Glossary Terms

  • AFUE
    Annual Fuel Utilization Efficiency. A measure of a gas furnace's efficiency in converting fuel to energy. The higher the rating, the more efficient the unit. For example a rating of 90 means that approximately 90 percent of the fuel is used to provide warmth to your home, while the remaining 10 percent escapes as exhaust.
  • Amperes
    The measured rate at which electricity is delivered to an appliance; it is limited by the size of the wire it must flow through.
  • BTU
    British Thermal Unit. This is the amount of heat it takes to raise one pound of water one degree Fahrenheit. For your home, it represents the measure of heat given off when fuel is burned for heating or the measure of heat extracted from your home for cooling.
  • Capacity
    The output or producing ability of a piece of cooling or heating equipment. Cooling and heating capacities are referred to on BTUs.
  • CFM
    Cubic Feet per Minute. A standard measurement of airflow. A typical system requires 400 CFM per ton of air conditioning.
  • Circuit Breaker
    Every circuit must be protected, circuit breakers break (interrupt) the circuit when it is over loaded. Current causes heat that can cause a fire hazard if circuit breakers are not sized properly to the wiring.
  • Circuits
    The wiring that travels through the walls and ceilings of your home. (Wiring between breakers and outlets.)
  • Compressor
    The heart of an air conditioning or heat pump system. It is part of the outdoor unit and pumps refrigerant in order to meet the cooling requirements of the system.
  • Condenser Coil and Outdoor Coil
    In an air conditioner, the coil dissipates heat from the refrigerant, changing the refrigerant from vapor to liquid. In a heat pump system, it absorbs heat from the outdoors.
  • Damper
    Found in ductwork, this movable plate opens and closes to control airflow. Dampers can be used to balance airflow in a duct system. They are also used in zoning to regulate airflow to certain rooms.
  • Dedicated Circuit
    A circuit installed to serve only one piece of equipment.
  • Ductwork
    Pipes or channels that carry air throughout your home. In a home comfort system, ductwork is critical to performance, in fact, it's as critical as the equipment.
  • Electrical Service
    Equipment including a meter and distribution panel at the point where power is delivered to the building.
  • Evaporator Coil or Indoor Coil
    The other half of your air conditioning system is located inside your home in the indoor unit. This is where the refrigerant evaporates as it absorbs heat from the air that passes over the coil.
  • Freeze Stat
    A thermostatic device used to initiate an operation to prevent freeze damage.
  • Gas Furnace Heat Exchanger
    Located in the furnace, the heat exchanger transfers heat to the surrounding air, which is then pumped throughout your home.
  • General Purpose Circuit
    A circuit installed that supplies a number of outlets for lighting and appliances.
  • Ground
    A means for an electrical circuit to continue a path back to Earth (whether intentional or accidental).
  • Ground-Fault Circuit-Interrupter (G.F.C.I.)
    A device (breaker or receptacle) intended to open a circuit if a fault to the ground exceeds a pre-determined value with a quick response time.
  • HSPF
    Heating Seasonal Performance Factor. This rating is used in measuring the heating efficiency of a heat pump. The higher the number, the more efficient the unit.
  • Package Unit
    A heating and cooling system contained in one outdoor unit. A package unit is typically installed either beside or on top of a commercial business, or sometimes used in residential applications.
  • Receptacle
    A device installed at the outlet for the connection of an appliance power cord.
  • Refrigerant
    A chemical that produces a refrigerating effect while expanding and vaporizing. Most residential air conditioning systems contain R-22 refrigerant. R-22 is regulated by international controls under the Montreal Protocol and in the United States by the Environmental Protection Agency. New refrigerants such as R-410A are currently an alternative replacement for R-22.
  • SEER
    Seasonal Energy Efficiency Ratio. A measure of cooling efficiency for air conditioners and heat pumps. The higher the SEER, the more energy efficient the unit. The government's minimum SEER rating is 13. (It's similar to comparing miles per gallon in automobiles.)
  • Split System
    The combination of an outdoor unit (air conditioner or heat pump) with an indoor unit (furnace or air handler). Split systems must be matched for optimum efficiency.
  • Surge Protector
    A device designed to handle unusual power surges that can enter a home on the electrical power line. Many surges are caused by indirect or near lightning strikes, while others may result from electrical disturbances caused by motors and equipment located along the power line.
  • Surge Suppressor
    A device designed to sense the servere rise in voltage and pass the excess current safely to ground. This keeps the voltage that reaches equipment inside a home to a manageable level, thus increasing the life of the equipment, or in many cases, saving it from being destroyed.
  • Switches
    Any device intended to open a circuit. (Must rate for amperage and voltage.)
  • Thermostat
    A thermostat consists of a series of sensors and relays that monitor and control the functions of a heating and cooling system.
  • Ton
    A unit of measurement used for determining cooling capacity. One ton is the equivalent of 12,000 BTUs per hour. A BTU is a British Thermal Unit and is equal to the amount of heat required to raise one pound of water one degree.
  • Volts or Voltage
    The measurement of electrical potential of any (2) wires of a circuit.
  • Weather Proof
    An installation to guard against exposure to weather.
  • Zoning
    A method of dividing a home into different comfort zones so each zone can be independently controlled depending on use and need.