Two high-capacity R290 heat pumps for a 19th-century castle
Saint Herblain (Loire Atlantique). France
2025
The Groupe Danois Bestseller was looking to replace the aging chiller unit that supplied heating to its headquarters, an 800 m² 19th-century castle, which was no longer repairable.
Panasonic and its partner Eco Solutions installed two 25 kW BIG Aquarea T-CAP M Series R290 heat pumps in cascade for a total output of 50 kW (compared to 70 kW with the previous unit). The two units, located at the rear of the building, supply a boiler room connected to cast iron radiators and provide a flow water temperature of 65°C for the building's heating needs. Thanks to T-CAP technology and natural R290 refrigerant, the BIG Aquarea T-CAP M Series units provide pleasant, carbon-free heat. In addition, significant floor space was saved thanks to the units' compact design.
Challenge
The challenge here was to retain the existing emitters—old cast iron radiators. To achieve this, it was necessary to provide a water flow temperature between 55 and 65°C without electrical backup to power the boiler room and, consequently, the radiators. Thanks to the natural refrigerant R290 and the T-CAP power maintenance technology, the two BIG Aquarea T-CAP Series M heat pumps were able to easily meet this challenge.
Solutions & applied technology
The Groupe Bestseller (the world's third-largest ready-to-wear group) has established its French offices in the Château de la Rivaudière, a building spanning nearly 800 m² near Nantes.
Built in 1880 and renovated upon Bestseller's arrival, the Château de la Rivaudière was heated by a chilled water system connected to a boiler room. A year ago, it broke down. Difficult to repair, the owner decided to replace it. The owner was looking for a robust, durable, and efficient solution capable of producing a flow water temperature between 55 and 65°C while retaining the existing cast iron radiators.
Panasonic proposed installing two of its high-power BIG Aquarea T-CAP M Series heat pumps running on natural R290 refrigerant. Both the installer and the end customer were impressed by the elegant, efficient, and compact solution, which uses a carbon-free fluid.
Two 25 kW BIG Aquarea T-CAP M Series heat pumps were installed in cascade for a total output of 50 kW (compared to 70 kW with the previous unit). Panasonic's T-CAP power maintenance technology—which maintains nominal capacity without a backup electric heater, even in extreme conditions down to -20°C, and can operate at temperatures as low as -28°C—allowed the installation of two units with a lower total output while delivering similar performance.
The new units, located at the rear of the building, have a smaller footprint than a conventional water chiller, and their noise impact is reduced by almost 20 dB(A) compared to the previous unit.
The choice of units operating on R290 and capable of high heating flow temperatures made it possible to retain the existing hydraulic circuit and cast iron radiators.
The Aquarea Cascade Manager heat pump management system was installed to control the two heat pumps and optimize the system's operation.
Green Impact of the project
Installing two BIG Aquarea T-CAP Series M R290 heat pumps with a total capacity of 50 kW significantly contributes to the decarbonization of this building, as the carbon impact of R290 is very low compared to other solutions that use fossil energy.
Partner
Installer: ECO SOLUTIONS
Capacity
50kW
