Heating and Cooling Glossary

Advanced Reciprocating Compressor: A compressor for better cooling efficiency.
AFUE: Annual Fuel Utilization Efficiency: tells you how much energy is being converted to heat from a furnace.
Airflow: The distribution/movement of air.
Air Handler: The indoor component of a heating and cooling system that moves cooled or heated air throughout the ductwork of your home.
Air Sourced Heat Pump: A heating/cooling unit that transfers heat between outside and inside air.
Air Supply for Combustion: The air a furnace, boiler, or space heater requires to burn fuel.
Aquastat: A thermostat controlling the water temperature in a boiler.
Bellows: An accessory that assists in boosting combustion in wood fires, feeding air to the flames as it is forced out of an expandable bladder.
Bioaerosols: Microscopic organisms suspended in the air that grow in humid places.
Boiler: A heating unit that uses a hot water distribution system.
BTU: British Thermal Unit: a measure of the heat given off when fuel is combusted.
CAE: Combined Annual Efficiency: the amount of heat produced for every dollar of fuel consumed by both home and water heating.
Capacity: The ability of a system to heat or cool a specific space.
Carbon Dioxide: A gas produced with complete combustion of carbon units.
Carbon Monoxide: An odorless, poisonous, flammable gas produced when carbon burns with insufficient air.
Catalytic Combustor: A device used on some wood burning stoves to reduce the temperature at which smoke is ignited.
Central Air Conditioner: A unit that cools a structure by removing heat from the inside air and releasing it outside.
CFM: Cubic Feet per Minute: a measurement of airflow that indicates how many cubic feet of air passes by a stationary point in one minute.
Chase: A decorative surrounding that covers a metal flue inside the chimney.
Chimney Cap: A vented cap placed on top of a chimney to prevent obstructions which could interfere with the draft.
Chimney Pot: A decorative pot set at the top of a chimney which extends its length in order to improve the draft.
Clearance: The distance required by building and fire codes between stove, smoke pipe, or chimney and any combustible materials, such as wood furniture or carpets.
Compressor: Part of a split system heat pump that controls the pressure applied to the refrigerant; it is necessary for taking in or getting rid of heat.
Condenser Coil: Part of a split-system air conditioner or heat pump which converts refrigerant (a gas) back to a liquid, then, through a coil, sends the heat outside.
Conventional Gas Furnace/Boiler: A gas heating unit with an AFUE less than 70 percent.
Cost-effective Heating/Cooling System: A system that produces an efficient value for your money after all the costs have been considered.
Creosote: A flammable byproduct of combustion that can build up within a chimney and ignite, thereby creating "chimney-fires."
Damper: A "valve" used in ductwork that opens or closes to control airflow.
db: Decibel: a measure of sound.
Direct Vent Appliance: An appliance that draws combustion air to the outdoors and, therefore, eliminates the need for a standard chimney system.
Distribution System: The component of a heating/cooling system which delivers warmed or cooled air, or water, to a living space.
DOE: Department of Energy: a federal agency responsible for setting industry efficiency standards and monitoring the consumption of energy sources.
Domestic Hot Water: Hot water used for household purposes.
Downflow: A furnace that takes cool air from the top and blows warm air to the bottom.
Draft: The flow of air through a system made to channels smoke and gases outside.
Ductwork: A method where air is channeled from the furnace to the rest of your home.
Earth Energy System: A heating/cooling system that obtains heat/coolness from the earth or ground water and transfers it to the house through an underground piping system.
Electronic Air Cleaner: A device that filters out large particles and bioaerosols in indoor air.
Electrical Resistant Heating: Heat produced by passing electricity through a resistor.
Emissions: Byproducts of combustion vented out of the home.
ENERGY STAR: An EPA designation attached to HVAC products that meet guidelines for high-efficiency performance above and beyond government guidelines.
Evaporator Coil: Part of a split system air conditioner or heat pump located indoors, which cools and dehumidifies the air by converting liquid refrigerant into a gas, which absorbs the heat from the air.
Fan Coil: A part of a heat pump which provides additional heating on days when the heat pump is not providing it properly.
Firebacks: Devices that help to protect fireplace masonry and mortar by shielding them from the extreme heat of the flames.
Fireplace Inserts: Heating units that retrofit into an existing fireplace and offer superior efficiency.
Firebox: An interior part of a fireplace where fire is built.
Firestop: A noncombustible device which seals and prevents openings between different floors.
Flame Retention Head Burner: A higher-efficiency burner in an oil furnace.
Flue: A vent or chimney that is used as a combustion device by channeling smoke from an indoor living space to the outdoors.
Flue Collar: A ring for attaching a draft hood or vent connector and therefore determines the size of a vent.
Fluorocarbon Refrigerants: The fluids commonly used in refrigerating/air conditioning equipment to create a cooling effect.
Forced Air: A distribution system where a fan circulates air from the heating/cooling unit to the rooms through duct systems.
Freestanding Stove: An appliance that occupies and radiates heat to a specific area of a living space.
Furnace: A heating unit using a forced air distribution system.
Gas Logs: Logs that provide dramatic realism as to that of wood-burning fireplaces; these manufactured logs have a burner that uses either natural gas or propane.
Glass Doors: Doors which close off the opening of the hearth so heat from an alternate source does not escape up the chimney when fireplace is not in use.
Grate: An iron frame used to hold burning fuel in a fireplace.
Heat Exchanger: In the furnace, this device transfers heat to the surrounding air, and then pumps it throughout the home.
Heat Pump: An HVAC unit that heats or cools by moving the air.
HSPF: Heating Seasonal Performance Factor: measure of the heating efficiency of a heat pump.
Horizontal Flow: A furnace installed on its "side which draws in air from one side, heats it, and then sends it out the other side.
Hearth: The floor of a fireplace on which a blaze is built.
Heat Recovery Ventilator (HRV): A device used in central ventilation systems to reduce the amount of heat lost as indoor air is replaced with outdoor air.
Heat Shield: A noncombustible protector used around appliances, smoke pipes, or chimneys.
High-Efficiency Furnace/Boiler: A heating unit with an AFUE of 90 percent or more.
Hopper: A container where fuel is stored before being fed to the burner.
HVAC: Heating, Ventilation, and Air Conditioning.
Humidifier: A device that adds water vapor to the air as it moves out of the furnace.
Humidistat: An device that maintains humidity at a fixed point.
Hydronic System: A distribution system in which hot water is circulated through pipes to other radiating heating systems (radiating wall vents, baseboards, or flooring units).
Instantaneous Water Heater: A device that heats water as required but does not store it.
Island Fireplace: A freestanding fireplace with four glass sides so that it can be viewed from any angle.
Integrated Hot Water System: A system that provides water heating from a single heat source.
Kilowatt: A unit of power used to measure the heating capacity of electric equipment.
Kindling: Small, dry wood used to start a fire.
Load Estimate: An analysis used to determine the heating or cooling requirements for a house.
Mantle: An ornamental shelf that is installed above a fireplace.
Matched System: A system made from certified products in order to perform at a promised comfort and efficiency level when they are used together.
MERV Rating: Minimum Efficiency Reporting Value: rating of a filter that describes the size of the holes in the filter that allow air to pass through.
Metal Liner: A liner used in fireplace inserts and placed inside an existing chimney in order to reduce the diameter of the flue for more rapid exit of smoke and combustion gases.
Mid-Efficiency Natural Gas/Propane Furnace/Boiler: A gas heating unit with an AFUE of 78 to 82 percent.
Natural draft (B-vent) Appliances: A gas-burning appliance which takes combustion air from the home and vents it outside.
Natural Gas: A clean-burning fossil fuel that is delivered throughout a home by using a pipeline network.
New Oil Furnace: A furnace that has an AFUE range from 78 to 86 percent.
Odors/Chemicals: Air contaminants in the form of gases.
Operating Cost: The day-to-day cost of running your heating/cooling systems.
Payback Analysis: Overall measure of the efficiency of your heating/cooling systems.
Pellets: Fuel that consist of 100% wood sawdust with no additives.
Peninsula Fireplace: A fireplace with three glass sides.
Pilot: A continuously burning flame that a gas appliance uses in order to ignite the main burner.
Programmable Thermostat: A thermostat that can record different temperature/time settings for your heating/cooling equipment.
Propane: Liquefied petroleum gas used in the home.
R-2000: A performance standard for new homes under a voluntary government program. The standard includes high insulation levels, air-tightness, heat recovery ventilation, and efficient heating/cooling systems.
R410A Refrigerant: A chlorine-free refrigerant that meets the EPA's most stringent guidelines.
Reclaiming: Returning used refrigerant to a manufacturer for disposal/reuse.
Reciprocating Compressor: A compressor used in air conditioners which compresses refrigerant by using a "piston" action.
Recycling: Removing, cleaning, and reusing refrigerant.
Refrigerant: A chemical that produces a cooling effect as it expands/vaporizes.
Refrigerant Lines: Two copper lines that connect the outdoor heat pump to the indoor evaporator coil.
Safety Pilot: A safety shutoff for gas flow that normally provides a heat source in order to ignite a main burner.
SEER: Seasonal Energy Efficiency Ratio: a measure of the cooling efficiency of your air conditioner or heat pump.
Scroll Compressor: A compressor that works in a circular motion versus a piston action.
Seasonal Efficiency: A performance rating that considers the heating/cooling delivered to a living space, the total energy in the fuel consumed, and the impact the equipment has on the heating/cooling load throughout an entire season.
Seasoned: Wood that has been dried before burning.
Setback Thermostat: An electronic thermostat with a built-in memory that is able to program and adjust to different predetermined temperature settings during different times of day.
Single Package: A heating/cooling system contained in one outdoor unit.
Space Heater: A heating unit providing heat directly to a particular living space but that is not connected to a distribution system.
Spillage: A failure of a venting system wherein the flue sends gases back into the home rather than outside.
Spill Switch: A device used to detect the occurrence of spillage and alert the homeowner.
Split System: An air conditioner or heat pump that has components in two different locations (typically one inside and one outside).
Steamers: Kettle-like devices that harness the heat energy from fireplaces/stoves and releases warm, moisturized steam into the air.
Storage-type Water Heater: A tank that heats and stores hot water.
Thermidistat: A device that monitors temperature and humidity, and then regulates heating/cooling systems to maintain a desired level.
Thermostat: A device that monitors and controls an HVAC system.
Ton: A unit of measure for cooling capacity.
Total Home Comfort System: A system that provides consistent home comfort despite changing weather.
Two-Stage Operation: Provides two levels of heating/cooling output for greater temperature control, energy efficiency, and improved indoor air quality.
Upflow: A furnace that draws cool air from the bottom and blows warm air out the top into the duct work.
Unvented/Vent-Free Appliance: An efficient burning device that draws combustion air out of the home and, therefore, eliminates the need for venting.
Variable Speed Motor: A motor that automatically adjusts the flow of warm/cool air for optimum comfort.
Vent-Free: A gas appliance with no need for a flue.
Ventilator: A unit that traps heating/cooling energy from stale indoor air and transfers it to fresh incoming air.
Water Column (WC): A measurement of gas pressure equal to one twenty-eight of a pound per square inch (PSI).
Zero-Clearance Fireplace: A factory-built fireplace made so that it can safely be placed next to combustible material.
Zoning: A way to increase your home comfort and energy efficiency by controlling when and where heating/cooling occurs in a home.