HVAC Glossary

AFUE

The measurement for heating efficiency is AFUE (Annual Fuel Utilization Efficiency), which ranges from 80% to 96% for new systems. The higher the AFUE, the more efficiently the system performs, the greater your energy savings.

______________________________________________________________

Airflow

The distribution or movement of air.

______________________________________________________________

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.

______________________________________________________________

Bioaerosols

Microscopic living organisms suspended in the air that grow and multiply in warm, humid places.

______________________________________________________________

Btu

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.

______________________________________________________________

Btuh

British thermal units per hour.

______________________________________________________________

CAE

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.

______________________________________________________________

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.

______________________________________________________________

CFM

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.

______________________________________________________________

Compressor

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

______________________________________________________________

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.

______________________________________________________________

Damper

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

______________________________________________________________

dB

A decibel is a unit used to measure the relative intensity of sound.

______________________________________________________________

DOE

The Department of Energy is a federal agency responsible for setting industry efficiency standards and monitoring the consumption of energy sources.

______________________________________________________________

Ductless Air Conditioner

See Mini-split System.

______________________________________________________________

Ductwork

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

______________________________________________________________

Electronic Air Cleaner

An electronic device that filters out large particles and bioaerosols in indoor air.

______________________________________________________________

ENERGY STAR®

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.

______________________________________________________________

EPA

The Environmental Protection Agency develops and enforces federal environmental regulations. The EPA oversees the nationwide Energy Star® program.

______________________________________________________________

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.

______________________________________________________________

FAQ

Stands for "frequently asked questions."

______________________________________________________________

Heat Exchanger

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

______________________________________________________________

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 circulates it through your home's air ducts. In the summer, it reverses the process and removes heat from your house and releases it outdoors.

______________________________________________________________

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.

______________________________________________________________

HSPF

The Heating Seasonal Performance Factor is the heating efficiency rating for heat pumps. The higher the rating, the more efficient the heat pump. HSPF will be regulated in 2006 at 7.7.

______________________________________________________________

Humidifier

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.

______________________________________________________________

Humidistat

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

______________________________________________________________

HVAC

Heating, Ventilation and Air Conditioning.

______________________________________________________________

Indoor Coil

See Evaporator Coil.

______________________________________________________________

ISO 9000

A family of international standards for quality management and assurance.

______________________________________________________________

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.

______________________________________________________________

Micron

A unit of measure equal to one millionth of a meter, or one thousandth of a millimeter.

______________________________________________________________

Mini-split System

A ductless air conditioning system that mounts in a single room, used to cool individual areas, particularly if a Window Unit is not desired or no windows are present.

______________________________________________________________

Odors/Chemicals

Air contaminants in the form of gases.

______________________________________________________________

Outdoor Coil

See Condenser Coil. 

______________________________________________________________

Particles (Particulates)

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.

______________________________________________________________

R410A Refrigerant

A chlorine-free refrigerant that meets the EPA's newest, most stringent environmental guidelines.

______________________________________________________________

Refrigerant

A chemical that produces a cooling effect while expanding or vaporizing. Most residential air conditioning units contain the standard R-22 refrigerant, or Freon.

______________________________________________________________

Refrigerant Lines

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

______________________________________________________________

Scroll Compressor

A specially designed compressor that works in a circular motion, as opposed to up-and-down piston action.

______________________________________________________________

SEER

The cooling performance of air conditioners and heat pumps is rated using the SEER (Seasonal Energy Efficiency Ratio) system, which ranges from 13.00 to 20.00 for new systems. The higher the SEER, the better the efficiency, the greater the energy savings.

______________________________________________________________

Single Package

A heating and cooling system contained in one outdoor unit.

______________________________________________________________

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.

______________________________________________________________

Thermidistat

Monitors temperature and humidity and adjusts heating or cooling system to maintain desired levels.

______________________________________________________________

Thermostat

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.

______________________________________________________________

Ton

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.

______________________________________________________________

Upflow

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.

______________________________________________________________

Ventilator (or Fresh Air Ventilator)

A system that exchanges stale, recirculated indoor air with fresh, filtered outside air.

______________________________________________________________

Window Unit

An air conditioner designed to be placed in the window, used for cooling individual rooms.

______________________________________________________________

Zoning

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