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Pre-heat/pre-feed system configuration


A pre-heat system (sometimes referred to as pre-feed) is when the solar-heated water from a solar water heating system is fed into your existing geyser. It is therefore connected in conjunction with your present electrical geyser.  Most configurations of solar water heating systems can be used as pre-heaters.

Pre-heat systems can be good for increasing the amount of hot water available at the time of use. The major benefit of a pre-heat/feed system is that you increase the amount of stored hot water available.

The pre-heat configuration is therefore convenient as the existing domestic geyser and plumbing is not disturbed when installing the solar system and you effectively increase the amount of storage capacity which allows you to utilize the stored solar water when your existing system calls for more water.

It is an Eskom requirement for the rebate that the existing domestic geyser be covered with a geyser blanket to improve efficiency and that the element in the existing geyser be downsized to a 2kW element. Electrical timers are supplied to cut out electricity during peak times.

The condition of your existing geyser must be good in order to effectively use the pre-feed system.

With solar you ideally want to have enough hot water stored that will provide sufficient hot water during the night as well as for the next morning if required, without the element turning on. It is therefore important  to select the correct size geyser to suit your specific needs.

Every household has a varying hot water usage but a good rule of thumb is 50 litres of water per day per person. Add in an extra 50 litres for storage. Therefore for example 2 people living in a one bathroom house will be well suited for a 150 litre system. 3 to 4 people a 200 litre system and so forth. Any combinations of systems are possible.


High pressure Thermosyphon (Pre-feed)

high pressure thermosyphon pre-feed

This is a Thermosyphon system that is connected to an existing household geyser as a pre-feed system.

High Pressure Pumped System

split pump system

This shows a split pump system

low pitched application

Low pitched application – most roof types have sufficient pitch for the collectors to lie flat without the raised frame

flat roof application

Flat roof application

Bulk SWH application

Bulk SWH application

Evacuated tubes being used in an Industrial Application

Evacuated tubes being used in an Industrial Application

Heat Pumps

heat pumps