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Thread: Geyser Timer vs Full Time Power

  1. #1
    Gold Member daveob's Avatar
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    Geyser Timer vs Full Time Power

    I see we have a number of electrically savvy people on the forum, so hope someone can solve this for me.

    We recently installed a geyser timer.

    Geyser is 150 liters and runs at 55 degrees in Durban area.

    Is there some easy way ( software application / spreadsheet, etc ) that could be used to determine the savings vs re-heat power required ?

    For example, if I use the time to cut the power to the geyser, then use 75% of the hot water and leave it off for 4 hours, would it use more power to re-heat compared to leaving it on permanently.

    Or, if the same as above, but we don't use any water from the geyser, what is the rate of temperature loss for a standing geyser, and how much more energy would be used, compared to just leaving it on all the time.

    Naturally, the list of combined factors could be a lot longer, but essentially I am trying to get a feel of weather we would be saving anything if we turned off the geyser for x amount of time each day. There must be some determinable point where it is cheaper to leave it running.
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  2. #2
    Gold Member twinscythe12332's Avatar
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    I found this article. read here supposedly switching it off will save electricity, but there are plenty of people who maintain this damages it (This article says it's a fiction, but the comments say otherwise)

    hope this helps

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  4. #3
    Diamond Member wynn's Avatar
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    Do the two week test.
    Leave the geyser on for a week taking readings before and after then do the same but switch on and off and see if there is a difference in the readings.

    I do not believe switching off for a period harms your element that much. it may be on its last leg anyway, but do make sure your geyser has the correct pressure control and vent valves to avoid unnecessary stress caused by the expansion and contraction on the tank.
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  5. #4
    Site Caretaker Dave A's Avatar
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    All the geyser is doing is topping up energy levels in the water using electrical energy. So it's really all about energy losses.

    The higher the temperature differential the faster the rate of energy loss.
    The poorer the insulation the faster the rate of energy loss.

    On the flip side, at lower temperatures the geyser element will draw a slightly higher current and there will be more losses/ineffciencies due to line resistance. So keeping line resistance low is important (frankly, an important point in all situations anyway).
    And then there's my observation of a higher failure rate for geyser elements that have been switched off for long periods of time. But that's anecdotal and probably isn't a problem the way you're considering going about things.
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