securely attaching air ducts to the plenum, ensuring no conditioned air is lost to the attic or crawl space – a common inefficiency source in many homes in the region.
Combustion Air: All gas appliances need to have a certain amount of “free air” for proper operation. This can be calculated via leakage around doors and windows and may require special ducting to make sure there is enough combustion air available to an appliance.
Compressor & Compressor Components: The heart of your outdoor AC unit or heat pump, the compressor works tirelessly in the heat to circulate refrigerant. Its proper function is paramount for effective cooling and dehumidification.
Condenser (or Outdoor Unit) & Condenser Components: This outdoor unit is highly visible in yards throughout the Metro Atlanta Area. It's where the heat from your home is released into the hot outdoor air during the cooling season. Keeping it clear of debris (like pine needles) is important for its efficiency.
Condenser Coil: This coil plays a critical role in rejecting heat from your home to the hot outdoor air. A dirty condenser coil significantly reduces cooling efficiency, leading to higher energy bills.
Condensate Drain Line & Emergency Condensate Drain Line: Given the high humidity of the Metro Atlanta Area, your HVAC system produces a substantial amount of condensate.
Damper (or Butterfly Damper): Used to adjust airflow, dampers are particularly useful in multi-story homes or those with additions, allowing for zone control and balancing temperatures across different areas.
Drain Pan: Collects the significant amount of condensation produced by your AC in the region's humidity. A clogged drain pan can lead to overflows and water damage.
Duct Design & Ductwork: For homes in the Metro Atlanta Area, proper duct design based on a thorough heat load calculation is paramount. Many older homes have undersized or poorly designed ductwork that struggles to distribute air efficiently, especially during extreme temperatures. Well-sealed and insulated ductwork is critical for energy efficiency in both summer and winter.
ECM (Electronically Commutated Motor): An excellent upgrade for homeowners in the Metro Atlanta Area seeking to save on energy bills and improve comfort. ECMs adjust speed, providing more consistent temperatures and better dehumidification, which is invaluable here.
Evaporator Coil & Evaporator Coil Components: This indoor coil absorbs heat and moisture from your home's air. Keeping it clean is essential for efficient cooling and dehumidification in the humid climate.
Float Switch: A highly recommended safety device for all HVAC systems in the Metro Atlanta Area. It prevents costly water damage from clogged condensate lines by shutting off the system, especially important in high-humidity conditions where clogs are more likely.
Flue Venting: This is the piping from the furnace to the outside. This pipe is typically a double wall pipe and requires certain clearance to combustibles by code. Having a properly-sized flue vent for the size of the heating equipment and height of the rise is critical for proper safe performance of a gas heating appliance
Furnace & Furnace Components: Many homes in the Metro Atlanta Area rely on natural gas furnaces for heating, especially during colder winter nights. An efficient furnace, coupled with a heat pump, provides a robust heating solution for the region.
Hard Start Kit: For older AC units or those struggling to start on hot days, a hard start kit can ease the strain on the compressor and extend its lifespan.
Heat Pump & Heat Pump Components: An incredibly popular and energy-efficient choice for homes in the Metro Atlanta Area, heat pumps provide both heating and cooling. Their ability to transfer heat, rather than generate it, makes them very cost-effective for the region's moderate heating season.
Heater: In electric HVAC systems common in the Metro Atlanta Area, the heater within the air handler provides supplementary heat when the heat pump's efficiency drops in very cold temperatures.
Plenum: The air-distribution box attached to the supply outlet of the HVAC equipment that connects to all of a home’s air ducts.
Refrigerant: A substance used in air conditioning and heat pump systems to transfer heat. A reusable gas/fluid found in the condenser, used to cool the condenser coil.
R-22 & R-410a: R-410a are older refrigerants. R-32 and R-454b commonly known as A2L refrigerants are now the current refrigerants used in air conditioners and heat pumps.
Refrigerant Lines: Pipes that carry refrigerant to and from the evaporator coil. Properly insulated lines are crucial in the extreme temperatures to prevent efficiency loss.
Return Air Grille: The larger grating that may hold the HVAC's air filter in a single return systems and there are multiple return grills in most single-family homes with a filter in the ducting at the air handler.
TXV (Thermal Expansion Valve): A small but critical component for maximizing efficiency in the demanding cooling season, ensuring the right amount of refrigerant flows into the cooling coil.
Vents & Vents Components: The placement and adjustability of vents significantly impact comfort in homes. Proper vent sizing and direction can help combat localized hot spots.

Air Quality for Homes in the Metro Atlanta Area

Air Filter: Absolutely essential in the Metro Atlanta Area due to significant pollen, dust, and general outdoor allergens. Regular replacement is the simplest and most effective way to improve indoor air quality.
ERV (Energy Recovery Ventilator): An excellent investment for homeowners in the Metro Atlanta Area, ERVs bring in fresh outdoor air while minimizing energy loss from heating or cooling. This is crucial for diluting indoor pollutants and maintaining good ventilation without driving up utility bills in the region's varied climate.
HEPA Filter (High-Efficiency Particulate Air Filter): For residents with severe allergies or asthma, a HEPA filter provides superior air cleaning, capturing almost all common allergens prevalent in the region.
Indoor Air Quality (IAQ): A major concern for homes here, influenced by pollen, humidity, pet dander, and off-gassing from building materials. Proactive IAQ solutions are highly recommended.
MERV Rating (Minimum Efficiency Reporting Value): When choosing filters for your home, consider the MERV rating. Higher MERV ratings (check compatibility with your system) offer better filtration against common allergens in the Metro Atlanta Area.
UV Light Systems: A beneficial add-on for homes, particularly for combating mold and mildew growth on the evaporator coil due to high humidity. They can help reduce airborne biological contaminants.
Ventilation: Proper ventilation is key in the Metro Atlanta Area, especially during the summer. It helps remove stale, humid air and introduce fresh air, reducing the concentration of indoor pollutants.
Whole-House Dehumidifier: An invaluable investment for homeowners here. While your AC provides some dehumidification, a dedicated whole-house dehumidifier can precisely control humidity levels, significantly enhancing comfort, preventing mold, and allowing you to set your thermostat higher, saving energy.

Additional Terms for HVAC in the Metro Atlanta Area

Geothermal Heating and Cooling: While a significant upfront investment, geothermal systems can be highly efficient for homeowners due to the relatively stable ground temperatures, offering substantial long-term energy savings.
Heat Load Calculation: Absolutely essential for proper HVAC sizing here. A thorough calculation accounts for the specific challenges of homes in the Metro Atlanta Area, including window efficiency, insulation levels (especially in attics), and the intense solar gain during summer. Empire HVAC performs precise heat load calculations to ensure your system is perfectly sized.
HVAC: An overarching term for Heating, Ventilation, and Air Conditioning, vital for comfort in every home in the Metro Atlanta Area.
Relay: A switch that uses low voltage to turn a fan motor off and on.
Service Panel/Disconnect: Every homeowner should know the location of this electrical shut-off for safety and convenience, especially during the busy summer service season.
Smart Thermostat: Highly recommended for the region's variable climate. They learn your habits and allow for remote control, maximizing energy savings by optimizing heating and cooling schedules.
Static Pressure: The resistance to airflow in your ductwork. High static pressure can reduce comfort and increase energy bills, especially with older homes with restrictive ductwork.
Tonnage: The common way to rate HVAC system size in the Metro Atlanta Area. Proper tonnage is crucial for efficient cooling and dehumidification in the summer.
Two-Stage Systems: A popular upgrade for homes here, offering better efficiency than single-stage systems by operating at a lower capacity for milder days, which helps with humidity control without overcooling.
Variable Speed Systems: The premium choice for ultimate comfort and efficiency. These systems run longer at lower speeds, providing superior temperature and humidity control – a huge advantage in the sticky summers – along with quieter operation and lower energy bills.
Zone System & Zoning: An excellent solution for larger or multi-level homes, allowing precise temperature control in different areas. This is particularly beneficial for managing comfort in upstairs bedrooms during hot summers or rarely used basements.