System schematic of a sealed system with an oil boiler, solar panel and an optional gas boiler as the heat sources. The heat outputs are a radiator heating zone, an underfloor heating zone and a domestic hot water (DHW) cylinder with two coils. The DHW cylinder can either be heated from the solar panel, or from the boilers.
The NRG Zone 4 manifold ensures that the boilers 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.