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Boiling water. What's best?


Jakes
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Guys

What's the best way to boil water? I'm thinking 500ml at a time.

I remember when microwave ovens came and we all thought this machine was the ultimate for boiling water. It soon proved differently.

We are heavy drinkers, and make quite many cups of tea a day. We boil the water with the electric kettle when the sun is shining. That feels like we've got eskom on the stoep. The other times we use the gas stove, but it's very much like the microwave, not all it was cranked up to be. It's not as fast as everybody thinks, and it costs. And then you've also got the groenes on your neck because you're burning fossil fuel.

I did some research on convection cooking. Last week the young lady showed me the kit of Snappy Chef. She couldn't say how long it will take to boil 2 cups of water. 2 Plates cost R4 000, and it needs it's own pots and pans. I've done some reading on convection cooking. Not everything is positive.

So, the question: what's the best way to boil 500ml of water?

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It takes 1.16Wh to heat one liter of water by 1 degree centigrade. This formula breaks down a bit as you approach boiling point, but it works until near boiling point. So it doesn't really matter what you heat it with, that bit stays the same. What matters is how efficiently you can transfer the energy into the water. In that respect, a good old kettle with an element that sits inside the water is darn near 100% efficient. Anything where a utensil sits on top of a heating element will be less effective. Boiling water on gas being the least efficient, and an induction stove being the most efficient (though still nowhere as efficient as a kettle).

 

The trouble however is that few kettles can boil that little water, they need a bit more to cover the element. For that you can employ a thermos flask. That would be your best bet I'd say.

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Jakes you probably meant "induction" cooking? R4000 for two plates seem a bit steep you can buy a two plate induction stove at R1999 on Yuppiechef and Snappy Chef sells the 2 plate for R2999 on their site, they saw you coming :) You don't need special pots and pans any magnetic pot will work so if a magnetic stick to the bottom of your pot it works. Induction stoves are cool and they work fast but why not just get a gas stove? Once you go gas you can never go back to electricity.

 

The perfect thing for you would be the Miito, this was a Kickstarter that raised R12 million to fund. If you're a DIY person it should be pretty easy to make your own Miito, it's basically an induction stove, a metal rod with some rubber on the top.

 

https://www.kickstarter.com/projects/747044530/miito-the-sustainable-alternative-to-the-electric/description

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12v element you buy from a motor parts store to boil a cup of water in your car, connected to a battery and solar panel.  ;)

Just make sure the solar setup is used for more than boiling water, for your need a ROI on that.  :D

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I view gas as a good part of your overall strategy, but on it's own it's not more economical than electricity. The reasoning behind this:

 

1. 9kg of gas has an energy content of about 115kwh (look up calorific content of LPG, convert to kwh).

2. 9kg of gas costs just under R200 per bottle (excluding bottle deposit).

3. 115kwh of electricity costs maximum R250 (Cape Town top end domestic rate).

 

So gas is 20% cheaper IF you can get the heat into the water efficiently enough. But this is where it breaks down. Where a kettle is near 100% efficient, and even an electric stove nears 70%, a gas flame is around 30%-40%, or this is what my research suggests.

 

This means it's cheaper by almost half to use the electric stove to boil the water, and cheaper still to use the kettle.

 

So if your target is independence (from Eskom), use gas. If your target is to save money, use electricity. For now at least...

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I did some tests on this. We got a R500 induction plate from Game (not the expensive snappy shef brand but it works the same) and it takes the same time to boil 1L of water in the 2Kw ketterl (element is not in the water) as on the induction plate, set to 2Kw. 

The induction plate doesn't need special pots & pans. Any magnetic pans will work so we're still using our old steel pots & pans. Can't use the fancy new aluminium non-stick pans though :(

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Hey Wetkit, i would think twice about drinking hot water from the solar geyser. I have seen the muck / sludge that collects in most hot water tanks.

Also some geysers have sacrificial anodes that slowly decompose over time. 

This is just my gut feeling.

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Hey Wetkit, i would think twice about drinking hot water from the solar geyser. I have seen the muck / sludge that collects in most hot water tanks.

Also some geysers have sacrificial anodes that slowly decompose over time. 

This is just my gut feeling.

 

I didn't want to be the first to say anything, but I fully agree with you. Never fill your kettle from the hot water tap and never use water from the hot water tap for cooking or any other consumption.

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Shame man, all that muck is just sediment that settles out of the standing water.

It will look the same when you take normal cold tap water and let it stand for some time.

When you boil water, you kill all the harmfull bugs in it.

Anyway, off topic...

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I did a test of my own last night. I used a measuring cup to check what the minimum amount of water is that covers the kettle's element. Turns out 500ml is sufficient. So the most efficient way to boil 500ml of water, for me, os to use my electric kettle :-)

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Thanks for the inputs. Much appreciated.

 

Doing some calculations I arrive at the following:

 

We've got 23.76kWh of battery capacity. (12 Narada 12V/165Ah's. They call them REX-C200's)

 

The (2kW) kettle boils water for 2 cups of tea in 2 minutes, which would use around 0.07kWh.

 

If we would only want to drain the battery pack down to 50% of its capacity, it would mean that boiling the kettle once would drain 0.6% of the available 12kWh of the battery pack.

 

I think we can peacefully carry on drinking.

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