Strike/sparge water question

OK, so I'm planning a SMaSH blonde with 11# of two row. I have to figure out strike and sparge water amounts.

Guideline I've seen is 1.5 quarts water per pound of grain. So that's 16 quarts initially. Sparge water (per guidelines again) should be at _least_ the same as strike water, so another 16 quarts. That gives me 8 gallons to be boiled down to 5. Does that sound right? Seems like a lot of water to boil off.

You are going to lose 1.375 gallons to the grain (11 x .125). I go with 1.25q per pound for the mash, so 3.45 gallons for the mash. Assume your boil off, if you don't know, is 15%. Therefore, 5 / (1 - .15) = about 6 gallons at the start of the boil.

You are going to get 3.45 - 1.4 grain loss = 2 gallons from your first runnings. You need a total of 6, so 6 - 2 = 4 gallons of sparge.

That does seem a little high for 5 gallons post-boil. I usually boil 7.7 to 8 gallons down to about 5.5 in 90 minute boils. I use 1.4 quarts per pound to mash and sparge to get to the right pre-boil volume for my particular boil-off rate and length of boil.

Doc Robinson said:

You are going to lose 1.375 gallons to the grain (11 x .125).

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That's what I was missing; thanks.

billvon said:

That's what I was missing; thanks.

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No doubt. Brew that f*cker hard and fast.

You'll also have to factor in any dead space in your MLT. Mine has about a 0.125 gallon dead space, so I increase my total sparge water by 0.125 gallons.

I highly encourage you to test your evaporation rate. Just boil 3 gallons of water or so in the same pot, same burner and same amount of heat you use to brew for 15 minutes and cool it down. Measure how much evaporated, multiply it by 4. That's your evaporation rate per hour in gallons. I don't have much luck with percentages. For me, it's almost always 1.3 gallons per hour this time of the season regardless of how much water I have at the start.

I always do what beersmith says. You can get the trial version for free.

Use 1.25 quarts/lb = 3.5 gallons (about) for 11 lbs.

The grain will absorb about 0.1 gallons/lb = 1.1 gallons (approximate)

You also have a dead space. It depends on your equipment, but say around a pint.

Loss due to dead space and absorption = 1.1+.125 = 1.225. Lets call it 1.5 gallons.

So starting with 3.5 gallons, you get 3.5 - 1.5 = 2.0 gallons.

You are brewing 5 gallons (I would recommend 5.5 to account for transfer and trub losses to end up with 5 gallons, but lets assume 5 gallons into fermenter).

+ boil off, you need an additional gallon; estimate of 60 minute boil. Longer would be more boil off, and need more starting volume.

So for a 5 gallons into the fermenter you need 6 gallons in the kettle for a 1 hour boil. From the initial Mash you get 2 gallons, so you have to add an additional 4 gallons of sparge water to get your initial boil volume.

A number of variables: dead space, boil off rate, boil time, and volume into fermenter. All are dependent on recipe and equipment.