Boil Off ExExperiment

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mgortel

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I will be brewing on Satuday....and I had lost all of my data in Beersmith due to a computer crash...so I ran an experiment tonite to determine my boil off rate.

10 Gallon SS Pot, diameter 15.5 inches

Start volume = 6.5 gallons
End volume = 5.0 gallons
Time = 60 minutes.....

Time does not include heat up....

So....1.5 gallons per hour....in this case 20.1%......seems aweful high but that is what I got.

Now, I did have a pretty rigorous boil....maybe it was excessive....but I did mark my gas nozzle location on my propane heater so I can repeat it on my brew day.....so I guess I will go with it.

I am WONDERING what others have for a boil off rate on their equipment.
 
Typically 15, but I've seen 20 before. If you have a refractometer, you can monitor SG while you're boiling and adjust the speed or duration of the boil to hit your numbers
 
I use Blichmann 20G kettles and get 2 gallons of boil off in an hour. I normally do 10 gallon batches. For most recipes, I start at 13 gallons pre-boil and end at 11 gallons in a 60 minute boil. I end up with about 10.5 into the fermenter after cooling.
 
My pot is 13.5" in diameter, and I boil off about 1.2 gallons/hour, so I think your numbers are definitely in line.

Just don't think of it in that percentage number, and don't enter it as a percentage into BeerSmith. The boiloff/hour is a constant variable for your particular pot no matter how much volume is in the pot, i.e., if you had 9 gallons in there, it would still be 1.5 gallons/hour, so the percentage is irrelevant.

You are good rolling with that 1.5 gallons/hour number for your pot.
 
Sounds like your in the ballpark. In my 8 gallon pot I start with 6.5 gallons and end up with 5 gallons after a 60 minute boil.
 
Just don't think of it in that percentage number, and don't enter it as a percentage into BeerSmith. The boiloff/hour is a constant variable for your particular pot no matter how much volume is in the pot, i.e., if you had 9 gallons in there, it would still be 1.5 gallons/hour, so the percentage is irrelevant.

Excellent point....thank you!
 
I use a Blichmann 10 gallon kettle and I get 1.25 gallons of boil off on average in an hour, and that's with a nice rolling boil. That's what I always count at and use as my basis. If I do a really aggressive rolling boil then 1.5 gallons in one hour but I don't usually boil that aggressively as it just wastes more propane and boils off more, only done that one time.


Rev.
 
Just FYI for all you guys posting your kettle volume, boil off is a factor of the liquid surface area, so the overall volume of the kettle is irrelivant. It's the diameter of the kettle that matters. A 3 gallon kettle with a 16" diameter will boil off more than a 15 gallon kettle with a 14" diameter. Larger volume kettles tend to be bigger in diameter than smaller volume kettles, but that isn't always the case. The guy I brew with has a short and fat 8 gallon kettle that is quite a bit larger in diameter than my tall and thin 11 gallon kettle, thus he has a higher boil off rate.

Also, as far as how vigorous the boil is, that is a variable you should keep constant if you want to hit your numbers. I boil as vigorously as possible right below the boilover point, which keeps that variable constant and therefore keeps that boil off rate constant. Controlling as many variables as possible = consistent beer!

Just some tips...seeing a few false assumptions in this thread :mug:
 
@Topher - yes, we know (at least I do) that surface area is what really matters in boil off rates. He asked, "I am WONDERING what others have for a boil off rate on their equipment."

I therefore told him my boil off rate and my equipment. He can feel free to lookup the Blichmann kettle dimensions. ;)


Rev.
 
Thanks for all the responses guys.....

Looking forward to my first brew in quite a while tomorrow.....have one planned for following week too....Im back......:ban:
 
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