Remote geyser switch off ‘does not increase power costs’

2018-07-25 06:02

THE remote switching off of geysers in Nelson Mandela Bay should not result in increased electricity costs for the affected consumers.

This reassurance was given by the first vice president of the Electrical Contractors’ Association (ECA), Graham Clarke, who said that the system in place does not use excessive amounts of electricity units when the geysers are switched on again.

The Nelson Mandela Bay Municipality recently enforced load-shedding where more than 90 000 geysers were remotely switched off in the Metro.

Regional director of the ECA, Lucas Bowles, said that this pilot project was launched to avoid a blackout in the Bay.

“The residents of the Bay have to take note of the fact that if we don’t comply with this project, the Metro won’t be in control anymore and Eskom will take over.”

The Nelson Mandela Municipality has not experienced any load shedding during these winter months, while other South African cities had load shedding of up to four hours per day. The main reason for this is that the municipality only used the geyser controlled system to shift the required energy load requested by Eskom.

In response to an enquiry from a concerned Port Elizabeth Express reader who said that this will increase consumers’ electricity costs due to the fact that geysers needed to be heated up again, Clarke said that the system in place does not use excessive amounts of electricity units.

“With the ripple relays turning off geysers at home there is no extra electricity used when the geyser comes back on as the energy consumed is directly proportional to the amount of water used. When the reheating takes place it is of no consequence.”

According to Clarke, there is a formula to calculate the energy and time needed:


q is the amount of energy

c is the heat capacity of water

?T is the change in temperature.

In the above example it will take approximately 12 minutes to heat 10 litres of water from 20 degrees to 55 degrees and use approximately 0,5KWH of energy – that would be on a 2Kw geyser element.

Ignoring any losses, if the water is heated immediately when using 10 litres or if the 10 litres is heated in three hours’ time, the same amount of energy is used.

The formula calculates the amount of energy to heat water from room temperature (20 degrees) to 55 degrees set by the thermostat.

There are also factors which determine the amount of units used: The size of the geyser, the size of element, the start temperature of water (cold), the thermostat temperature setting example 55°C and whether water is used during the heating cycle.

“A geyser is either on or off – there is no slow trickle of electricity to keep the water warm in a geyser,” Clarke said.

The geysers will be remotely switched off from 17:00 to 21:00 every day in July and August in the Metro.


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