Author Topic: Estimated pre-boil volume...at what temperature?  (Read 10935 times)

Offline MichaelBrock

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Estimated pre-boil volume...at what temperature?
« on: July 02, 2012, 07:55:00 AM »
I have been using Beersmith since day one, roughly 18 all grain brews.  My volume calculations and measurements never really added up but everything was otherwise working out so I didn't pay it much heed.  This past weekend I  finally go around to making an accurate measuring stick for my boil kettle.  Turns out I have been overestimating my volume into the kettle by roughly 1/4 gallon. I started looking into the volumes in beersmith in a bit more detail.   Of course this just let to more questions.   Mainly,  what temperature  is assumed for the "pre boil" volume of wort?   The directions and tool tip simply state that this is the volume at the "start of the boil".  Which of course begs the question of what is meant by "the boil".  Is the volume at 212 degrees? or is the volume of runnings from the mash, which is roughly 168 degrees?     I tried to research this first and found a few people asking the question but failed to find a definitive answer.

Thanks,

Michael

Offline merfizle

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Re: Estimated pre-boil volume...at what temperature?
« Reply #1 on: July 02, 2012, 03:49:16 PM »
My preboil volume is measured when mash tun is done draining.  When wort is hot it expands so volume reading will be inaccurate.
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Offline MichaelBrock

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Re: Estimated pre-boil volume...at what temperature?
« Reply #2 on: July 02, 2012, 06:43:04 PM »
Right....that is the point of my question.   Water density changes with temperature.  So, what temperature does Beersmith assume for the "pre boil volume"?  Do you think it assumes that the temperature is the final mash temperature?

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Re: Estimated pre-boil volume...at what temperature?
« Reply #3 on: July 03, 2012, 08:11:38 AM »
I'm assuming it is after draining the mash - I've not done a temperature adjustment to the volume for this calculation, though at 150F the difference should be small.

Brad
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Offline MikeinRH

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Re: Estimated pre-boil volume...at what temperature?
« Reply #4 on: July 03, 2012, 09:12:54 PM »
Interesting question, but probably non-consequential.

Definitely get a yard stick from Depot and make markings on it by adding one gallon at a time. Pretty soon, you'll be able to eye-ball the volume you need on your kettle. I usually do 90-minute boils and shoot for 6.5-7.0 gallons of wort. After the boil, I "chill and fill" to an area right where the 6-gallon carboy shoulder begins. That usually provides enough space for a 500-600ml yeast starter. I ALWAYS use a sanitized blow-off cap and tubing stuck into a bucket of sanitizer right after aereating. I never use a fermenting bucket anymore because I like to see the "action". I've also lost a few batches due to leaky lids and oxidation. Our cat hates the sound of the carboy belching into the bucket of sanitizer, but it's my wife's cat.

Offline nut4wine

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Re: Estimated pre-boil volume...at what temperature?
« Reply #5 on: October 15, 2012, 07:51:21 PM »
I'm assuming it is after draining the mash - I've not done a temperature adjustment to the volume for this calculation, though at 150F the difference should be small.

Brad

I don't understand this answer.  If there's a 4% volume increase from "room temperature" (call it 70 degrees F) to boiling, wort at 150F would be more than 1/2 way to boiling, so wouldn't at least 1/2 of the volume expansion have taken place?  That would be a quart of difference (or so), wouldn't it?

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Offline MichaelBrock

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Re: Estimated pre-boil volume...at what temperature?
« Reply #6 on: October 15, 2012, 08:17:23 PM »
I didn't get it either (or the previous answers) and kind of gave up on the topic out of frustration.  I'm not sure any of the repliers quite understood the question.   I took Brad's answer as a bit of a "smirk" so I figured I was missing something obvious.

Offline tom_hampton

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Re: Estimated pre-boil volume...at what temperature?
« Reply #7 on: October 15, 2012, 08:29:39 PM »
I was hoping brads answer would have been definitive. Here is how I do it.

From the mash I work in points. I want a certain amount of sugar from the mash. To that end, I correct all volumes to room temperature.  I basically eyeball water into the mash tun. 2-4 percent error there doesn't affect my final beer.

Once I get to the kettle, I figure my final, COLD target volume by dividing my total points by my target og.  Then I add trub loss, and multiply by 1.04 for expansion. That gives me my HOT volume to boil down to---my flame out volume.  A little more math good gives me my total boil time.  Then work back to hop additions. 

I repeat this math several times during the boil to ensure I'm on track. 


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Offline MikeinRH

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Re: Estimated pre-boil volume...at what temperature?
« Reply #8 on: October 23, 2012, 06:07:51 PM »
Michael: I re-read your original post and saw that all you wanted was a definition of "start of the boil".
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Offline jomebrew

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Re: Estimated pre-boil volume...at what temperature?
« Reply #9 on: October 24, 2012, 08:57:54 AM »
Mainly,  what temperature  is assumed for the "pre boil" volume of wort?   The directions and tool tip simply state that this is the volume at the "start of the boil".  Which of course begs the question of what is meant by "the boil".  Is the volume at 212 degrees? or is the volume of runnings from the mash, which is roughly 168 degrees?   

Thanks,

Michael

I never gave it much thought.  I just assumed it was post sparge kettle volume.  I am, already heating the wort to a boil by the time I am finished with my batch sparge to the temp is closet to 180-190.  That is when I measure.   I asked a couple pro brewers and they said they don't measure.  With the calculations for strike water and sparge water volume they know how much will be in the kettle.  One system uses a sight glass on the HLT.  I am pretty sure they are not worried about being a few gallons off.

As with many things in homebrewing, pre-boil volume is unique to your system and process.  You should pick the point you will measure and consistently use that point for all brews.  You should adjust beersmith to align with that process. 




 

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