Myth Buster - Hot Water Geysers

Having read many articles circulating the internet, from quiet credible sources, relating to the possible savings of electricity if consumers turned their hot water geysers OFF when not in use, Suntricity decided to carry out our own research, to verify the reality.

We installed WiFi electricity monitoring devices to the geyser electricity circuit (more information on this soon) to register electricity consumption of the geyser under the normal 24/7 operation, to then compared this to electricity consumption if the geyser electricity supply was turned ON between the hours of 01:00 and 05:00 OFF PEAK operation hours only.

The result: Little or no difference in electricity consumption.

The electricity consumption will of course vary in the summer, as water entering the geyser tank in the summer, is at a much warmer temperature, to that of winter water temperature.

What was very interesting is that we were able to satisfy hot water demand with Off Peak Hours operation only - between the hours of 01:00 and 05:00). This is important as in truth, the Municipal grid is under far less operational stress during Off Peak hours. The pie chart above details Peak, Standard and Off Peak Hours.

Effectively, the best way to reduce electricity consumption of hot water is to reduce water consumption, through efficiency measures, such as: No Baths, Shorter Showers, aerators to taps, high efficiency dish washers, etc.

Renewable energy has an important role to play:

Solar PV - where the geyser is only heated in the solar hours - this is particularly important for schools with Solar PV installed.

Solar Thermal - which heats hot water during the day and stores on the tank - more applicable to the residential sector.

Heat Pumps - which extract energy from the ambient air - will publish more information on this shortly.

This information is not new, although certainly a myth buster. The answer to reducing electricity hot water cost need serious thought, particularly with electricity tariff increases being introduced over the next 3-years. We will be publishing more information on this specific subject shortly.

For more information, please contact:

For further interesting reading: Smart water heating could help in South Africa’s energy crisis