Turn off the immersion to save energy?

05 September 2013



I have heard that people can save large amounts of electricity by switching their immersion heaters off and I really would like to understand how this works.

One needs to understand that the geyser trip switch does not switch the geyser on, what it does is make electricity available to the thermostat which then can turn the heater on once the temperature drops to the point where heating is required. So why would turning it off have an effect, assuming minimal heat loss from the container?

Kind Regards,
Rob Bernstein


Dave - So essentially, with something like a hot water tank, the hotter it is, the more energy it's going to be losing. So, if it's not very well insulated, the effect is even bigger. Essentially, if you keep it hot all the time, then you'll be losing lots of electricity and lots of energy. You're going to have to put more electricity in there to keep it hot. If you turn off the electricity, it will cool down and the more it cools down, the less heat it will lose. Now, almost the best solution would be to improve the insulation but if you can't do that or that's expensive or difficult, turning it off will save energy. I can't say off the top of my head how much it's actually going to lose.

Dominic - It's interesting if you look at the typical electricity usage of a house. I think heating is one of really big costs you tend to have and that's water heating, but also, space heating. If you look at an airing cupboard where you've got a hot water tank in there and you feel it, it feels hot. So, that heat is leaking out of that tank into your house. So, if you've got that on all night then you're basically heating your house with your hot water tank all night.


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