Geyser Timers: Facts to Consider in 2022

As South Africans we are faced with many unforeseen challenges, particularly the threat of load shedding of our electricity stands out. As homeowner one wonders if switching off your geyser really helps to reduce overall demand on the grid while you saving electricity at the same time? It’s important to assess the facts and common myths that people have about geysers and the need for a geyser timer. Eskom has shared that South Africa’s residential sector consumes approximately 17.5% of the total electricity generated and this increases to over 30% during peak periods.

What most people don’t realize is that the geyser accounts for 40% to 60% of the total electricity used in an average household in a month. When you think about this exponentially that’s thousands of geysers country wide running all day and night, this places terrible strain of the electricity supply grid. This is why Eskom frequently asks consumers to install geyser timers in order to control the geyser’s operating times. A geyser timer is a consistent way to ensure that your geyser remains off during peak electricity demand periods. What you should know is that your geyser is fundamentally a giant kettle. You can imagine that keeping your kitchen kettle running all day would significantly increase your electricity usage. Ironically there are a lot of debates around whether keeping your geyser on permanently ends up costing more electricity than if you only turned it on when you actually needed it.

Now the main argument for switching off your geyser is that when off, the element in the geyser is not heating the water and therefore not using electricity. However if you keep your geyser on, the water is permanently at high temperatures, thus requiring little or no heating from the element. However the element will use higher amounts of electricity after the hot water is used up and then the new cold water refills the geyser chamber. If you leave a geyser to get cold you will need a massive amount of power to fully heat it back up. When you reduce your geysers energy consumption, it will not only be good for your monthly expenses but will also lower your carbon footprint on the environment.

Eskom Residential Mass Rollout (RMR) programme has specifically targeted household geysers and recommends the installation of both geyser timers and geyser blankets to help reduce power demand. It seems simple to grasp but it really is way more complicated than you may think. You will find that some geyser makes are designed to heat up much faster, which in turn uses a lot more energy, but they are able to maintain high temperatures without much more energy use. As it stands modern geysers are already manufactured to be much more energy efficient than older models. Other factors will or may also play a role in whether your geyser is using more electricity than usual.

There are 4 factors that will affect energy use in your geyser: (1) the type and condition of your geyser, (2) how much hot water you use, (3) how often you use it and (4) the type of insulation you do or do not have. Turning off your geyser will not save much electricity according to most professionals, and this is included Eskom’s Geyser Fact Sheet.  You will only see 10°C of heat loss in the 24 hours after your geyser is switched off. This is what is called ‘standing loss’ and this is also a quality standard set forth by the SABS.

 If you were to use this slightly cooler water instead of reheating it may save a small amount of electricity. However when you turn the geyser back on the electricity needed to reheat the now diminished temperature will unfortunately cancel out those savings. Heat will leak out of the geyser into the surrounding area and the rate of the heat leak will depend on the quality of the geyser’s insulation.

Does switching the geyser on and off consume more energy?

A geyser functions by using electricity to heat the water inside to the set temperature of the thermostat. As the heat from the water dissipates the thermostat then switches the element back on to reheat the water, this due to natural thermodynamics. This cycle can happen between 15 to 30 times per day. Most people are working during the day and as a result they don’t need hot water during it. So this often means that a lot of electricity is wasted when the geyser is heating water when no one is home.

In practice a 150 litre geyser takes about an hour to heat water to the set temperature from when it’s cold. So switching the geyser off when the hot water is not required and then switching it on an hour or so before the hot water is needed will help cut the amount of electricity used. You will also see higher electricity wastage especially in winter, and even more so if the geyser does not have a geyser blanket to prevent the additional heat loss.

Will switching your geyser on and off damage the thermostat?

Your geyser’s thermostat switches on and off during the normal operational cycle, which means that is not a factor. However you may likely begin to see damage to the geyser breaker switch as it is designed to trip only when there is a problem with the geyser, and is not designed to be frequently switched on and off.

Will switching a geyser on and off will cause it to crack?

This is another popular myth which is not true in the least. Your geyser switches on and off during it’s normal operation and is designed to withstand the kinds of temperatures and pressure that is created as your water heats up.

If you are using a geyser blanket, does your geyser need to be switched off?

When your geyser does switch on, the average saving achieved with a geyser blanket alone is only about 8%. If you were to control the operational times of your geyser using a geyser timer, it would add between 15% and 18% more electricity savings over and above the use of the geyser blanket. You will also find that using a geyser timer alone is about twice as effective in reducing your energy usage, than just using a geyser blanket alone.

Can geyser blankets overheat, explode or catch fire?

You will find that geyser blankets that have been made from recycled PET (i.e. 2L Coke bottles) don’t burn, overheat or explode. Should there be a fire in your roof, your geyser blanket would simply melt in the intense heat.

Is using a geyser timer a more efficient way of managing electricity demand?

The geyser timer will allow you to take over control of how many times your geyser heats up its water. So instead of allowing it to be permanently on, you can plan ahead and schedule your geyser timer to bring down the bill. Statistics show that geysers that are set to heat their water once a day for two hours will cut more than 60% off their geyser expenses.

A geyser timer set to twice a day for two hours will saves about 37%, which the preferred choice among bigger families. A timer is going to save you a lot of money, the trick is to know when you will be needing hot water and whether you can stick to your routine.

Is there dangerous bacteria lurking in your geyser?

According to a Stellenbosch University (SU) study geysers provide an environment that is conducive to the growth of legionella, when kept in temperatures ranging from 37°C to 42°C they begin to thrive. Dr Wendy Stone from SU’s Water Institute said: “Our research highlights the connection between heating regimes (when and for how long a heater is switched on) and the increase in legionella, specifically the pathogenic species L. pneumophila, in water heaters or geysers.” “In South Africa there is no information about the prevalence of legionella in domestic water heaters, which normally heat water to 65°C. However, since temperatures as low as 40°C are considered sufficient for user satisfaction, many users who struggle financially choose to operate at a lower temperature or turn off their water heaters to save money,” said Stone.

While it is becoming more common for geysers temperatures to be lowered for financial savings, it does also create an environment that is ideal for bacteria of various forms to thrive. The symptoms of legionellosis are often be confused with common forms of pneumonia.

How do you use your geyser efficiently and more effectively?

Be sure to install a geyser timer, geyser blanket and energy-saving or water-saving shower-heads. Analyse your water usage patterns and then have a geyser timer or similar controller installed to ensure that your geyser will only operate to meet those specific usage requirements.

If you were to have the geyser come on at around 4am and go off at 6am will provide enough hot water for the morning up to around 12pm without having to run the geyser again, if you have a geyser timer and blanket installed. It’s advisable to then have the geyser on between 1pm and 2pm just to maintain the water temperature. After which the geyser can be switched off until around 4pm, and then can stay on until 6pm. Then you are able to switch it off for the rest of the night. By doing it this way, your geyser will not be running during peak demand periods and this will contribute to lower demand on the grid.

In addition energy-saving and water-saving showerheads reduce the flow volume of the water by more than half. You see an average showerhead uses about 20 litres of water per minute, of which around 40% is hot water. So in a single 5-minute shower, that will amount to a 100 litres of water and 40 litres of that will be hot water. When you have installed energy and water efficient showerheads you can further reduce that flow to just 9 litres per minute.


What are the best ways to save electricity in the household?

You should only use the hot tap when necessary to wash your hands etc. Try using less hot water when you do by taking shorter showers or shallow baths. You can also lower the temperature settings on your washing machine and dishwasher to save electricity.

You can also ensure that your geyser and water pipes are properly insulated, which will ensure that your heat leakage is lessened. Keeping your geyser running with proper insulation will help you reduce the amount of power required to maintain high temperatures. Tests have shown that effective insulation will save you about 20% of your electricity cost when reheating a geyser that has been off for 24 hours or more.

You can additionally set your geyser’s thermostat to 60°C to optimise your electricity use. Higher temperatures are really unnecessary and this will in turn use more energy. Another tip is to install your geyser as close to the areas in your home where hot water will be needed. This reduces the cooling down of water that is experienced when it is resting in the pipes. As mentioned before a great way to save up to 24% in electricity and water use is to install a water-saving and energy-saving showerhead. Another great tip is to simply turn your geyser off when you are going away for a few days or on holiday.

As we have learned you can really save electricity by managing your hot water use, and taking good care of your geyser. In practice older or damaged geysers will tend to drain electricity. In truth your power savings will only be affected through responsible management of whether you will choose to turn off your geyser regularly or keep it running all the time. While solar power may be costly to initially install, you may find a solar water heater will save you vast amounts of energy and is decidedly more environmentally friendly. The choice is up to you…