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Need some help with some brewing math.
I'm trying to keep better track of numbers now as I try to get into designing my own recipies and become a better brewer as a whole. I plan to use Promash to help me do this. One bit of information that it wants for the "water needed" calculator is the evaporation rate (of the boil) in % per hour.
Saturday I brewed a porter, and collected 7.5 gal of wort pre-boil from both runnings(batch sparge) and ended up with 6 gal left after the 60 min. boil. I'm guessing that this is a 20% loss. Is that correct? I haven't really haven't had work with percentages in awhile, but I figured that 6/7.5=0.8. Which means that 6 gallons is 80% of 7.5 gallons, or a 20% loss from the original volume. Is that right?
That's exactly it.
An easy way to think about it is to do a base 10 example; i.e. if you started with 10 gallons of wort, boiled for an hour, and ended up with 7 gallons of wort, it would be intuitively obvious that you lost 30% of your water to evaporation in one hour. It may be less obvious when working from a "less rounded off" starting point, but it's the same thing...1 - (7/10) = .3 -- ergo 1 - (6/7.5) = .2
With evapouration calculations it is important not to forget about other equipment losses depending on your setup. Losses in tubing, your mash tun, and spent grains etc will reduce your pre-boil volume and ultimately your calculated rate of evapouration.
A great book that I've found extremely useful for calculations in all aspects of brewing and in particular, calculating water requirements is "Designing Great Beers"by Ray Daniel. This book is brilliant and will assit you will all your brewing calculations, including evapouration.
I'm just about to do a Biere de Garde in my own little inner city farmhouse with a touch of coffee to enhance the colour! Ray Daniels book has helped my generate my own spreadsheet which gives me greater control and understanding about all the figures involved
Cheers, Rob.
Hmm...Maybe I should have started this post with "After reading 'Designing Great Beers'...". It's a great read and is my inspiration for trying to be more accurate with my numbers.
Freelance, I checked the volume after the wort was pumped into the kettle and I already had the full volume in there. So I don't think that the 3/4 gal of wort that was left in the MT will effect anything as far as the pre-boil volume goes. And I try not to leave any wort in the tubing, it all goes into the kettle. But thanks for the input, I will keep it in mind.
Joe, thanks for your input too. I wanted to make sure that my logic was correct. I'm not really a big numbers guy. And I don't think that I'm gonna be auditioning for a certain game show hosted by Jeff Foxworthy anytime soon either.
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