Ait-Group launches residential heat pumps with low propane charge

Germany’s Ait Group has introduced residential ground-source heat pumps using less than 150 grams of propane, based on results from the Fraunhofer ISE LC150 research project. The new systems deliver up to 6 kW of heating with a seasonal coefficient of performance of 5.14.

July 11, 2025 Emiliano Bellini and Sandra Enkhardt

Image: Ait-Group

Ait-Group, a Germany-based heat pump manufacturer, said it has started selling two new types of ground-source heat pump systems for residential use.

The new products are based on the results of the Fraunhofer ISE’s LC150 research project. The team launched the project in 2020 to develop a standardized, refrigerant-reduced cooling circuit using propane (R290) as the working fluid, in collaboration with heat pump manufacturers and suppliers.

Fraunhofer ISE developed heat pump prototypes that use just 146 grams of propane to deliver a heating output of 11.4 kW. The specific refrigerant charge was 12.8 grams per kW – enough to meet the needs of most single-family homes.

Propane-based heat pumps already exist, but most use about five times more refrigerant. Because propane is flammable, German law prohibits installing such systems inside buildings if they exceed 150 grams of propane. Systems that meet this limit may be installed in basements.

Ait-Group said it is the first industrial partner to bring reduced-refrigerant heat pumps based on LC150 findings to market maturity.

The new models, Alpha Innotec WZSV 63 and Novelan WSV 6.3, offer a wide source temperature range of -13 C to 30 C. Ait-Group said this makes them compatible with several renewable heat sources, including geothermal probes, groundwater, wastewater, ice storage, and photovoltaic-thermal (PVT) collectors.

Both units have a seasonal coefficient of performance (SCOP) of 5.14 at 35 C and 3.96 at 55 C. They offer a heating capacity of 6 kW and a cooling capacity of 7.5 kW. The integrated hot water tank holds 178 liters.

The space-saving design targets single-family and multi-family homes. A separable cooling circuit module allows easier transport and reduces installation time, especially in retrofit applications.

Ait-Group said both models support flow temperatures up to 75 C and feature electric anodes that reduce maintenance needs. Sound levels are rated at 45 dB(A).

The systems are compatible with home energy management platforms and can be integrated with photovoltaic and energy storage systems, the company added.

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