Delcor's Glossary of HVAC

HVAC Glossary


The Annual Fuel Utilization Efficiency (AFUE) measures a gas furnace’s efficiency in converting fuel to energy. A higher AFUE rating means greater energy efficiency.


One British Thermal Unit (BTU) represents the amount of heat required to raise or lower the temperature of one pound of water one degree Fahrenheit. The heat extracted from your home by an air conditioner is measured in BTUs.


The heat extracted from your home by an air conditioner is measured in BTUs, while cooling and heating capacities are referred to in British Thermal Units per hour (BUTH). For reference, 12,000 BTUh equals one ton of cooling.

Central air conditioning

Central air conditioning refers to either a split system or a packaged system. Central air conditioning involves ductwork, as opposed to a window unit.

Charter Member

Our Trane Comfort Specialist® program is dedicated to achieving excellence in service and customer satisfaction. Charter members have been committed to these values since the inception of this program in 1998.

Clean Air Delivery Rate

Clean Air Delivery Rate (CADR) is the number of cubic feet of clean air that an air filtration system delivers in a minute. The CADR is recognized across the industry as the indicator for air filter efficiency.

Climatuff® Compressor

The Trane Climatuff® compressor was the world’s first successful heat pump compressor. It is part of your outdoor unit, and it pumps refrigerant in order to meet the cooling requirements of the system.


The compressor is the part of an outdoor unit that pumps refrigerant. The compressor maintains adequate pressure to cause refrigerant to flow and meet the cooling requirements of your home.

Connected control

A connected control does more than just monitor and adjust temperature settings. Trane connected controls can manage energy use, adjust temperature and humidity levels by room and floor, turn on and off lights, lock and unlock doors and check security cameras. All of this can be managed remotely via internet-enabled computers, tablets and most smartphones.


A decibel (dB) is used to measure the intensity of sound.

Dual fuel

Dual fuel systems have the option of using two fuel sources to maximize efficiency.


Ductwork consists of the pipes and channels that carry air throughout your home.


EER (Energy Efficiency Ratio) is an older way to evaluate an air conditioner’s efficiency. Unlike SEER, no seasonal temperature changes are accounted with the EER rating. EER is typically determined by a set outside air temperature, a set inside air temperature and a 50% relative humidity. For a comparison point, 11 EER is roughly equivalent to 13 SEER.


ENERGY STAR® is a government-backed program that helps businesses and individuals reduce energy costs and protect the environment through energy efficiency.

Energy tax credit

Energy tax credits are incentives to encourage the use of renewable energy, conserve resources and decrease pollution. Government agencies, utility companies and other organizations sometimes offer energy tax credits.

Evaporator Coil

The evaporator coil works with the indoor unit, functioning with the air conditioner or heat pump to cool and condition indoor air that flows over it by drawing out heat and moisture.

Geothermal Systems

Geothermal systems heat and cool your home by using renewable energy from under the earth’s surface.

Heat Pump

A heat pump, as part of a central heating and cooling system, uses the outside air to efficiently heat your home in the winter and cool it in the summer. Unlike a furnace, a heat pump doesn’t burn fuel to make heat. It simply uses electricity to move heat from one place to another.


The Heating Seasonal Performance Factor (HSPF) is used to measure the efficiency of heat pump. The HSPF is a ratio of the heat output to electricity use over an average heating season, and the higher the HSPF the greater the energy efficiency.


A humidifier is a device to increase humidity and moisture in your home.


HVAC commonly refers to heating, ventilation and air conditioning.

Matched System

A matched system is the combination of Trane products as every part of your system. Depending on your region, a matched system can be composed of the following: an air conditioner and furnace , a heat pump and furnace, a heat pump and air handler , an air conditioner and air handler, or an all-in-one “packaged” system. By combining Trane components that are made to work seamlessly together, you can create a more efficient ideal system.


Allergens like dust, smoke and bacteria are particulates that are often .3 microns or less. At that size, they can get deep into your lungs, because they aren’t filtered well by your nose and throat. If you’re concerned about controlling those airborne particulates, it’s good for you to know that Trane CleanEffects™ removes 99.98% of particulates, all particulates, from the air inside your home.

NATE Certified

NATE (North American Technician Excellence) is an independent organization that certifies installation or service technicians with a knowledge-based test.

Oil Furnace

An oil furnace is the heating component in some systems in colder climates, most commonly in the northeastern United States, that converts oil to heat.

Packaged System

Packaged systems are all-in-one solutions, with most of the components for heating and/or cooling housed in a single cabinet.


“Particulates” is a label used for particles that are really, really small. Some particulates are visible to the naked eye, but most are only visible through a microscope: mold spores, skin flakes, bacteria, household dust, pet dander, tobacco smoke, cooking smoke.

Pleated Filter

Pleated filters are part of your indoor air quality system. They filter dirt, pollutants and other particles, leaving you with cleaner air.


Refrigerant absorbs heat from the environment, and it can cool and dehumidify air when combined with other components such as compressors and evaporators. In 2010, the EPA mandated we discontinue the use of the refrigerant R-22 (often called Freon®) in new air conditioning systems because it contributes to ozone depletion. The new standard is a refrigerant R-410A (often called Puron®).

Refrigerant lines

Refrigerant lines are the pipes connecting your outdoor air conditioner or heat pump to your indoor evaporator coil.


SEER (Seasonal Energy Efficiency Ratio) is the most common way to evaluate an air conditioner’s efficiency.

Single-stage heating

Single-stage heating means a furnace has one level for heat output, regardless of the temperature outside your home.

Smart home

Smart homes are modern homes installed with communicating technology that have controls accessible via internet-enabled computers, smartphones or tablets. They allow you to monitor temperatures and manage energy use for optimal efficiency and comfort. Some systems even link into security features like locks, lights and cameras.

Spine Fin™ Coil

Our exclusive patented Spine Fin™ all-aluminum outdoor coil provides greater heat-exchanging capabilities (meaning higher efficiencies) and is more resistant to corrosion than a traditional copper/aluminum coil.

Split System

A split system has two parts: an outdoor unit and an indoor unit. Split systems are the most common HVAC systems in modern homes. There are different types of split systems, so they can fit the needs of a variety of homes.

Two-stage heating

Two-stage heating means a furnace has two levels, high and low, as opposed to a single-stage heating system which only has one level.

Variable-speed motor

A variable-speed motor inside your air handler or air conditioner can run at a wide range of speeds, giving you precise control over the temperature in your home.