SUWANEE, Ga. — Mitsubishi Electric Trane HVAC US (METUS), a supplier of energy-efficient, high-performance ductless and ducted variable-capacity heat pump systems and variable refrigerant flow (VRF) heat pump and air conditioning systems, announces Heat2O™️, an all-electric domestic hot water heating system designed to improve sustainability and reduce energy consumption in multifamily buildings and large-scale commercial facilities.

Domestic hot water (DHW) accounts for roughly 25% of annual energy usage in typical multifamily buildings[1] and is among the largest single energy uses of energy for new multifamily construction in the Northwest.[2] The Heat2O heat pump water heater (QAHV-N136TAU-HPB(-BS)) reduces the environmental impact of DHW through energy-efficient operation while using CO2, a natural and environmentally friendly refrigerant with a global warming potential (GWP) of 1 and an ozone depletion potential (ODP) of zero. Able to produce high-volume DHW without fossil fuels, Heat2O can help multifamily buildings, offices, hotels, gyms, educational institutions, and other large-scale and commercial facilities qualify for sustainability certifications or achieve zero-energy and passive house status. 


Engineered Solution

METUS provides Heat2O as an engineered solution with comprehensive technical support. The system includes pre-assembled and pre-plumbed components designed and selected to ensure installation quality and ensure optimal performance of the heat pump. Components include hot water storage tanks, swing tanks, secondary heat exchangers, and variable-speed secondary circuit pumps.


Heat2O transfers ambient thermal energy from outdoor air to potable water by cycling refrigerant. Natural CO2 refrigerant enables Heat2O to supply hot water up to 176° F even in low ambient conditions without burning fossil fuels. 

Using Mitsubishi Electric’s patented Twisted Spiral Gas Cooler, the system achieves highly efficient heat exchange with three refrigerant lines wrapped around a twisted water pipe.

The CO2 refrigerant flows in the opposite direction of the water. Running the refrigerant lines along the pipe’s grooves increases the heat conductive area while the spiral helps create a vortex in the pipe, accelerating the turbulence effect of water and reducing pressure loss in the heat exchanger. Additionally, the copper pipes make for double-walled construction. 

An INVERTER-driven scroll compressor increases Heat2O’s energy efficiency by enabling the system to modulate refrigerant flow and heating capacity to match loads. 

“For more than 30 years, Mitsubishi Electric has been a leader in heat pumps for space conditioning,” said Cain White, director, commercial product management, Mitsubishi Electric Trane HVAC US. “By applying our variable-speed, INVERTER-driven technology to water heating with Heat2O, we’re giving building owners far greater control over energy consumption and sustainability than is possible with fixed-capacity hot water heat pumps.” 



Heat2O can provide over four times more energy as heat than the system consumes in electricity. With a coefficient of performance of up to 4.52, Heat2O offers significant energy savings for building owners and tenants. Energy savings combined with incentives from utilities can ultimately offset first costs. 


Cold-Climate Performance and Scalability

Heat2O can operate at high capacity even in cold climates such as climate zones 5 and 6. The system delivers 100% heating capacity of 40 kW at ambient temperatures as low as 36°F. When down to minus 13° outside, the system can still supply 176° hot water but at 50% of the heating capacity. 

In extreme cold, Heat2O’s compressor uses flash-injection technology to operate at high speed, maintaining high discharge pressure and ensuring the compressor shell is kept cool at all times to capture ambient heat. 

Heat2O heat pump water heater is capable of operating at three capacities: 136,485 Btu/h (40 kW), 170,607 Btu/h (50 kW), and 204,728 Btu/h (60 kW). Up to six units can be piped in parallel for a maximum size of 682,425 Btu/h (240 kW). Plans are in the works to expand the allowance of up to 16 units in the future and for a capacity of 2,183,760 Btu/h (640 kW). 

METUS is introducing Heat2O in New York, Massachusetts, Washington, Oregon, and northern California, with other regions to follow. For more information, visit or


[1] U.S. Energy Informational Administration 

[2] Bonneville Power Administration