Aire Serv® Of Austin

This section is designed to give you a little knowledge of air conditioner, heat pump and furnace efficiencies.

Air Conditioning Efficiency

Most people use a term of SEER when describing the efficiency of an air conditioning system. This stands for Seasonal Energy Efficiency Ratio. Put in simpler terms, the higher the number – the more efficient the unit.

The federal government has instituted standards requiring equipment manufacturers to make their systems more efficient. In 1992, a law was passed requiring all systems to be a minimum of 10 SEER. Beginning with January 2006, a new law now requires all systems to be a minimum of 13 SEER. To best illustrate the example, a 13 SEER system uses ½ the electricity of a 6.5 SEER system, which was available prior to 1992. Systems are available currently that reach over 20 SEER, but the higher efficiency is reflected in the higher up front investment.

If you have a new system installed, chances are it will be more efficient that what you currently have. Your overall savings will be dependent on the total cost of electricity, weather (is it hotter or cooler than last year?) and usage.

Heating Efficiencies

When looking at heating efficiencies, don’t get confused. You need to take in consideration the cost of the fuel versus the amount of heat it produces (Cost per therm), and the efficiency of how well it uses this fuel. An electric furnace is effectively 100% efficient, but the cost of an electric furnace can be 3 times the cost of a gas furnace – due to the per “therm” cost of gas versus electric.

Heat Pump Efficiency

Heat Pumps use a heating efficiency rated call COP, or Coefficient of Performance. The higher the COP, the more cost-effective the heat pump is at producing heat. Heat pumps use reverse cycle of an air conditioner to produce very efficient heating costs. See How a Heat Pump Works.

Gas Efficiency

Systems that use either natural gas or propane for heating are rated using a term called AFUE, or Annual Fuel Utilization Efficiency. This is used to determine how much of the heat that the fuel uses actually ends up in the house, and how much goes up the chimney to the outside.

When gas is burned, it creates a certain amount of heat. Any burning fossil fuel also produces combustion byproducts (flue gases) that need to be exhausted to the outside. Manufacturers have designed systems to reach efficiencies of 95% and more by limiting the amount of heat that escapes with the flue gases.

Gas furnaces designed before 1992 had efficiencies as low as 50% but the standard was set at that time to 78%. An 80% or 90% efficient furnace is very common, your location in the country and other configuration factors determine which is most appropriate for you.

Oil Efficiency

Oil efficiency is measured in the same terms as gas – using AFUE. The effective cost to use this heat source is determined by the cost of a gallon of fuel oil and the amount of heat (cost per therm) that is produced.

Multi-Stage Burners

Systems are available now, particularly with gas fired units that adjust the amount of heat produced by the system based on the amount required. For example, if the weather is mild outside the burner may burn less gas allowing the unit to run longer as opposed to short cycling by turning on and off frequently. This feature increases the cost effectiveness and comfort provided by the system.

Variable Speed Blowers

Until recently, most blowers (fans) in furnaces were either all the way on, or off. This sometimes causes an uncomfortable movement of the air when furnaces or heat pumps first start up. New variable speed technology slowly increases and decreases the blower speed as needed for maximum comfort.

An additional benefit of a variable speed blower is the ability to continually move the air. If you have a central air cleaner or air purification system, you can’t clean the air unless the air is moving through the system. A variable speed system allows the air to move slowly when cooling or heating is not required, and speeds the system up when necessary. This allows for the most effective use of an indoor air quality system.