[quote=“ITsPossible”]Stormy I’m sure what you just mentioned is on for batch sparging I wouldn’t know as I have never looked at the method really, just bits and pieces. The thing is though you brought back to my attention an aspect that could be huge for the OP which is this:
You will have dead space in your kettle from hot-cold protein breaks that could be .25 gal to 2 gal
etc…and you will lose on average a gallon an hour from boiloff. So lets look at it this way shall we>>>>
Using myself as an example I find that depending on hop load I will lose .75-1.25 gallon on average to protein break and hop etc material in the bottom of the kettle after chilling. I have a dip tube and other but I will start picking up tons of trub so therefore I found that if I start my boil with 7.5 gallons for a 60 minute boil. I will boil off 1 gallon to evap and lose .25 gallon to chilling so I’m down to 6.25 gallons remaining and will lose on average 1 gallon to trub after whirl-pooling. So I am left with 5.25 gallons of crystal clear wort running off to fermentor.
6.25 gallons is the amount I always base the recipe SG/ IBU formulation on also.
YRMV of course as you will need to see what these numbers actually are during a few preliminary brews, but its one thing to consider pre-1st batch for higher incident of hitting all numbers first time out of the gate. :cheers: [/quote]
I’m not saying any of my numbers are magic, just an example. As you’ve said above, much thought goes in to detemining pre-boil so you can get the appropriate post boil. Lots of variables.
But the math for determining sparge, for batch sparge, is very simple as I noted above, once you’ve determined how much you want your total pre-boil volume to be…which takes into account your system: grain/water ration, grain absorption rate, boil-off rate, boil time, etc.