I don’t use ProMash, but…
I measure the recipe’s volume for input into the software immediately at flameout, and I measure specific gravity after boiling and chilling at between 60-70 F, which is where hydrometers are calibrated. This might not be correct – I have never been certain whether to measure volume while hot at 212 F or after chilling at 60-70 F. However I am certain that the volume must be measured sometime after the boil.
So the point of debate is whether to measure post-boil volume hot or chilled. Honestly, I do not know the “right” answer for this, if there is one, but temperature certainly does introduce a discrepancy of up to 4% efficiency due to the different density of wort when hot versus cold.
To illustrate this point, if you are supposed to measure volume cold but you measure it hot, then your volume measurement for estimating brewhouse efficiency will be too high by 4%. To the software, this is treated just the same as if you hadn’t boiled quite hard or long enough, and should have boiled a few extra minutes to get to the right volume for the software, which would result in an increase in your specific gravity, and thus result in a brewhouse efficiency that is 4% higher than it truly is.
So… if she weighs the same as a duck… er, I mean…
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If you are supposed to measure volume cold but you measure it hot, then your calculated brewhouse efficiency is 4% too high.
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Conversely, if you are supposed to measure volume hot but you measure it cold, then your efficiency is actually 4% higher than you thought.
I have to admit, I am not certain which of these two conclusions is correct. What I am sure about, though, is that exactly one of them is correct.
I also stumbled upon the idea of chiller volume during this thought process… If you were to mistakenly measure your post-boil volume while a copper coil chiller is still submersed in the wort, then your volume measurement will mistakenly be way too high, as if you had not boiled long enough… thus resulting in an extremely wrongly high brewhouse efficiency calculation. So if you are measuring volume with a chiller in your wort, then you could mistakenly be calculating your efficiency to be higher than 100%, which is totally wrong because you need to get that chiller out of there for accurate volume measurement. So in that case…
Maybe the right answer really is that we should be measuring volume after the chiller has done its job of chilling, and left the wort. We probably really should be measuring volume cold. So conclusion #1 is more likely to be the correct one. Which means that I have been measuring efficiency wrong myself… or should I say, I have been lackadaisical about my volume measurements with respect to temperature. Maybe. But maybe I’m wrong and conclusion #2 is indeed correct. I really do not know.
Okay, enough procrastination… I’d better get back to my real job…