Glossary of Heating & Air Conditioning Terms 

When purchasing a new heating or air conditioning system, consumers are overwhelmed by the terms never heard of before.

Understanding the basic terminology will help you in selecting the equipment that best serves your needs as well as conserving energy.

HVAC - Heating, ventilating and air conditioning.

AFUE – Annual Fuel Utilization Efficiency is a measurement of a furnace's efficiency in converting energy the higher the rating, the more efficient the unit.   For example: A rating of 90% means approximately 90% of the fuel is used to provide warmth to your home, while the remaining 10% as exhaust.

ARI - Air-Conditioning and Refrigeration Institute is a non-profit, voluntary organization comprised heating, air conditioning and refrigeration manufacturers.  ARI publishes standards for testing and pumps and air conditioners to provide you with a standardized measure of comparison. So, ARI a level of quality within the industry.

DOE - The Department of Energy is a federal agency in charge of setting industry efficiency standards and monitoring the consumption of energy sources.

Watt (W) - a Watt is a unit of electricity.

Kilowatt (kW) - a kilowatt equals 1,000 Watts. A kilowatt hour (kWh) is the amount of kilowatts electricity used in one hour of operation of any equipment.

BTU - Stands for British Thermal Unit, a standard for measuring the capacity of a cooling and system. A BTU is the amount of heat required to raise the temperature of one pound of water on the Fahrenheit scale. (Remember your high school science class?) The work capacity of air conditioning equipment is expressed in total BTUs.

PTAC - Acronym for "Packaged Terminal Air Conditioner".

Ton - is the total BTU capacity of a system. Going back to "class," a ton is equal to the BTUs required melt one ton of ice in a 24-hour period.  Since there are 12,000 BTUs in a ton, a 3-ton air conditioning will produce 36,000 BTUs and so forth. The size of the area to be cooled determines the correct the system in tons.  It s mportant to note that actual capacity is not constant and will change outdoor or indoor temperatures.  The pulished capacity rating of air conditioners and heat pumps based on performance at the ARI standard temperature levels of 95 F outside, 80 F inside.

Efficiency - A rating on equipment is similar to the Energy Star rating on your appliances. The higher the rating number, the more efficient the system and the lower your fuel or electric consumption will be.

ENERGY STAR - Products/Homes/Buildings that earn the ENERGY STAR prevent greenhouse gas emissions by meeting strict energy efficiency guidelines set by the U.S.

SEER - Seasonal energy efficiency ratio is the amount of cooling your equipment delivers per every dollar spent on electricity. SEER rates the cooling efficiency of an air conditioning system, much like the "miles per gallon" rating used for automobiles. In the past, a unit with a SEER of 10.00 was considered standard efficiency, and a unit with a 14.00 SEER was considered high efficiency. After January 1, 2006, the minimum SEER required by the DOE was 13.00 and 15.00+ SEER is considered high efficiency.

HSPF - Heating seasonal performance factor is similar to SEER, but it measures the efficiency of the heating portion of your heat pump. Like SEER, industry minimums have been raised recently, and the minimum is now 13.00 HSPF.

COP - Coefficient of performance is a ratio that compares a heat pump’s heating efficiency to that of electric resistance heat. A COP’s will vary with outside temperature: as the temperature falls, the COP falls because the heat pump is less efficient at lower temperatures. ARI standards compare equipment at two temperatures, 47 F and 17 F, to give you an idea of the COP in both mild and colder temperatures.

For example, a heat pump system with a COP of 3.0 provides heat at 3 times the efficiency of electric resistance heat. A heat pump's system COP will decrease as outdoor temperatures drop, eventually providing little or no efficiency advantage over electric resistance heat - and that's when your auxiliary heat strips start to heat your home.

Sound Ratings - Although sound does not affect the efficiency of a unit, it will certainly affect your comfort. If your unit has a low sound decibel the quieter it will be. But if it has a higher sound level, it may mean a good night's sleep is disturbed every time it runs!

Decibel (db) - a decibel describes the relative loudness of a sound.

Sound Rating Number (SRN) - sound is measured in BEL’s (a BEL equals 10 decibels). The SRN of a unit is based on ARI test, performed at ARI standard rating conditions. Average sound rating ranges from 7.0 to 8.0 decibels, The lower the SRN rating, the quieter the unit.

Refrigerant – A chemical gas that removes heat from the air due to is low boiling point producing a refrigerating effect. 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. It is scheduled to be in production until the year 2020. It's used in approximately 95 percent of air conditioning equipment manufactured in the U.S. today. The new refrigerant that will replace R-22 is called R410-A or Puron.

CFM – Cubic Feet per Minute is a standard measurement of airflow. A typical system requires 400 CFM per ton of air conditioning.

Indoor Coils -A homes comfort system consist of two components: the outdoor unit (air conditioner or heat pump) and the indoor unit (coil or blower coil). Combinations of various units will result in vastly different efficiency ratings.

The Price of Quality

There is more to buying a heat pump or air conditioner than ratings. The quality of construction and materials used as well as the reliability of the manufacturer and installing contractor can all affect your long term satisfaction and comfort. Top quality, high efficiency equipment will cost more initially, but it will save you money on utility bills and service calls for years to come. Be sure to weigh all the factors before choosing your new system.