Vaillant heat pump proven in residential refurb
21st February 2026
GERMANY: Heat pump technology, such as Vaillant’s Energy Unit 2.0, is helping to drive the European energy transition in existing multi-family buildings.
The latest development sees Vaillant’s modular heat pump system, using R290 refrigerant, being successfully commissioned in the renovation of a block of residential flats in Dortmund.
The two apartment buildings, constructed in 1967, each comprise ten residential units with approximately 720m2 of living space per building. Previously, heating was provided by a gas-fired central heating system. Following the failure of one of the heat generators and due to the limited space in the utility room, the owners opted for the Energy Unit 2.0. This modular prefabricated six-stage heat pump cascade system, achieving a total output of approximately 80kW, was delivered ready for connection, and installed outdoors.
The Energy Unit 2.0 is based on a two-part concept consisting of a hydraulic module with fully integrated hydraulic, storage, and control technology, and a variable heat pump module. Four sizes are available with two to six Vaillant heat pumps.
Compared to its predecessor, the Energy Unit 2.0 is more compact and acoustically optimised. Thanks to the internal arrangement of the heat pumps and the sound-insulated housing, the maximum sound power level in the standard Dortmund version is 64.2dB(A) during daytime operation.
The Energy Unit can also be equipped with sound-absorbing weather protection grilles, allowing for significantly reduced distances to residential buildings. A modern wooden facade and steel elements, as well as an optional green roof, enable discreet integration into the surrounding neighborhoods.
The technical heart of the Energy Unit 2.0 in the XL version is a six-stage cascade of Vaillant AroTherms plus VWL 125/8.1 air/water heat pumps using R290. Two 800-litre AllStor plus buffer tanks and the EloBlock VE 14 electric auxiliary heater. The expected seasonal performance factor is at least 3.5.
