Adding water before or after cooling the wort

For my third batch I'm doing a Scotch Ale. Like the recipe before it, I am supposed to use 2 gallons of water for the boil [with grain steeping, malt and hops addition], then cool the wort to 70*F. Once this temperature is reached, I am supposed to add 3 gallons of water to make a total of 5 gallons.


My question is why not add the cool water once the boil is done to help facilitate a faster cooling? Does the cooling with a smaller volume of water have any significance in relationship to the trub (?) still in the wort?

Thanks.

I put my water in the freezer at the beginning of the whole brew process. Then I add the water as I begin the cooling process, unless you have a wort chiller (I don't). So yes you can add the water to help cool the wort.

I have done partial boils & pre-chilled the make-up water. You still should cool the boiled wort somewhat before adding, as it is easier to cool a small amount of hot water than a large amount of warm water.

Yeah, I played with the intricacies of thermodynamics last night for an epic fail.


Next time, clean water in the freezer.

I hated thermo, glad I am not a sophomore anymore. It's all about delta T...:cross: