using those figures and the cost of electricity from my latest bill (27.10
p/Kwh ) using the kettle costs 1.49p which isn't a lot more than using the hob
(1.125 p).
It's not really a game changer, so thanks everyone for contributing.
I will now try and investigate why my gas boiler keeps on firing up when it
kicks in, even though I have used solar to heat my tank. It has been suggested
that the solar heats the top part of the tank via the immersion heater, and the
gas heats the bottom part of the tank via the heating coil.
Peter.
On 29/08/2022 13:24, Ian Morris via dorset wrote:
So I just boiled my kettle (500ml, fresh from tap). Mains here = 242 volts,
Kettle takes 12.3 A (pretty much constant) Power taken = 0.055kWh (so pretty
close to my calculation!) I allowed the kettle to trip using the steam
generated by the then boiling water (so addressing both the loss and latent
heat aspects of the question.)
On 29/08/2022 12:28, Peter Merchant via dorset wrote:
I had considered that, but it's so long ago in my ancient past that I studied
thermodynamics, I didn't look into calculating it. My concern about it is the
cost of raising the temperature to 100 deg, then the latent heat of
vaporisation to actually boil it.
Peter M. [ Applies to any form of boiling water of course. ]
n 29/08/2022 11:31, Ian Morris via dorset wrote:
500ml of water = 500g water. let's assume you want to go from 20-100 C =>
increase of 80C
Specific heat capacity of water = 4.184 J/g-K
=> 167,360 J = 0.0465 kWh Electricity @27p/kWh = 1.2552p
So rather similar???? (OK, I don't know efficiency of electric kettle ... but
heating elements are 100% efficient... sure there will be some losses to both
the kettle and the wider environment, but i doubt somehow that they are
huge....) Of course this is about cost for the consumer ... I'm totally
ignoring the ineffeciency of turning gas into electricity and transmitting it
around the country in the first place.
On 29/08/2022 09:33, Peter Merchant wrote:
I was curious, so I took the water from the kettle and put it in a pot on the
stove. It was very close to 500ml.
Watching the gas meter while it boiled it used 0.014 m(cubed) of gas, which
converted to 0.15788Kwh and at my current rate of 7.123p/Kwh cost me 1.1.25p to
boil up.
Unfortunately I can't see my electricity meter easily to see what it costs me
to boil that amount in the kettle or by Microwave. Does anybody have that
facility? And also there is always other electricity being used.
Cheers,
Peter
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