Why cover candles for heat? Watch

NJA
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This "internet sensation" (over 2 million vies) says to cover the candles
http://www.youtube.com/watch?v=brHqBcZqNzE

... how will this create more heat?
Also it reduces light so you have to use more energy by putting a light on ... can someone explain?
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uberteknik
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(Original post by NJA)
This "internet sensation" (over 2 million vies) says to cover the candles
http://www.youtube.com/watch?v=brHqBcZqNzE

... how will this create more heat?
Also it reduces light so you have to use more energy by putting a light on ... can someone explain?
Simple explanantion:

The way the pots are shown arranged in the video, will not produce more heat. But they will act to improve the convection air circulation in the small room in much the same way as a heating radiator does.

In effect the arrangement of pots and candles is the same principle as an old parafin heater. (Both use hydrocarbon based fuel.)

Unfortunately, if people think more energy is produced with this arrangement, they are mistaken. This is forbidden by the law of energy conservation

It simply means the heat output from the candle is distributed with that air in the room in a more efficient way. i.e. the convection of heated air is (to an extent) improved.
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Stonebridge
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Despite the claims to cheap heating in the YouTube Vid, it is more expensive to heat the room with candles than with an electric fire.

I've done a rough calculation and it turns out to be about 4 times more expensive to burn sufficient candles than an electric fire. It depends, of course, on how cheap you can get the candles and how much you are paying for your electricity.

If you want to see the calculations they are here:

The power output of a small tea light is around 25W

Detailed Calc here
Spoiler:
Show

The small candles are about 1cm deep and 3.5cm in diameter.
This gives a volume of about 9.6 cm3
The density of paraffin wax is about 0.9 g/cm3 giving the candle a mass of about 8.7g
Paraffin wax has an energy content of 42kJ/g
This gives an energy content of about 340kJ per candle.
If it burns for 4 hours this is equivalent to a power output of
340 kJ / (4 x 60 x 600)

This comes to about 24W



To create a 1000W (1kW) heater you would need 40 candles.

The best price I could find for IKEA white tealights was £26 for a bag of 500

The cost of 40 candles is at best very nearly £2

So to heat your room at a rate of 1kW you need 40 candles at a cost of £2
This will last for 4 hours, which is the typical life of such a candle.

To heat your room with an electric 1kW heater costs about 14p per hour. This is the best estimate I could get for unit (kW hour) costs in the UK at the moment. It does vary and can be cheaper on some tariffs.

So 4 hours of heat with the 1kW fire costs about 52p

So it really isn't cheaper to use candles, whether or not you use flowerpots. As uber says above, you can't get more energy out of the candle, but you might be able to distribute it more efficiently in the room.

I suggest the guy stops buying the candles and just turns his heater on.
If it really was cheaper to burn IKEA candles for heat, I'd be down to my nearest store with a truck and buy their whole stock before winter. And so would everyone else, I reckon.
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Scoobster
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Good post ^^

I also wondered this!
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NJA
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(Original post by uberteknik)
Simple explanantion:

The way the pots are shown arranged in the video, will not produce more heat. But they will act to improve the convection air circulation in the small room in much the same way as a heating radiator does.

In effect the arrangement of pots and candles is the same principle as an old parafin heater. (Both use hydrocarbon based fuel.)

Unfortunately, if people think more energy is produced with this arrangement, they are mistaken. This is forbidden by the law of energy conservation

It simply means the heat output from the candle is distributed with that air in the room in a more efficient way. i.e. the convection of heated air is (to an extent) improved.
I see! Less vertical convection - heating the ceiling, more radiation - heating the air - so they do have that bit of science right.

It will take a biologist to explain if the burning up of oxygen in the room has a negative effect of brain efficiency & bodily health though.
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