4 ms·

> If you're using gas or resistive heating anyway this achieves very little. ? This isn't correct. If my kettle boils in 2 minutes when it's half full, and 3.5

> If you're using gas or resistive heating anyway this achieves very little. ? This isn't correct. If my kettle boils in 2 minutes when it's half full, and 3.5 minutes when it's full, then by only half filling it you are saving 1.5 minutes worth of (gas/electricity). Low absolute impact, but high relative impact, and adds up if you boil the kettle 3+ times a day

Schroedingersat 4y ago
If you're using resistive heating then you're just heating the house with a different resistor. If you're using gas, it depends on how your electricity is generated and how much heat escapes through your boiler's exhaust etc (some very old boilers are less efficient than a gas turbine + transmission losses).
- benj111 4y ago
  That's assuming you're only drinking tea when you want the heating on though. Plus you seemed to have gone on the boilers rather than kettles.
  - Schroedingersat 4y ago
    > That's assuming you're only drinking tea when you want the heating on though. Yeah, I meant using in the present tense, sorry (ie. The system is keeping the room above ambient even if it's presently idle due to the thermostat). If you're cooling the space, it's much worse. > Plus you seemed to have gone on the boilers rather than kettles. The boiler would be the gas central heating system. The kettle is making the tea.
- kwhitefoot 4y ago
  My house doesn't need heating from April to October. And if you have a modern condensing gas boiler it is considerably more efficient (over 90%) to burn gas in it than use electricity generated in even the most modern and efficient gas fired power station. So unless you have some quite specific circumstances it is almost always better to boil only as much water as you need at the time.
  - Schroedingersat 4y ago
    > And if you have a modern condensing gas boiler it is considerably more efficient (over 90%) to burn gas in it than use electricity generated in even the most modern and efficient gas fired power station. If your grid is low carbon it might still break even (it will cost you money though). This is all relatively pointless minuitae though. The main advantage is it's faster so one should do it anyway as there's no downside. Unrelated, I've always been fascinated by the idea of a solid state heat engine driven kettle. Peltiers are so inefficient that it's not really pointful even as a toy though. I keep waiting for magnetothermal to be a thing.
lupire 4y ago
$7GBP/yr for 5 kettles per day, every day. (Electicity is cheap in UK!) https://www.wolframalpha.com/input?i2d=true&i=+3Divide%5BkW%2Cpot%5D+*+Divide%5Bhr%2C40%5D+*+5*Divide%5Bpot%2Cday%5D+*+365*Divide%5Bday%2Cyear%5D+*+Divide%5B50+GBP%2CMW*hr%5D https://www.wolframalpha.com/input?i2d=true&i=+3Divide%5BkW%...
- SECProto 4y ago
  That's using 50£/MWh, which sounds like an inaccurate wholesale price to me. With a quick search, I'm seeing the average rate in 2022 around £0.225/kWh, or 4.5x your rate. 5 kettles a day sounds right for my household, and would be £31.5/yr
  - nsteel 4y ago
    From October 2022 it's fixed at £0.34/kWh for consumers. £50/MWh is miles off reality.

Schroedingersat 4y ago

If you're using resistive heating then you're just heating the house with a different resistor. If you're using gas, it depends on how your electricity is generated and how much heat escapes through your boiler's exhaust etc (some very old boilers are less efficient than a gas turbine + transmission losses).

benj111 4y ago
That's assuming you're only drinking tea when you want the heating on though. Plus you seemed to have gone on the boilers rather than kettles.
- Schroedingersat 4y ago
  > That's assuming you're only drinking tea when you want the heating on though. Yeah, I meant using in the present tense, sorry (ie. The system is keeping the room above ambient even if it's presently idle due to the thermostat). If you're cooling the space, it's much worse. > Plus you seemed to have gone on the boilers rather than kettles. The boiler would be the gas central heating system. The kettle is making the tea.
kwhitefoot 4y ago
My house doesn't need heating from April to October. And if you have a modern condensing gas boiler it is considerably more efficient (over 90%) to burn gas in it than use electricity generated in even the most modern and efficient gas fired power station. So unless you have some quite specific circumstances it is almost always better to boil only as much water as you need at the time.
- Schroedingersat 4y ago
  > And if you have a modern condensing gas boiler it is considerably more efficient (over 90%) to burn gas in it than use electricity generated in even the most modern and efficient gas fired power station. If your grid is low carbon it might still break even (it will cost you money though). This is all relatively pointless minuitae though. The main advantage is it's faster so one should do it anyway as there's no downside. Unrelated, I've always been fascinated by the idea of a solid state heat engine driven kettle. Peltiers are so inefficient that it's not really pointful even as a toy though. I keep waiting for magnetothermal to be a thing.

lupire 4y ago

$7GBP/yr for 5 kettles per day, every day. (Electicity is cheap in UK!) https://www.wolframalpha.com/input?i2d=true&i=+3Divide%5BkW%2Cpot%5D+*+Divide%5Bhr%2C40%5D+*+5*Divide%5Bpot%2Cday%5D+*+365*Divide%5Bday%2Cyear%5D+*+Divide%5B50+GBP%2CMW*hr%5D https://www.wolframalpha.com/input?i2d=true&i=+3Divide%5BkW%...

SECProto 4y ago
That's using 50£/MWh, which sounds like an inaccurate wholesale price to me. With a quick search, I'm seeing the average rate in 2022 around £0.225/kWh, or 4.5x your rate. 5 kettles a day sounds right for my household, and would be £31.5/yr
- nsteel 4y ago
  From October 2022 it's fixed at £0.34/kWh for consumers. £50/MWh is miles off reality.