System schematic of an open and sealed system with an heat pump and a solid fuel stove, three central heating zones and domestic hot water (DHW) cylinder. The heat pump and central heating zones are a part of a sealed system while the solid fuel stove is a part of an open system.
The DHW cylinder is on the gravity fed circuit of the solid fuel stove and acts as the heat leak of the stove. Since the cylinder has two coils it can also be heated by the heat pump when the solid fuel stove is not burning.
When the solid fuel stove is firing and the heating zones call for heat, the pump between the NRG Zone 5 manifold and the solid fuel stove starts running. This transfers the heat from the stove to the manifold which then can be used in the heating zones. The injector tee ensures that there is still circulation through the DHW cylinder.
The non-return valve on the pipework between the manifold and the stove ensures that no heat is drifting from the sealed system to the open system when the stove is not firing.
The NRG Zone 5 manifold ensures that the heat pump receives the coldest possible return water so that it is working under optimum conditions and with optimal efficiency. The manifold also ensures that the central heating zones and the DHW cylinder have access to the warmest possible water for their flow. The manifold also provides the system with a full bypass, meaning that the heat pump can always maintain its optimal flowrate.
At the same time, it allows any unused heat from the heat pump to have a direct bypass back to the solid fuel stove to minimise condensation in the solid fuel appliance. This is beneficial since condensation in a solid fuel appliance can lead to corrosion in the appliance.
The Non-Return Valve on the secondary DHW coil is used to prevent any back circulation of the stored hot water from drifting back out of the cylinder to the system.