Gravity points first runnings vs sparge runnings

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javedian

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I need some help. I have found many mash and sparge calculators that tell the amounts of water needed for various parts of the mashing process. I even found a no-sparge calculator that scales the grain bill for no-sparge brewing.

What I am trying to understand is how many points (or percentage of potential) do I get for mashing a certain amount of grain? I know that most of the sugars come off the first running. How much? How much would I get off a partial sparge - i.e. not full extraction, but only sparging enough to get to a specific pre-boil volume? The water calculators don't factor the gravity, and the gravity / recipe calculators don't factor mash & sparge volumes, just total batch size.

EX: (numbers from a step mash spreadsheet I found)
I have 10 lbs of 2-row grain, and expect to get 70% utilization under normal circumstances. For a normal sparged 5gal batch, this should yield a OG at pitching of 1.052, or 260 points. At 1.25 qt/lb single infusion mash with mashout, how many points do I get in my 3.1 gal of first runnings? If I sparge with 1.9 gal, I should get 5gal to brew pot, and about 4.4 gal to fermenter after boil off and hop loss. What gravity would this be?

Saccharification Rest
Ratio of water to grain quarts/pound 1.25
Grist Temperature T1 65° F
Target Rest Temp T2 154° F
Weight of Grain in Pounds G 10.0
Strike Water Quarts ---> Wm 12.5
Strike Water Temperature ---> Tw 168° F
Space Used Gallons ---> 3.91

Initial Mash Temp T1 154° F
Target Mash Temp T2 168° F
The temperature (°F) of the infusion water 210° F
Infusion Amount Quarts --> Wa 4.8
Space Used Gallons ---> 5.1

Total Water Added Quarts 17.3
Grain Absorbtion Quarts 4.8
Additional Losses Quarts 0
Total Gallons First Runnings 3.1
 
Something isn't adding up. 12.5qts of strike water minus 4.8qt grain absorbtion equals 7.7 quarts first runnings or just under 2 gallons (IF you have no deadspace in the MLT) and I have no idea what the gravity will be. You'll need at least a 3 gallon sparge to get close to 5 in the kettle, but I'd add two extra quarts for good measure. In fact, save a little extra hot sparge water in case you need to eek out another few quarts. In my stout last weekend my first runnings were 1.060 and my batch sparge was 1.026 which turned into a post boil of 1.054. I don't recall the first runnings volume though so that doesn't help you.
 
The scenario aboveis hypothetical - I should have used my 11.5 lb recipe I am working on. There is a mash out, so total water added is 17.3 qts.

Bobby - how many lbs grain did you use?

I only have starting boil capacity of 4.5 gal comfortably. I am looking at the math & science behind sparging to evaluate options for either boiling a slightly higher gravity boil, and adding a little top-up water to get 5-5.5 gal into fermenter, or just scaling everything down to a 3.5 gallon post boil batch. I need a 40qt pot, but wallet is a little light now, and would rather get a few more brews. I did just splurge for an immersion wort chiller - :rockin: . Just used it on two brews this past weekend.

I am leaning towards the dilution method, since my next batch, a saison, (first AG) has a grain bill of 11.5 lbs (which I already have ready to go), with 1.5 lbs sugar added to hit target gravity of 1.065 for 5.5gal using normal process. I want at least 5 gal to fermentor, so I can scale down to 5, add more sugar to make up for what I am not extracting, or add another lb or 2 of grain. But I need to get an estimate of gravity of first runnings, and what a 1.5 gal sparge might produce.
 
Oops, didn't catch the mash out since I don't do it. I boil right away so no real need for it.

I used 11.25 lbs of grain.

I'd really suggest taking a bigger sparge and boiling it in a separate pot until you reduce both down enough to recombine. If you really want to use the single pot but kick up the gravity, you could just add a pound or two of DME.
 
If you have three runnings, all about the same size, they will be (very roughly) 1/2 the sugar, 1/3rd the sugar, 1/6th the sugar. In your case, you probably got about 1/2 and 1/4 and left 1/4 in the mash.
 
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