The system consists of two cylinders in a single body:  the upper tank is a calorifier for the production and storage of domestic hot water (DHW) equipped with a high efficiency heat exchanger that can be powered by a heat pump, while the lower tank is a primary water buffer store for the heating system that is also fed by a heat pump.

Types:

- 2in1 – Buffer + glass-lined DHW storage a one above the other design
- 2in1(X)-xx1 – Buffer + inox DHW storage a one above the other design
- 2in1 FRESH(1/2)-xx1 – Buffer + flow-through DHW production a one above the other design
- TRX AC-xx6 series - Buffer + flow-through DHW production in a design that can be rotated one above the other