Undoubtedly the most expensive running cost for any home is generating hot water but developers, architects and specifiers have a wide range of options in water heating technology to choose from.

By Benjamin Brits | Images by VIESSMANN

The amendments to the National Building Regulations in 2012 stipulates that all hot water generated annually must comprise a system that uses 50% of any other heating technology other than the conventional geyser / element system. These alternative solutions (in their various forms) continue to undergo improvements in engineering, technology as well as efficiency.

In the affordable housing market water heating solutions are highly important in terms of the sustainability aspect as typically purchasers or tenants already have limited financial resources and cannot be burdened with unnecessary costs or inefficient systems.

Alternatives gain popularity

Solar heating technology through flat plat collectors (a heat exchanger that converts the radiant solar energy from the sun into heat energy using the greenhouse effect), can produce up to a 60% saving on a home’s water heating requirements, while a heat pump that uses natural ambient air coupled with compressed gas through a condensing unit, can produce similar savings. These are both dependant on the time of year whether it is summer or winter. Gas boilers have the advantage of supplying instantaneous hot water and are both energy efficient and water efficient.

Although to be ‘safe’ suppliers specify savings of between 50 to 60%. “This may also be more – as high as 90% – as South Africa generally has the ideal circumstance to be able to maximise our climate conditions,” says Laetitia Botha, mechanical engineer at Energas South Africa.

The developments in the solar thermal flat plat collector models and similar solar technology now include options to have a back-up system through both gas and electrical elements, and all depend on how much sunshine is available at the time. This allows hot water to be generated even when weather conditions are not ideal.

“If this technology can work in European countries where they are on the forefront of these technologies and have much softer sun, it can work without a doubt in South Africa. Also, as with products such as the Viessmann range of solar technology that Energas supplies, because of the intensity of the sun’s heat in South Africa there is a likelihood of overheating and therefore the products have a thermo-protective layer that will switch the solar collectors off when they reach a specific temperature. When this temperature is reached, changes in the crystalline structure of the absorber layer increases the rate of heat radiation and reduces the collector output. The Viessmann-patented technology significantly lowers the maximum temperature inside the collector and prevents steam formation in the solar circuit,“ adds Nicole Viljoen, project administrator at Energas South Africa.

Quality outlasts price

In our country with the already stressed economy and further stressed construction industry, developers seek the most cost-effective solution, however this should not result in installation of products which are inferior quality.

Developers and specifiers should, under the circumstances of long-term sustainability, be more aware and opt for a quality system up front that is more efficient in the long run for users or residents. There have been cases where developers had to replace entire systems after just a year and a half due to the installation of inferior products, resulting in costly maintenance issues.

Naturally, finding a balance between price and quality is a challenge for the sector as all costs are important in the affordable housing space but comebacks, downtime and replacements down the line are far more costly to rectify.

A cutaway example of a hot water storage cylinder.

A cutaway example of a hot water storage cylinder.

Developments in water heating solutions

Alternative solutions in this space have boomed over recent times and the multitude of brands each work on their own research and development of their products to devise their own unique designs and benefits.

“The most significant advancement currently in alternative heating solutions is the ability to integrate all of the available products into a combination system. As an example you may have a tank that has coils that are heated by the sun, but you can also have coils coming from a heat pump and a gas heater as a backup, so you have a combination of all of the systems that allow you to achieve the most efficiency overall,” adds Botha.


As with most alternate solutions, maintenance of the product is minimal as there are very few moving parts, however a build-up of debris or dust is common and requires cleaning to maintain efficiency.

“Some product ranges such as the Viessman brand, are equipped with self-cleaning mechanisms such as sprinklers, otherwise an appropriate process of cleaning should be performed. It must be noted that timing is important when performing any type of maintenance as you don’t want to be working on a hot system with cold water for example, as this poses a risk,” says Viljoen.

Solutions subject to location

Most solar thermal installations are designed according to a sizing programme that captures variables, of which one is location, that will produce minimum and maximum temperatures, humidity and so on. All of these variables play a role in determining the type and scope of system to be installed.

Similarly, with other alternatives, solutions vary from KwaZulu-Natal where you have relatively high temperatures and humidity [even in winter] to the Free State where winter temperatures produce freezing conditions that can burst pipes.

“In such conditions where freezing is common, units can be equipped with an electrical element that ensures that this problem is eliminated by not allowing vessel temperatures to drop low enough to freezing point,” adds Botha.

Mindset change to alternative solutions

In South Africa, we are unfortunately faced with an unreliable and over-stressed energy supplier in Eskom, that in reality forces a mindset change of how energy is generated and consumed.

Although alternative energy solutions attract a slightly higher initial cost, many case studies illustrate the real energy savings over the long term, which may accumulate to as much as 300% of the initial cost over a five to 10-year period.

Solar application is essentially a free source of energy and gas (in its various forms such as LPG, CNG and LNG), is also a highly competitive option when comparing equivalent units of energy produced, in fact, it is cheaper than conventional electricity. This cannot be overlooked when considering the end user’s monthly costs where these savings will be offloaded as a benefit.

“In recent weeks we have again experienced things [such as load shedding], which is detrimental to small industry, businesses and right down to the people on the ground – people who have children and people who look after babies, for example.

“How we have done business from the past is changing and if you keep up with current affairs you will know that the problems we face in South Africa are not just temporary, there are very big issues with maintenance at Eskom and this is the reality of what we will continue to experience going forward. So if developers, architects or quantity surveyors want to offer something different to the market to secure a comfortable and sustainable existence for homeowners or tenants through alternative solutions such as gas facilities for heating and even cooking, the inclusion of alternative solutions must be sought out,” Botha concludes.