Some Alaskans are pushing air source heat pumps to their limits, running them even when outdoor temperatures plummet to nearly –30 degrees Fahrenheit (–34.4 Celsius).
Andy Romanoff, the executive director of Juneau-based nonprofit Alaska Heat Smart, estimates that there are about 2,000 heat pumps covering roughly 15 percent of the city, a number that he expects to grow. “We do see a 10 to 15 percent, maybe even 20 percent, increase year-after-year in the number of permits that are being applied for,” he says.
Heat pump installers in Alaska recommended by Heat Smart also say demand for the devices is rising. One installer, Mark Houston, describes a spike in inquiries about heat pumps at the beginning of 2023, more than the number of inquiries he’d received for the whole of 2022. Another, Kris Karsunky, says he installs between 50 and 70 heat pumps a year but fields twice that many requests via phone. Businesses are increasingly adopting the technology, too, he adds.
Juneau gets most of its electricity from lakes that offer a clean hydropower resource. This means that it is particularly ecofriendly to install electrified heating systems in the city.
But, to be fair, Juneau lies at the warmer end of the state and doesn’t tend to experience the same blisteringly cold winter weather that can afflict places farther north like Anchorage or Fairbanks, where using heat pumps could be less cost-effective.
In the village of Eklutna, not far from Anchorage, electrician Derek Lampert has found a heat pump that copes with extreme temperatures. He lives in a house that he built with his father during the pandemic. The walls are 22 inches thick, he boasts. Lampert planned for the house to be as energy efficient as possible, and so he invested in a SANCO2 heat pump, which uses CO2 for a refrigerant. The machine provides space heating and hot water supply.
“We’ve had it as cold as –20 degrees Fahrenheit and it still worked,” says Lampert. “I was getting 135-degree water.”
High efficiency was certainly Lampert’s goal, and overall he’s happy with the results. Financially, at least, the well-insulated house and heat pump setup has proved beneficial. “People in my neighborhood spend more [than my entire electricity bill] on propane and heating oil,” says Lampert.
However, because a heat pump sucks heat indoors from outside, sometimes for long periods, the outer part of the machine can get especially cold and make the device less energy efficient. Heat pumps are generally designed to defrost themselves periodically, but Lampert argues that his model could be better at this. He says he has noticed a fair amount of frosting and ice build-up around the exterior of his heat pump when it’s very cold. “Certainly, the colder it gets, the worse it gets. It just struggles with all the moisture,” he explains.
John Miles, a spokesman for Eco2 Systems, which makes the SANCO2 heat pump, says the current model works down to –26 degrees Fahrenheit (–32 Celsius). He adds that it has various means of checking for frost build-up and that any ice that does form will, eventually, melt away.