Len’s Heating & Air Conditioning HVAC Term Glossary

AFUE 

Annual Fuel Utilization Efficiency: Efficiency rating for furnaces (e.g. a 95+ efficiency indicates that at least 95 percent of the fuel is heating your home and the balance is expelled as exhaust).

BTU

British Thermal Unit: The amount of heat required to raise a pound of water 1 degree Fahrenheit. It is used to measure heat lost in the process of cooling your home.

CFM

Cubic Feet per Minute: A measure of airflow through a system. It is of particular importance in measuring the effectiveness of air quality systems.

Capacity

A measurement of the output of a piece of heating or cooling equipment. Heating and cooling capacities are measured in BTUs.

Comfort-R™ Airflow System

An exclusive feature of a high-efficiency home comfort system from Trane. This method of ramping airflow gives you greater humidity control when cooling and provides warmer air during heating start up.

Compressor

The heart of an air conditioning or heat pump system. It is part of the outdoor unit and uses refrigerant to meet the cooling requirements of the system.

Condenser Coil or 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.

Ductwork

Pipes or channels that carry air throughout your home. In a home comfort system, ductwork is as critical to performance as the equipment.

Evaporator Coil or Indoor Coil

The other half of your air conditioning system 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.

Gas Furnace Heat Exchanger

Located in the furnace, the heat exchanger transfers heat to the surrounding air, which is then pumped throughout your home.

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 beside or on top of the home or sometimes in the attic.

Refrigerant

A chemical that produces a refrigerating effect while expanding and vaporizing. Historically, residential air conditioning systems have contained R-22 refrigerant. The EPA mandated a change to R-410A by 2010 for environmental reasons.

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.)

SEET

Seasonal Extreme Environmental Test Lab: This is Trane's torture chamber for heating and air conditioning systems, where five years of service are condensed into 16 weeks. If a product doesn't make it through their SEET lab, it's not manufactured. Trane's equipment is pushed to extremes in a lab rather than in your home.

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.

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.

Zoning