System schematic of a sealed system with a heat pump, 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 heat pump and/or gas boiler from the heating system.
The NRG Zone 4 manifold ensures that the boiler and heat pump 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.
In the optional configuration the heat pump can used to pre-heat the water at a very high efficiency before the boiler takes it and raises it to a higher temperature at a lower efficiency. This means that the system has the high efficiency of a heat pump for medium temperature applications while the gas boiler can heat the water to a higher temperature than a heat pump if needed. It also means that the heat pump can be used for most days of the year since it is cheaper and more environmentally friendly to run, while the boiler can be used to help out on the coldest days of the year when the heat pump is unable to deliver enough heat.