Because our electricity is by the unit I only put the immersion on in the evening for showers, Will it be cheeper per day if I leave it on all day? My firends say it takes more energy to heat from cold that top up as required when its on all day?
It will be cheaper to heat up what you need, when you need it, if it is left on 24 hours you have the convenience of having hot water on demand, but energy is wasted simply because of heat losses which you will get to varying degrees depending on levels of insulation.
Think of it like a kettle, if you are out all day, and only have a cup of coffee when you come home at night, which is going to be cheaper?
A) boiling a cupful of water when you come in.
or
B) trying to keep the kettle boiling all day so it is ready for your cuppa when you need it.
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