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Geyser Timers

by Russell Brown in April 2013 - Green Life

To recap, over the last two months we addressed low cost hot water energy saving interventions in the form of lower flow shower heads
and insulation.

Now that you are familiar with the concept of a payback period and are aware of how quickly the costs spent on an intervention can be recovered from your savings, have you made the decision to make these two changes to save energy? Every month you delay the decision will cost you. I will now continue and discuss the final of the low cost interventions – Geyser timers and controllers.

There are two types of technologies which are similar but have different purposes and therefore have different related results. I would like to start with a word of caution. Over the past few years as electricity costs have been rising rapidly many unsuspecting business and home owners have fallen foul to geyser timer/controller scams. These scams claim to have a black box of magic tricks to save you vast amounts of money.

Geyser timers have their limitations and these should be understood so as not to fall foul of one of these scam artists. A geyser timer is purely a device that saves you money by switching a geyser off and on for specific time periods. It does not magically control a geyser itself to perform thermally more optimally or more efficiently.

A way to protect yourself from these scams is to understand how much a geyser timer or controller type product costs. A geyser timer should not cost you more than R1000. Do not get fooled into signing multiple year contracts for this type of device.


It is an electronic (digital) timer or an electro-mechanical timer designed to switch your geyser on and off during specific time periods. The timer should be able to maintain time (with a backup battery) during power outages and should meet the specification of the geyser, i.e. the correct amperage for the kW rating of the element.


You need to understand that a geyser timer should be used effectively by knowing your water usage patterns. The most optimum saving that
can be achieved by a geyser timer is typically heating of water for two hours a day for one period, i.e. once a day for two hours – 4am to 6am with usage immediately at 6am. Tests show that around 69% savings can be achieved with this usage pattern. If you heat water for two time periods – from 4am to 6am with usage at 6am and then 5pm to 7pm with usage at 7pm – savings move to around 37%.


A geyser controller can often also perform the same function as a geyser timer but the main function of a geyser controller is to facilitate Eskom or the Municipality switching your geyser off during peak periods. The main function of a geyser controller is to allow Eskom or the Municipality to manage demand and hence minimise the risk of exceeding their supply reserve margin. Controllers are not intended to save the consumer electricity.

Cost: R750 (plus installation +- R250).
Saving: R1 126 to R2 284 per year (R102 to R190 per month)*
Payback: five to nine monthsr*
*Based on tests done on a 150l geyser switched off for a one time period for two hours and two time periods for two hours. Capital cost of R1 000 and R1.40 per kWh (cost used for payback calculations).

Next month we will look at higher cost interventions for hot water.

Russell Brown is a passionate sustainability consultant who researches and applies current trends in sustainability to both his personal and business life. He has assisted corporate clients achieve their goals of operating more sustainably through the application of sustainable or green practises. For any questions please email Russell on


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