FEATURE 17
Low-pressure solar geyser A low-pressure geyser generally operates as a gravity-fed, vented system, where water is supplied from a header / cold-water tank rather than directly relying on full municipal mains pressure. The water pressure at the outlet is therefore determined largely by the height of the water above the outlet.
Advantages of low-pressure solar geysers The most obvious advantage of a low-pressure system is lower installation cost. Because these systems generally require fewer pressure-control components, both material and installation costs can be reduced. The system is also relatively straightforward, making it easier to install and maintain compared with a pressurised system. Because the geyser is not subjected to the same mains pressure as a high-pressure system, there is generally less stress on the geyser cylinder and associated plumbing components.
Insurance input for solar geysers
• All products should be fit for purpose, be of the‘ approved type’ and installed in observance of the relevant SANS standards and in accordance with the manufacturer’ s stipulated requirements.
• The attending plumber also needs to be appropriately qualified and accredited.
• Report on compliance as required.
A low-pressure solar system can also be appropriate where the available incoming water pressure is insufficient for a conventional high-pressure system. For a household with modest hot-water requirements, a low-pressure system can provide an economical way to take advantage of solar water heating. The simpler hydraulic arrangement and fewer pressure-control components can also mean fewer components requiring servicing or replacement, potentially resulting in lower maintenance costs.
Like a high-pressure solar system, a low-pressure system uses solar energy to heat the water, reducing reliance on the electrical backup element. It can also be a good option for certain existing installations. Where a property already has a low-pressure plumbing arrangement, replacing the system with another correctly specified low-pressure solar geyser can avoid the need for significant plumbing modifications.
Disadvantages of low-pressure solar geysers The trade-off is lower water pressure. Showers, taps and baths may have noticeably lower flow rates, particularly where a property has multiple outlets. All water has to be balanced at the mixing point so no mixers may be used unless the hot and cold water pressure is equal.
Some modern mixer and thermostatic shower systems perform better with higher and more stable water pressure. A low-pressure system can also show reduced performance when several outlets are being used simultaneously. For example, if someone is showering while another person opens a tap or flushes a toilet, the available hot-water flow can be affected more noticeably.
Supplied by Louis Bornman
On this picture, the hot water outlet is at the bottom of the lowpressure solar geyser.
A low-pressure geyser is designed for a specific hydraulic arrangement. It should not simply be connected into a conventional high-pressure mains system without the correct design and components.
Low-pressure systems can also offer less flexibility for larger homes. Houses with multiple bathrooms and high simultaneous hot-water demand will generally benefit more from a properly designed highpressure system.
Background by Magnific. com
November 2026 Volume 32 I Number 09 www. plumbingafrica. co. za