German heat pump manufacturer Ait-Group has announced the start of sales for two new residential ground source heat pump systems. The new products are based on the results of the LC150 research project at the Fraunhofer Institute for Solar Energy Systems (Fraunhofer ISE).

The LC150 research project, launched in 2020, aimed to collaborate with heat pump manufacturers and suppliers to develop a standardized, low-refrigerant cooling circuit using propane (R290) as the working fluid. Fraunhofer ISE developed a heat pump prototype that delivers 11.4kW of heating output using only 146g of propane, achieving a refrigerant charge ratio of 12.8g per kW—sufficient for most single-family homes.

While propane heat pumps already exist, most use approximately five times more refrigerant than propane systems. Due to propane's flammability, German law prohibits the installation of such systems with more than 150g of propane inside buildings; systems complying with this limit can be installed in basements. Ait-Group states that it is the first industrial partner to bring a low-refrigerant heat pump based on LC150 research results to market.

The new Alpha Innotec WZSV 63 and Novelan WSV 6.3 models feature a wide source temperature range of -13°C to 30°C, compatible with various renewable heat sources, including geothermal probes, groundwater, wastewater, ice storage, and photovoltaic-thermal (PVT) collectors.

Both units have seasonal coefficient of performance (SCOP) values of 5.14 at 35°C and 3.96 at 55°C, with a heating capacity of 6kW and cooling capacity of 7.5kW. They include an integrated 178-liter hot water tank.

Their space-saving design is suitable for single-family and multi-family homes. The separable cooling circuit module facilitates transportation and shortens installation time, particularly advantageous in retrofit applications. Ait-Group notes that both models support fluid temperatures up to 75°C, feature an electric anode to reduce maintenance needs, and have a rated noise level of 45dB(A).

Additionally, these systems are compatible with home energy management platforms and can be integrated with photovoltaic and energy storage systems.