Anthony Murdoch, who is an electrical engineer, said these factors influence a geyser’s electricity usage:
• The distance of the geyser from the hot water taps. The greater the distance, the higher the hot water losses and the added cost of electricity.
• Flat roof homes normally have geysers located on an exterior wall, which means the geyser and pipes need insulating.
• Pitched roof homes should have the geyser located between the kitchen and bathroom – reducing the distance water has to travel.
• Steeply pitched roofs usually ensure geysers can be placed in an optimal position in a ceiling, as opposed to a cramped area caused by a low pitched roof.
• The coldest part of the dwelling (in the Southern Hemisphere) is on the south side of the building. The kitchen and bathrooms are normally located on the south side and this compounds temperature losses.
• The size of geyser in relation to the volume of hot water. The geyser capacity must be capable of carrying more than the family’s bathing needs. That way the geyser will have a chance to get up to temperature and, when hot water is drawn, the capacity will still have warm water reserves and then the element has only to raise the water several degrees and not from scratch.
• The higher the geyser element Wattage rating the faster the geyser will attain the required temperature.
• The geyser temperature setting is another point for consideration. A typical temperature setting is 60 degrees. If the geyser is some distance from the point of usage, in the case of flat roof dwellings, the temperature should be increased to compensate for the line losses.
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Murdoch said a timer is the most effective in modern geysers.
“In modern geysers, the thermostat is housed together with the geyser element which is in close proximity to the water inlet point,” he said.
“As soon as hot water is drawn from the geyser, the inrush of cold water has an effect on the water temperature adjacent to the thermostat, causing the thermostat to respond which then switches on the geyser element.
“Accordingly, frequent drawing of hot water causes the geyser to stay on for a considerable length of time, thereby increasing the consumption of electrical power.
“Given the uncontrolled switching on of the geyser element, it is prudent to regulate the power supplied to the geyser by means of a suitably rated timer.”
He said a timer is most effective because it allows the geyser to attain its maximum temperature, thereby reducing the repeated switching on and off of the thermostat.
The timer should be set to be in the “on” state during off peak times – typically mid-afternoon and during the early hours of the morning.
This will afford the availability of hot water for the family’s peak time requirement.
Murdoch said solar geysers will also be cost effective in the long run, as they tend to be more expensive than normal geysers.
