Help with boiloff calculation?

[Johnnyhamer]

Going to do a 2.5 gallon batch boiled for 60 minutes.
AG and BIAb. Using about a gallon to mash and about a gallon for sparge.

The kettle has a 11 inch diameter and holds about 4 gallons.

So, how much should my starting volume be?

 

[Yooper]

Going to do a 2.5 gallon batch boiled for 60 minutes.
AG and BIAb. Using about a gallon to mash and about a gallon for sparge.

The kettle has a 11 inch diameter and holds about 4 gallons.

It would depend on the flame strength, the wind, and even the humidity where you live.

You can start with 3 gallons of water, boil for an hour and measure what's left. That would be your boil off. It would be impossible for me to make a 2.5 gallon batch in a 4 gallon pot. I boil off a bit over 1.5 gallons an hour in my system- but of course yours will be different.

 

[Johnnyhamer]

Alright, wasn't sure if there was a rough calculation floating around.

 

[gcdowd]

It's pretty much dependant on your system. I have a large diameter pot and boil off 2 gallons per hour. It's best to test it with water, that's what I did

 

[ron,ar]

This.........what Yooper said
You can start with 3 gallons of water, boil for an hour and measure what's left. That would be your boil off

 

[prankster1590]

This.........what Yooper said
You can start with 3 gallons of water, boil for an hour and measure what's left. That would be your boil off

Maybe first put sugar in that water. I think a sugar solution boils different than pure water

 

[jtratcliff]

You can start with 3 gallons of water, boil for an hour and measure what's left.

Or if you're pressed for time.... start w/ 1 gallon and boil for 15 mins. Multiply by 4.

Rate should be the same... Though early losses from preboil heat might skew things a bit for smaller volume and boil time...
But it should get you into the right ball park...

Then, when you do your *real* batch, you measure more carefully and adjust your equipment profile for the next batch.

It's an iterative process to dial in all of your equipment & process parameters... Boil off, grain absorption (bag squeeze vs no squeeze?), kettle losses (dump it all into fermenter vs leave trub in kettle?, efficiency (mash, lauter, brewhouse), etc.

It'll take a few batches to figure everything out... But in the meantime you'll make beer... if even if you don't hit all your numbers on the first try, like the rest of us did

Keep good notes and tweak each time until you get to where you want to be... And enjoy the journey (as well as the beer)

 

[Pkrd]

Or if you're pressed for time....

Well, it's been 8 years, so probably not.