System Schematic of a sealed and open system with a heat pump and a solid fuel cooker as the heat sources, and two radiator zones and a (domestic hot water) zone as the loads.
The system uses a buffer tank as the interconnection between the sealed and the open system. Both the heat pump and the solid fuel cooker heat the buffer tank, the heat pump indirectly through a coil, and the cooker directly. The radiator zones take water directly from the buffer tank to heat the building, while the DHW takes the heat indirectly through a coil.
This means that the heat pump and DHW can be pressuized while the cooker and central heating zones are not.