Innovation in heat pump technology

Inverter heat pumps have a variable-speed compressor that adjusts with ambient air temperature and heating or cooling loads. This eliminates energy losses associated with frequent stopping and starting of the refrigerant cycle, as in standard compressors. The latest inverter heat pumps have a Coefficient of Performance (COP) of up to 5, meaning they produce five times the heat energy than the electricity consumed. Inverter systems are 30 to 50 percent more efficient than conventional heat pump systems, and can operate effectively at colder outdoor temperatures, down to -20 celsius. Inverter technology offers the added benefits of quieter operation as well as reducing wear and tear on the compressor.



Inverter-driven heat pumps are also branching out in flexibility of application. According to Hoyt Corbett, a hydronic product inventor and developer:  "Previous air-to-water reverse cycle chillers and heat pumps did not feature variable speeds, were not packaged as well integrated units for heating, cooling and domestic hot water with solar thermal options. These models were less efficient and often noisy. That is now changing with the introduction into North America of a sophisticated new generation of air-to-water heat pumps based on variable speed inverter technology.... Most of these units will come packaged to do both heating and cooling, use a strategy to make or at least to preheat domestic water, and tie in to solar thermal systems. Heated water is made by means of a refrigerant-to-water heat exchanger."

These heat pump systems are well-established in Europe and Asia, but are relatively new in North American markets. Therefore testing standards have not yet been developed to prove their performance and government-funded energy rebate programs do not yet support these efficient products. However, Corbett predicts that "the combination of efficiency, a low carbon footprint, the ability to provide heating, cooling and domestic hot water with a solar thermal option means these new air- to-water heat pumps should generate a big growth in hydronics." Daikin Altherma is one such ground-breaking air-to-water heat pump that can connect to in-floor heating, air handlers, or low temp radiators, and can be configured to provide space heating and cooling as well as domestic hot water with optional solar heat kit. This case study of an ultra eco-friendly Portland, OR residence profiles the first application of a Daikin Altherma system in North America.