|
||||||||
Cooling | ||||||||
For Your Home | ||||||||
Energy-Efficient Air Conditioning | ||||||||
Energy Efficiency of Central Air Conditioning Systems Efficiency Losses Zoning When to Replace an Air Conditioning System Factors to Consider When Replacing an Air Conditioning System Sizing of Air Conditioning Systems Cooling Load Calculations Oversizing System Maintenance Central air conditioning uses a considerable amount of electricity, particularly in warmer climates, and is one of the most expensive home appliances to operate. The difference between central air conditioning and a room (or window) air conditioner is the distribution system. A central air conditioner uses a blower and ductwork to distribute chilled, dehumidified air throughout the entire house. In contrast, a room air conditioner, typically installed in a window or, in some cases, through a wall, will cool a small area, generally a single room or perhaps two to three adjacent rooms. Central air conditioning is becoming much more common in this country, and is now present in over 47% of existing homes and over 77% of new homes!
The conditioned air is then routed back to the rooms through the supply air ductwork. The refrigerant, which is converted to a vapor by the heat, is pressurized by the compressor and moved to the outside coil, or condenser, where the heat is dissipated. As the heat is removed by the condenser, refrigerant turns back into a liquid and then is sent (by way of the copper pipes) to a metering device (that is usually inside the cooling coil cover). And the process starts over again. Energy Efficiency of Central Air Conditioning Systems Efficiency Losses Zoning When to Replace an Air Conditioning System Home air conditioning systems can be expected to last for 15 years or more. Good maintenance practices will, of course, provide an even longer service life. Deciding when to replace an old cooling system is not easy. Unless your present system is old and in very poor working condition, it may be hard to justify a new high efficiency system on energy savings alone. If your system doesn't seem to be working as well as it used to, you should have a service person look at it to determine the likely cause of the problem. If there is a significant problem, simply comparing the price to repair the system with the cost of replacement will give you a good idea of what you should do. Keep in mind, however, that, due to improvements in efficiency, a new system will have the added benefit of reducing your operating cost. If your system is over 10 years old, you may want to consider a new unit. Especially if you have a large home with a high cooling load, the annual dollar savings from installing a new system may pay for itself in a short time. HomeSmart from Xcel Energy sells and installs name brand cooling systems. We also offer appliance repair and replacement plans to ensure your system lasts. You can customize your coverage to include preventive maintenance.HomeSmart for Minnesota customers Factors to Consider When Replacing an Air Conditioning System When planning for the replacement of your central air conditioning system, you will have an opportunity to make some efficiency improvements. You must first consider the tradeoff between the efficiency and cost of the new system. Furthermore, if your outdoor (condenser) unit is mounted on the roof or in an attic, you may want to move it to a cooler location when you install a new unit. That alone can make a large improvement in efficiency. If you are thinking of just changing the outdoor unit; keep in mind that the indoor unit may be just as old. Changing the outdoor unit to a newer high efficiency style may not give you the results you are paying for due to the mismatching of SEER ratings and age of equipment between units. Sizing of Air Conditioning Systems Cooling Load Calculations The contractor should measure your home to determine size of windows, the direction they face, the type of glass , the size of each room, the areas of walls and ceilings, and the amount of insulation. Preferably, they should do a room-by-room calculation to determine whether the existing ducts are adequate for the new system. In most cases, the time it takes them to perform these calculations should be offset by the savings in a smaller installed system. Oversizing System Maintenance In addition, the first time your air conditioner is serviced, the technician should check the refrigerant levels by testing something called "superheat" or "subcooling" (depending on the type of unit). Once they verify the proper refrigerant charge, no service person should attach refrigerant gauges again, unless you notice a decrease in performance or a sudden increase in your electric bills. Also have the technician show you how to change the air filter. Dirty and clogged air filters result in improper supply of conditioned air and are the largest source of air conditioning service calls. In most cases, filters are easy to replace and result in more effective air conditioning. We recommend checking the air filters monthly, and replacing at least once a season as needed. Always follow the manufacturers instructions when replacing filters.When choosing an air filter, you have to be concerned about both filtering effectiveness and resistance to air flow. "Washable" electrostatic air filters create a lot of resistance which can reduce air flow and operating efficiency. On some systems, depending on the size of the ductwork, even a pleated filter can cause air flow problems. This can be checked by observing airflow with one and then the other filter in place. Air filters can be either permanent or disposable. Permanent electrostatic air filters, which require frequent cleaning, rely on static electricity to attract charged particles in the air stream. Permanent filters cost approximately $60 to $300, depending on size. High efficiency filters do not need to be replaced as often, but still should be checked at the beginning of the cooling season and replaced if dirty. Disposable panel air filters can be purchased at your local hardware store and range in price from as little as $1 to well over $40. The less expensive disposable fiberglass filters are not as efficient, and may cost you more in the long run. Upgrading the efficiency of the filter to remove smaller particles can help maintain the equipment as well as the health of employees and consumers. Always keep the air vents open in a central air conditioning system, and don't obstruct them with furniture or draperies. In addition, do not attempt to cover or shade the outdoor coil; even a deck built above the unit, with open sides, can cause recirculation and reduce efficiency dramatically. Keeping leaves and dirt from accumulating on the sides of the outdoor unit helps to maximize heat transfer and minimize cooling bills. | ||||||||
| ||||||||
|