Air conditioners look and operate very much like heat pumps with the notable exception that they provide cooling only. While air conditioners and heat pumps do require the use of some different components, they both operate on the same basic principles. This section will explore five topics to consider when you are looking at air conditioners.
- How They Work
- Energy Efficiency
- Tips on matching indoor & outdoor coils
How They Work
Heat pumps and central air conditioners are "split systems," which means that there is an outdoor unit and an indoor unit. The job of the heat pump or air conditioner is to transport heat either into or out of your home. The "vehicle" your system uses to carry the heat is called refrigerant.
For cooling operation, air from your home passes through the indoor coil. Heat is absorbed from the indoor air and the resulting cooler air is circulated back into your home through your duct system. Heat from your home exits through the outdoor coil.
While its keeping you cool, your air conditioner or heat pump also works as an effective dehumidifier. The process is similar to what happens when moisture condenses on the outside of a glass of ice water on a hot, humid day.
For heating, a heat pump basically reverses the cooling process to warm your home during cold weather.
Where does a heat pump get the heat to warm your home when its cold outside? Even though 35 F air may feel cold to humans, it actually contains a great deal of heat. A heat pumps heat exchanger can squeeze heat out of cold air, then transfer that heat into your home with the help of a fan coil or a furnace, which circulates the warm air through your ducts.
Heat pumps are often installed with back-up electric resistance heat or a furnace to handle heating requirements when more heat is needed than the heat pump can efficiently extract from the air. Carrier also offers a Smart Heat accessory package that provides back-up electrical heat in stages. This option allows homeowners to enjoy the energy-saving benefits of a heat pump and still maintain comfortable indoor temperatures as outdoor temperatures gradually drop.
Purchasing a brand name that has a reputation for quality and reliability can save you headaches and extra expense down the road.
New Carrier air conditioners and heat pumps, for example, undergo 34 quality tests and checks during production, with more than 20 of these being performed on every unit not just on random samples. Your local Carrier dealer has details on limited and extended warranties.
Some air conditioners and heat pumps offer additional features that provide greater comfort (as well as additional energy savings).
Two-speed units can run on low speed (using 50% of the energy) up to 80% of the time, so they operate more quietly and run for longer periods of time than single-speed models. Longer operating periods translate into fewer on/off cycles, fewer drafts and much smaller temperature swings -- only two or three degrees instead of the four-degree swings common with single-speed units. Plus, better air circulation helps prevent air "stratification" warm air rising to the ceiling and cold air settling on the floor. In short, you get consistent, even cooling throughout your home.
Multi-Speed Indoor Unit
If you purchase a multi-speed or variable-capacity furnace or fan coil with your unit, you will enhance both the comfort and the efficiency of your air conditioning or heat pump system even further.
Cooling efficiency for air conditioners and heat pumps is indicated by a SEER (Seasonal Energy Efficiency Ratio) rating, which tells you how efficiently the unit uses electricity.
Heat pumps also have heating efficiency ratings, indicated as an HSPF (Heating Seasonal Performance Factor).
In general, the higher the SEER or HSPF rating, the less electricity the unit will use to cool (or heat) your home. The government-mandated minimum efficiency standards for units installed in new homes at 10.0 SEER and 6.8 HSPF. Most air conditioners and heat pumps manufactured before 1992 had SEER ratings below 7.0 and HSPF ratings below 5.0.
Air conditioners and heat pumps manufactured today have SEER ratings that range from 10.0 to about 17. Heat pumps are available with HSPF ratings from about 6.8 to 10.0.
Usually, the higher the efficiency, the more expensive the unit. If you live in a warm and/or humid climate, you will probably see the higher cost of a high-efficiency air conditioner or heat pump paid back (through lower utility bills) in a few short years. Your dealer can use cooling data from your area to help you determine about how long it would take you to recover the additional cost in energy savings. Of course, after the payback, you continue to save on your energy bills for the life of the system.
Tips On Matching Indoor & Outdoor Coils
Your central air conditioning or heat pump system is a split system. That means it consists of two parts: an indoor unit (coil) and outdoor (condensing) unit. Both components are necessary for a working system. So if you install a new outdoor unit, be sure to include a new, equally efficient "matched" indoor unit.
If you don't replace both your indoor and outdoor units, you wont be getting what you paid for. In fact, your system could be up to 15% less efficient than stated and you'll be less comfortable, too. That's why simply replacing just the outdoor unit isn't a bargain in the long run.
Replacing the outdoor unit but leaving the old indoor unit may offer you the lowest price, but it wont give you the best value. When your air conditioning or heat pump components don't match, you'll be sacrificing comfort. The system may still "work," but it wont perform up to the promised energy efficiency. Over time, this will cost you more money. When the components aren't matched, it could create undue stress on your cooling system, resulting in unnecessary, premature failure.