HVAC Terms Explained
This glossary breaks down common HVAC terms you may see when scheduling service, reviewing recommendations, or learning more about your heating and cooling system. Our goal is to explain industry language clearly, without jargon or guesswork.
hvac terms
An air conditioner cools indoor air by removing heat and humidity and releasing that heat outdoors. Central air conditioning systems are common in North Alabama due to extended warm seasons and high humidity. When properly sized and maintained, an AC system helps improve comfort, indoor air quality, and energy efficiency.
Air Conditioner (AC)
The air exchange rate measures how often indoor air is replaced with outdoor air within a specific time period. Proper air exchange supports ventilation and indoor air quality.
Air Exchange Rate
The blower assembly includes the blower motor and fan that move air through the HVAC system and ductwork.
Blower Assembly
A chiller is a commercial cooling system that removes heat from a liquid and circulates it through a building to provide cooling. Chillers are typically used in larger facilities such as industrial buildings, hospitals, or data centers. Proper maintenance is critical to ensure reliable operation and efficiency.
Chiller
The control board is the electronic component that manages HVAC system functions such as ignition, fan operation, and safety controls.
Control Board
The control system coordinates thermostats, sensors, and mechanical components to regulate HVAC operation.
Control System
A damper is a movable plate inside ductwork that controls airflow to different areas of a building.
Damper
A defrost cycle is a process used by heat pumps to remove ice buildup from the outdoor coil during colder weather.
Defrost Cycle
Ductwork is the system of channels that carries heated or cooled air throughout a building. Properly designed and sealed ductwork is essential for even temperatures, good airflow, and efficient system performance. Leaks or poor design can lead to energy loss, uneven comfort, and higher utility bills.
Ductwork
A fan coil unit is an indoor HVAC component that uses a fan and coil to heat or cool air within a space.
Fan Coil Unit
A fresh air intake allows outside air to enter the HVAC system to support ventilation and indoor air quality.
Fresh Air Intake
A furnace is a heating system that warms air and distributes it through ductwork to heat a home or building. Furnaces are commonly powered by natural gas, electricity, or propane. Regular maintenance helps ensure safe operation, consistent heat, and reliable performance during colder months.
Furnace
A heat pump is an energy-efficient HVAC system that provides both heating and cooling by transferring heat instead of generating it. In warm weather, it removes heat from indoors to cool the space. In cooler weather, it pulls heat from outside air to warm the building, making it a popular option for North Alabama’s climate.
Heat Pump
HVAC stands for Heating, Ventilation, and Air Conditioning. An HVAC system is responsible for regulating indoor temperature, airflow, and air quality in homes and commercial buildings. In North Alabama, HVAC systems must handle hot, humid summers and cooler winter months, making proper installation and maintenance especially important.
HVAC
Indoor Air Quality refers to the cleanliness and comfort of the air inside a home or building. Factors such as humidity levels, ventilation, filtration, and airborne particles all affect IAQ. Poor indoor air quality can impact comfort and health, especially in tightly sealed buildings.
Indoor Air Quality (IAQ)
A load calculation is a detailed assessment used to determine the correct HVAC system size for a building. It accounts for factors like square footage, insulation, windows, occupancy, and local climate. Accurate load calculations help prevent issues such as short cycling, uneven temperatures, and excessive energy use.
Load Calculation
Mechanical ventilation uses powered equipment to circulate and replace indoor air rather than relying on natural airflow.
Mechanical Ventilation
An occupancy sensor detects whether a space is in use and adjusts HVAC operation to improve efficiency and comfort.
Occupancy Sensor
Preventative Maintenance
Preventative maintenance refers to routine HVAC service performed to keep systems running efficiently and help prevent unexpected breakdowns. Regular inspections allow technicians to catch small issues before they turn into costly repairs. Maintenance can also extend equipment life and support consistent comfort year-round.
A pressure switch is a safety device that monitors airflow or pressure and prevents system operation if unsafe conditions are detected.
Pressure Switch
Return air is indoor air drawn back into the HVAC system to be filtered, conditioned, and recirculated.
Return Air
A rooftop unit is a commercial HVAC system typically installed on the roof of a building. RTUs provide heating and cooling to larger spaces and help free up indoor floor space. They are commonly used in retail buildings, offices, and industrial facilities.
Rooftop Unit (RTU)
A setback temperature is a reduced heating or cooling setting used during unoccupied periods to conserve energy.
Setback Temperature
Short cycling occurs when an HVAC system turns on and off too frequently. This can be caused by improper system sizing, airflow issues, or mechanical problems. Short cycling reduces efficiency, increases wear on components, and can lead to higher energy costs.
Short Cycling
Supply air is the conditioned air delivered from the HVAC system into occupied spaces.
Supply Air
An HVAC tune-up is a scheduled service visit that includes inspecting, cleaning, and adjusting system components. Tune-ups are often performed before peak heating or cooling seasons to prepare the system for heavier use. Routine tune-ups can improve performance, reduce energy use, and help identify potential problems early.
Tune-Up
A Variable Refrigerant Flow (VRF) system is a commercial HVAC system that adjusts refrigerant flow based on demand. This allows different areas of a building to be heated or cooled independently. VRF systems are known for energy efficiency, zoning flexibility, and precise temperature control.
VRF System
A zone control panel directs airflow to different zones based on thermostat input and system demand.