With energy costs on the rise, homeowners are looking for ways to offset higher bills. Geothermal heat pumps are one of the best options, as they currently offer the highest efficiencies of any heating and cooling system available today. A study by MIT emphasizes the potential for geothermal, and manufacturers are offering more options for consumers. While at the Midwest Builders show, I stopped by ClimateMaster and WaterFurnace booths to learn more about their newest offerings. Before diving into the respective systems, let’s review the three main components of a geothermal system; the heat-pump unit, the liquid heat-exchange medium (open or closed loop), and the air-delivery system (ductwork).
The heat pump simply moves heat energy from one place to another, just like your refrigerator or air conditioner. But a major difference is that air conditioners and refrigerators transfer heat in only one direction, while a heat pump can transfer heat in two directions, thereby heating or cooling the space. In the cooling mode, the geothermal heat pump takes heat from indoors and transfers it to the colder earth through either groundwater or an underground earth loop system. In the heating mode, the process is reversed.
The buried pipe, or earth loop, is the most important technical advancement in heat pump technology to date. The idea to bury pipe in the ground to gather heat energy began in the 1940s. But it's only been in the last twenty-five years that new heat pump designs and more durable pipe materials have been combined to make geothermal heat pumps the ultimate in efficiency. The two main types of loops available are open and closed. An open loop system is less expensive to install, but over time could require more maintenance. A closed loop system is more expensive up front, but requires almost no maintenance. As manufacturers phase out R-22 (HCFC) refrigerant, there have been more environmentally friendly liquid mediums brought into the marketplace to use in your system. The most common antifreeze solutions in the U.S. and Canada are propylene glycol, methyl alcohol, and ethyl alcohol.
Finally, ductwork must be installed in homes that don't have an existing air distribution system. If you have existing ductwork, geothermal systems will likely work, but you may have to do some minor modifications. Another method of delivery worth looking into is in-floor radiant heating, in which hot water circulating through pipes under the floor heats the room. For more detailed information on geothermal systems, visit the Basic Geothermal Info thread on GBT.
ClimateMaster showcased their Tranquility 27 series at the builder's show. Both the Tranquility 27 two-stage system and the Tranquility 27 two-stage split geothermal system are the highest efficiency water-source heat pumps on the market, offering 27EER to 31EER. The energy-efficiency criteria for geothermal heat pumps to qualify for the Energy Star program requires an EER rating of 14.1 (closed) or 16.2 (open). The Tranquility 27 has an EER rating of 27. This system also use Earthpure, a new refrigerant that is non-chlorine based with zero ozone depletion potential.
For retrofit projects, ClimateMaster offers its Genesis Outdoor Split unit that can replace your current outdoor unit by connecting directly to your existing interior equipment. You'll just need to add a ground loop to implement this system. Also, ClimateMaster's patent pending ClimaDry feature provides dehumidified, neutral temperature air. The ClimaDry modulating reheat option is the only water-source heat pump reheat option that provides neutral supply air temperature regardless of entering water temperature. Simple controls allow humidistat or dehumidistat to activate the option and the system has an internal microprocessor that automatically adjusts reheat capacity to maintain neutral supply air temperature.
WaterFurnance has captured a large portion of market share with their "Geo Comfort" lines. Their new Envision Series system is the company’s most efficient with one of the highest ARI/ISO ratings at 30EER and 5 COP. The units utilize ozone-safe R-410A refrigerant, which produces higher efficiencies and warmer discharge air temps. They have many other system types to choose from including All-in-One, Split, and Hydronic systems. The All-in-One provides heat in the winter and cooling all summer. Split systems allow for installation flexibility with the capacity to be installed with a remote air handler. Hydronic units are designed for heating and cooling water in applications such as radiant, domestic hot water and snow/ice melt. Use Waterfurnace’s ‘savings calculator’ to find out how much you’d save with one of their systems.
A geothermal typical unit supplies 4 to 5 kilowatts of heat for every kilowatt of electricity used. Three to four of the kilowatts of heat come directly from the earth (free), while the other kilowatt is used to power the compressor, fan and controls. Where a fossil fuel furnace may be 78-90 percent efficient, a geothermal heat pump is about 400 percent efficient. Even though the installation price of a geothermal system can be several times that of an air-source system of the same heating and cooling capacity, the additional costs are returned to you in energy savings in 5-10 years. System life expectancy is estimated at 25 years for the inside components and 50+ years for the ground loop.
The upfront costs for a new construction geothermal installation can be included in the monthly mortgage payment. The increase in mortgage costs is typically more than offset by the decreased operating costs of the geothermal system, providing a net positive cash flow. Another option is an Energy Efficient Mortgage (EEM). This type of mortgage uses your monthly energy savings to increase both the value of your home and the loan amount your qualify for. This allows you to pay for your geothermal system without increasing your total monthly outlay. A Fannie Mae loan also adjusts the home’s value to reflect the added value of a geothermal system. Energy Star is a good source for information on EEMs, along most geothermal companies. Federal tax credits are also available, and can add up to a substantial cost offset. Geothermal is the ultimate in green living, and can be possible even on the tightest budgets; you’ll just need to figure out which system is best for you and research all your financing options.