How to determine mash/sparge volume?

[NOISEpollution]

What’s the procedure for determining the amount of water I’ll need for an all grain, 5 gallon, mash and sparge?

For my last IPA, I just guessed and used 4.6 gallons for the mash and sparked with 4.4 gallons. I forget what the pre-boil volume was... either 6.5 or 7.5 but boiled down to 5.5 on the dot after 60 minutes. Assuming there’s a better way to go about this.

 

[JonM]

A sight glass on the kettle makes things really simple.

But before I had that, I just had to take pencil and paper and calculate how much water I'd lose to grain absorption in the mash (.15 gal per pound of grain) and then work backwards from the expected final volume to figure out the sparge.

 

[myndflyte]

A good rule of thumb is to have the same amount of water collected from the first runnings as you do from your sparge. So lets go through an example.

Let's say your recipe has 10 lbs of grain and you want to mash at 1.5 qt/lb and want a preboil volume of 6.5 gal.

You mash with 3.75 gallons (15 qts) and assume you'll lose .15 gal/lb (1.5 gal) to absorption. So your first runnings, right now, would be 2.25 gal (3.75 - 1.5).

But if you want your first runnings and sparge amount to be the same, then we need to run off 3.25 gal. So you could do a mash out by heating a gallon of water to boiling, and add it to the mash once it is done. This will raise the temp and then you'll collect your 3.25 gal.

Then you just sparge (assuming your batch sparging) with 3.25 gal, run it off and now you should have close to 6.5 gal. You may have to change some things based on your mash tun dead space but this should be pretty close.

 

[McKnuckle]

Count back from your desired fermenter volume. Here's an example:

Let's say you want to end up with 5.25 gallons in the fermenter.

How much will you leave behind in the kettle after boiling? Let's say one cup, or 0.06 gal. Add that to 5.25: 5.31 So you'll need to end up with 5.31 gal in the kettle after boiling.

What's your boil-off rate? Let's say 1 gal/hr, or 1 gal. in a 60 minute boil. Add that to 5.31: 6.31 This means you need to start the boil with 6.31 gallons in the kettle.

How much are you leaving in your mash tun that can't be recovered? Let's say another cup, or 0.06 gal. again. Add that to 6.31: 6.37

Now, how much water will your grain absorb that can't be recovered? Let's call it 0.12 gal/lb, a good general estimate. With 10 lb of grist, that's 1.2 gal. Add that to 6.37: 7.57

In this example, you'll need 7.57 gal. of total water to mash and sparge with. Split that volume in half if you like, which makes it easy, or divide it into any number of infusions/rinses you prefer. But make sure to use exactly that much water, no more, no less, and you'll hit your numbers pretty darn closely.

 

[Biscuits]

or just use one of the many calculators out there to determine how much brewing liquor you'll need. I recommend https://pricelessbrewing.github.io/BiabCalc/#Advanced

 

[bgriff]

I mash in a 10 gallon round water cooler with a false bottom. For the first 2 years I used this online calculator,
http://www.brewcalcs.com,
To determine the amount and temp of strike water I needed to mash.

I’ve used this one for the past 4-5 brews and it works just as good plus I can edit from my phone which saves me from having to be at my laptop.
http://www.brew365.com/mash_sparge_water_calculator.php

 

[McKnuckle]

Calculators are great tools. But sometimes it's also good to just know how stuff works.