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By Charles Linn, FAIA

From a thermodynamics standpoint, the LTHP has always been possible, and Shaw says that most of the knowledge and components necessary to make LTHPs have been around “since I got in the business in 1958,” but they were never developed. Low prices for fossil fuels, and low first-costs for equipment have assured that furnaces and boilers continue to dominate the U.S. space-heating market. This didn’t deter him, and he tackled the problem in the mid-1990s, knowing full well the market forces needed to make the product a home run might not converge for years. Considering what is now known about global warming, and unprecedented prices for fossil fuels, it might be time for the LTHP to start changing the world, because it seems impossible that millions of individual residential and light-commercial heating systems, each burning its own fossil fuels, can be sustained indefinitely. In terms of carbon production alone, it is better to have hundreds of utilities produce the power to run millions of heat pumps. Electric utilities have lots of options available to them for reducing their carbon footprint that are not available to the natural gas industry. These include carbon capture and storage, nuclear power, wind generation, and other renewables.

 

click images to view them larger 1 2 3 The difference between a conventional heat pump (1) and the LTHP is the addition of a second “booster” compressor and a “subcooling economizer,” which is a heat exchanger. In Stage 1 mode (2), the booster compressor is activated when the outside temperature reaches 25 degrees Fahrenheit. The extra capacity it provides allows a much greater quantity of low-density refrigerant to be compressed into the liquid required to bring heat to the interior of the building. In Stage 2 (3), the economizer kicks in. It is a heat exchanger that uses heat usually wasted to produce refrigerant vapor sent directly to the primary compressor, instead of into the evaporator coil. Renderings: Courtesy Hallowell International

In 2005, Platts E Source, a Boulder-based consulting group that does research for the utility industry, released a report called “Can the Low-Temperature Heat Pump Defrost the Status Quo in the Space Heating Sector?” The authors, Jay Stein, Andria Jacob, and Jon Slowe, indicate that none of the major U.S. HVAC manufacturers is even doing research in the area of LTHPs. Without the market demand, the big companies simply aren’t interested in the concept, even though E Source estimates that the market could be as high as 2.2 million units annually.

But the paper also describes how far the LTHP has to go. Very few LTHPs of Shaw’s design—only between 150 and 200—have ever been installed. Nyle Special Products, of Bangor, Maine, licensed the rights to Shaw’s patents for a few years and made them under the Cold Climate Heat Pump name between 2002 and 2005. A number of electric utilities conducted tests of the Nyle product with mixed results, mostly due to manufacturing glitches and installation problems. When they worked, they worked very well. But Shaw decided to take his patents elsewhere, and Nyle can no longer manufacture the products that used them. Shaw has become the chief technology officer of a new company, Hallowell International (http://www.gotohallowell.com), also of Bangor. Hallowell hopes to start producing 2000 LTHPs for beta testing this year. Shaw also says that his company’s heat pump will only cost about 20 percent more than conventional heat pumps, which doesn’t seem like much, of course. But, as long as heating with natural gas or heating oil is cheaper than heating with electricity month after month, year after year, it will be hard to persuade consumers to buy them. On the other hand, utility companies often use economic incentives to push new technologies out to consumers. Those that have excess capacity to sell in winter, or experience peak-loading conditions at this time of year, are very interested in the product.