The 4.5 kW Sanden heat pump is a split system with an outdoor unit paired with storage tanks of varying sizes. It is capable of delivering about 16,000 BTUs/hour and can produce 149 °F water with outdoor temperatures as low as -15 °F.
Using CO2, the heat pump is “almost four times more energy efficient than any electric resistance water heater, and 40% to 50% more efficient than any synthetic refrigerant heat pump,” said John Miles, general manager, Eco Systems, Sanden International USA, based in Plymouth, Mich.
As for gas hot water heaters, the CO2 heat pump has a 3.5 energy factor compared to a 0.96 for the best gas heater, said Miles. However, because the price of gas is so low, the overall total cost of ownership for a gas heater is better, he acknowledged.
The initial cost of the CO2 heat-pump water heater is 20% to 25% higher than that of the larger capacity synthetic heat pump, and considerably more than an electric water heater. However, taking advantage of utility or Energy Star rebates, plus the almost quadruple gain in efficiency, the CO2 heat pump can offer a four-to-six year payback on the cost difference over an electric water heater, said Miles.
The CO2 heat pump is warranted for 10 years and has an expected lifespan of 12 to 15 years. It also produces “more hot water in an hour than most electric water heaters,” he said.