What happens if you boil water in this situation?

[bengasman]

...A saucepan lid acts in the same way as a pressure cooker weight, by increasing the ambient air pressure inside the saucepan when the water reaches its boiling point. This raises the vapour pressure of the hot water, and so raises its boiling point...

Really heavy lid, 1 kg, that is one solid lid.
Suarface kind of small, 300 sqare cm , that is not a big pan.
Increase in pressure: 0.003 bar; you need one hell of thermometer to be able to measure the temperature increase due to that.

 

[Corgigrouch]

Goldie, I think that you will find that there are two reasons why sensible folk don't boil their kettle with the lid off...

1. With the lid off, steam is not directed to the bimetalic strip which switches off the kettle

2. On most kettles the handle is directly above the lid, so the steam coming from the water below would scald ones fingers and hand.

The theory of the saucepan lid although in theory has some validity but many saucepan lids do not weigh 1Kg and are in fact lighter.. your theory also assumes that the lid is a perfect fit... Any benefits in the real world are very small and could be regarded as negligable.

How does increasing the depth of the water increase the boiling point... No, let me guess... the weight of the water increases the pressure of the water in the lower part of the pan... No?