Immersion heater help

22 Sep 2015
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Hi everyone,

I’ve just moved into my first flat and I’m trying to figure out the immersion heater.

The immersion heater has two heat switches- top and bottom.

When I first moved in I switched the top immersion heater on for 2 hours and the water was still cold. So I switched the bottom immersion on as well for a further 3 hours and the water was then piping hot.

My question is: why is there two immersion switches and is it best to use the top or bottom immersion, or both at the same time?

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the top one is probably faulty then, or it might be a wiring fault.

Each of them will (should) heat about 1 litre of water per minute. Because hot water rises, the top one will heat (say) the top quarter of the cylinder, let's say 25 litres, in about 25 minutes. Enough to wash up.

The lower one will heat, say 90 litres, but will take 90 minutes to make it hot enough for a bath.

If you have economy 7 or other off-peak electricity, heat the whole cylinder with the lower heater at cheap price, and try to make it last all day. Only use the more expensive daytime rate if you run out.

The cylinder needs to be well-insulated to stay hot all day, otherwise you are wasting energy and money.
Worth having a look at FAQuestions
Good read about these heaters that may be of help to you.

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