Pre-boil volume calc?

[Jubilee]

I've been reading a LOT on AG brewing, and one thing I'm still confused about is how to know what your pre-boil volume should be. Space for the pre-boil won't be an issue for me, as I'll be doing (batch sparge) 5 gal batches with a 15 gal boil kettle. So, do you stop your sparge at a certain gravity or an arbitrary volume? I'm confused...

 

[BargainFittings]

Edit. Read to fast.

Batch sparging - Collect until you reach your volumes.

Some brewing software will help you calculate your preboil by taking into account how much you boil off, how much deadspace you have and how much you plan to leave behind (hop sludge, break material)

By adding in the variables it allows the software to adjust your ingredients and volumes.

 

[ajf]

I know that I need 7g in the kettle at the start of the boil in order to end up with sufficient wort to bottle or keg 5g beer. I fly sparge, and monitor the gravity of the runnings towards the end of the sparge. I stop sparging when I have collected the required 7g or when the gravity of the runnings drops below 1.010. If the running drop below 1.010 before I have collected 7g (this is usually the case with beers with an OG < 1.060), then I add water to the kettle to achieve the required volume without running the risk of extracting excessive tannins.

-a.

 

[Jklinden]

He asked about batch not fly! For batch your goal is to do two equal sparge volumes to total up to your desired preboil volume. For me, I drain the tun, see how much more wort I need and go from there. Remember if you over sparge your not losing efficiency per se just diluting the wort with extra water. However wort that is left in the tun is indeed compromising efficiency. Plan it all out. PM me if you want a spreadsheet I built to calc out your sparge volumes
J

 

[Jubilee]

Thanks guys... B.F. I'll be ordering a cooler kit and weld-on kettle hardware from you very soon!

Sounds like it'll take a couple batches to familiarize myself with how my gear behaves. Will play with BeerSmith at home tonight.

 

[JonM]

Here's what I do for a 2.5 gal batch:

Say I have 5 lbs grain. I mash with 1.25 qt/ lb. That's 6.25 qts or 1.56 gal. for the mash.

I know I'll lose .15 gal per pound of grain to absorption. .15 x 5 lb is .75 gal.

So yield from my mash is 1.56 - .75, or .81 gals.

I know my stove boils off .85 gals/ hour, so for a 2.5 gal batch I need 3.35 gals to start.

3.35 minus the yield from the mash (.81 gals) is 2.54. So 2.54 gals is what I sparge with. 2.54 plus the .81 from the mash is my total volume.

 

[Esmitee]

Here's what I do for a 2.5 gal batch:

Say I have 5 lbs grain. I mash with 1.25 qt/ lb. That's 6.25 qts or 1.56 gal. for the mash.

I know I'll lose .15 gal per pound of grain to absorption. .15 x 5 lb is .75 gal.

So yield from my mash is 1.56 - .75, or .81 gals.

I know my stove boils off .85 gals/ hour, so for a 2.5 gal batch I need 3.35 gals to start.

3.35 minus the yield from the mash (.81 gals) is 2.54. So 2.54 gals is what I sparge with. 2.54 plus the .81 from the mash is my total volume.

I know this is an old thread BUT,

John, is the .15 gal per pound absorption rate , a standard for all grains?
Im new 2 AG and have several recipes to make, but none state the pre boil volume. I too, still don't get how to come up with that.

From what I gathered from excessive reading hear.....LOL
You work backwards from your "choosen" pre boil volume.
Is that correct? Meaning to get mash, strike and sparge amounts of water?

Man I'm confuzed!

 

[tektonjp]

I know this is an old thread BUT,

John, is the .15 gal per pound absorption rate , a standard for all grains?
Im new 2 AG and have several recipes to make, but none state the pre boil volume. I too, still don't get how to come up with that.

From what I gathered from excessive reading hear.....LOL
You work backwards from your "choosen" pre boil volume.
Is that correct? Meaning to get mash, strike and sparge amounts of water?

Man I'm confuzed!

At first it can be daunting. It's a long equation,but you can break it down into small bits. And you can work/ solve any part of it.

These are all volumes, okay?

If you put preboil volume in the center, here are the before and after inputs.
pre-boil = into fermenter + leftover in pot + evaporation

pre-boil = total mash/sparge water - grain absorption

Moving any of these to the other side of the equation let's you solve it. ie. total mash/sparge water needed is preboil + grain absorption.

If you recipes calls for 3 gallons, that's probably the finish size. plug it in and start adding up what is needed. Clear as mud?

 

[Esmitee]

plug it in and start adding up what is needed. Clear as mud?

Tektonjp, thanks, I'd say kinda like murky mud, Like I can almost see the bottom through the water......... SO

Would you mind if I did some calculations and let you review them in a post here, to see if I can clearly see the bottom LOL

 

[tektonjp]

post away. if i can't get them, without a doubt someone else way smarter than I will join in the fray.

 

[JonM]

I know this is an old thread BUT,

John, is the .15 gal per pound absorption rate , a standard for all grains?
Im new 2 AG and have several recipes to make, but none state the pre boil volume. I too, still don't get how to come up with that.

From what I gathered from excessive reading hear.....LOL
You work backwards from your "choosen" pre boil volume.
Is that correct? Meaning to get mash, strike and sparge amounts of water?

Man I'm confuzed!

.15/pound is an estimate. I always measure the actual first runnings and then make adjustments in the sparge volume kind of on the fly.

Yep, work backwards. Know how much you'll boil off in one hour, add that to the batch size, and work backwards from there. Cheers!