The Other Heat Pump Gas Absorption Heat Pumps Make Sense in Cool Climates—Can They Cool Homes Efficiently, Too?
“I was an enemy of environmentalists!” proclaims John Ruhnke of his younger days working on race cars. Now president of JR’s Comfortable Heat in Norwalk, Connecticut, one of the nation’s premier installers of gas absorption heat pumps (GAHPs), Ruhnke has come around.
He’s gone from “making cars go faster” to saving energy, and has won multiple awards from the Radiant Panel Association, including a Best in Show in 2005. While conventional furnaces and air conditioners either heat or cool, heat pumps take technology invented for refrigeration and make it reversible, pumping hot air in or out depending on weather conditions. While older electric heat pumps developed a bad reputation, particularly in colder climates, newer technologies are more cost efficient. Geothermal heat pumps (profiled in the January/February 2009 edition of E) rely on the constant temperature underground to save energy, but the up-front cost of drilling can run into the tens of thousands of dollars.
Heat Pumps for Cold Places
GAHPs, by contrast, are powered by natural gas, and employ the heat already available in the outside air. They use “an ammonia-water absorption cycle to provide heating and, if it’s a reversible heat pump, cooling” explains Christina Kielich, spokesperson for the U.S. Department of Energy (DOE). The initial cost is comparable with geothermal, but GAHPs are only efficient in certain conditions: where it is very cold, where electricity costs are high, and for larger houses (3,000 square feet and up), according to Brian Cullinane, vice president of Clover Corporation in East Hartford, Connecticut. His company brings GAHPs, manufactured by the Italian corporation Robur, to the New England area.
In the right circumstances, GAHPs can bring big savings to your pocketbook and to the environment. For heating, GAHPs are up to 130% efficient (since they draw on external air for their operation), compared to a maximum of 95% for furnaces, according to Cullinane. And they save 20% to 50% on heating, Kielich says. This also means a great reduction in destructive global warming gases, as much as 4.2 tons annually for a 2,500 to 3,000 square foot house, says Cullinane. The amount of energy saved, however, varies depending on climate and what other technology it’s being compared to. Cullinane points out that GAHPs use “40%renewable energy (the air), and zero ozone depleting refrigerant.”
Nevertheless, “the absorption heat pump achieves energy savings only in the heating season,” says Kielich. “During the cooling season, absorption systems tend to use more energy than conventional electric systems, but in some cases, they can achieve energy-cost savings, depending on the electric rate structure,” she explains.
Ruhnke, however, believes that the DOE relies on an outdated system for measuring energy efficiency, and advocates a new standard developed by the European Commission. He claims a 40% to 48% total fuel bill reduction with GAHPs.
In areas with high electricity costs, the benefits are evident. For cooling, GAHPs “use very little electricity,” says Cullinane, greatly reducing demand on the electrical grid when it is most stressed. He characterizes GAHPs as “a well rounded technology ideal in colder climates.”
Finding Support…for Now
Currently, Robur is selling about 3,000 units a year in the U.S., but most of those are for commercial use.
Like much high efficiency and renewable technology, GAHPs rely on government subsidies. But Ruhnke says the inconsistency of these subsidies make business decisions unstable. Rather than today’s patchwork system, which shifts with the political winds, he calls for a comprehensive review of all systems to determine which are most efficient.
Still, federal subsidies are available for GAHPs, and interested consumers should look into state and local subsidies. “For high-efficiency air conditioners and heat pumps, the federal tax credit for 2010 can be as high as 30% of installed cost, up to $1,500, while tax credits for geothermal heat pumps can be even higher,” Kielich says.