Two common types of systems are: 1) Conventional "split" systems and 2) Electric Heat Pump systems
Both types of systems are Heat Exchangers. It is always heat energy which is being moved, not "cold" energy. In the summer, heat is removed from the home's interior (at the evaporator coil, and discharged to the exterior at the condenser unit.)
1) Conventional Split systems have an exterior condenser/compressor unit (located on the outside of the home) and an evaporator coil/air handling unit (located somewhere inside the home - often in an interior closet or in the attic)
2) Electric Heat Pump systems basically work in the same way as a conventional split system (utilizing the same "freon" refrigerant and refrigerant lines), but have the ability to work in reverse and act as a heating system in the winter: in the summer cooling mode, the exterior unit acts as the condenser (which discharges heat removed from the interior to the exterior of the home.) In the winter heating mode, the interior unit acts as the condenser (discharging heat into the home; Yes, heat is actually removed from the relatively outside cold air at the exterior unit and discharged into the home!)
Regardless of what type you have, remember that models will vary in efficiency ratings and efficiency has a direct impact on operating costs, so optimizing efficiency should be a priority. Consider buying an ENERGY STAR®-qualified model.
Central cooling
If you decide to, or need to, replace your cooling system, the choice of 1) a typical "split system" or 2) an electric heat pump is an important decision. Your cooling choice has a big impact upon your heating and heating bills.
Window units
Window air conditioners are effective if you only need to cool a specific area of your home. They will cost less to install than a central air conditioning system. If you don't have duct work, they might be your most practical choice. It is important to match the capacity of the window air conditioner with the size of the area to be cooled. Window units should either be covered in winter or, better still, removed to minimize heat loss.
The following measures will help keep your home more comfortable:
- Keep doors and windows properly weatherstripped.
- Consider installing new, energy-efficient windows. ("low-e" windows)
- Use ceiling fans to circulate air, and adjust the thermostat to save on your energy bills.
- If you're planning for the long term, plant trees that lose their leaves in the fall on the east, south and west side of your house.
- Close the drapes or blinds on south and west-facing windows during sunny summer days to reduce heat gains.
- Turn off lights and appliances when they are not in use.
- Install awnings for patio doors and windows that face the sun.
- Open windows during the "swing" seasons between winter and summer.
