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Mrs Fiddlesticks



Joined: 02 Nov 2004
Posts: 10460

PostPosted: Fri Oct 14, 05 2:37 pm    Post subject: Reply with quote
    

dougal wrote:
Agree with JB's maths. Around 1p to boil an electric kettle.

Previous related threads
https://forum.downsizer.net/about5628.html
https://forum.downsizer.net/about1948.html

What is it with Julie and kettles?


I hadn't realised! I've got a ceramic hob, so I guess the difference is negible?

 
dougal



Joined: 15 Jan 2005
Posts: 7184
Location: South Kent
PostPosted: Fri Oct 14, 05 3:15 pm    Post subject: Reply with quote
    

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

 
Mrs Fiddlesticks



Joined: 02 Nov 2004
Posts: 10460

PostPosted: Fri Oct 14, 05 3:29 pm    Post subject: Reply with quote
    

ah well, thanx Dougal, thats the sort of info I was after. So if my kettle blows up then I need to persuade himself to invest in a woodburning Aga! On cost grounds don't think I'll win that one!

 
wellington womble



Joined: 08 Nov 2004
Posts: 15051
Location: East Midlands
PostPosted: Fri Oct 14, 05 8:36 pm    Post subject: Reply with quote
    

I want one to get the space on the worktop back that I lost fitting a bigger gas hob (typical!) and then maybe I can squeeze a food processor in! Also it can go on the woodburner when it happens to be alight (quite a lot in the winter)

 
Lozzie



Joined: 25 May 2005
Posts: 2595

PostPosted: Sat Oct 15, 05 6:34 pm    Post subject: Reply with quote
    

The "Low Energy Cooking" area of George Marshall's website www.theyellowhouse.org.uk has some interetsing notes about the use of boiling water in the kitchen ... I have just spent about 10 mins looking for the bit on his website that explains why a hob kettle is better than an electric one but I have come up blank - sorry!

 
Mrs Fiddlesticks



Joined: 02 Nov 2004
Posts: 10460

PostPosted: Sat Oct 15, 05 7:20 pm    Post subject: Reply with quote
    

Lozzie wrote:
The "Low Energy Cooking" area of George Marshall's website www.theyellowhouse.org.uk has some interetsing notes about the use of boiling water in the kitchen ... I have just spent about 10 mins looking for the bit on his website that explains why a hob kettle is better than an electric one but I have come up blank - sorry!


wonderful site, thanks for that! But no I couldn't find about hob kettles either!

 
Lozzie



Joined: 25 May 2005
Posts: 2595

PostPosted: Sun Oct 16, 05 11:00 am    Post subject: Reply with quote
    

Thinking about it, I am pretty sure it was part of the CD-Rom of his that I looked at recently. For some reason not on his website.l

 
marigold



Joined: 02 Sep 2005
Posts: 12458
Location: West Sussex
PostPosted: Sun Oct 16, 05 1:44 pm    Post subject: Reply with quote
    

When I boil the kettle (electric - I'm not a Luddite about everything - I like that it switches itself off ), I usually fill a flask at the same time and use that for the next few drinks.

Flask-hot water is fine for most things and I figure you have to heat the kettle as well as the water each time you boil it, so the more water you boil the more efficient it is (as long as you use all the water) ..... But I could be wrong about that

 
ele



Joined: 05 Sep 2005
Posts: 814
Location: Derby
PostPosted: Sun Oct 16, 05 2:59 pm    Post subject: Reply with quote
    

Lozzie wrote:
The "Low Energy Cooking" area of George Marshall's website www.theyellowhouse.org.uk has some interetsing notes about the use of boiling water in the kitchen ... I have just spent about 10 mins looking for the bit on his website that explains why a hob kettle is better than an electric one but I have come up blank - sorry!


Interesting site, I guess cos it says as lot of extra heat is used to take water into the final stage of boiling then switching off the kettle before it quite gets there would save some leccy and be fine for most drinks.

I liked the little rant about how you can't buy dishwashers with hot and cold water feeds, when I bought ours I spent ages trying to find one that would

 
jema
Downsizer Moderator


Joined: 28 Oct 2004
Posts: 28238
Location: escaped from Swindon
PostPosted: Sun Oct 16, 05 3:17 pm    Post subject: Reply with quote
    

ele wrote:


I liked the little rant about how you can't buy dishwashers with hot and cold water feeds, when I bought ours I spent ages trying to find one that would


Very true that would save a lot of energy.

 
dougal



Joined: 15 Jan 2005
Posts: 7184
Location: South Kent
PostPosted: Sun Oct 16, 05 3:42 pm    Post subject: Reply with quote
    

ele wrote:
I liked the little rant about how you can't buy dishwashers with hot and cold water feeds, when I bought ours I spent ages trying to find one that would

Its off topic for this thread, but these days good dishwashers
1/ only use a little water, rather less than 20 litres for the cycle
2/ and don't get it very hot - a 50C wash is usually fine (needing only half the heat energy of an 80C wash).
so, actually, they don't use much energy for heating water.
Also, as the yellowhouse site mentions, there is often a comparable amount of water (cold) in the hot pipe between tank and appliance.
The yellowhouse people insulated those pipes - but STILL run off water at the sink until it 'comes hot'.
This would be very energy wasteful if the water was NOT heated by solar, as the yellowhouse people do.
Adding the hot fill connection, and its extra powered valve and its control system, is going to add a few quid to the cost of the machine, and use more materials, to no good effect for ordinary customers.

So - summary: dishwashers nowadays don't have hot water inlets because there's no benefit, and some disadvantage, for almost all buyers.

 
suse



Joined: 15 Sep 2005
Posts: 1

PostPosted: Wed Oct 19, 05 3:18 pm    Post subject: yellow house Reply with quote
    

what an excellent site!

 
thos



Joined: 08 Mar 2005
Posts: 1139
Location: Jauche, Duchy of Brabant (Bourgogne-ci) and Charolles, Duchy of Burgundy (Bourgogne-�a)
PostPosted: Wed Oct 19, 05 3:31 pm    Post subject: Reply with quote
    

marigold wrote:

Flask-hot water is fine for most things ...


Not tea, which is about the only thing I use the kettle for.

 
thos



Joined: 08 Mar 2005
Posts: 1139
Location: Jauche, Duchy of Brabant (Bourgogne-ci) and Charolles, Duchy of Burgundy (Bourgogne-�a)
PostPosted: Wed Oct 19, 05 3:36 pm    Post subject: Reply with quote
    

Fiddlesticks Julie wrote:
So if my kettle blows up then I need to persuade himself to invest in a woodburning Aga!


Sorry, Agas are only oil, gas or electric. You can have a Rayburn.

I'm looking into ranges at the moment - I'm amazed how many companies make them. Unfortunately, most only seem to sell to the UK or Ireland.

 
marigold



Joined: 02 Sep 2005
Posts: 12458
Location: West Sussex
PostPosted: Wed Oct 19, 05 3:44 pm    Post subject: Reply with quote
    

thos wrote:
marigold wrote:

Flask-hot water is fine for most things ...


Not tea, which is about the only thing I use the kettle for.



You are quite right, though tea made with flask-hot water is a little better than tea kept hot in a flask. I did say "most things"

 
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