AFUE: Annual Fuel Utilization Efficiency. Efficiency rating of a gas furnace, calculated by dividing its output heat energy by its input in the total energy available in supply gas, which tells you how much energy is being converted to heat. For example, an AFUE of 90 means that 90% of the fuel is being used for heating your home, while the other 10% is wasted in the chimney.

Air Handler: The portion of a split duct type air conditioner or heating system, that forces air through the ductwork.

BTU: British Thermal Unit. Used for both heating and cooling as a measure of the heat transferred into or extracted out of an area. It is approximately the amount of energy needed to heat 1 pound (0.454 kg) of water 1 °F (0.556 °C).

BTUH:  BTUH is British Thermal Units per Hour.

CFM: Cubic Feet per Minute as a measurement of airflow, indicating how many cubic feet of air pass in one minute. The higher the number, the more air is being passing the system.

Capacity: Heating or cooling ability of a system to heat or cool a space. Expressed in BTUs, tons, Watts (or Kilowatts), Joules (or Kilojoules), Calories (or Kilocalories) or horsepower.

Chiller:Specific type of air conditioning or heating equipment that cools or heats water as a medium to transfer heat between the indoor and outdoor units.

Compressor: Part of a split-system heat pump or air conditioner, where the refrigerant is pressurized to travel through the system, to transfer heat from indoors to outdoors for cooling or vice versa for heating purposes.

Condenser Coil: Heat Exchanger part of a split-system air conditioner or heat pump, that is located outdoors. Used for converting refrigerant that is in a gas form, into a liquid form by removing heat from the refrigerant.

DB: Decibels (dB), which is a unit measuring the noise levels.

Damper: A manual or automatically operated air valve as a part of the ducting, used for zone control in air distribution.

Downflow: A type of duct connection, where either supply air ducting (for a furnace) or both the supply and return air ducting (for a package unit), are attached to through bottom of the equipment.

Ductwork: Air distribution piping works, for transferring air from (and/or to) the air handler or a package unit, to/from the air vents throughout the conditioned space.

Ductless System:A split type air conditioning or heat pump system, without any requirement for ductwork for the air distribution.

EER: Energy Efficiency Ratio (EER) measures the efficiency of an equipment, calculated by dividing its total output energy by its total input energy.  Expressed in BTUs/Watts or Watts/Watts..

Electronic Air Cleaner (EAC): A high voltage electronic air purifying device that first filters out large particles and then electronically attracts tiny particles by magnetizing, such as viruses and bacteria, into its collector plates.

Evaporator Coil: The indoor heat exchanger of a split-system air conditioner or heat pump. The evaporator coil cools and dehumidifies the air by converting liquid refrigerant into a gas, in cooling mode or vice-versa, in heating mode (heat pump).

Fan Coil: Indoor component of a split air conditioner or heat pump system, comprising of an evaporator coil and an air blower to change the refrigerant from a gas to a liquid (or vice-versa) and blow air over the coil to cool or heat the indoor space.

HSPF: Heating Seasonal Performance Factor, which indicates the heating efficiency of a heat pump.

HVAC: Short for the term: Heating, Ventilation, and Air Conditioning.

Heat Exchanger: Part of a system used to transfer heat from refrigerant to air and vice versa.

Heat Pump: Reversible flow version of an air conditioner, which cools in cooling mode and heats in heating mode, by reversing the flow of the refrigerant.

Horizontal Flow: Type of equipment where the air flow from its fan or blower is blown out in horizontal direction.

Humidifier: Equipment that adds water moisture to the air, for added comfort, to protect furnishings and reduce static electricity.

Indoor Coil: see Evaporator Coil

Load Estimate: A study to calculate the heating or cooling requirements of an area, based on its area, volume, windows, doors, insulation quality, and other heat generating devices and persons located within.

Matched System: Components of a split type heating and cooling system, which have been designed to work together to perform at promised comfort and efficiency levels.

MERV: Minimum Efficiency Reporting Value. Indicates the efficiency of an air filter in a scale of 1 (least efficient) to 16 (most efficient).

Mini Split System: Compact design split air conditioning or heat pump, available in a multitude of capacities, designs, styles and simplified installation techniques.

Multi Split System: Same as a mini split system, but multiple indoor units can be coupled with a single outdoor unit for ultimate some control and comfort.

Operating Cost: The daily cost of running HVAC equipment, based on energy it uses.

Outdoor Coil: see Condenser Coil

Payback Analysis: A calculation of time it takes to recover the extra expense by installing a better efficiency HVAC system, through the cost of the extra energy saved versus a lover efficiency version.

R410A Refrigerant: R410A refrigerant is an environmentally sound refrigerant (also called Puron®), is a blended refrigerant that is required in some areas.

R-22 refrigerant: R-22 is a single component HCFC refrigerant with low ozone depletion potential. It is most widely being used in a variety of air-conditioning and refrigeration applications in many areas.

Reciprocating Compressor: Type of compressor, that incorporates a piston or multiple pistons to compress the refrigerant.

Reclaiming: Removing refrigerant from equipment, in a safe manner without releasing it into the atmosphere to return to a recycling facility or for reuse.

Recycling: Safely removing, cleaning and reusing used refrigerant.

Refrigerant Lines: A set of two copper pipes that connect the Outdoor and the indoor sections of a split system air conditioner.

SEER: Seasonal Energy Efficiency Ratio is a measure of the cooling efficiency of an air conditioner or heat pump. A higher SEER means more electricity is being converted into cooling power.

Scroll Compressor: A newer technology compressor, that works in a circular action versus piston action.

Single Package Product: Asingle unit that contains both a heating and a cooling system, and all required components into a single casing that is located entirely outdoors..

Split System: An air conditioning or heat pump system with components in two locations, one part located inside (evaporator coil and blower) and the other located outside (condenser coil, compressor and fan).

Thermostat: Used for setting, controlling and monitoring theHVAC system products.

Thermostatic Expansion Valve (TXV): An automatically adjustable flow valve that regulates the amount of refrigerant flowing through the system automatically depending on varying conditions.

Ton: Used as a measure for cooling capacity. One ton = 12,000 BTUs per hour. One ton also equals to the amount of energy, required to convert 1 ton of water, exactly at freezing temperature, into one ton of ice in same temperature (without changing temperature) or vice versa.

Two Stage Compressor: A special compressor that runs at different RPM speeds to supply varying amounts of refrigerant depending on the load, and therefore saving energy.

Upflow: A Type of equipment where the air flow from its fan or blower is blown out in vertical upward direction.

Variable Refrigerant Volume (VRV-VRF): Multi zone systems comprising single (or grouped) outdoor units feeding ever-varying volume of refrigerant into a network of pipes attached to multiple indoor units. Compressors on these systems are almost infinitely adjustable in their speeds, therefore adjust the capacities and therefore the energy consumption at the best possible way.

Ventilator (ERV or HRV): For capturing heating or cooling energy from stale indoor air and transfers it to fresh incoming air.

Zoning: Method of increasing the comfort and energy efficiency by controlling when and where heating and cooling should occur.