An all-electric CO₂ refrigerant heat pump water heater for commercial buildings

SUWANEE, Ga. – February 1, 2022 – Mitsubishi Electric Trane HVAC US (METUS), a leading 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.  

Introducing Heat₂O
Domestic hot water (DHW) accounts for roughly 25% of annual energy usage in typical multifamily buildings^[1] and is the largest single energy use 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 one 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.

A special twist 
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 thirty years, Mitsubishi Electric has been a leader in heat pumps for space conditioning,” says 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.”

Savings
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 energy savings of 60 to 70% for building owners and tenants compared to electric-resistance water heaters. 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 -13° F outside, the system can still supply 176° F 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 City and New York State, Massachusetts, Washington, Oregon and Northern California with other regions to follow. To learn more about the Heat₂O heat pump water heating system, visit MitsubishiComfort.com and Heat2O.com.

[1] U.S. Energy Informational Administration

[2] Bonneville Power Administration