Does your head ever spin when talking about your HVAC system? With all the technical terms, acronyms, and other jargon thrown around, it can be easy to get lost in the jargon. 

To help you out, we have compiled this glossary of HVAC terms that will have you talking like an old pro in no time. 

30 HVAC Terms Every Homeowner Should Know 

AC (air conditioner). A cooling system that lowers the temperature and removes humidity from the air within a building. An air conditioning system typically consists of an evaporator coil, compressor, condenser coil, and expansion valve, all working together to cool your home.

ACH (air changes per hour). The number of times the total volume of air within a space is replaced with fresh outdoor air each hour. A typical home has an ACH of 0.5 to 1.0, indicating a complete air exchange every 1-2 hours.

Air flow. The movement of air through a building’s HVAC system. Air flow deals with the circulation of indoor air, or the introduction of cooled air, moved by fans, ducts, and vents.

AFUE (annual fuel utilization efficiency). A measure of a furnace or boiler’s efficiency in converting fuel into usable heat. A higher AFUE rating indicates the furnace extracts more heat from the fuel, resulting in lower fuel consumption and operating costs.

Air handler. The indoor unit of a forced-air heating and cooling system. The air handling unit houses the blower fan, evaporator coil, and other components that circulate and condition the air within your home. Imagine it as the central “engine” that pushes conditioned air through your ductwork.

Air purifier. A device that removes airborne contaminants like dust, pollen, allergens, and smoke particles from the air within a space to improve indoor air quality. Different types of air purifiers use various technologies like filtration, electrostatic precipitation, or photocatalytic oxidation to achieve this.

BTU (British Thermal Unit). A unit of heat measurement equal to the amount of heat required to raise the temperature of one pound of water by one degree Fahrenheit. For cooling systems, higher BTU ratings indicate greater cooling capacity.

Central air conditioning. A system that cools and removes humidity from the air in a building using a central unit located outdoors and ductwork to distribute the conditioned air throughout the building. It offers efficient cooling for larger spaces compared to individual room units.

Coil. A heat exchanger component made of tubing or fins that transfers heat between a refrigerant and air or water. In HVAC systems, evaporator coils absorb heat from the air, while condenser coils release heat to the outside environment.

Compressor. The workhorse of an HVAC system. It increases the pressure of the refrigerant gas, enabling it to absorb and release heat more efficiently throughout the refrigeration cycle.

Condenser. A heat exchanger component located outdoors in an air conditioner or heat pump. It condenses the high-pressure refrigerant gas into a liquid by releasing heat to the outside air.

Condensate. The moisture that is removed from the air by an air conditioner as it cools or by a high efficiency furnace as it heats. This water needs proper drainage to prevent moisture buildup and potential damage.

Damper. A movable plate or valve that controls the airflow within an HVAC system. Dampers can be used to direct air to specific rooms, regulate airflow volume, or prevent backdrafting. 

Dehumidifier. A device that removes excess moisture from the air, improving comfort and preventing condensation buildup. Lowering your home’s humidity is a highly effective way to bring down the relative temperature, because humid air feels warmer. 

Expansion valve. Located between the liquid and evaporator sections, it regulates the flow of refrigerant into the evaporator coil. The expansion valve creates a pressure drop, allowing the refrigerant to expand rapidly, cool down, and absorb heat from the indoor air. 

Filter. The filter is a removable component in the furnace designed to trap and filter airborne particles from the circulating air and entering the inner workings of the furnace. It’s important to change the filter regularly to ensure your furnace functions properly. 

Flow. The rate or volume of air, refrigerant, or water moving through an HVAC system. It’s crucial for ensuring proper system performance and efficient climate control. 

Fresh air intake. An opening that allows fresh air from outside to enter your home ventilation system. It helps maintain good indoor air quality by replacing stale air with fresh air.

Furnace. A heating system that generates heat and distributes it throughout a building, often using forced air circulation or hot water radiant systems. Furnaces can be fueled by gas, oil, propane, or even electricity. 

Geothermal. A heating and cooling system that uses the Earth’s constant underground temperature to regulate your home’s climate. It uses a network of pipes buried underground to transfer heat to and from the Earth, providing energy-efficient heating and cooling.

Heat exchanger. A device that transfers heat between two fluids or between a fluid and a solid surface. It facilitates the exchange of thermal energy without the mixing of the fluids involved. In HVAC systems, it’s responsible for extracting heat from your home in summer and adding heat in winter. 

Heat pump. A system that can provide both heating and cooling by transferring heat between the indoor and outdoor environments. In heating mode, the heat pump extracts heat from the outdoor air (even in cold temperatures) or the ground and transfers it indoors. In cooling mode, it removes heat from indoor air and releases it outdoors. 

High efficiency furnace. A furnace that converts a high percentage of its fuel into usable heat, minimizing energy waste and lowering your heating bills. To be considered high efficiency, the efficiency rating must be 90% or higher—although modern units can reach as high as 98% efficiency. 

Humidifier. A device designed to add moisture to the air. It can be used to maintain optimal humidity levels, especially during dry or winter months when indoor air can become excessively dry. Just as you want to remove moisture from the air in the summer, you want to add it in the winter to increase the feeling of warmth in your home. 

Ductless mini-split. A split-system air conditioner without ductwork. It consists of an outdoor condenser unit and one or more indoor evaporator units mounted on walls or ceilings. It provides efficient cooling for targeted areas without requiring ductwork installation. 

HVAC (heating, ventilation and air conditioning). This one gets tossed around a bunch, but how many people actually know what it stands for? HVAC is an umbrella term for the technology of maintaining comfortable indoor temperature, humidity, and air quality within buildings. It encompasses all systems for heating, cooling, ventilation, and air filtration.

MERV (Minimum Efficiency Reporting Value). A standard rating that measures the effectiveness of air filters in HVAC systems. The MERV rating indicates how well a filter can capture and hold dust, pollen, mold spores, and other airborne particles. Ratings range from 1 to 16, where higher numbers represent a greater ability to filter out fine particles.

Refrigerant. A specialized chemical substance that absorbs and releases heat as it changes from a liquid to a gas and back again. This cycle forms the heart of refrigeration and heat pump technology. 

SEER (seasonal energy efficiency ratio). A measure of an air conditioner’s efficiency in cooling mode. It indicates how much cooling energy the unit delivers per unit of electricity consumed during the cooling season. The higher the SEER, the more efficient the air conditioner. 

Thermostat. The control center of your HVAC system. It allows you to set and adjust the desired temperature for your home, sending signals to the system to send cool or warm air until the target temperature is reached. 

Two-stage. This refers to a furnace or heat pump that operates in two stages of heating or cooling output. The first stage provides low-capacity operation for milder conditions, while the second stage kicks in for more extreme temperatures. The two stages allow for efficient operation based on current heating needs.

Welter. The Twin Cities’ most trusted and reliable HVAC service and installation company since 1912. 

Zoning Systems. A method used in HVAC to divide a building or space into zones, which can be individually controlled for temperature and air flow. Each zone has its own thermostat and can adjust the heating, cooling, and ventilation independently of other areas. This targeted control helps in improving comfort and increasing energy efficiency by heating or cooling only the areas that are in use.

The Definition of HVAC Expertise 

Whether you need your air conditioner replaced or routine furnace maintenance, our expert HVAC technicians have got you covered. Contact us to schedule an appointment for all of your heating and cooling needs.