Mash and Sparge Water Calculations

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BPal75

BPal75

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So I have a question that's been nagging at me for a while and I haven't been able to find any answers in my searches.

When calculating mash and sparge water volumes to hit pre-boil gravity, at what temperature are these volumes? For instance I know that if I want to hit 5 gallons post-boil and I lose 1 gallon/hour in boil-off, I also need to account for cooling losses from 212F to 68F, or about 4%. So my pre-boil volumes should be about 6.25 gallons (1 gallon boil off and .25 gallons cooling losses).

To hit 6.25 gallons of pre-boil, lets say my calculator tells me I need 4.8 gallons of mash water and 2.25 gallons of sparge water (7.05 gallons, assuming .8 gallons lost in grain absorption and no deadspace). However, wouldn't this be the amount of mash and sparge water needed at 212F, or at boiling, because the only expansion/cooling adjustments I'm making is from 212F down to 68F? If so, shouldn't I be factoring in some expansion gains when filling my vessels with 65F tap water? I think this has been my problem with why I keep overshooting my volumes. I don't need 7.05 gallons of tap water, I need some lesser amount that will expand to 7.05 gallons at 212F correct? If so, why don't any of the online calculators or beersmith account for this expansion rate? Does anyone else do this?
 
The water starts off cold and ends up cold. Why bother with the 4% expansion/contraction in the middle? It over-complicates things, and factors itself out anyhow. The liquid doesn't really shrink. It expands and then returns to its prior state. The time that it spends in the expanded state is somewhat irrelevant, because it is transient. As such, if you normalize your volumes to room temperature, the calculations will make a lot more sense.
 
I do all my volume calculations at 68˚F. If I make volume measurements at other temps, I adjust the measured volume to 68˚ before using it in a calculation. @pricelessbrewing 's BIAB (don't let the name fool you, it's for more than BIAB) calculator gives volumes at both 68˚ and at process temp (mash or boil depending on the particular measurement.)

https://pricelessbrewing.github.io/BiabCalc/

Brew on :mug:
 
Most people's volume measurements are probably only good within a margin of error of 5-8%, so the hot vs. cold question of 4% is moot for many or most people. I don't worry about it.
 
I work the number backwards, starting with the volume of beer to be packaged. To package 5 gallons of beer I put 5.25 gallons in the fermentor. To get the post-boil volume the 5.25 gallons are added to the kettle trub loss and tubing wort loss of .5 gallons for a total of 5.75 gallons post-boil volume.

Keeping a gallon or so of near boiling water handy at flameout, to add in case you undershoot, will help you hit your post-boil volume, as long as your kettle is large enough to hold it all. I never think in terms of temperature when calculating volumes, but I am mindful of the fact that boiling wort will expand.
 
I just fly sparge to volume into the boiler. If I want 11 gallons into fermenter, and my wort is near boiling when I am done sparging, I would sparge 11 gallons + 2 GPH boil off + .5 Gal trub/equipment loss + 4% expansion = 14 gallons in boiler at time of boil.
 
For my anal retentive self trying to consistently nail an OG with a hydrometer calibrated at i, calculators calibrated at j, hydrometer samples at temp k, volume readings at temp l, boil off rate m, new recipe, new equipment, new techniques, etc. is just too many variables for me to juggle.

I try not to worry too much about mash and sparge volumes myself and just do what beersmith says in that regard, it'll get me close enough. It's after collecting my runnings that I'll make my adjustments to zero in on my target OG. I like to break down my wort into two simple components: preboil mass of extract and preboil mass of water. Break down your target postboil wort to mass of extract and water and it's a simple matter of addition and subtraction to get where you want to be. Take away the temperature variables and density ratio (gravity) b.s. and it's soo much easier to make accurate adjustments on the fly. This was kind of a light bulb moment for me.

If this is your kind of thing let me know and I'll explain the details of my method. I kind of take the art out of it but hey, I'm an engineer...
 
thekraken said:
For my anal retentive self trying to consistently nail an OG with a hydrometer calibrated at i, calculators calibrated at j, hydrometer samples at temp k, volume readings at temp l, boil off rate m, new recipe, new equipment, new techniques, etc. is just too many variables for me to juggle.

I try not to worry too much about mash and sparge volumes myself and just do what beersmith says in that regard, it'll get me close enough. It's after collecting my runnings that I'll make my adjustments to zero in on my target OG. I like to break down my wort into two simple components: preboil mass of extract and preboil mass of water. Break down your target postboil wort to mass of extract and water and it's a simple matter of addition and subtraction to get where you want to be. Take away the temperature variables and density ratio (gravity) b.s. and it's soo much easier to make accurate adjustments on the fly. This was kind of a light bulb moment for me.

If this is your kind of thing let me know and I'll explain the details of my method. I kind of take the art out of it but hey, I'm an engineer...
Click to expand...
OK, let's see it.

Brew on :mug:
 
doug293cz said:
OK, let's see it.

Brew on :mug:
Click to expand...

I typed this all out once and my browser crashed while I was proof reading... Let's try again

<rant>
So my problem is that when we think of a wort we think of it as a volume of a solution (that changes with temperature) that has a specific gravity (that changes with temperature AND calibration). Here is where the problems start for us beginners, gravity is convoluted unit of measure - the ratio of the density of a solution to the density of water at an "standard" temperature. I just want to measure the sugar in the wort not the (deep breath) ratio of the density of a solution to the density of water at an "standard" temperature! Plato is simply the percent sugar content by weight, that's easier to wrap my head around. Gravity is a headache, I say we should all switch to plato... but that's just me.

I prefer to simply think of wort as a mass of water + a mass of extract. We're just making sugar water here. Mass doesn't care what temperature it is (and scales don't either). For example consider a wort of 5 gallons at 1.050 gravity at 68F, this same kettle of wort is a different volume at any other temperature and a different gravity as well. But consider that the 5 gallons of 1.050 wort at 68F = 5.5 lb of extract + 38.3 lb of water at ANY temperature.

Also another moving target here is that the standard practice is to try and hit a preboil volume and gravity, boil for a fixed amount of time and try and hit a different volume and gravity. Being able to do this consistently and hit your mark is what sets apart the men from the boys. I suck at it for some reason.

So let's take that 5 gallons of 1.050 wort at 68F from before, let's say that our brewing software calculated that we needed a starting wort of 6.4 gal at 1.041 at 170F, if I normalize that preboil wort I'll see that I need a preboil wort of 48.7 lb of water and 5.5 lb of extract.

Preboil wort = 48.7 lb water + 5.5 lb extract
Postboil wort = 38.3 lb of water + 5.5 lb extract

That it. That's the plan. That those two lines above describe what I want to achieve with the boil. I want to remove water. No screwing around with density ratios and temperatures. If my actual preboil wort only has 5 lb of extract then I'll add 0.5 lb of DME. If my preboil wort has 51 lb of water I'll boil a few extra minutes.
</rant>

So this is my basic process:
  1. Convert my recipe's postboil wort volume and gravity to mass water + mass extract
  2. Collect my runnings, record volume, volume's temperature, gravity, gravity's temperature in spreadsheet.
  3. Convert my wort into mass of water + mass of extract
  4. EXTRACT ADJUSTMENT: If I didn't get enough extract from the grains I can add DME here (simply target_extract_amount - current_extract_amount). If I got too much :)ban:) the spreadsheet uses plato and density to accurately calculate how much wort to discard from the kettle.
  5. Boil for 30 minutes or so and kill the heat for a moment to get volume and gravity and plug it into the spreadsheet one last time
  6. WATER ADJUSTMENT: Now the spreadsheet can calculate the actual boil off rate and tell me how much water I'll end up with at the end of the boil. If I'll have too much it'll tell me how much longer to boil, if I have to little it'll tell me how more to add right now (simply target_water_amount - projected_water_amount)
  7. Sit back and relax as my boil finishes up at the volume and gravity it was supposed to despite my sloppy mashing skillz

I hope my babbling is making sense. The math for working with wort as a mass of water and extract is much more straight forward than doing the same with volumes/gravity/temperature/calibrations. However, "normalizing" a wort to these masses can be a little tricky, for that I use couple functions that the great ajdelange shared with me in this thread: https://www.homebrewtalk.com/showthread.php?t=531216&page=2

So getting back to OP's question: I now worry less about nailing mash/sparge volumes and efficiencies (I still worry a little bit) and use the steps above to zero in on my recipe's targets during the boil.

This is my method. There are many like it, but this one is mine.
 
thekraken said:
I typed this all out once and my browser crashed while I was proof reading... Let's try again

<rant>
So my problem is that when we think of a wort we think of it as a volume of a solution (that changes with temperature) that has a specific gravity (that changes with temperature AND calibration). Here is where the problems start for us beginners, gravity is convoluted unit of measure - the ratio of the density of a solution to the density of water at an "standard" temperature. I just want to measure the sugar in the wort not the (deep breath) ratio of the density of a solution to the density of water at an "standard" temperature! Plato is simply the percent sugar content by weight, that's easier to wrap my head around. Gravity is a headache, I say we should all switch to plato... but that's just me.

I prefer to simply think of wort as a mass of water + a mass of extract. We're just making sugar water here. Mass doesn't care what temperature it is (and scales don't either). For example consider a wort of 5 gallons at 1.050 gravity at 68F, this same kettle of wort is a different volume at any other temperature and a different gravity as well. But consider that the 5 gallons of 1.050 wort at 68F = 5.5 lb of extract + 38.3 lb of water at ANY temperature.

Also another moving target here is that the standard practice is to try and hit a preboil volume and gravity, boil for a fixed amount of time and try and hit a different volume and gravity. Being able to do this consistently and hit your mark is what sets apart the men from the boys. I suck at it for some reason.

So let's take that 5 gallons of 1.050 wort at 68F from before, let's say that our brewing software calculated that we needed a starting wort of 6.4 gal at 1.041 at 170F, if I normalize that preboil wort I'll see that I need a preboil wort of 48.7 lb of water and 5.5 lb of extract.

Preboil wort = 48.7 lb water + 5.5 lb extract
Postboil wort = 38.3 lb of water + 5.5 lb extract

That it. That's the plan. That those two lines above describe what I want to achieve with the boil. I want to remove water. No screwing around with density ratios and temperatures. If my actual preboil wort only has 5 lb of extract then I'll add 0.5 lb of DME. If my preboil wort has 51 lb of water I'll boil a few extra minutes.
</rant>

So this is my basic process:
  1. Convert my recipe's postboil wort volume and gravity to mass water + mass extract
  2. Collect my runnings, record volume, volume's temperature, gravity, gravity's temperature in spreadsheet.
  3. Convert my wort into mass of water + mass of extract
  4. EXTRACT ADJUSTMENT: If I didn't get enough extract from the grains I can add DME here (simply target_extract_amount - current_extract_amount). If I got too much :)ban:) the spreadsheet uses plato and density to accurately calculate how much wort to discard from the kettle.
  5. Boil for 30 minutes or so and kill the heat for a moment to get volume and gravity and plug it into the spreadsheet one last time
  6. WATER ADJUSTMENT: Now the spreadsheet can calculate the actual boil off rate and tell me how much water I'll end up with at the end of the boil. If I'll have too much it'll tell me how much longer to boil, if I have to little it'll tell me how more to add right now (simply target_water_amount - projected_water_amount)
  7. Sit back and relax as my boil finishes up at the volume and gravity it was supposed to despite my sloppy mashing skillz

I hope my babbling is making sense. The math for working with wort as a mass of water and extract is much more straight forward than doing the same with volumes/gravity/temperature/calibrations. However, "normalizing" a wort to these masses can be a little tricky, for that I use couple functions that the great ajdelange shared with me in this thread: https://www.homebrewtalk.com/showthread.php?t=531216&page=2

So getting back to OP's question: I now worry less about nailing mash/sparge volumes and efficiencies (I still worry a little bit) and use the steps above to zero in on my recipe's targets during the boil.

This is my method. There are many like it, but this one is mine.
Click to expand...

Yeah, I also love it when a system or operator error eats something I spent an hour typing.

I understand all the Plato = wt% extract in the wort, and volume to weight (and vice versa) calculations. But, I'm not seeing how that really simplifies things. You still have to take volume and gravity measurements, correct them for temperature, and then convert to weights. Seems like all the simplification is just due to the spreadsheet that "hides" all the calculations. A good spreadsheet, that does what you want it to, is a great tool.

Brew on :mug:
 
doug293cz said:
Yeah, I also love it when a system or operator error eats something I spent an hour typing.

I understand all the Plato = wt% extract in the wort, and volume to weight (and vice versa) calculations. But, I'm not seeing how that really simplifies things. You still have to take volume and gravity measurements, correct them for temperature, and then convert to weights. Seems like all the simplification is just due to the spreadsheet that "hides" all the calculations. A good spreadsheet, that does what you want it to, is a great tool.

Brew on :mug:
Click to expand...

What I mean to say is it's much simpler for *me* to conceptualize manipulating wort in this way, it is just add and subtract. The spreadsheet does indeed use a little VBA magic to get from conventional measurements to "normalized" values.

I just realized the second gravity measurement can also be taken out of the method with a little refinement.
 
thekraken said:
What I mean to say is it's much simpler for *me* to conceptualize manipulating wort in this way, it is just add and subtract. The spreadsheet does indeed use a little VBA magic to get from conventional measurements to "normalized" values.

I just realized the second gravity measurement can also be taken out of the method with a little refinement.
Click to expand...

I know that when doing detailed efficiency calcs and sparge/lauter simulations, doing everything with weights is almost required. I think an understanding of how volumes, gravity, Plato, weights, etc. all fit together would help just about any brewer's understanding.

Brew on :mug:
 
BPal75 said:
If so, why don't any of the online calculators or beersmith account for this expansion rate? Does anyone else do this?
Click to expand...

There is an option in the beersmith equipment profile for cooling shrinkage, the default is 4%. If you change that to zero the preboil volume decreases, so it does take that into account for mash and sparge volumes(at least for batch sparging).
 

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