Blog

Tokyo, October 30, 2025 – Mitsubishi Heavy Industries Thermal Systems, Ltd. (MHI Thermal Systems), a part of Mitsubishi Heavy Industries (MHI) Group, has added two new models to its “Hydrolution EZY” series of air-to-water (ATW) heat pumps for the European market that utilize R290 (propane). This is a natural refrigerant with low environmental impact and high energy efficiency. The new models have capacities of 6kW and 7.1kW and are scheduled for release this winter.

ATW heat pumps extract heat from the air to supply cold and hot water for domestic water supply, heating, and cooling, replacing traditional fossil-fueled boilers.
The models added to the lineup are monobloc types in which the water heat exchanger is housed in an outdoor unit, with only water piping required. Compared to split-type ATWs, which require the refrigerant pipe connections between an outdoor unit and an indoor unit, installation is easier.

The R290 refrigerant used in these models has a very low environmental impact(Note1) while retaining high energy efficiency. This is particularly important for the European market, as environmental regulations are tightened.

Modifications that allow the use of R290 also enable the units to maintain a flow temperature of 75℃ in a wide range of environments, from an outside temperature of -25℃, to 43℃, meaning the unit can be relied upon for heating and domestic hot water applications even in the coldest regions. These latest models, in addition to high-temperature water-heating capabilities, are silent and easy to install, with only water piping and an electricity supply to the outdoor unit required. When operating at maximum capacity, the 6kW model has a sound pressure level, a measure of noise intensity, of just 34dB(A)(Note2). The unit also has a quiet mode for reduced operating noise, providing flexibility to comply with noise regulations in densely populated residential areas.

In addition, as a safety measure, the units are equipped with a refrigerant leak detection sensor. In the event of a leak, the unit will stop running, and a fan engaged to dissipate any escaped refrigerant.

In order to better integrate into a range of installation environments across Europe, including residential areas, the models have been visually redesigned with an understated, modern appearance. The front of the now all-black unit is fitted with a fan guard accented with a silver vertical line and is designed to make it difficult to see the fan from an oblique direction.

By promoting the transition from boiler combustion using fossil fuels that emit high concentrations of CO₂, to ATW using electricity, Hydrolution EZY can make a significant contribution to carbon neutrality in European countries, and the achievement of MHI Group’s MISSION NET ZERO.

In October 2021, MHI Group announced its MISSION NET ZERO declaration to achieve carbon neutrality across the entire corporate group by 2040 by reducing CO₂ emissions from its own plants and other production-related facilities, as well as through reductions in the CO₂ emissions at customer facilities that use MHI Group products.

Going forward, MHI Thermal Systems will continue to develop environmentally friendly technologies and products that take advantage of the breadth of the refrigeration and heating sector, and contribute to carbon neutrality in Europe and countries around the world.

• 1 R290 has a global warming potential (GWP) of only 0.02. Global Warming Potential (GWP) is a coefficient expressing the greenhouse effect of a gas relative to carbon dioxide (CO₂), which has a fixed GWP of 1.0. The lower the value, the lower the greenhouse effect and the better for the environment. The GWP value of “0.02” is adopted based on the IPCC Sixth Assessment Report.
• 2 Value measured at three meters in front of the unit.