We'd like to remind Forumites to please avoid political debate on the Forum... Read More »
📨 Have you signed up to the Forum's new Email Digest yet? Get a selection of trending threads sent straight to your inbox daily, weekly or monthly!
(Rough) Cost Comparison of boiling the kettle, electric vs Gas.
Options
bikerchris
Posts: 157 Forumite
This seems a little sad, but while I was recovering from an evil RTA, I had plenty of time on my hands. I had an old kettle (the type that has an exposed coil) and wondered if it was cheaper to boil water for a coffee/tea on the gas hob. I then bought a modern kettle (internal hot plate type) later on because the original went pop. I did check MSE and there was only claims and no evidence (although the guesses were pretty believable).
So here's the results. Appreciate that I'm not that technical and just tried my best to get it roughly useful:
ELECTRIC:
Kettle type 1 (exposed coil, this meant more water was necessary to cover the element): Energy used: 0.057Kwh (revised, thanks rogerblack)
Kettle type 2 (hot plate type, so precise amount of water for one 'proper' cup): Enegery used: 0.036kwh (revised, thanks rogerblack)
Kettle type 1: 0.57 x 12.67 = 0.72pence (revised, thanks rogerblack)
Kettle type 2: 0.36 x 12.67 = 0.46pence (revised, thanks rogerblack)
GAS:
This is more complicated because of the way gas usage is calculated. I didn't have a stove kettle, so I used a small saucepan with a lid over instead.
Gas used: 0.03 cubic feet
To convert to charged units:
0.03 x 100 x 1.02265 ("Correction factor") = 3.06795
3.06795 x 0.283 ("Conversion factor") = 0.086822985
0.086822985 x 39 ("Calorific Value") / 3.6 ("Conversion factor") = 0.9405823375
So gas used is: 0.94
Gas units are: 8.61pence each
ACTUAL COST: 8.0984 pence.
Perhaps not that interesting, but it'll save someone some boring time. Do say if you think I've got something wrong, no ones perfect! To calculate the power used, I used the plug in meter type. To measure gas I read directly from the meter (gas is not used to heat the property, only the cooker). Prices include VAT but not a portion of any standing charge. I'm officially the sadest person in the world :rotfl:
So here's the results. Appreciate that I'm not that technical and just tried my best to get it roughly useful:
ELECTRIC:
Kettle type 1 (exposed coil, this meant more water was necessary to cover the element): Energy used: 0.057Kwh (revised, thanks rogerblack)
Kettle type 2 (hot plate type, so precise amount of water for one 'proper' cup): Enegery used: 0.036kwh (revised, thanks rogerblack)
Kettle type 1: 0.57 x 12.67 = 0.72pence (revised, thanks rogerblack)
Kettle type 2: 0.36 x 12.67 = 0.46pence (revised, thanks rogerblack)
GAS:
This is more complicated because of the way gas usage is calculated. I didn't have a stove kettle, so I used a small saucepan with a lid over instead.
Gas used: 0.03 cubic feet
To convert to charged units:
0.03 x 100 x 1.02265 ("Correction factor") = 3.06795
3.06795 x 0.283 ("Conversion factor") = 0.086822985
0.086822985 x 39 ("Calorific Value") / 3.6 ("Conversion factor") = 0.9405823375
So gas used is: 0.94
Gas units are: 8.61pence each
ACTUAL COST: 8.0984 pence.
Perhaps not that interesting, but it'll save someone some boring time. Do say if you think I've got something wrong, no ones perfect! To calculate the power used, I used the plug in meter type. To measure gas I read directly from the meter (gas is not used to heat the property, only the cooker). Prices include VAT but not a portion of any standing charge. I'm officially the sadest person in the world :rotfl:
If someone is worth thanking - click on the 'Thanks' button on their response. It's just a nice thing to do :-)
Started debt at 17, stopped by 25 :-D ...I'm in debt again because of property :-/
Started debt at 17, stopped by 25 :-D ...I'm in debt again because of property :-/
0
Comments
-
Naah - I'm actually making myself an energy efficient kettle.
That beats just measuring.
One thing to note.
'Concealed element' kettles generally have a plate, onto which is bolted a conventional 'wiggly' element.
This means a considerable extra mass of stuff to heat.
It's quite easy to see how much or little you can safely put in a kettle.
When underfilled, part of the element will get very hot, and you will see rapid boiling at the edge of the water.
All kettles of the wiggly element type that I've come across actually do not heat the 'ends' of the element, where they rise up to meet the body of the kettle.
Also, I suspect you may have mis-measured.
0.36 units, if using a 2000W kettle is 0.18 hours, or about 10 minutes.
This seems rather excessive, and is enough energy to boil from 20C over 3 litres of water.
Are you sure it wasn't 0.036?0 -
bikerchris wrote: »This seems a little sad, but while I was recovering from an evil RTA, I had plenty of time on my hands. I had an old kettle (the type that has an exposed coil) and wondered if it was cheaper to boil water for a coffee/tea on the gas hob. I then bought a modern kettle (internal hot plate type) later on because the original went pop. I did check MSE and there was only claims and no evidence (although the guesses were pretty believable).
So here's the results. Appreciate that I'm not that technical and just tried my best to get it roughly useful:
ELECTRIC:
Kettle type 1 (exposed coil, this meant more water was necessary to cover the element): Energy used: 0.57Kwh
Kettle type 2 (hot plate type, so precise amount of water for one 'proper' cup): Enegery used: 0.36kwh
Kettle type 1: 0.57 x 12.67 = 7.22pence
Kettle type 2: 0.36 x 12.67 = 4.56pence
GAS:
This is more complicated because of the way gas usage is calculated. I didn't have a stove kettle, so I used a small saucepan with a lid over instead.
Gas used: 0.03 cubic feet
To convert to charged units:
0.03 x 100 x 1.02265 ("Correction factor") = 3.06795
3.06795 x 0.283 ("Conversion factor") = 0.086822985
0.086822985 x 39 ("Calorific Value") / 3.6 ("Conversion factor") = 0.9405823375
So gas used is: 0.94
Gas units are: 8.61pence each
ACTUAL COST: 8.0984 pence.
Perhaps not that interesting, but it'll save someone some boring time. Do say if you think I've got something wrong, no ones perfect! To calculate the power used, I used the plug in meter type. To measure gas I read directly from the meter (gas is not used to heat the property, only the cooker). Prices include VAT but not a portion of any standing charge. I'm officially the sadest person in the world :rotfl:
I am even sadder to correct you!
You are not comparing like with like.
1. You are using the Tier 2 kWh price for electricity(12.67p/kWh) but the Tier 1 price for gas(8.61p/kWh). The tier 2 price for gas is around 3.5p/kWh)
2. A gas unit on an Imperial gas meter is 100 cubic feet, so I suggest you are using 3 cubic feet not 0.03 cubic feet. A gas unit is approx 33kWh so 3 cubic feet would be approx 1kWh(you made it 0.94kWh)
3. I believe your measurements of electricity used are completely wrong(probably by a factor of 10). For 1 litre of water (i.e. 4 cups) from tap temp to boiling, my kettle uses 0.10kWh so 4 cups cost 1.27pence(using your price) so around 0.3p a cup.
4. Similarly whilst I don't have a gas hob, I don't believe that a gas hob will use 0.94kWh for a single cup. about 30 times more than electric.0 -
bikerchris wrote: »Gas units are: 8.61pence each
I'm paying 3.2 pence per kWh for gas, or about £1 per imperial unit.
The gas example is flawed, as you have to heat the whole kettle up first.
This is actually quite a good Richard Hammond segment, but I would say use six different approaches for one cup of tea, 2, 3 and 4 cups of tea. We need the time to boil as well.
If we are using 3kW kettles, then the gas burner should be 3kW as well.
Gas
Kettle with whistle.
Electric
1. Electric exposed coil
2. Electric concealed coil
3. Microwave, 800W Magnetron.
4. In-Sink-Erator HC-1100 hot water dispenser, which claims 98 degrees, with microwave to bring it to boil.
5. Quooker, which claims 100 degrees, so no need to microwave.
I assume Quooker keeps a small tank at 95 degrees, and heat the flowing water to boil as it flows out.
Without doing the experiment, I expect the microwave to be the winner for being the cheapest for one cup of tea, but slowest, because it is only 800W.
The Quooker should be the fast draw in the west of course.0 -
3. Microwave, 800W Magnetron.
Without doing the experiment, I expect the microwave to be the winner for being the cheapest for one cup of tea, but slowest, because it is only 800W.
QUOTE]
Don't forget that the 800watt rating of a microwave is the magnatron output; the appliance consumes a lot more power than 800watts.0 -
In all of these comparisons of costings, it is easy to forget the Laws of Thermodynamics which state that energy cannot be created or destroyed.
Using, say 1 kWh of electricity for any purpose produces heat. So that 1kWh for heating kettles(gas or electric) produces heat for the fabric of the house which, for at least the winter months, is one less kWh needed from a conventional heater.
My PC setup uses around 200watts, but that is 200watts less I need to heat my study.0 -
That is a bit simplistic. To be more accurate you cannot say that a 1KWh heater produes 1KW per hour of heat energy. The same can be said for your 200W PC. Both also dissipate the energy mechanically and audibly.In all of these comparisons of costings, it is easy to forget the Laws of Thermodynamics which state that energy cannot be created or destroyed.
Using, say 1 kWh of electricity for any purpose produces heat. So that 1kWh for heating kettles(gas or electric) produces heat for the fabric of the house which, for at least the winter months, is one less kWh needed from a conventional heater.
My PC setup uses around 200watts, but that is 200watts less I need to heat my study.0 -
bikerchris wrote: »
ELECTRIC:
Kettle type 1 (exposed coil, this meant more water was necessary to cover the element): Energy used: 0.57Kwh
Kettle type 2 (hot plate type, so precise amount of water for one 'proper' cup): Enegery used: 0.36kwh
Kettle type 1: 0.57 x 12.67 = 7.22pence
Kettle type 2: 0.36 x 12.67 = 4.56pence
I'm officially the saddest person in the world :rotfl:
Sorry bikerchris but I am even sadder than you so you can't be world champ.:rotfl::rotfl:
I don't have any figures for gas, but I know a lot of heat escapes into the air - useful in the winter but wasted in the summer.
Electricity: I have carried out numerous experiments in my laboratory and here are the results for boiling 250ml (1 mug):
Kettle: Morphy Richards Perfection 436732 with temperature display and concealed element:
Manually switching off at the earliest possible point while still achieving 100deg 0.027kWh cost 0.34p
Leaving the kettle to switch off automatically 0.043kWh cost 0.54p
Microwave: Sanyo EMS1552 (900W output, 1420W input)
Boiling in the mug: 0.068kWh cost 0.86p
HTH Fred Bear
So that's why he takes so long to make the tea!
Oh and it isn't his laboratory, it's my kitchen.
- Mrs Bear0 -
That is a bit simplistic. To be more accurate you cannot say that a 1KWh heater produes 1KW per hour of heat energy. The same can be said for your 200W PC. Both also dissipate the energy mechanically and audibly.
Firstly no such thing as a 1kWh heater.
However a 1kW heater running for an hour will use 1kWh of electricity and all(100%) of that electricity will be converted into heat. Even if it has a fan.What happens to the energy used to rotate the fan? Some will be used to overcome the friction in the bearings (generating heat here), and some will be used to
move air, and when the air slows down due to
its viscosity, the energy again gets turned into heat which warms the air. Add it all up, and you'll find the amount of heat created by a heater exactly matches the energy input into it. (That applies not only to heaters, but all electrical
devices - they all produce heat equal to the energy consumed, but hopefully do something useful before the heat release).
My computer consuming 200watts, even with the loudspeakers on, the hard drive operating etc will still be(eventually) converting that energy into heat.
You cannot destroy energy.0 -
[QUOTE=Cardew;56482777Don't_forget_that_the_800watt_rating_of_a_microwave_is_the_magnatron_output;_the_appliance_consumes_a_lot_more_power_than_800watts.[/QUOTE]
Yes, always correct for the nominal factor.;)
Peter Ustinov, can't remember the movie.0 -
This discussion has been closed.
Confirm your email address to Create Threads and Reply
Categories
- All Categories
- 351.2K Banking & Borrowing
- 253.2K Reduce Debt & Boost Income
- 453.7K Spending & Discounts
- 244.2K Work, Benefits & Business
- 599.2K Mortgages, Homes & Bills
- 177K Life & Family
- 257.6K Travel & Transport
- 1.5M Hobbies & Leisure
- 16.1K Discuss & Feedback
- 37.6K Read-Only Boards