Help me understand how much water to use

[Ben_Persitz]

I am having a hell of a time figuring out sparge and mash water calculations.

Check out my recipe and planned calculations here and see if I'm understanding this. I've tried using online calculators but it seems like I'm going to have TOO MUCH water.

My setup is a 5 gallon brew pot, a 10 gallon converted cooler stainless steel with about .5 gallon deadspace. I'm adjusting for a 10% boiloff per hour, about .25 gallon loss in trub.

Is the .25 gallon loss pretty bold? Should I be more conservative?

This is a 3.5 gallon batch with an o.g. of 1.058 (based on a 3.5 gallon batch in beersmith with a 4.01 gallon boil). My mash thickness is 1.4 qt/1 lb

I'm using about 8 pounds of grain.

So the calculator is telling me to mash with 2.75 gallons of water and sparge with 3. This would give me 5.75 gallons.

I'm assuming a gallon or so of loss to grain absorption which means I'm at 4.75 gallons pre-boil. There's no way that's going to boil down to 3.5 gallons in one hour. Maybe about 4.25--then we're looking at about 4 gallons going into the fermenter, not 3.5

I'm worried that'll screw up my O.G.

So what am I doing wrong? Can someone explain this?

 

[bherder]

How much grain are you using? You should use 1 qt to 1.25 qt per pound of grain for mash. Then a half gallon of water for each lb of grain for sparge. That is what my book told me anyway.

 

[motobrewer]

yeah i donno. i generally get rid of at least a gallon of water in a 60 minute boil.

the key is finding out how much your system boils off.