Serving Sampson County, NC
Since 1978

The HVAC industry can be full of unfamiliar acronyms and industry terms.
This dictionary will help to break down the most common terms you'll come across during your decision making process. If you have any questions, feel free to call us for assistance!



AC Alternating Current - A type of current where the polarity is perpetually reversing, causing the directional flow in a circuit to reverse at regular intervals.

ACCA - Air Conditioning Contractors of America.

Acoustical - Relating to sound, the science of sound, or a sense of hearing.

AFUE - Annual Fuel Utilization Efficiency. A measurement used to rate furnace efficiencies by dividing the ratio of heat output by heat input.

AGA - American Gas Association, Inc.

Air Conditioner - A device that changes humidity levels, temperature or quality of air.

Air Flow Volume - Measured in cubic feet per minute (cfm), this is the amount of air circulated in a space.

Air Handler - Parts of a system including the fan-blower, filter and housing.

ARI - Air Conditioning and Refrigeration Institute.

ASHRAE - American Society of Heating, Refrigeration and Air Conditioning Engineers.



BTU - British Thermal Unit. Measures the amount of heat required to raise or lower the temperature of one pound of water one degree Fahrenheit. (One BTU is approximately equal to the heat given off by a wooden kitchen match.)

BTUh - British Thermal Units per hour.

Burner - The device that facilitates the combustion of air and gas.

Burner Orifice - The opening in the burner through which the gas or fuel passes prior to combustion.


Capacity - HVAC capacity is the output produced by the heating or cooling unit and is measured in BTUs per hour.

Celsius - A temperature scale that registers the freezing point of water as 0° and the boiling point as 100° under normal atmospheric pressure.

CFM - Cubic Feet per Minute. A measurement of airflow volume that indicates how many cubic feet of air pass by a stationary point in one minute. The higher the number, the more air is being forced through the system.

Capacity - The ability of a heating or cooling system to heat or cool a given amount of space. For heating, this is usually expressed in BTUs. For cooling, it is usually given in tons.

Carbon Monoxide - A colorless, odorless, highly poisonous gas produced when carbon-based fuels, such as natural gas, burns without sufficient air nearby.

Charging a System - Adding coolant, or refrigerant, to an HVAC system.

Compressor - A pump that increases the pressure of gas. Part of a split-system heat pump or air conditioner's outdoor unit that controls the pressure applied to the refrigerant, necessary for taking in heat to warm your home with a heat pump or getting rid of heat to keep your home cool.

Condensate - Vapor that is turned into a liquid as its temperature is lowered.

Condenser Coil - Also an outdoor coil. A device that removes heat from the refrigerant, allowing the refrigerant to be converted from vapor to liquid. Part of the outdoor portion of a split-system air conditioner or heat pump. By converting refrigerant that is in a gas form back to a liquid, the coil sends heat carried by the refrigerant to the outside.

Condenser Fan - A fan that passes air over the condenser coil to facilitate the removal of heat from the refrigerant.

CSA - Canadian Standards Association.



DC - Direct Current. A type of electrical current that only flows in one direction.

DB - Decibels (dB) are a unit measuring the intensity of noise.

Damper - Found at the exit point of ductwork, this plate usually contains grates that can be opened or closed to control the flow of air into a zone.

Degree-Day - Calculated by subtracting the average outdoor temperature for an area from 65º Fahrenheit. This measurement is used to estimate the amount of heating or cooling a home or building will need.

Dehumidifier - A device that removes humidity, or moisture, from the air.

Diffuser - A grille over an air supply duct with vanes that distribute the discharging air in a specific pattern or direction.

DOE - Department of Energy.

Downflow Furnace - A furnace with an intake on the top and an air discharge at the bottom.

Drain Pan - Also a condensate pan. As the refrigerant vapor is liquefied, the drain pan collects the condensate and funnels it to the drain line.

Dry Bulb Temperature - The temperature as measured without the consideration of humidity.

Ductwork - A network of metal, fiberboard or flexible material flowing throughout a space which delivers air from an HVAC unit to the respective zones of a home or office.



EER - Energy Efficiency Ratings (EER) measure the efficiency with which a product uses energy to function. It is calcuated by dividing a product's BTU output by its wattage.

Electronic Air Cleaner (EAC) - An electronic device that filters out large particles and contaminants in indoor air. It then electronically pulls out tiny particles that have been magnetized, such as viruses and bacteria, drawing them to a collector plate.

EPA - Environmental Protection Agency.

Expansion Valve - A valve that meters the levels of refrigerant through a temperature or pressure control.

Evaporator Coil - Also an indoor coil. A device that is designed to absorb heat in the air in order to change the liquid refrigerant that flows through it into a vapor.

Energy Star - Energy Star is a government-backed program helping businesses and individuals protect the environment through superior energy efficiency. Products with the Energy Star rating will be efficient and save cost on energy bills.



Fahrenheit - A temperature scale in which water freezes at 32 degrees and boils at 212 degrees at normal atmospheric pressure.

Fan - A device that creates air flow.

Fan Coil - An indoor component of an air conditioner or heat pump system, used in place of a furnace and evaporator coil, to provide change the refrigerant from a gas to a liquid (or vice-versa) and blow air over the coil to cool or heat your home.

Filter - A device that acts like a strainer to remove dirt or undesired particles.

Flue - A vent that removes the byproducts of combustion from a furnace.

Furnace - The major component in heating a home. A device that facilitates the combustion of fuel and air to create heat.

Fuse - A delicate metal strip connecting two parts of an electrical circuit. This strip breaks, or melts, in the event of excess electrical charge, breaking the electrical circuit.



GAMA - Gas Appliance Manufacturers Association.



Heat Exchanger - A device through which heat is transferred to a cold area or surface.

Heat Gain - The amount of heat added or created in a designated area.

Heating Coil - A coil that acts as a heat source for a heating system.

Heat Loss - The amount of heat subtracted from a designated area.

Heat Pump - A device used for either the heating or cooling of a space by transferring heat between two reservoirs.

Heat Transfer - Moving heat from one location to another.

HSPF - Heating Seasonal Performance Factor. This factor rates the efficiency of the heating portion of the heat pump. The higher the HSPF number, the more efficiently the heat pump heats your home.

Humidifier - A device that adds humidity, or moisture, to the air.

Humidistat - The device that measures humidity and turns the humidifier on and off.

Humidity - Dampness in the air caused by water vapor. A piece of equipment that adds water vapor to heated air as it moves out of the furnace. This adds necessary moisture to protect your furnishings and reduce static electricity.

HVAC - Heating, Ventilation and Air Conditioning.

Horizontal Flow - A type of furnace, installed on its "side", that draws in air from one side, heats it and sends the warm air out the other side. Most often used for installations in attics or crawl spaces

Hybrid Heat - Hybrid Heat systems deliver exceptional performance by using a heating source that provides the most energy-efficient comfort during moderate heating conditions.



Ignition - Elevating the temperature of a substance to the point of causing a combustion reaction.

Indoor Coil - see Evaporator Coil



Kilowatt (kW) - 1,000 watts.



Latent Heat - A type of heat that when added to an area produces an effect other than an increase in temperature.

Load Estimate - A series of studies performed to determine the heating or cooling requirements of your home. An energy load analysis uses information such as the square footage of your home, window or door areas, insulation quality and local climate to determine the heating and cooling capacity needed by your furnace, heat pump or air conditioner. When referring to heating, this is often known as a Heat Loss Analysis, since a home's heating requirements are determined by the amount of heat lost through the roof, entry ways and walls.

Low Boy - Low Boy is a type of furnace configuration in which the furnace is lower in height and occupies more floor space.



Media - The fine material of a filter that traps dirt, dust, mildew or bacteria.

MERV - The Minimum Efficiency Reporting Value is the standard comparison of the efficiency of an air filter. The MERV scale ranges from 1 (least efficient) to 16 (most efficient), and measures a filter's ability remove particles from 3 to 10 microns in size.

Matched System A heating and cooling system comprised of products that have been certified to perform at promised comfort and efficiency levels when used together, and used according to design and engineering specifications.



NEC - National Energy Council / National Electric Code.

NEMA - National Electrical Manufacturing Association.



Orifice - An opening or hole.

Operating Cost - The day-to-day cost of running your home comfort equipment, based on energy use.

Outdoor Coil - see Condenser Coil



Package Unit - A heating and cooling system contained in one outdoor unit.

Payback Analysis - Overall measure of the efficiency and value of your home comfort system. By combining your purchase price and ongoing operating costs, a payback analysis determines the number of years required before monthly energy savings offset the purchase price.

PSI - Pounds per square inch.

PSIA - Pounds per square inch, absolute.

PSIG - Pounds per square inch gauge.

PVC - Polyvinyl chloride; a type of plastic.

Puron Refrigerant - Puron® Refrigerant is an environmentally sound refrigerant designed not to harm the earth's ozone layer. Federal law requires that all manufacturers phase out ozone depleting refrigerants in the next few years. Puron Refrigerant is approved by the US Environmental Protection Agency as a replacement from Freon 22*.



Reciprocating Compressor - A type of compressor used in cooling systems to compress refrigerant by using a piston action.

Refrigerant - A chemical that condenses from a vapor to liquid and, in the process, decreases in temperature.

Refrigerant Charge - The amount of refrigerant in a system.

R-22 refrigerant - R-22 is a single component HCFC refrigerant with low ozone depletion potential. It has long been used in a variety of air-conditioning and refrigeration applications in a variety of markets. Production of R-22 will cease in 2015 per the Montreal Protocol.

Reclaiming - Returning used refrigerant to the manufacturer for disposal or reuse.

Recycling - Removing, cleaning and reusing refrigerant.

Refrigerant Lines - Two copper lines that connect the Condenser (Outdoor) Coil to the Evaporator (Indoor) Coil



SEER - Seasonal Energy Efficiency Ratio. A rating system developed by the U.S. Government to indicate the efficiency level of cooling equipment.The higher the SEER number, the more efficient the system is at converting electricity into cooling power.

Self-contained System - A package unit.

Sensible Heat - Heat added or subtracted that causes a change in temperature.

Sensor - A device that reacts to a change in conditions.

Split System - Refers to an air conditioner or heat pump that has components in two locations. Usually, one part of the system is located inside (evaporator coil) and the other is located outside your home (condenser coil).

Scroll Compressor - A specially designed compressor that works in a circular motion vs. an up and down piston action.

Setback Thermostat - A state-of-the-art electronic thermostat with a built-in memory that can be programmed for different temperature settings at different times of the day.

Single Package Product - One outdoor unit that contains both a heating and a cooling system.

SmartRecovery - Smart Recovery starts the system in advance to be sure that each zone reaches your selected temperature setting at the scheduled time.



Thermostat - Sensors that monitor and control the output of an HVAC system.

Thermidistat - The ThermidistatT Control monitors temperatures both inside and outside, as well as indoor humidity and adjusts system operation to maintain the temperature and humidity levels set by the homeowner.

Thermostatic Expansion Valve - A thermostatic expansion valve (TXV) is precision device used to meter the flow of liquid refrigerant entering the evaporator at a rate that matches the amount of refrigerant being boiled off in the evaporator..

Ton - A unit of measure for cooling capacity. One ton = 12,000 BTUs per hour.

Two Stage Compressor - Two Stage Compressors are capable of two levels of operation, a low stage and a high stage. Properly sized equipment will operate 80% of the time in low stage, enhancing efficiency and comfort with lower humidity levels and quieter operation. It's like getting two air conditioners or heat pumps in one system.



Upflow Furnace - A furnace that pulls in air from the bottom and releases it through the top into the duct work. This type of furnace is usually installed in a basement or an out-of-the-way closet.

UL - UL is an objective, non-profit organization that tests and rates electrical products for public safety.



Vacuum - A space where the pressure is significantly below that of standard atmospheric pressure.

Volt - A unit of electro-motive force.

Voltage - The force pushing electrical current along wires and cables.

Ventilator - A ventilator captures heating or cooling energy from stale indoor air and transfers it to fresh incoming air.



Watt - The unit of electrical power equal to the flow of one amp at a potential difference of one volt.

Wet Bulb Thermometer - A thermometer that measures the relative humidity in the air.

WeatherShield - WeatherShieldT is a special coating of the outdoor condensing unit coil to resist corrosion from salt air found mainly in coastal areas.



Zoning - A system that divides a home, office or space into different regions in order to better control the temperature and effectiveness of a heating and cooling system. Programmable thermostats are used to control operating times of the equipment. Dampers are used to direct air flow to certain parts or "zones" of the home.