Beersmith: Estimated pre-boil volume...at what temperature?

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

Pre-boil ...is "Total" amount of wort collected at the star of boil.For me around 7 Gallons.<<< In boil kettle
Post-boil...is "Total" amount of wort left after the boil.For me after 60min,I'm left with 5.5 Gallons.<<<< Into fermenter.
Beersmith needs to know the amount of water you boil in a hour.. called
Boil-off rate...is "Total" amount of Water you boil in a hour..For me its 1.5 gallons a hour.
To find this I filled to pot with 7 gal of H2O.Then when it "Started to boil" ,I timed it a hour..was left with 5.5Gal...

Thanks for the reply That much I understand though. My question is what water temperature does the "pre boil volume" assume? Due to the varying density of water with temperature it could make quite a difference. Seems like a simple question but I'm having trouble finding a definitive answer.

MichaelBrock said:

Thanks for the reply That much I understand though. My question is what water temperature does the "pre boil volume" assume? Due to the varying density of water with temperature it could make quite a difference. Seems like a simple question but I'm having trouble finding a definitive answer.

Click to expand...

I don't know what it assumes, but even assuming a coolage percentage of 4% (if it's boiling hot), that's not much at all. Just call it "once the BK is up to boil volume" regardless of temperature and then build that into your boil off.

What I mean is this- use your measuring stick and see that you have 7 gallons as you finish the sparge (or whatever you start with). When your boil is finished, measure the amount you have left with the measuring stick and consider the difference all boil off, and then the shrinkage percentage will be dead on. Change the settings in Beersmith from "percentage boiled off in one hour" to "boil off volume" and use that amount from now on. Does that make sense? Temperature is totally out of the equation that way, since your system/temperatures won't vary by much in future batches.

That does make sense. I guess now that I have accurate volume measurements I need to do an accurate measure of the boil off. I intended to with this last brew but I got distracted roasting coffee and missed my 60 minute hop addition by 10 minutes so extended the boil (but still ended up with almost 2 quarts too much wort (and .003 too low OG).

4 years late, but i think i know what OP is talking about. Basically I would fill up by BK to what beermsith told me to (e.g. 20 gallons), but by the time it was almost at boiling, I managed to read an extra 0.5 gallons in my sightglass (20.5 gallons). I also fly sparged with cold water though, and so the wort getting measured into the boil kettle was more like 130 degrees F. Assuming a 4% expansion at boiling vs. 68 degrees, 130 is roughly 2% of 20 gallons which gets me to 20.5 by the time it heats up to boiling. My logic may be completely wrong though - I was super confused the first few brew sessions.

My gut tells me that beersmith wants us to measure at near boiling temperature. This thread I just found, someone contacted Brad from beersmith and said pre-boil volume is measured hot:
https://www.homebrewtalk.com/showthread.php?t=477899

The answer is yes. Beersmith gives you hot side volumes using the expansion factor you plug into the equipment profile. From my experience with dialing in the volumes on my processes, it applies a linear scale going from ambient temperatures to the max expansion at boiling.

In the equipment profile it has cooling loss, preset at 4%. So I would say that hot measurements would be taking that into account so that when cooled you obtain the proper amount. I made my dip stick using cold water. I don't know how accurate it is. But, after a few batches I determined I need a bit over the 7 gallon mark to get cooled - just over 5 gallons into the fermenter.

You can reset that number but I don't know how long it would take to figure out the effect.

I say just make a dip stick and determine on it how much you need preboil, to end up with the right volume into the fermenter. It should only take a couple of batches. As far as that goes, I am not too worried if I get +/- .5 gallon.