# One should always cover a pan while heating

Tradition says: "One should always cover a pan while heating".

In other words, if you heat water (or something else), it comes to the boil faster with a lid on the pan than without.

True or false? Let's try the experiment...

52,4494.0/5

## Step by step recipe

##### Stage 1
2 min.
1 litre of water is measured and poured into a pan without the lid and put on the hob with a thermometer in it.

Starting temperature of water (and room): 70°F (19°C).
##### Stage 2
9 min.
The heat is switched on. The water reaches 210°F (100°C) in 9 minutes and 30 seconds.
##### Stage 3
1 hour
The hob is left to cool for about one hour, to allow it to reach room temperature again.

Another 1 litre water is put in the same pan covered with the same thermometer in it, on the same hob.

Starting temperature of water (and room): 70°F (19°C).
##### Stage 4
9 min.
The heat is switched on. The water reaches 210°F (100°C) in 9 minutes and 27 seconds.
##### Stage 5
The result is shown more clearly in the diagram: the temperature of the uncovered pan in red and that of the covered pan in green.

#### Conclusion

False: The time difference is too small to be significant. It really doesn't matter whether the pan is covered or not.
And to drink?: We are going to heat 1 litre of water in an uncovered pan and measure the time it takes to boil , then another litre in a covered pan, heated and measured in the same way.

Comparing these times will tell us if it is really necessary to cover the pan.

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• This is going to be a most interesting addition to your site, jh. Now I wonder if hot water or cold water makes any difference in the boiling time?
Posted by Louise october 24th 2009 at 17:48 (n° 1)

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