OverviewFor Quick Facts on Space Cooling see Air Conditioning
Space cooling has probably been the single largest residential growth segment for the electric utility since the invention of the electric refrigerator. Air conditioning is very energy intensive. Equipment continues to be improved making it more energy efficient, but home owners continue to increase the number of installations and run hours increasing the demand on the electric system. Many electric utilities now in northern climates have switched from being 'winter peakers' to 'summer peakers' (the season when they have the highest overall demand for hourly delivery).
Air conditioners are rated in Tons of capacity. It is literally a unit of measure based on the days when ice was used for cooling and the relative cooling affect of melting one-ton of ice! One ton of cooling is the movement of 12,000 BTUs. (It is a basic thermal dynamic principal that you don't 'make cold' but you 'remove heat'.)
Standard residential air conditioners are about 3 tons; larger for larger homes and homes in southern and high humidity climates, up to about 5 tons is considered typical for residential units.
Window air conditioners are generally sold according to their BTU ratings that are in fractions of a ton. For example, a 6,000 BTU window unit would be 1/2 ton.
In addition to central systems
and window units, there is the PTAC (Packaged
Terminal Air conditioner). PTAC units are most commonly found in hotels
as through the wall, combination heating and cooling. They can also be
used in apartments, condos, small homes, or home additions not connected
to the central heating and cooling system.
Size Air conditioners 400 square feet of home per 1 Ton of a/c (moderate to warm climate; well insulated)
A 3 Ton a/c unit costs about $0.35/hour to operate (standard unit at $0.10/kWh)
1 Ton Cooling = 12,000 BTUs Moved
The Higher the (S)EER, the more efficient the unit; EER = 10 typical
Central units with indoor coils in a furnace and separate outdoor units are called 'split systems'; window units are called 'DX' (Direct Expansion - all one unit)
An air conditioner must remove both heat (sensible load) and humidity/moisture (latent load). Just as condensation forms on the outside of a cold drink container, the cold coil of an air conditioner collects condensation. Both the formation of condensation and the lowering of the air temperature represents a movement of BTUs. The movement of BTUs requires input energy to keep them moving.
The electric air conditioner uses a refrigeration cycle to move BTUs. Because BTUs are MOVED and not created, space cooling is actually about 3 times more energy efficient than space heating with electric resistance heat. This is the same basic principle behind the energy efficiency of a Heat Pump.
Refrigerant Cycle
Starting at the Compressor - the compressor uses electric energy to compress the refrigeration gas, increasing its temperature and pressure. The hot gas/liquid enters the outdoor Condenser Coil where the outdoor fan blows outdoor air across the coil to remove as much temperature from the hot gas/liquid as possible. The cooled gas/liquid flows to a regulator valve where it is allowed to quickly expand in the Evaporator Coil. The sudden expansion of the gas causes it to become very cold, even below freezing. The indoor fan circulates indoor air across the cold coil, causing moisture to condense (latent cooling) and the sensible air temperature to drop. The gas warmed by the indoor air then flows (is 'sucked into') the compressor where the cycle is repeated.
See also Heat Pumps for more information on the refrigeration operating cycle.
Air conditioners use electric energy to run the compressor (the largest user of energy) and the indoor and outdoor fans. Energy efficiency improvements have been made to all. Compressors are now multi-staged and multi-speed, and fans are multi-speed.
Efficiency is highly affected by the outdoor ambient temperature. As the outdoor temp goes up, the efficiency drops.
See Cooling Tips for information about reducing cooling costs
Friedrich® Air Conditioning
Co.
Manufacturers of window, room, split and PTAC units.
Since its founding in 1883, Friedrich Air Conditioning Co. has had one manufacturing standard – quality without compromise. Over the years, the company's products have changed, but the commitment to quality has endured. Friedrich products are manufactured in a modern 600,000 square foot facility in San Antonio, Texas and sold worldwide in over 160 countries.
4200 N. Pan Am Expressway
P.O. BOX 1540
San Antonio, Texas 78295-1540
(210) 357-4400
Go to the Friedrichs web site at www.friedrich.com
Lennox
HSX19 Air Conditioner is the most quiet and efficient central air conditioner you can buy. Carrying unprcedented efficiency ratings of up to 19.2 SEER, the HSX19 is nearly twice as efficient as standard air conditioners. The HSX19 not only cuts energy costs, but it also delivers the lowest annual operating costs possible. It's two-speed, scroll compressor operation (the first of it's kind) runs at low speed up to 80% of the time making it far less expensive to operate and capable of removing more humidity. And using chlorine-free R410A refrigerant, the HSX19 meets the EPA's most stringent environmental guidelines, saving energy and protecting the environment.
Corporate Headquarters:
2100 Lake Park Blvd.
Richardson, TX 75080
P.O. Box 799900
Dallas, TX 75379-9900
Telephone: 1-800-9-LENNOX (1-800-953-6669)
Go to the Lennox web site at www.lennox.com
Ruud/ Rheem
RUUD® RESIDENTIAL AIR CONDITIONING features Copeland® Compliant Scroll® Compressors for proven efficiency, noise reduction, and reliable performance. But that's just the beginning.
From the wraparound galvanized steel cabinet to the painted, one-piece corrosion-resistant base pan, every RUUD air conditioning unit is designed with reliability, durability and low-cost operation in mind. Choose from 5 efficiency levels, each with available capacities to meet your cooling needs. With units available in 10, 11, 12, 13, and 14 SEER, chances are we have a model to suit your lifestyle.
5600 Old Greenwood Road
Fort Smith, Arkansas 72903
Phone: 1-800-848-RUUD (1-800-848-7883)
Go to the Ruud web site at www.ruudac.com
Note: Ruud and Rheem are two brand names of mostly the same product lines
Trane
With a SEER rating of up to 19.50, the XL19i offers the unbeatable combination of energy efficiency and lower operating costs. The XL19i has dual Climatuff® compressors that allow for two-stage cooling. And because it operates at a low speed (first stage) most of the time you get quiet, efficient and extremely comfortable cooling for your home.
Residential Customer Relations
PO Box 9010
Tyler, TX 75711-9010
Phone: 1-866-GET A TRANE.
Go to the Trane web site at www.trane.com
York
Stealth Series Super High Efficiency (HTS)
The York® Stealth™ Series is an exclusive line of up to 16.2 SEER air conditioners proven to lower operating costs as much as 40%, while delivering better humidity control, reduced air stratification, and sound levels designed to be the quietest in the industry. The series is engineered using the revolutionary Bristol® Twin-Single™ compressor. This unique design handles larger cooling and heating requirements by allowing two pistons to operate in the forward direction. For smaller air comfort requirements, the compressor is reversed and one piston remains idle. As a result, the compressor provides two capacities more effectively than conventional two-speed or even variable-speed compressors.
Unitary Products:
5005 York Dr.
Norman, OK 73069
United States
(405)364-4040
Go to the York web site at www.york.com
Source: Text Bob Fegan 8/2003; Images and info about manufacturer's products are from their web sites referenced and linked above 8/2003