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 + hot water tank
- 2in1(X)-xx1 – Buffer-/ DHW storage integrated
- 2in1 FRESH(1/2)-xx1 – Two-in-one buffer store for heat pumps
- TRX AC-xx6 series - one heating buffer tank with one DHW coil on top, bottom buffer tank can be optionally sized and rotated