Efficient way to boil water

Mr_S_in_Easton

I'm looking for a new kettle but all I can find are endless clones which use the same old-fashioned electric elements, which devour up to 3KW, which is a lot of leccy! We all know about the revolution that LED technology has brought to lighting - does anyone know if there are any super-efficient kettles on the market, which use some sort of new technology? I'm currently (HoHo...) boiling water for tea by measuring exactly how much I need & popping it in the microwave...

Browntoa

One cup kettle

http://www.argos.co.uk/product/4230429

Press button , only heats that cup of water

grumpycrab

I suspect boiling water on gas hob is cheaper than using electric.

AnotherJoe

Mr_S_in_Easton wrote: »

I'm looking for a new kettle but all I can find are endless clones which use the same old-fashioned electric elements, which devour up to 3KW, which is a lot of leccy! We all know about the revolution that LED technology has brought to lighting - does anyone know if there are any super-efficient kettles on the market, which use some sort of new technology? I'm currently (HoHo...) boiling water for tea by measuring exactly how much I need & popping it in the microwave...

Why dont you just put less water in the kettle?

A microwave is also much less efficient than an electric element since pretty much all the energy that goes into an element is heat that is transferred to the water (some will be transferred to the kettle) whereas in a microwave, you lose about 1/3 straight off creating the microwaves and not all those will go into the water.


The fact a kettle is 3kW is irrelevant, it doesn't mean its wasting power, if it was 1kW it would take 3x as long to heat the water so you'd use the same amount of electricity.


The key is heating less water, only what you need hence these one cup type devices as posted by previous poster. If you get one look for a model you can alter how much it produces each press, because if you get one that produces too little, odds are a second press will end up with too much.

onomatopoeia99

The elements in electric kettles are very efficient already, their purpose is to turn electric energy into heat and they do it very well so pretty much all of that 3kW of power is being turned into heat.

Comparisons with lighting aren't relevant - incandescent lightbulbs turned electrical energy into light but also a lost of waste heat, as they were very ineffiicient, LEDs make a lot more light and a lot less heat from the same amount of energy.

Microwave ovens are much less efficient (perhaps 60-70%) than kettle heating elements (over 90%).

neilmcl

grumpycrab wrote: »

I suspect boiling water on gas hob is cheaper than using electric.

A totally inefficient way to heat up anything.

grumpycrab

neilmcl wrote: »

A totally inefficient way to heat up anything.

Sorry - thought gas was (much) cheaper than electricity.

r2015

Sorry - thought gas was (much) cheaper than electricity

Per kWh it is but just think of all the wasted heat going up the side of the kettle from the gas hob.

psychic_teabag

The heat capacity of water is 4184 J/kg, or J/l. So it requres 376kJ of energy to raise the temperature of 1l of water from 10 degrees to 100 degrees. A 3kW kettle is generating 3kJ per second. So if things were 100% efficient, it needs about 125 seconds to generate that much energy. (Hope I've got my sums right.)

So if your 3kW kettle takes about 2 minutes to boil a litre of water, it's about as efficient as you can get. As has been said, simplest way to reduce cost is to boil only as much as you need.

I do wonder if a lower power kettle running for longer might be more efficient - thermodynamic reversibility comes into it. But the longer it takes to boil, the more heat it loses. So probably swings and roundabouts - depends how well insulated it is.

My bugbear is a kettle that gets the water boiling and then continues to boil for many seconds - that wastes a lot of heat (in the form of excess steam being pushed out to the air). Previous kettle was always bad, but recently just sat and boiled till it ran dry. So we promptly replaced it. The new one started out pretty good, but has been steadily getting worse. Perhaps the problem is scale building up and interfering with the cut-off mechanism. But at least this one has a mechanism to cut the power if it boils dry. (Quite clever, really - when it's empty, it's not heavy enough to engage fully with the power outlet. Havent actually tested it, though.)

Le_Kirk

If someone with the user name psychic teabag posts info about boiling water, I would take that as gospel.

psychic_teabag

(Have you seen what boiling water does to us teabags ? If only we had some way of knowing what was coming...)

One thing that might save some energy... during the summer, if you put the minimum of water into the kettle straight after use, that will absorb some of the residual heat from the kettle, and also warm up to room temperature. So next time you need to boil it, it's starting from a slightly higher temperature. (Does leaving water standing affect the taste ? OH seems to think so.)

But in winter, it's your central heating that will be providing the heat to get to room temperature, and that may be less efficient. (But might still be cheaper, if it's gas. Not sure...)