Gas geysers, also known as gas water heaters, can provide a money-saving and energy-efficient solution in the face of rising electricity prices and rolling blackouts. 

Unlike electric ones, gas geysers do not store large amounts of water for energy-intensive heating and reheating. Instead, the water is heated on demand when the hot water tap is turned on. As the water flows through the pipes, it triggers a sensor inside the geyser to ignite the gas burner, and the water is heated within seconds. 

However, as with other energy-efficient alternatives to the electric grid, such as solar power, it is important to understand a home’s needs, as well as the three main kinds of gas geysers to choose from before settling on which gas geyser to buy. Additionally, gas geysers will need to be installed by a certified professional.

Choosing the right size

Typically, a standard gas geyser will heat water up to an additional 25 degrees above ambient temperature. For example, if the temperature of the incoming water is 20 degrees, the geyser will heat it up to 45 degrees. Depending on size and functionality, gas geysers generally cost between a couple of thousand rand to about R15,500, and come in different sizes, mostly from 5 litres to 20 litres, although some have a capacity as high as 28 litres. 

Rather than storage capacity, the size is an indication of how much water the geyser is able to heat per minute. This means that the difference between a 5 litre and a 20 litre gas geyser is that the former is able to heat up to 5 litres of water every minute, while the latter can heat up to 20 litres per minute. Therefore, a small house with a single occupant, who might not need more than one hot-water tap to be on at any given time, would do with a smaller geyser, whereas a family of four, where two people might be taking a shower while another is using a kitchen sink, would do better with a larger-capacity geyser.

Additionally, installers will look at a household’s water flow rate, since the geyser’s ignition will be rated for a specific flow rate in order to be triggered. Not to be confused with water pressure, the rate at which water flows is determined by a combination of water pressure and the diameter of the house’s pipes. 

The larger the diameter, the higher the flow rate. A registered gas geyser installer will take this into consideration when advising on the minimum size tank that might work best for your home. 

Choosing the right size depends a lot on each household’s needs and the number of taps one expects to be on at any given time. Depending on the layout, a home can also be fitted with more than one gas geyser to supply different taps in the house. As explained by Joshua Waurich from Gas Installers, a sink might do with a 6 litre geyser, while a single shower would be optimally served by a 16 litre geyser. 

Different types of gas geysers

National Gas Installers explains that there are primarily three types of gas geysers: standard or manual, constant temperature, and forced fan gas geysers. 

The standard option will typically range from 6 litres to 20 litres capacity and be the most affordable up-front. However, these do not allow for setting exact hot water temperatures, and they can’t efficiently supply water to multiple taps. They also can’t supply water to an upstairs bathroom and may be sensitive to fluctuating water pressure, and as a result may keep switching off. 

Hence they are typically recommended for small flats, cottages or single-storey homes, where they are required for just one tap with hot water. At larger capacity, these would be suitable to supply a single bathroom with a shower, for example. 

Constant temperature geysers, on the other hand, are basically standard geysers that allow for setting exact temperatures. This could allow for greater efficiency and water saving, as one need not mix cold and hot water if the geyser is set to an ideal water temperature for a shower. These can also run two hot-water taps simultaneously. However, they are not suitable for multistorey homes. 

Although they have a higher up-front cost, forced fan geysers offer the best long-term value overall. They are more gas-efficient, have greater functionality and typically come with longer warranties of up to 10 years, while the standard and constant temperature models might have only one- to two-year warranties. They offer all the benefits of the two other systems, while also being able to supply water for multistorey homes as well as for multiple taps. However, unlike the other versions, which can ignite off a battery, they require a connection to an electric power supply or generator or UPS back-up to get going. 

Other factors to consider

It is advisable to install a standard geyser within 5m of the tap it needs to supply water to. Depending on make, forced fan geysers, on the other hand, can supply water up to a 20m range. As mentioned above, low water pressure can present problems for standard geysers and cause them to switch off. 

However, as per gas geyser retailer Give it Gas, this can be overcome by installing a pressure pump to stabilise the pressure. But the more advanced forced fan geysers are fitted with an electronic system that is able to operate even with low pressure water. DM/ML

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Check your geyser – it’s an efficient way to save energy and slash your electricity bill