Air conditioner v. Heat Pump?

To push the air in in air conditioning or heating unit a homeowner has two basic options, the choice between an air handler or a furnace. To cool a house, there are also two basic options. One of them is central air conditioning as provided by a condenser that sits outside and uses a refrigerant to cool the air. However, the other choice is a heat pump. Heat pumps provide heating and cooling depending on the weather and usually use an air handler to push the air through the house. Heat pump v. air conditioning The way that a heat pump converts ground heat into heating or cooling energy is described by national geographic’s green guide at http://news.nationalgeographic.com/news/2004/10/1028_041028_alternative_energy_2.html

“Ground Heat Tapping into the ground offers another option to regulate household heating and cooling. In most areas of the United States, the ground below the frost line maintains an average temperature between 50 and 54 degrees Fahrenheit (10 to 12 degrees Celsius). Ground-source heat pumps, also called geo-exchange systems, use this relatively constant temperature to keep homes at comfortable temperatures. The devices employ a series of underground, liquid-filled tubes or wells. Liquid flows through the pipes into the home, where a heat exchanger either adds or subtracts heat from indoor air, depending on the season. In winter, that means added warmth captured from the ground. "If you can [do that], your furnace doesn't have to work so hard," Hayter said. A U.S. Environmental Protection Agency study found that geo-exchange systems can save up to 70 percent of home-heating costs.”

They further go into the advantages and disadvantages at http://www.thegreenguide.com/doc/ask/geothermal Filed under: Energy efficiency, Eco-Renovation This response was written to a homeowner in Northern California who wanted to be more eco-friendly in her heating and cooling options.

“The Green Guide Responds: Geothermal heat pumps (GHPs) are an extremely efficient mode of not only heating your home in the winter but cooling it in the summer. The technology exploits the difference between above ground and below ground temperatures. Ground temperatures range from 45 degrees to 75 degrees Fahrenheit and remain relatively constant throughout the year. The open air temperature is cooler than the ground temperature during the winter and warmer during the summer. Using a system of underground or underwater pipes filled with a coolant—like antifreeze—the GHP exchanges the heat above ground with the heat below ground. Operating on the same principal as a refrigerator, the heat, carried by piped water and coolant, is elevated through a process of compression, evaporation, condensation and expansion. This process requires substantial electricity, though far less than an electric heating system requires. Within the heat pump, liquid refrigerant absorbs heat from the warmed water or other low temperature source as it flows from the ground, which causes the refrigerant to evaporate and become gaseous. The gas is then pressurized in an electric compressor. This raises the temperature to 180+ degrees Fahrenheit. The heat is pumped into the house, and as the refrigerant cools, the process begins all over again. Advantages • Compared with a home with electric heat, cooling, and water heating, the GHPs use between to 25% and 50% less electricity. According to the Department of Energy (DOE), a housing project in Louisiana with 4003 units will save 25.8 million kilowatt hours in a typical year after switching to GHP. EnergyStar-rated pumps are also available. www.eere.energy.gov/consumerinfo/factsheets/geo_heatpumps.html • During the summer GHP (equipped with a device called a "desuperheater") using heat taken from the home will warm your water for free. During the winter, you can expect a 50% reduction in the cost of heating water. • GHPs are smaller and quieter than gas and oil furnaces. • New homes may come equipped with GHP, but older homes can be retrofit as well. Obviously efficiency is an issue in either case, and for the full benefit to be realized, ducting and insulation must be properly installed. And the house must be thoroughly weather proofed. • GHP systems have few moving parts and require very little maintenance. • Switching to a GHP system is cost effective. Installing a system will cost approximately $7,500, where a comparable conventional system (heat and cooling) costs around $4,000, but, according to the Department of Energy, the savings from lower untility bills, will pay for the difference in two to ten years. Disadvantages • The initial cost is quite high. • Leaks in underground pipes are hard to repair. • Water is a better heat source than earth, but water-coupled systems require a body of water, more complex engineering and the built-in cost of a water pump. For more information about GHP systems and a list of certified service providers in California visit the Geothermal Heat Pump Consortium website (www.geoexchange.org). Many states offer incentive programs, but surprisingly not California. EnergyStar labeled models are usually eligible for low interest loans. The EPA has more information about financing, and they encourage home owners to call their free hotline: 1-888-STAR-YES Given that you're currently using wood heat, another option would be to trade in your old stove for a super-efficient advanced combustion wood burning stove. (See "Is Burning Wood Greener Than Burning Gas?")"

However, in order to determine how best to heat or cool your home, it is important to speak to a licensed contractor who has your best interest in mind. Research your options. A heat pump is most beneficial in more humid southern climates. The highest percentages of heat pumps are installed in Florida.