The Dictionary of Home Heating Terminology

Home heating terminology confusing you? Check out this glossary filled with key terms that will help you make the right decision when researching the best heating and/or cooling system for you home. Everything you need to know, all in one spot.

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Editors of the Portable Fireplace Blog update this Glossary whenever new terms are discovered. If you have a question or have a term that you feel should be included on this list, please send us a message using our Contact Form.



– Air Changes per Hour is a measurement of air infiltration. It is the total volume of air in a home that is turned over per hour. ACH is a way to measure insulation efficiency, the amount of air and potentially heat/cold air that can be escaping through windows, cracks, and vents. Tightly constructed homes have an ACH of 0.25-0.35 ACH. New homes have an ACH of 1.75 while older homes may have a higher rating at 2.5 ACH.

AFUE Rating

– Stands for Annual Fuel Utilization Efficiency. This measures the average efficiency of heating equipment derived from a comparison of the amount of heat it delivers and the amount of fuel that must be supplied. All furnaces are required to have an AFUE Rating of at least 78% in the United States.

Air Infiltration

– A term that relates to air leaking into or out of a home through small cracks in windows, outlets, walls, floors, roofing, door frames, and other areas. It is the primary component of heat loss and is measure in Air Changes per Hour (ACH).


– The American National Standards Institute is a nonprofit accreditation organization that oversees the development of standards for various products and services in the United States and across the globe. The ANSI ensures that American products are safe and compatible for use in other countries. This organization represents the U.S. at the International Organization for Standardization (ISO) and the International Electrotechnical Commission (IEC).


– The American Society of Heating, Refrigeration and Air-conditioning Engineers. ASHRAE is a global society that promotes collaboration, education, innovation, and professional growth in the associated industries.


– A circuit breaker is a heat activated electrical switch that is used to open (or close) an electrical circuit to protect it from an excessive flow of current that could potentially cause damage or short circuits. Unlike a fuse that is only good for one time use, a breaker can be reset to resume normal operation. You may hear this term used when asked to “flip the breaker” or “check the breaker” or “it may have tripped the breaker.”


– The British Thermal Unit is a traditional unit of energy equal to about 1055 joules. It is the amount of energy needed to cool or heat one pound of water by one degree Fahrenheit. Learn more about BTU’s or Determine How Many BTU’s Your Home Needs.(LINK)(LINK)

Carbon Monoxide

– Carbon Monoxide or “CO” is poisonous gas that is produced as a byproduct of incomplete combustion of fossil fuels such as natural gas or propane. Carbon Monoxide is colorless, tasteless, and odorless. It is a dangerous gas that can create a significant danger. Most homes have fire alarms that will indicate if unsafe levels of CO2 are present. Electric fireplaces do not emit any Carbon Monoxide and thus eliminate air pollution in the home that is cause by traditional wood burning or gas fireplaces.


– Cubic Feet per Minute. CFM measures airflow, how many cubic feet of air passes through a given point in a single minute. CFM used to determine how much heat can be moved by a particular heat source, fan, and other mechanical device. The higher the CFM, the more air is being forced through the system.

Coefficient of Performance

– The efficiency ratio of the amount of heating or cooling provided by a heating or cooling unit to the energy consumed by the system. The higher the Coefficient of Performance (COP), the more efficient the system is. Electrical heating has COP of 1.0. This means that all of the energy consumed is directly transformed into heat. Similar to AFUE for gas furnaces.

Convection Heating

– Convection heaters operate by air convection currents circulating through the body of the appliance and across its heating element. This causes the air to increase in temperature. Convection heaters can use electrical, water, coil, or steam as a means of heating the air. They are quieter than fan heaters because they already require ventilation to create heat.

CSA Certified

– Canadian Standards Association tests products and provides certifications for electrical, mechanical, plumbing, gas, and other types of industrial and consumer products. CSA certified products are intended to increase assurance of quality and safety. Visit their website.


Dry Bulb Temperature

– The temperature read using a standard thermometer. Contrasts Wet Bulb Temperature.

Electric Heat

– Heat that is produced by using resistance to convert electrical energy. Commonly seen in space heaters and electric fireplace inserts.

Energy Efficiency Ratings

– EER measures the efficiency at which a given product operates. Calculated by dividing BTU output by wattage. Learn more about heating efficiency.

Energy Star

– An international standard for energy efficient consumer products originated in the United States. Created in 1992 by the Environmental Protection Agency (EPA) and the Department of Energy (DOE). The goal of the Energy Star program is to reduce air pollution and increase energy efficiency.

Flue Pipe

– The part of a gas furnace that exhausts combustion products out of the home.


– A furnace is a device for heating. The name derives from the Latin word for oven, “fornax.” A furnace creates hot air and distributes this air throughout the home through a connection of air ducts. Furnaces can use natural gas, propane, oil, or electricity as a fuel source.


– A fuse is a type of low resistance resistor that acts as protects devices from current overload. Essentially, a fuse will blow if too much power is sent to a given device. This protects the device which typically costs much more than a fuse that can be purchased for a few dollars. A fuse is composed of a metal wire or strip of metal that will melt when too much current flows through it, interrupting the circuit. Electrical current carries heat and too much of this will blow the fuse to protect appliances. Many electric fireplaces use a fuse(s).


Geoexchange System

– Heating and cooling systems that rely on stable underground temperatures. Related to geothermal systems. Heat energy taken from the ground is low grade and doesn’t provide adequate heat. While it is low in heat, Geoexchange systems are powerful because they are a relatively warm source of constant energy. This heat is then placed through a process that concentrates and upgrades the heat into something that homes can use.


– As described by Physicist Max Born, heat is the transfer of energy from a hotter body to a colder one. This can be done through conduction, radiation, or convection circulation. Heating is a dissipative process.


– Heating Seasonal Performance Factor. This is the estimates seasonal heating output (BTU’s) divided by the amount of energy it consumes (watt-hours).


– A humidifier is a household appliance that increase humidity (moisture) by adding water vapor to heated air exiting the furnace. It is commonly used in the winter when humidity levels drop inside the home. Standalone humidifiers can also be purchased for single room or point-of-use applications. Humidifiers increase moisture whereas dehumidifiers lead to dryer environments.


– Heating, Ventilation, & Air Conditioning. HVAC systems are used to heat and cool the home. Generally speaking, all modern homes have some type of HVAC system installed to control indoor climates.

Hydronic Heating

– This is a type of radiant heating system that provides warmth by heating water or other types of liquids. The liquid is then circulated through the building to control temperature. Similar to the way in which a car’s radiator works.


– Indoor Air quality refers to the quality of air found inside of a home.


– This term refers to the air escaping or entering a building through small cracks. Infiltration is used in reference to insulation leaks. In heating, it is used to measure heat loss. See ACH.

Infrared Heat

– Infrared heat is a type of radiant heat that transfers energy through electromagnetic radiation. These invisible wavelengths are ideal for windy outdoor spaces because they directly transfer heat rather than heating air that can be lost due to wind gusts or unpredictable weather. Learn How Infrared Heaters Work.


– A Kilowatt Hour is a unit of energy equal to 1,000 watt-hours or 3.6 megajoules. If the energy is being transmitted or used at a constant rate of power over a period of time, the total energy in Kilowatt Hours is the product of the power in kilowatts and the time in hours. kWH’s are used to measure electrical consumption for most homes in the United States and is what you are billed for.


Latent Heat

– Latent heat is the energy released or absorbed by a body or a thermodynamic system during a constant-temperature process. When added or removed, latent heat causes a change in state but not a change in temperature.


– The Leadership in Energy and Environmental Design is a set of rating systems for the design, construction, operation, and maintenance of green buildings, homes, and neighborhoods. LEED was developed by the U.S. Green Building Council (USGBC) in an effort to help building owners and operators become environmentally responsible and use resources efficiently. Visit their Website.



– The National Fire Protection Agency was established in 1896 and has now grown to become an international organization. The mission of the NPA is to reduce the worldwide burden of fire and other hazards on the quality of life by providing and advocating consensus codes and standards, research, training, and education.


Radiant Heating

– A technology for heating indoor and outdoor areas. The most common example of radiant heating is energy that comes from the sun. The principles of radiant heat are used to transfer radiant energy from and emitting heat source to a given object. Radiant heating largely replaced conventional convection heating in outdoor spaces.


– The ability of a material to resist the flow of heat. The higher the value, the harder it is for heat to pass through a given object. Often used as a means to measure insulation standards.



– Seasonal Energy Efficiency Rating – An efficiency rating of air conditioning systems. SEER is a ration of annual BTU’s of cooling provided divided by the electric energy input used.


– Also referred to as the “comfort zone.” The setpoint is the temperature at which a thermostat is set for desired comfort level. Used heating devices that offer climate control. Keeps temperature at a constant by automatically adjusting output.

Tinted Glazing

– Also referred to as “tint.” A window film that blocks or absorbs portions of the sun’s rays. This limits the amount of heat that passes through the window. Tint is commonly seen on automobiles and commercial buildings.


– A temperature sensitive switch used to control the operation of a cooling or heating system.


– Also referred to as a ton, tonnage is unit used to measure the heating/cooling output. 1 ton is equal to 12,000 BTU’s.


– The Underwriter’s Laboratories is an association that sets and validates product safety standards for industrial and consumer products. Products stamped with the UL Certification have been proven to to comply with UL safety standards. UL Recognized electric fireplaces eliminate the risk of faulty products that can cause a danger to homeowners.


– The United States Fire Administration is a branch of the Federal Emergency Management Agency (FEMA) that focuses on firefighting and fire safety. FEMA is managed by the US Department of Homeland Security (DHS). THE USFA gathers and manages statistics of fire incidents, grand funding, and other information pertaining to the home fire safety.


– A unit that measures the ability of a material to conduct heat (conductivity). Also referred to as the coefficient of heat transmission. U-Value is the reciprocal of the R-Value. The higher the value, the more heat that the material can conduct.


Wet Bulb Temperature

– A temperature reading taken by a thermometer whose bulb is encased with a wetted wick. Contrasts Dry Bulb Temperature.


Zone Heating

– A heating system that controls climate in different areas. Zone heating is the opposite of central heating which heats the entire home/building. Zone heating can be achieved through zone heating thermostats that control temperature or alternatively by space heaters, electric fireplaces, and gel fireplaces. Zone heaters are energy efficient and can be an effective means to lower utility bills.


About the Author
is an interior design consultant focusing on crisp modern interiors with a tinge of retro styling. She offers design and consulting services for residential and commercial spaces. Follow her for fool proof design tips for everyday homeowners.