Temperature controlled kettle?

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Richard_C

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Really a continuation of the recent energy saving topics. I need a new kettle, current one is very old and as we live in a hard water area and I don't descale as often as I should it's past redemption. The steam powered cut off seems to take ages.

I see there are temperature controlled ones, which strikes me as sensible because you only need 100 C for black tea, and if I remember my O level physics right the energy needed to 'make steam' hence make the cut off work on a conventional kettle is significant. If half my hot drinks only need 80 or 90 some energy may be saved. Not enough to give a sensible payback time but a small step in the right direction.

Any thoughts, experiences or recommendations?
 

Dibs-h

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I've seen those "adjustable" ones and replacing a working kettle - I can't see the payback myself (unless you are off-grid & then the considerations are different).

However, if you are replacing a "dead" one and you are going to spend in that ballpark - I'd go for it.

Being a tight wad tho - I recently picked up a brand new kettle in Morrison's for £6. I need to (pre)heat engine coolant to 80 degrees prior to pouring it in the car\engine\etc - I didn't want to have "coolant" flavoured tea if you know what I mean, had I used the house kettle.

So a cheapy one - over it's lifetime would still have a lower Total Cost of Ownership than the adjustable one.

[In case anyone is wondering WT* - it's far easier (for me) to hook into the expansion bottle flow and return pipes and divert the return to the drain or bucket and pour the replacement coolant into the flow. Gives a complete change and no messing about with radiator clamps\drains that don't want to budge etc. nor remove a pineapple of a thermostat. Or try and bleed the cooling system afterwards.]
 

Sandyn

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in the interests of science and general curiosity, I checked how much power it took to boil a cup of water , then repeated with the same amount noting the readings at 80C, 90C and switch off.
The first run, used 58Wh to reach switch off, but as you hinted, the kettle sat boiling for a few seconds before switching off.
Second run, it took 32Wh to reach 80C, 39Wh to reach 90 and 54Wh to switch off.
A saving of approx 41% if you shut off at 80C and approx 27% if you shut off at 90C.
My test was just using commercial test equipment, but it gives a good indication that what you suggest makes a lot of sense if you can use water at 80C and not heat more water than you need each time.
 

aforjeh

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I got one of those fancy variable temp kettles years ago. I never use the lower temps for tea or for coffee (of any sort).

With lower temps, in practice I find tea stews too slow and coffee doesn’t stay hot enough through any brewing process I use.

I just try to boil the minimum I need.
 

Spectric

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We have the test on energy needed to heat the water but what about a test to find the ideal temperature to brew tea or make coffee? Does tea really need boiling water or would 90° C be ok which if you have 10 cups a day for 5 days a week or over 2500 cups a year at a saving of 20Wh per cup would give 50,000Wh. What about those taps that provide instant hot water, anyone done any homework on them? With a kettle you are often taking water at 10° C and raising it to 100° C but with those taps it is maintained to a temperature so which is more energy efficient?
 

Doug71

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I had one of the Franke boiling water taps for a few years, it was really convenient but that's about all it had going for it.

It cost about £750+fitting and you had to change the filter at least every 6 months at £45 a time.

In the time I had it Franke replaced the water tank on it twice and the full tap once, couldn't knock the customer service but I ended up going back to a normal kettle.

Don't know how efficient the tap was but I've had my £50 kettle for about 5 years now and the tap would have cost about £450 in filters alone over that time.
 

Geoff_S

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We’ve had our Kitchenaid kettle for 5 years now. TBH we only bought because it’s red. Can’t think of any time we’ve adjusted the temperature slide but other than that it’s quite nice.
 

woodieallen

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I think there are two issues at work here. First is saving money/energy. But for me and the missus, it's that we drink Japanese tea and that really likes 70 degrees. Decent ground coffee needs 90. Mint tea does very nicely at 90 as does ginger.
 

MARK.B.

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We use a Breville kettle that just heats enough water for one cup at a time , takes around 30 seconds and seems to my untrained palette to work just fine for both tea and coffee it seems to me a bit weird to boil a full size kettle only to then let most of its contents go cold again .There is a full size kettle in the cupboard that comes out if we have a few people around that all need a cuppa at the same time but it is not used very much at all. I don't know if you could get one with adjustable temp control but they may be out there.
 

MorrisWoodman12

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in the interests of science and general curiosity, I checked how much power it took to boil a cup of water , then repeated with the same amount noting the readings at 80C, 90C and switch off.
The first run, used 58Wh to reach switch off, but as you hinted, the kettle sat boiling for a few seconds before switching off.
Second run, it took 32Wh to reach 80C, 39Wh to reach 90 and 54Wh to switch off.
A saving of approx 41% if you shut off at 80C and approx 27% if you shut off at 90C.
My test was just using commercial test equipment, but it gives a good indication that what you suggest makes a lot of sense if you can use water at 80C and not heat more water than you need each time.
Thanks @Sandyn for your analysis. I've had an adjustable temperature kettle for about 5 years now and always heat water to 90C for tea, mint tea and coffee. Always perfectly ok. The question of energy saving has always been put down to another one of Dad's stupid ideas: now I have the independent proof. 😇
Martin
 

Geebee

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we have one of these Bosch twk7203.
Works really well for the wife as she loves her fruity teas which are best at 80°c.
No idea about the energy saving, but every little bit helps surely.
 

flying haggis

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we have one of these Bosch twk7203.
Works really well for the wife as she loves her fruity teas which are best at 80°c.
No idea about the energy saving, but every little bit helps surely.
I have the previous version of that kettle. Brand new from a car boot £5
does your bleep when it switches off? ours used to ..............
dont think i have used the reduced temp facility though, will have to try it
 

Dibs-h

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We have the test on energy needed to heat the water but what about a test to find the ideal temperature to brew tea or make coffee? Does tea really need boiling water or would 90° C be ok which if you have 10 cups a day for 5 days a week or over 2500 cups a year at a saving of 20Wh per cup would give 50,000Wh.

I think even with 5 cups a day (every day) and at today's leccy prices - the purchase cost (of the Daewoo, Gerry linked to) would have paid for itself in 2-3 years.

Got me wondering. Cheers Gerry\Sandy.
 

Richard_C

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would have paid for itself in 2-3 years.
I've been doing the same sums. Assumiung 100 degrees for tea brewing twice a day - no change or just marginal change, but 5x for coffee (we are party retired, part working from home so 5x is realistic) there is a saving, plus its double Sandyn's helpful figures because its 2 cups each time, payback is maybe 1 to 1.5 years. BUT - in my case I need a new kettle soon anyway so lets assume the incremental cost of a temperature controlled one over a steam cut off one is about £15, payback is under one year.

That Daewoo looks almost too good a deal, reviews are mixed but on Amazon it looks like one or two people weigh in with "don't buy this because" comments on everything. Time for a serious look.
 

Dibs-h

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I was going to buy the Daewoo one from Curry's - easier to return if an issue.

Looking at the online reviews - Curry's & Amazon, they were a little mixed.

Ended up getting a Bosch one - Online help, spare parts and accessories | Bosch UK - £49.99.

Bigger buttons on the top and a 1 cup min amount unlike the 0.5L of the Daewoo & 3KW as opposed to the 2.2KW of the Daewoo.

I'll dig out a PowerPlug measuring thingie in the next few days and post up what it says the energy consumption is for heating at the various temps.
 

Ollie78

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My wife has a glass one with digital temperature control, from Amazon about £20. The temp is adjustable in 5 degree steps.
The reason she got it was because it has a tea brewing basket you can lower down into it and she brews green tea in it which you are not supposed to overheat.

Not sure about any energy saving, especially because if you leave it on the base it has a blue Led light on it that illuminates the entire kitchen !! i take it off the base if not using it, otherwise its great.

Ollie
 

Dibs-h

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I was going to buy the Daewoo one from Curry's - easier to return if an issue.

Looking at the online reviews - Curry's & Amazon, they were a little mixed.

Ended up getting a Bosch one - Online help, spare parts and accessories | Bosch UK - £49.99.

Bigger buttons on the top and a 1 cup min amount unlike the 0.5L of the Daewoo & 3KW as opposed to the 2.2KW of the Daewoo.

I'll dig out a PowerPlug measuring thingie in the next few days and post up what it says the energy consumption is for heating at the various temps.
So I got the PowerPlug thingie out - reset to zero and definitely working.

Each time I put a standard size mug (full to the brim) of water into the kettle (approx 300ml) from the cold tap. The water level indicator on the kettle said somewhere around 1.25 cups.

After each test, I emptied the hot water out, filled it at least half full from the cold tap, swirled it around and emptied it. And reset the PowerPlug - easier pressing the button than doing cumulative readings. :LOL:

Here's the numbers:

70 degrees - 0.024KWh [47% saving]
80 degrees - 0.027KWh [40% saving]
90 degrees - 0.031KWh [31% saving]
100 degrees - 0.045KWh

At each reading - I heard the beep from the kettle & the PowerPlug register 0KW usage (i.e. switching off).

The % savings are based on 100 degrees - unless my maths deserted me. LOL

Cheers

Dibs
 

Richard_C

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That's good news, thanks. Quite independently I arrived at the same decision on exact same kettle, old one being pretty useless now and needing manual switch off. New one arrived yesterday evening and I'm now enjoying a cafetiere coffee made at 80.

I think the model might be an old one. Hard to find so ended up with Amazon which is retailer of last resort these days, the newer version which turns up in searches is 50% more and has the controls on the base.

I did some measuring last evening and now have a list blutacked to the back of the mug cupboard door with amount needed for our many and various teapots and coffee making devices.

Happy, and your data makes me happier.
 

againstthegrain

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Depends on how full the kettle is. We have cheap kettle (less than a tenner) and only fill it enough for one mug or two depending on who's around.
 
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