When to Retrofit > SolaPlug

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Retrofitting to the existing cylinder is often the most cost effective way of fitting solar.

The following important conditions need to be followed:

The cylinder is large enough.

The cylinder must be large enough to supply all the hot water needs when heated only once daily.

It's easy to try this by setting the water heating timer to heat once a day only. - It is also best practice for energy efficiency.

Hot water consumption varies considerably between households.

The EST domestic hot water monitoring report here at BSRIA is a comprehensive guide to current consumption.

The average is 80 litres per day at 60C.
Or 35 + 25 x N litres at 52C ( Where N is the number of occupants )

The cylinder is in good condition

The cylinder must not be leaking or damaged.

Older cylinders are not necessarily in worse condition than newer ones.

Scale can be an issue in hard water areas, if no water softener is used, particularly if the cylinder is heated to higher than normal temperatures.

The cylinder is well insulated.

Heat loss in the cylinder or airing cupboard can be considerable.

All new cylinders are well insulated and in most cases the majority of the heat losses come from the connecting pipes.

Fortunately cylinder heat loss is easily and cheaply corrected by fitting jackets to older cylinders, and lagging the connecting pipes adequately.

The boiler controller allows the central heating and hot water heating to be operated separately.

All solar systems where the boiler and the solar heat the same cylinder ( twin coil & retrofit ) are sensitive to the timing of the boiler heating.

For solar to work effectively it must not compete with the boiler - the boiler water heating must be timed to come on at the end of the day, if required.

Almost all boiler controllers now operate this way, but the installer must check.

Clear instructions about boiler water heating timing must be left with the user.

The solar system should be sized correctly.

To prevent overheating, the collector should be well matched to the cylinder. Ideally for a typical south facing system, the cylinder volume should be between 40 and 60 litres per m² of collector.

The heat exchanger capacity of a SolaPlug is sufficient for up to 4.5m² of flat plate collector or 30 Thermomax or 58mm tubes.

The installation must comply with building regulations G3.

If retrofitting to an unvented cylinder, the solar system must be controlled by a manual reset cut out. - usually set at 85C.

Solar controllers do not have this facility.

The Horizontal SolaPlug includes a purpose made cut out to help the installer comply with G3 more easily.

Any Questions ? Ask your installer or get in touch with us.

Revision:08 03 2011

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