Might be old news, but it's new to me..
CO2 Water Heater 4.5~9kW - - Ess Aircon
"The Sanyo CO2 hot water heaters offer environmentally friendly and efficient water heating for homes and commercial premises. Now available in 4.5kW and 9kW models, the external air source heat pumps use heat energy recovered from outside to provide highly efficient heating for your water supply. The use of CO2 as a refrigerant enables supply of hot water to the tank up to 65°C.
* Abundantly supply space heating and tap water
* Environmentally friendly with CO2 natural refrigerant
* Low ambient operation down to -20°C
* DC rotary 2 stage compressor
* High reliability
* Expand operation range
* High efficiency C.O.P.s up to 3.8
* Low noise and vibration
"
