BPal75
Well-Known Member
So I have a question that's been nagging at me for a while and I haven't been able to find any answers in my searches.
When calculating mash and sparge water volumes to hit pre-boil gravity, at what temperature are these volumes? For instance I know that if I want to hit 5 gallons post-boil and I lose 1 gallon/hour in boil-off, I also need to account for cooling losses from 212F to 68F, or about 4%. So my pre-boil volumes should be about 6.25 gallons (1 gallon boil off and .25 gallons cooling losses).
To hit 6.25 gallons of pre-boil, lets say my calculator tells me I need 4.8 gallons of mash water and 2.25 gallons of sparge water (7.05 gallons, assuming .8 gallons lost in grain absorption and no deadspace). However, wouldn't this be the amount of mash and sparge water needed at 212F, or at boiling, because the only expansion/cooling adjustments I'm making is from 212F down to 68F? If so, shouldn't I be factoring in some expansion gains when filling my vessels with 65F tap water? I think this has been my problem with why I keep overshooting my volumes. I don't need 7.05 gallons of tap water, I need some lesser amount that will expand to 7.05 gallons at 212F correct? If so, why don't any of the online calculators or beersmith account for this expansion rate? Does anyone else do this?
When calculating mash and sparge water volumes to hit pre-boil gravity, at what temperature are these volumes? For instance I know that if I want to hit 5 gallons post-boil and I lose 1 gallon/hour in boil-off, I also need to account for cooling losses from 212F to 68F, or about 4%. So my pre-boil volumes should be about 6.25 gallons (1 gallon boil off and .25 gallons cooling losses).
To hit 6.25 gallons of pre-boil, lets say my calculator tells me I need 4.8 gallons of mash water and 2.25 gallons of sparge water (7.05 gallons, assuming .8 gallons lost in grain absorption and no deadspace). However, wouldn't this be the amount of mash and sparge water needed at 212F, or at boiling, because the only expansion/cooling adjustments I'm making is from 212F down to 68F? If so, shouldn't I be factoring in some expansion gains when filling my vessels with 65F tap water? I think this has been my problem with why I keep overshooting my volumes. I don't need 7.05 gallons of tap water, I need some lesser amount that will expand to 7.05 gallons at 212F correct? If so, why don't any of the online calculators or beersmith account for this expansion rate? Does anyone else do this?