System schematic of an open and sealed system with an oil boiler and a solid fuel stove, two central heating zones and domestic hot water (DHW) cylinder. The boiler and central heating zones are a part of a sealed system while the solid fuel stove is a part of an open system.
To connect the two different system types an NRG Link is used. The NRG Link ensures that the solid fuel stove has an open system as required for safety reasons, while still being able to transfer its heat to the sealed 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 sealed system when the solid fuel stove is not burning. 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.
In this system, the gravity circuit is going in the attic, above the heat leak cylinder. Therefore a heat lock is needed to prevent the heat in the cylinder from drifting up into the attic.
The NRG Zone 5 manifold ensures that the boiler receives the coldest possible return water so that it is working under optimum conditions and with optimal efficiency. This is especially important for condensing boilers as it greatly increases the likelihood of the boiler operating in condensing mode, which is by far the most efficient. 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 boiler can always maintain its optimal flowrate.