Glossary

Airflow : The distribution or movement of air.

Air-Conditioning, Heating and Refrigeration Institute (AHRI) : AHRI is an industry trade association that develops standards for measuring and certifying product performance.

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.

Backdrafting : The reversal of airflow in a combustion system, causing combustion byproducts, like carbon monoxide, to enter the living space.

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 (CO) : 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.

Coefficient of Performance (COP) : A measure of the efficiency of a heating or cooling system, representing the ratio of useful heat movement to the input energy.

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, that 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.

Demand Response : An energy management strategy where the utility company can control or adjust a building’s energy usage during peak demand periods.

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

Dry-charged or Dry-shipped : An air-conditioner or heat pump that is shipped dry and charged with refrigerant at the place of installation. Dry charged units are appropriate for homeowners who need a replacement unit compatible with R-22 refrigerant.

Dual Fuel : A comfort system that pairs an electric heat pump with a gas furnace, providing an energy-efficient alternative to the conventional furnace/air conditioner combination.

Ductless Mini-Split System : An HVAC system that provides heating and cooling to specific zones without the need for ductwork.

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

Economizer : A device that introduces outside air into a building to assist in cooling, improving energy efficiency.

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.

Equipment : Referring to the main components of the HVAC system. The condenser, furnace, evaporator coil, heat pump and air handler would be considered equipment.

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.

Fan Coil Unit (FCU) : A unit consisting of a fan and a heat exchange coil used to condition air in small spaces.

Garage Heaters : Garage heaters are an excellent product for combating cold garages and workshops during the winter months. Heating capacities provide warmth for a 1 car garage up to a 4 car garage application. Separated combustion models provide heating for hard-to-heat applications.

Geothermal Heat Pump : A system that uses the constant temperature of the Earth as a heat source or sink for heating and cooling.

Grid-tied : A grid-tied system is the most common and least expensive of all residential solar HVAC systems. It allows you to use your own solar-generated electricity to save energy and reduce costs. At times when the solar system isn’t producing electricity, such as at night, electricity is provided by the utility company’s grid, or network of power stations.

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.

Heat Recovery Ventilator (HRV) : A ventilation system that exchanges heat between incoming and outgoing air, improving energy efficiency.

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 (HVAC) is the technology of indoor and vehicular environmental comfort. Its goal is to provide thermal comfort and acceptable indoor air quality.

Indoor Coil : See Evaporator Coil.

Inverter Technology : A technology that allows the compressor in an HVAC system to operate at variable speeds, improving energy efficiency.

ISO 9000 : A family of international standards for quality management and assurance.

Joule Heating : The process of heat generation due to the passage of an electric current through a conductor.

Kilowatt (kW) : A unit of electrical power equal to 1,000 watts.

Latent Heat : Heat absorbed or released during a phase change (e.g., from liquid to vapor), contributing to the cooling or heating process

Manual J Calculation : A method used to determine the heating and cooling loads of a building to properly size HVAC equipment.

Media Filter : A media filter is a large filter that is typically installed into an external rack. Their purpose is to remove more air particles cleaning the air. These filters are usually more expensive than standard filters but can have a much longer life span as well. It is recommended that home owners check these filters every 6 to 12 months for debris clogging the air way.

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 but typically you don’t want to go above MERV 11 with HVAC or you could end up restricting air flow too much and causing major issues.

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

Natural Ventilation : The use of natural airflow to ventilate and cool indoor spaces.

Odors/Chemicals : Air contaminants in the form of gases.

Off-grid or Off-the-grid : An off-grid electricity-generating system operates independently from the utility grid, providing all of the electricity needed in the home. Stand-alone systems are much more expensive than grid-tied systems. However, for homes located in remote areas without utility service, or where installing power lines would be extremely costly, a stand-alone system is a good option.

Outdoor Coil : See Condenser Coil.

Ozone Depletion Potential (ODP) : A measure of the environmental impact of a refrigerant on the depletion of the ozone layer.

Particles : 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.

Parts : Referring to the items that make up the components of an HVAC system.

Passive Solar Heating : The use of architectural design and building materials to capture and store solar energy for heating purposes.

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

Quality Installation (QI) : Ensuring that HVAC systems are installed according to industry best practices for optimal performance and efficiency.

R-22 Refrigerant : The old standard for residential air conditioners, R-22 refrigerant is now being phased out by the U.S. EPA. Some companies still offer dry- charged units for those who still have R-22 compatible systems.

R-410A 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. Also called line sets.

Reverse Cycle Chiller (RCC) : A system that provides both heating and cooling by reversing the refrigerant flow.

Sensible Heat : Heat that causes a change in temperature without a change in state.

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

SEER  : 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.

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.

Thermal Comfort : The state of mind that expresses satisfaction with the surrounding thermal environment.

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.

Ultraviolet Germicidal Irradiation (UVGI) : The use of UV light to disinfect air and surfaces, reducing the spread of airborne pathogens.

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.

UV Light : UV lights are installed on HVAC systems to help kill micro-organisms such as dust mites.

Vapor Compression Refrigeration : The most common refrigeration cycle, using a compressor to pump refrigerant between the evaporator and condenser coils.

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

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

Watt-Hour (Wh) : A unit of electrical energy equal to one watt of power consumed for one hour.

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