pre boil volumes

[mwfripp]

I've noticed on some recipes people use 3.5gal or 2.5 gal pre boil volume for a 5 gal batch. Does one make difference over the other in any part of the brewing process? FG, yeast efficiency, Etc?

 

[kh54s10]

I've noticed on some recipes people use 3.5gal or 2.5 gal pre boil volume for a 5 gal batch. Does one make difference over the other in any part of the brewing process? FG, yeast efficiency, Etc?

This is common for an extract recipe. You boil the 2-3.5 gallon wort adding the extract and hops at the appropriate times then add top up water to your finished batch size.

You obviously cannot boil 2.5 gallons and end up with 5....

 

[balrog]

Less boil volume affects hop utilization to some extent (more volume, better extraction) plus having more sugar concentration (early LME/DME addition to the boil versus late) affects hop utilization also-I've read boiling with some extract is better for hop utilization but having too concentrated a wort is bad for hop utilization. You also might get more carmelization with more concentrated wort boil, hence some folks do late extract additions.

 

[dcbw]

It's really hard to get a vigorous 7 gallon boil on most residential stoves, whether electric or gas.

It's also a lot easier and less disaster prone to carry 3G down to a basement or outside to chill instead of 5G of burning hot lava in a burning hot kettle.

So instead you boil less and top up in the fermenter.