Does hot or cold water boil faster?

Answer 1

Cold water requires a higher temperature elevation than warm water does, and therefore will take longer to heat to boilinIf you start with hot water there is not enough difference in temperature from top to bottom to create an effective convection loop, because hot stuff only rises while in the presence of cold stuff to rise above. Warm water promotes a slower convection loop and hence will take longer for "ALL OF THE WATER" to hit 212 degrees.

according to scientists, the notion that a body of cold water will reach boiling temperature more quickly than an identical body of hot water under the same parameters is simply false.

This kitchen myth may have started as a way to encourage people to cook with cold water, not hot, which can contain more impurities. It may also have its origins in the fact that cold water generally gains heat more rapidly than water that is already hot, though it will not boil faster.

But under the right circumstances, the reverse phenomenon can occur, and hot water can freeze more quickly than cool water.

THE BOTTOM LINE

Cold water does not boil faster than hot water, but hot water can freeze more quickly than cool water.

Answer 2

Hot water does, as the water particles are already partly "excited".