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Mrs Fiddlesticks
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twoscoops
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Nanny
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Jb
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Mrs Fiddlesticks
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sean Downsizer Moderator
Joined: 28 Oct 2004 Posts: 42219 Location: North Devon
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dougal
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twoscoops
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Mrs Fiddlesticks
Joined: 02 Nov 2004 Posts: 10460
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dougal
Joined: 15 Jan 2005 Posts: 7184 Location: South Kent
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Posted: Fri Oct 14, 05 3:15 pm Post subject: |
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Fiddlesticks Julie wrote: |
hmm still no votes for a hob model then. 3kw to boil a mug ful say in what minute or two compared to same amount on hob which has a ring wattage unknown - well thats helpful isn't it? |
Its important to distinguish between kilowatts (kw, a thousand watts), which measure *rate* of energy usage/supply, and kilowatt hours (kwh or "units"), which measure the *quantity* of energy used.
Use electricity at a *rate* of 1 kw for an hour and the *quantity* of electricity used is 1 kwh.
Ignoring detail pedantries (like heat loss), if you boil a set quantity of water, that will always take the same *quantity* of electricity (for the same quantity of water and the same start temp) regardless of the wattage - but the time it takes will depend on the *rate* that that the kettle uses electricity (ie the rate it supplies heat).
OK, time for detail pedantries. For electricity, its just a question of where heat is wasted. And less is wasted from a plastic kettle with a submerged element than in heating the ceramic hob, and the metal kettle or pan (and heat losses therefrom) as well as the heat that goes around the side of the kettle. And with almost every electric kettle having an auto shut-off (which a hob hasn't) there's no wasted heat/electricity after its up to temperature.
So sadly an electric hob is *not* a good way to boil water.
EDIT: Though an electric *induction* hob will waste much less heat than any conventional electric hob...
Because gas is *much* cheaper than electricity, an inefficient gas hob will usually do the job more cheaply than an efficient electric kettle.
So Sean (probably) didn't make it up...
Last edited by dougal on Fri Oct 14, 05 10:58 pm; edited 1 time in total |
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Mrs Fiddlesticks
Joined: 02 Nov 2004 Posts: 10460
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wellington womble
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Lozzie
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Mrs Fiddlesticks
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Lozzie
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