The Low Carbon Partnership

Hot Water Storage

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Twin coil hot water store


A typical system will replace a conventional hot water cylinder with a twin coil store.

The bottom coil contains the heat transfer fluid from the solar collectors while the other carries heat delivered from a back up boiler.

The water heated by the solar input at the bottom rises to the top of the cylinder where it is piped to sinks, baths, showers, etc. The cool water that sinks ensures the temperature of the heat transfer fluid returned to the collectors is low and ensures high system efficiency.

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Separate pre-heat store


In this type of store, solar heat and heat provided by an immersion or boiler are delivered to separate water cylinders.

The heated water in both cylinders is combined whenever there is a demand for hot water at sinks, baths, showers, etc.

In some cases, separate pre-heat stores are easier to install and can provide flexibility of system layout. This can be especially useful where high capacity water storage is required in a limited space.


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