Boil off volume ???

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OHIOSTEVE

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Is there anything I can do to get my boil off volume more consistent? I generally boil off about 1 gallon per hour, BUT sometimes a lot more and sometimes a bit less...It is aggrivating . I brew on the stove top and use the exact same burner and exact same pot every time but have different boil off rates every time.
 
How different are the beers you're brewing, in terms of gravity and such? Just thinking out loud (or in type), and maybe it's the dissolved stuff affecting things?
 
very varied...from 1.030 to 1.088 or better...hmmm maybe there is something to that?
 
That's the only thing I can think of, unless relative humidity will effect it. But it's been a decade since I took chemistry, so...
 
Different gravity worts will boil at different temperatures. The temperature will affect the boil off volume. It is the same concept as salting roads. That just reduces the freezing temp of water. Anything dissolved in water will affect it's boing and freezing temps.
 
Different gravity worts will boil at different temperatures.

Is it higher or lower gravity that boils off more? It never occurred to me there would be an impact from the pre-boil gravity (and I guess my brews haven't been in wildly different ranges either).
 
A higher gravity wort should boil off more water per hour. Pretty much anything dissolved in water will raise it's boiling temp and lower it's freezing temp.

I can't really say how much. I'm sure there are some chemists out there who can, though.
 
I have similar problem. I brew 10 gallon batches and boil off 2+ gallon per hour. My boil is a nice esay rolling boil. I don't worry to much about it. I have just adjusted my sparg water.
 
Also take in to account that for extract/PM brews you're adding a lot of solids (LME/DME) to your boil, so that will affect volume as well.
 
A higher gravity wort should boil off more water per hour. Pretty much anything dissolved in water will raise it's boiling temp and lower it's freezing temp.

I can't really say how much. I'm sure there are some chemists out there who can, though.


Higher gravity will actually lessen the boil off I think. I just learned about this, and if I could find out the exact sugars and concentrations in the boil I could tell you exactly how much. But basically the more stuff thats in it the HIGHER the boiling point, and the less will be vaporized and lost in the boil.

Higher OG less boil off
Lower OG more boil off
 
Anyone had any issues with wind? I brew outside, and yesterday was a breezy brew day. I usually experience a 1 - 1.5 gallons per hour boil off. Yesterday was 2.25 gallons in an hour! OG was 1.054.
 
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