HVAC Defined

Are you in the process of buying a house and not sure what you’re looking at when you get to the home’s furnace room or utility closet? Maybe you’ve been in your home for a few years but still don’t quite understand the meaning of HVAC and the system that is in place to heat and cool your environment.

Nearly every household utilizes an HVAC system to manage and circulate heated or cooled air throughout the home. These systems vary in type. Knowing what components are included with your home’s HVAC system can help ensure you stay on top of preventative or reoccurring maintenance to protect its performance and longevity. Below we break down the common HVAC related terms that every homeowner should know. This essential HVAC vocabulary will educate you on one of the most critical aspects of your home and equip you with the knowledge to move forward no matter where you are in your home journey. This will also help you communicate with your HVAC contractor during service or when making a purchase decision.

Let’s start with the basics.

HVAC: Heating, Ventilation, and Air Conditioning

HVAC: Heating, Ventilation, and Air Conditioning

• Heating: There are two common ways to heat your home with an HVAC system.
• • Furnace Heater: Furnaces create heat in your home by burning fuel or using electricity, depending on the system. These furnaces use forced-air systems that circulate heated air through a blower in the home’s air ducts.
  • Heat Pump: Heat pumps keep your home warm by pumping in heat from outdoor air without burning fuel like a furnace, and don’t require pilot lights or exhaust vents. In much colder climates, a heat pump may be combined with a furnace to heat homes on colder days.
  • Other types of heat that may be present in your home include:
    • Boiler: A boiler works by heating water, which is then circulated through pipes to radiators or underfloor heating systems in different rooms. The heat from the water warms the surrounding air, providing a comfortable indoor temperature. Boilers can be powered by various fuels, including natural gas, oil, electricity, or even renewable sources like biomass.
    • Ductless Mini-Split System: A ductless mini-split system is a type of heating and cooling system used in homes that consists of an outdoor compressor unit and one or more indoor air-handling units, connected by refrigerant lines. Unlike traditional HVAC systems that rely on ductwork to distribute air, ductless mini-splits deliver conditioned air directly into individual rooms or zones. Each indoor unit is controlled independently, allowing for customized temperature control and energy efficiency. These systems are often used in homes without existing ductwork or in spaces where ductwork installation is impractical.
    • Radiant Heating: Radiant heating is a method of heating indoor spaces by transferring heat directly to the objects and surfaces in a room, rather than relying on the circulation of heated air. In a home, radiant heating systems typically involve installing heating elements, such as electric cables, hot water tubing, or heating panels, beneath the floor, within walls, or in the ceiling. These elements emit infrared radiation, which warms up nearby surfaces, including floors, walls, and furniture.
    • Baseboard Heating: Baseboard heating consists of electric or hydronic (hot water) heating elements installed along the baseboards or near the floor of each room. In electric baseboard heating, electrical resistance elements generate heat when electricity passes through them. In hydronic baseboard heating, hot water from a boiler or other heating source flows through pipes within the baseboard units, radiating heat into the room. Baseboard heaters operate independently in each room and are controlled by individual thermostats, allowing for zone heating and customized temperature settings. They are often used as supplemental heating or as the primary heating source in smaller spaces.
  • Ventilation: Ventilation in your HVAC system includes floor, wall, and ceiling vents, ductwork, and other ventilation shafts that help to move air throughout the system and your home. Ventilation helps to normalize the temperature in your home in tandem with the heating and air conditioning portions of your HVAC system.
  • Air Conditioning: A common misconception about air conditioning is that it blows cool air into your home, but that’s not the case. The air conditioner in your HVAC system uses refrigerant to absorb heat from your home and move it to the outdoor unit, where a fan blows hot air over the coils and exhausts it to the exterior.

Now, we’ll dive into other components.

• • Air Purifier: Also known as an Air Cleaner, this essential system enhancement is designed to improve Indoor Air Quality by removing airborne pollutants that pass through the filtering system. Unlike portable air purifiers that are limited to specific rooms, whole-house air purifiers are integrated into the HVAC (Heating, Ventilation, and Air Conditioning) system. They include a cabinet and filter and work by the furnace or blower continuously circulating and purifying the air in all rooms, providing a comprehensive solution for maintaining clean and healthy indoor air. Learn more about AprilAire Whole-House Air Purifiers here.
  • Air Filter: The air filter is the essential component of the whole-house air purifier, capturing airborne pollutants including viruses, allergens, dust, and more as air flows through the system. AprilAire Air Filters also help to lengthen the HVAC system’s life and improve your home’s energy efficiency by reducing dust buildup in the system itself. Learn more about the types of air filters AprilAire offers here.
  • Blower Motor: The blower motor is a critical component of the HVAC system, responsible for circulating air throughout the system. It is usually located within the furnace (or air handler). The blower motor draws air from the return ducts, passes it through the system’s filtration and then distributes the air back throughout the home via the supply ductwork.
  • BTU: BTU stands for British Thermal Unit and is a unit of measurement for thermal energy commonly used regarding HVAC systems. For heating, one BTU is the amount of heat required to raise the temperature of one pound of water by one degree Fahrenheit. In heating systems, the BTU rating indicates the heating capacity of the system. In air conditioning systems, BTUs are used to measure the cooling capacity. It represents the amount of heat that the air conditioner can remove from a space per hour.
  • Coil: The coil inside your HVAC system facilitates the transfer of heat between two mediums (typically air and a refrigerant). The two primary types of coils in HVAC systems are an evaporator coil and condenser coil. The evaporator coil is located indoors, typically within the air handler unit or furnace, and absorbs heat from indoor air as it passes over the coil. In air conditioning systems, the evaporator coil is where the refrigerant evaporates, absorbing heat from the indoor air and cooling it. The cooled air is then distributed throughout the building via the ductwork. The condenser coil is in the outdoor unit of an air conditioning system. It releases the heat absorbed from indoor air by the evaporator coil. The refrigerant, now in a high-pressure, high-temperature state, flows to the condenser coil where it condenses back into a liquid state, releasing heat to the outdoor air in the process. This allows the refrigerant to cycle back to the evaporator coil to repeat the cooling process.
  • Ductwork: A home’s ductwork refers to the network of ducts or channels used for distributing heated or cooled air from the HVAC system throughout the various rooms and spaces within a house. The main components of the ductwork system include supply ducts, return ducts, branch ducts, and trunk ducts.
  • Dehumidifier: A whole-house dehumidifier removes excess moisture from the air throughout the entire home. While portable dehumidifiers are standalone units that are typically used to control humidity in specific rooms or areas, whole-house dehumidifiers are integrated into the home’s HVAC system. A whole-house dehumidifier offers a higher dehumidification capacity as well as energy savings compared to running multiple portable units. Learn more about AprilAire Whole-House Dehumidifiers here.
  • Energy Recovery Ventilator (ERV): An ERV is used in homes to improve Indoor Air Quality while conserving energy. It exchanges stale indoor air with fresh outdoor air, while also transferring heat and moisture between the two air streams. This process helps maintain comfortable temperatures and proper humidity levels indoors while reducing energy costs. Learn more about the AprilAire V22BEC Energy Recovery Ventilator here.
  • Heat Recovery Ventilator (HRV): An HRV is also used in homes to improve Indoor Air Quality while conserving energy. HRVs primarily transfer heat between the outgoing stale air and the incoming fresh outdoor air. They are particularly effective in climates where heating is a primary concern, as they help retain warmth in winter by recovering heat from the outgoing air systems. ERVs, as you’ve just read, offer the added benefit of managing humidity levels in addition to heat transfer.
  • Heat Exchanger: A heat exchanger in an HVAC system transfers heat between two fluids or mediums without direct contact. It heats or cools air by transferring heat from a combustion chamber or refrigerant to the air circulated throughout the building, depending on whether the system is providing heating or cooling.
  • Humidifier: A whole-house humidifier adds moisture to the air throughout the entire house. Unlike portable humidifiers, which are typically used to humidify individual rooms, a whole-house humidifier is connected directly to the ductwork of the HVAC system. Learn more about AprilAire Whole-House Humidifiers (steam and evaporative) here.
  • HVAC System Efficiency Rating: The HVAC system efficiency rating refers to a measure of how effectively the system converts energy into desired heating or cooling output. This rating helps consumers assess the energy efficiency and performance of HVAC equipment, allowing them to make informed decisions when purchasing or upgrading their systems.
  • Minimum Efficiency Reporting Value (MERV) Rating: The MERV rating is a standard measurement used to rate the effectiveness of air filters in trapping airborne particles. It ranges from 1 to 16, with higher ratings indicating greater efficiency at capturing particles. MERV ratings consider the filter’s ability to capture particles of varying sizes, including pollen, dust, pet dander, and other contaminants. Generally, higher MERV ratings indicate better filtration performance, but they may also restrict airflow, potentially affecting HVAC system efficiency. Discover AprilAire Air Filter offerings and their MERV ratings here.
  • Pressure Drop: Pressure drop refers to the decrease in air pressure that occurs as air passes through the filter in the whole-house air purifier attached to the HVAC system. As air moves through the filter, it encounters resistance from the filter media and the particles trapped within it. This resistance causes a reduction in air pressure, which can impact the airflow through the HVAC system. A higher pressure drop means that the filter offers more resistance to airflow. As mentioned, while high-efficiency filters with higher MERV ratings may provide better filtration, they often have higher pressure drops, which can reduce airflow and strain the HVAC system. Balancing filtration efficiency with acceptable pressure drop is important for maintaining system performance and energy efficiency.
  • Radon Mitigation: A radon mitigation system reduces indoor radon gas levels, which can cause lung cancer. It typically includes sub-slab depressurization, ventilation improvements, sealing cracks, and monitoring to ensure safety standards are met. Learn more about AprilAire Radon Mitigation solutions here.
  • Refrigerant: Refrigerant in HVAC systems is a substance used to transfer heat from inside a home to the outside, enabling cooling. It circulates through the system, alternately evaporating and condensing to absorb and release heat. Common refrigerants include hydrochlorofluorocarbons (HCFCs), hydrofluorocarbons (HFCs), and newer, more environmentally friendly options like hydrofluoroolefins (HFOs).
  • Seasonal Energy Efficiency Ratio (SEER) Rating: The SEER Rating is measure of the efficiency of an air conditioning system. It represents the ratio of the cooling output of the system (in British thermal units or BTUs) to the energy input (in watt-hours) over an entire cooling season, typically measured in British thermal units per watt-hour (BTU/Wh) or in tons of cooling capacity per watt (tons/W). In simpler terms, it indicates how efficiently an air conditioner can cool a space over the course of a typical cooling season. Higher SEER ratings indicate greater energy efficiency, meaning the system can provide the same amount of cooling while consuming less energy. SEER ratings range from around 13 for older, less efficient systems to over 20 for the most efficient models available today.
  • Steam Canister: The steam canister is the beating heart of your AprilAire Steam Humidifier, responsible for generating the steam that your humidifier then distributes throughout your home. Current runs between two electrodes within the canister, heating your water to a boil and creating steam that is distributed through your HVAC system.
  • Thermostat: A thermostat controls the HVAC system by regulating the temperature inside the house. It allows users to set their desired temperature, and the thermostat works to maintain that temperature by signaling the HVAC system to turn on or off as needed. A smart thermostat is a Wi-Fi-enabled device that allows users to remotely control and manage their home heating and cooling systems using a smartphone, tablet, or computer. Learn more about AprilAire Thermostats here.
  • UVC Coil Cleaner: AprilAire UVC Coil Cleaners kill up to 99.9%* of mold that can build up on the coil in your HVAC system, protecting you from the harmful effects of mold and other pollutants like bacteria and viruses. AprilAire UVC Coil Cleaners not only help provide you with Healthy Air but improve your HVAC system’s efficiency. This means you save money by having a system that performs better for longer.*Testing performed on Aspergillus niger mold spores in a sheet metal duct with a new lamp placed 18 inches from the surface
  • Water Panel: A humidifier water panel, also known as a humidifier filter, is a critical component of your whole-house evaporative humidifier designed to add moisture to the air in the home. It absorbs water and facilitates its evaporation into the air, which increases indoor humidity levels.
  • Zoning: Zoning involves dividing the home into separate areas, or zones, and controlling the temperature independently in each zone. This allows for more precise and efficient climate control, as occupants can adjust temperatures based on their preferences and occupancy patterns. Zoning typically relies on multiple thermostats and dampers within the ductwork to regulate airflow to different zones, optimizing comfort and energy usage throughout the space.

There you have it—you’re well on your way to understanding the meaning of HVAC! Have any questions? Not sure what’s in your home? Contact an AprilAire Healthy Air Professional nearest you to discuss your home’s specific system and Indoor Air Quality needs today.