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Simplifying Common HVAC Terms

common HVAC terms Brown's

The HVAC industry has a lot of terms; it can get confusing and overwhelming if you’re not a technician. As a NJ homeowner or a business owner, which ones do you really need to know about? Our experts at Brown’s Heating Cooling and Plumbing have identified some of the most common HVAC terms below.

HVAC Terminology: What You Need To Know


Annualized Fuel Utilization Efficiency is a measure of your furnace’s heating efficiency. The higher the AFUE percentage, the more efficient the furnace. The minimum AFUE percentage established by the DOE for furnaces is 78%.


The distribution or movement of air.

Air-Conditioning and Refrigeration Institute (ARI)

ARI is an industry trade association that develops standards for measuring and certifying product performance. For instance, ARI Standard 270 provides guidelines for establishing sound levels for outdoor air-conditioning equipment.

Air Handler/Coil Blower

The indoor part of an air conditioner or heat pump that moves cooled or heated air throughout the ductwork of your home. An air handler is usually a furnace or a blower coil.


The blower is the portion of an HVAC system that pushes the filtered air from a return duct over the coil or heat exchanger. After the air is conditioned, the blower continues to direct the air into the supply ducts to be redistributed back into the home.


A boiler is a unit in which water or other fluid is boiled to generate heat. The heated or vaporized fluid can be used for various applications, including central heating. Though not as common nowadays in homes, boilers (and other steam heating systems) are among the most reliable on the market.


A British Thermal Unit is a unit of heat energy. One BTU is the amount of heat required to raise one pound of water by one degree Fahrenheit. The higher the BTU rating, the greater the heating capacity of the system.


British Thermal Units per Hour.


The Combined Annual Efficiency is a measure of the amount of heat produced for every dollar of fuel consumed for both home and water heating.

Carbon Monoxide

An odorless, colorless, tasteless, poisonous, and flammable gas that is produced when carbon burns with insufficient air. It is toxic to humans and animals.  Carbon monoxide (CO) is slightly lighter than air. When encountered in high concentrations it can cause sudden illness and death.

The most common symptoms of carbon monoxide poisoning include:

  •        Headache
  •        Dizziness
  •        Weakness
  •        Nausea
  •        Vomiting
  •        Chest pain
  •        Confusion

Note: If you or anyone in your family suspects they are suffering from carbon monoxide poisoning or you believe there is a CO leak, evacuate immediately. A carbon monoxide leak should be treated like a fire as it can and does kill in minutes.

Central Air Conditioning System

System in which air is treated at a central location and distributed to and from rooms by one or more fans and a series of ducts.

Central Heating System

A central heating system, much like a central air conditioning system, is an HVAC component that supplies heat through the entire building from one single source via a network of air ducts.


Stands for Cubic Feet per Minute. This measurement indicates how many cubic feet of air pass by a stationary point in one minute. The higher the number, the more air is being moved through the ductwork by the system.


The part of the outdoor air conditioner or heat pump that compresses and pumps refrigerant to meet household cooling requirements.

How’s it work?

The compressor is a component of your air conditioner housed outside of your home in the portion of your air conditioner or heat pump called the condenser. The compressor is used to compress the refrigerant—which travels back and forth between the condenser and the evaporator, cooling the indoor air—back into a liquid.

The refrigerant is constantly transforming from liquid to gas as it moves from the condenser to the evaporator. When it’s in liquid form—after it’s been compressed by the compressor—the refrigerant is extremely cold, so when it travels to the evaporator coil, it can absorb the heat in the indoor air and cool it. As it absorbs the heat, the refrigerant turns into a gas and is sent back to the compressor to be compressed again. This cycle continues over and over until the house reaches the temperature set on the thermostat.

There are a number of reasons why your compressor (major part inside condenser)  may not be working properly, including:

  •        Age of your compressor
  •        Unbalanced refrigerant levels
  •        Poor airflow
  •        And more

If you’re having problems with your compressor or you need air conditioning services in New Jersey, contact Brown’s Heating, Cooling & Plumbing. Our highly trained technicians can help you with air conditioning that might be on the fritz!

Condenser Coil

The outdoor portion of an air conditioner or heat pump that either releases or collects heat, depending on the time of the year.


A movable plate, located in the ductwork, that regulates airflow. Dampers are used to direct air to the areas that need it most. Typically used in a zoning application.


Home dehumidifiers are installed to work in conjunction with your heating and cooling system. They draw warm, moist air through the return ductwork and cool it. When the air is cooled, moisture in the air condenses and turns into water droplets which fall into a collection pan or go directly down a drain. The dry air is passed over another set of coils so that it can reach the desired room temperature again before it’s circulated through your home.

Ductless HVAC

Ductless HVAC is a great alternative to central heating and air conditioning systems. In fact, it works similarly to central heating and cooling except that it doesn’t require bulky ductwork. Your ductless mini-split system will have an indoor and outdoor unit, but it will only require a small hole to be cut through the exterior wall—just big enough for a tube of refrigerant to pass through. Inside your home, the air will be conditioned and returned into the room by the same unit.

Learn more about ductless HVAC systems »


The method by which air is channeled from the furnace or the blower coil throughout your home.


An EPA (Environmental Protection Agency) designation attached to HVAC products that meet or exceed EPA guidelines for high-efficiency performance above the standard government minimums.

Evaporator Coil

The part of the air conditioner or heat pump that is located inside the air handler or attached to the furnace. Its primary function is to absorb the heat from the air in your house.

Learn more about your AC evaporator coil »

Forced Air Heating System

A forced air HVAC system is one where the heated or cooled air is pushed (or forced) by a fan over the coil or heat exchanger and into the supply ducts to be redistributed back into the building


A furnace is a forced air HVAC system that heats the air in your home. Whether gas, oil or electrical, the furnace works by blowing the air from the return ducts through the plenum and into the furnace itself to be heated. After the air has been heated, the blower fan pushes the air into the supply ducts to be returned back into the house.

Learn more about furnaces »

Heat Exchanger

Located in the furnace, the heat exchanger transfers heat to the surrounding air, which is then pumped throughout the home.

Heat Loss

The heat that escapes from the interior of the building into the outside air is known as heat loss. Drafts and insufficient insulation are common causes of heat loss. In order to improve energy efficiency, you want to minimize your home’s heat loss.

Heat Pump

A heat pump is an HVAC unit that heats or cools by moving heat. During the winter, a heat pump draws heat from outdoor air and transfers it into the indoor air. In the summer, it reverses the process and removes heat from your house and releases it outdoors.

Learn more about how a heat pump works »

Heating Capacity

Sometimes called “specific heat,” the heating capacity is the quantity of heat necessary to raise the temperature of a specific mass of substance (in the case of a furnace or heat pump this would be air) by one degree.

Horizontal Flow

When an air handler or furnace is positioned on its side and circulates air in one end and out the other. Ideal for attic or crawl space installations.


An indoor air quality device that introduces moisture to heated air as it passes from the furnace into the ductwork for distribution throughout the home.

Learn more about whole-house humidifiers »


An automatic device used to maintain humidity at a fixed or adjustable set point.


Heating, Ventilation and Air Conditioning.

Indoor Air Quality

Indoor air quality (IAQ) can be defined as the air quality within and around buildings and structures, especially as it relates to the health and comfort of building occupants—and it can be affected by microbial contaminants (like mold and bacteria). Systems like air cleaners and humidifiers can help improve the indoor air quality of homes.

Learn more about our IAQ products »

MERV Rating

The MERV (Minimum Efficiency Reporting Value) rating of a filter describes the size of the holes in the filter that allow air to pass through. The higher the MERV rating, the smaller the holes in the filter, the higher the efficiency.


Any substances measuring less than 100 microns in diameter. The EPA has found that small particles (less than 2.5 microns) are responsible for the health effects of greatest concern.

Programmable Thermostat

A thermostat with the ability to record different temperature/time settings for your heating and/or cooling equipment.

Learn more about programmable thermostats »


See R-410A

R-410A Refrigerant

A chlorine-free refrigerant that meets the EPA’s newest, most stringent environmental guidelines. R-410A is a chlorine-free refrigerant—also known as Puron—that meets the EPA’s newest, most stringent environmental guidelines.

Learn more about the R-22 phase-out »


A chemical that produces a cooling effect while expanding or vaporizing. Most residential air conditioning units contain the standard R-22 refrigerant (which is being phased out) or R-410A.

Refrigerant Lines

Two copper lines that connect the outdoor air conditioner or heat pump to the indoor evaporator coil.


The register is the vent connected to your ductwork where the conditioned air is redistributed through the house.


The Seasonal Energy Efficiency Ratio is an energy efficiency rating for air conditioners. The higher the SEER, the better the energy performance, the more you save. The DOE’s established minimum SEER rating for cooling is 13.00.

Split System

An HVAC system in which some components are located inside the structure of the house and some are located outside. Split systems should be matched for optimal efficiency.


Usually found on an inside wall, this device operates as a control to regulate your heating and cooling equipment, allowing you to adjust your home comfort at the touch of a switch.

Learn more about our thermostats »


Unit of measurement for determining cooling capacity. One ton equals 12,000 BTUH.

Two-Stage Operation

Provides two levels of heating or cooling output for greater temperature control, energy efficiency and improved indoor air quality.


When an air handler or furnace is installed in an upright position and circulates air through the side or bottom and out through the top. Typically used in basement, closet and attic installations.

Variable Speed Motor

A motor that automatically adjusts the flow of warm or cool air for ultimate comfort.


A method of partitioning a home into independently controlled comfort zones for enhanced comfort and efficiency.

Brown’s Providing Trusted HVAC Service in Monmouth County

No matter what common HVAC term you’re trying to decipher or problem you’re trying to solve, we are more than happy to visit your home to assist you with your heating and cooling issues – 24/7, 365 days a year.

Call the Brown’s Heating, Cooling and Plumbing experts at 732-741-0694. We offer the most reliable HVAC services throughout Toms River, Middletown, Brick, Holmdel, Freehold and surrounding NJ areas.