All grain brewing

[mparmer]

does the water that is used in the "rest(s)" steps become part of the wort or is it discarded and only the water that comes out once the sparge starts what makes up the wort. I'm confused because the instructions I've found will say to heat up 2 or 3 gallons for the strike and so on for the rest steps and then say to heat up another 6 to 7 gallons for the sparge. How can it take 8 or 10 gallons to wind up with 5 or 6 gallons of wort. Is the balance left in the mash tun with the spent grains once all the sugars are sparged out and the wort is collected? Thanks

 

[EvilGnome6]

The grain will absorb water. On my last batch, I used 8 gallons and ended up with 6.5 in the kettle (1.5 absorbed by the grain).

 

[The Pol]

You can typically assume .12gal of water being absorbed per pound of malt.

ALSO, instructions are generic. You will lose water to:

Grain absorption
Losses in the MLT
Losses in the BK
Boil off (remember this can be 1-2 gallons alone)

Also, they will tell you 6-7 gallons to sparge with... this is so that you have enough. You wont use all of this, you stop running off when you have met your PRE BOIL volume.

A 10 pound grain bill will absorb 1.2 gallons of water, typically.

If you begin with 3 gallons in the mash, it will absorb say 1 gallon. Leaving you with 2 gallons, almost every MLT has dead space, so you wont get that whole 2 gallons out. Your pre-boil volume should be 6.5-7 gallons generally. You will get 1.5-1.75 gallons from the mash in this scenario and have to use about 6 gallons of sparge water. Remember you are losing wort to hops and trub after the boil, so you dont even end up with everything that is left in the BK when you are done.

Youjust dont want to run out when you are sparging, so it is good to have some extra on hand.