The second-generation of the TripleAqua heat pump, using CO2 (R744) as the refrigerant for the first time, will be showcased by Czech manufacturer Sinop at Chillventa 2022 in Nuremberg, Germany, October 11–13.

The air-to-water heat pump is designed to provide heating, cooling and hot water for medium and large residential and commercial buildings, explained Menno van der Hoff, the Dutch inventor of the TripleAqua, in a recent interview with It is suitable for both new build projects and refurbishments, he added.

TripleAqua’s CO2-based indoor and outdoor units will be displayed at Sinop’s stands – #126 and #224 – in Hall 6 of the NürnbergMesse exhibition center. At Chillventa, Sinop aims to engage partners to support the European distribution and servicing of the heat pump as demand for the product grows, said van der Hoff.

TripleAqua’s CO2-based indoor (pictured) and outdoor units will be displayed at Sinop’s stands at Chillventa 2022.

The product offers heating capacity from 45kW (12.8TR) to 500kW (142.2TR). According to van der Hoff, there will be two product lines: below and above 200 kW (56TR). CO2 is better for these medium- and larger-capacity applications of up to 500kW, as the provision of hot water is important, and other options are facing some charge restrictions.

The TripleAqua 3-pipe series can provide flow water temperatures ranging between 28°C (82.4°F) and 50°C (122°F) for heating, over 80°C (176°F) for sanitary hot water and between 7°C (44.6°F) and 12°C (53.6°F) for cooling. Return water temperatures are always at average building temperature.

In addition to providing heating and cooling, the TripleAqua system can store surplus heat and cooling in external “charge buffers” if the energy produced cannot be used directly. This function can also be used to produce and store heating and/or cooling and hot water at times when electricity prices are low.

Unorthodox design

TripleAqua includes several design elements that differentiate it from all traditional heat pumps and result in up to a 50% reduction (from pilot data) in energy consumption and a calculated 25% reduction in installation costs, said van der Hoff.

While conventional heat pumps reverse the refrigerant flow to provide cooling or heating, TripleAqua includes three separate heat exchangers – one for heating, one for cooling and one to support both functions – which optimizes system efficiency and user demands, said van der Hoff.

In addition, a four-way reversing valve has been omitted. “The plate heat exchangers always remain in their optimized countercurrent status,” said van der Hoff. “This results in outstanding SCOP [Seasonal Coefficient of Performance] and TER [Total Energy Ratio] values for CO2.”

In addition to providing efficiency savings, this approach also allows the system to provide any variable quantity of heating and cooling simultaneously, which is useful for multi-use facilities, such as hotels, hospitals and many renovation projects, said van der Hoff.

“The plate heat exchangers always remain in their optimized countercurrent status. This results in outstanding SCOP [Seasonal Coefficient of Performance] and TER [Total Energy Ratio] values for CO2.”

Menno van der Hoff, TripleAqua

Another unusual aspect of the TripleAqua heat pump is that it uses three water pipes instead of the traditional four, reducing the amount of piping and labor required for installation by 25%, he said. One pipe is used to transport hot water, another is used to transport cold water, and the third returns water to the compressor unit.

The system requires no piping of refrigerants in buildings, just water, which further simplifies installation. According to the product website, “any installer can handle this technology.”

Award-winning system

Originally patented in 2014, the first-generation model of the TripleAqua heat pump used propaene (R433A) – a mix of propane and propene (R1270) – as its refrigerant.

Within the first few years of pilots, Beijer Ref, TripleAqua and van der Hoff had received numerous awards in recognition of the product’s innovation, including the European Technology and Innovation Platform on Renewable Heating and Cooling’s (RHC-ETIP) most innovative project and the Accelerate Europe Person of the Year award – both in 2017. (Accelerate Europe was produced by ATMOsphere, publisher of

The technology was tested in the Netherlands, which offered insights into how the product performed and how it could be improved.

While there was a lot of interest in TripleAqua, the market wasn’t quite ready for the product, explained van der Hoff. Awareness of heat pumps was relatively limited, and natural refrigerant for heat pumps was at that time very new.

However, with the demand for heat pumps and natural refrigerants growing significantly across Europe, van der Hoff believes now is the perfect time to launch the second generation of the TripleAqua heat pump system.

In addition to the change of refrigerant to CO2, the new generation is better suited to current building design trends, with a smaller profile that is less than 1.5m (4.9ft) tall.

According to van der Hoff, a high-temperature version of TripleAqua is currently in development. This product is designed for old refurbishment projects of large residential buildings to replace fossil-fuel based heating systems that require water temperatures from 45°C (113°F) to more than 75°C (167°F).

New experienced manufacturer

TripleAqua will be manufactured by Sinop, which was founded in 1994 and has been working with CO2 as a refrigerant since 2010.

Sinop manufactures a range of CO2 booster, cascade, parallel, ejector and other customized systems, such as the retrofitted refrigeration system at St. Olav Hospital in Trondheim, Norway. Sinop produces systems for commercial, marine, off-shore and high industrial applications up to 900kW (255.9TR) cooling capacity.

To meet the growing demand for heat pumps and other products, Sinop is investing in and plans to open its fourth manufacturing plant in the Czech Republic in 2023.

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