Prototype CO2 Heat Pump for Older Homes by Reftronix

Prototype CO2 Heat Pump for Older Homes by Reftronix

Case Study - Heat Pumps / Domestic

Danish controls manufacturer Reftronix, with funding support from Energy Cluster Denmark, a government group, has developed a cost-effective CO2 (R744) heat pump capable of replacing an oil or gas furnace used in older residential homes in Europe for radiator-based space heating and domestic hot water.
Older homes, absent expensive insulation, require water temperatures of 70°C (158°F), while conventional air-water heat pumps using F-gases or propane (R290) as a refrigerant only meet European efficiency standards (a COP over 3.0) up to 55°C (131°F), which is sufficient in modern homes. This leaves an opportunity for a CO2 heat pump, which isn’t efficient at 55°C but can leverage the transcritical cycle to efficiently produce 70°C water temperature.
Reftronix’s CO2 prototype benefited from the availability of small compressors used for two decades by Japanese manufacturers of Eco-Cute CO2 heat pump water heaters. The prototype uses a two-stage (booster) 2HP Panasonic compressor. The prototype also features a brazed-plate gas cooler, four-way valve, four-inlet evaporator, four open-economizer receivers, Reftronix controller and Invertek inverter.

Energy Efficiency

COP up 3.0 at 60°C (140°F) water temperature, and a COP of 2.5 at 70°C (158°F)
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