Bruce Harley is a Vermont energy consultant and heat-pump specialist. To GBA readers, he is probably best known as the author of the Taunton book, — one of the best available books on residential energy retrofit work.
As the recent Better Buildings By Design conference in Burlington, Vermont, Harley shared a wealth of information on ductless and ducted minisplits. The title of his February 8 presentation was “Real-Life Air Source Heat Pump Performance Testing: Results and Reasons.”
Since Harley left his longtime job at Conservation Services Group, he’s been working as an independent consultant. Harley told the audience, “Now 90 percent of my work is related to heat pumps.”
Asian manufacturers have developed models for cold climates
Until recently, North American homeowners’ opinions of heat pumps were strongly influenced by the unimpressive performance of U.S.-made forced-air units designed for warm climates.
Harley explained, “Air-source heat pumps got a lot of bad press in the 1980s. Occupants noticed they cost a lot to run because of the electric-resistance heaters. Back in 2012, when I wanted to install a ductless minisplit at my house in Vermont, a contractor told me, ‘A heat pump won’t heat your house in Vermont. Maybe if you were in Texas in Oklahoma.’”
Japanese engineers have revolutionized the market for heat pumps, however, by improving their units’ cold-climate performance. “Ductless split-system heat pumps have been in mass production for 40 years,” Harley noted. “The technology has made steady advances. Now they are optimized for cold weather. It’s a rapidly growing market. Most of these heat pumps do not have an electric-resistance heater. Lots of people are installing one in an existing home with oil heat to offset the high energy bills.”
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