Author Topic: Water loss to absorbtion and evaporation.  (Read 1321 times)

Offline quest4watneys

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Water loss to absorbtion and evaporation.
« on: March 18, 2011, 05:44:44 PM »
So how much water is lost to grain absorbtion during mashing and evaporation during boiling?
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Offline euge

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Re: Water loss to absorbtion and evaporation.
« Reply #1 on: March 18, 2011, 05:48:34 PM »
So how much water is lost to grain absorbtion during mashing and evaporation during boiling?

One to two gallons per hour depending on boil intensity. As for absorption off the top of my head about a cup per pound.
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Offline timberati

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Re: Water loss to absorbtion and evaporation.
« Reply #2 on: March 18, 2011, 06:00:31 PM »
Absorption - According to Denny's write up of "Cheap 'n' Easy Batch Sparge Brewing" ( found at http://hbd.org/cascade/dennybrew/ ) water absorbed by grain is around .1 gal./lb.

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Offline tygo

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Re: Water loss to absorbtion and evaporation.
« Reply #3 on: March 18, 2011, 06:44:28 PM »
For grain absorption.  0.12 gallons per lb is the common convention if memory serves.  I generally use a slightly higher factor to account for not only actual grain absorption but dead space losses.  But it hovers around that value depending on the size of the mash and how much water I use.

Evaporation during boiling can vary widely.  It depends a lot on the dimensions of your pot as well as boil vigor.  Shorter, wider pots will have a higher evaporation rate and taller, thinner pots a lower one.  From experience I've found that ambient humidity has an impact as well, although I can't quantify it exactly.

Both absorption and boil off are going to be a little bit different for everyone depending on your system.  Experience will give you an indication of what it's going to be for you.
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Offline quest4watneys

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Re: Water loss to absorbtion and evaporation.
« Reply #4 on: March 18, 2011, 07:10:30 PM »
How would I calculate the amount of water needed for a given recipe from mash tun to fermenter for a 5 gallon recipe? I'm having a little trouble wrapping my head around how to end up with the correct amount of wort to boil. I guess I should've stayed awake during math class :)
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Offline denny

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Re: Water loss to absorbtion and evaporation.
« Reply #5 on: March 18, 2011, 09:36:39 PM »
Absorption - According to Denny's write up of "Cheap 'n' Easy Batch Sparge Brewing" ( found at http://hbd.org/cascade/dennybrew/ ) water absorbed by grain is around .1 gal./lb.



I appreciate the citation, but that's an estimate and was rounded off for the sake of easy calculation.  I suggest you take a few brews to actually measure it.  I think that these days mine is running pretty close to .12 gal./lb.
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Re: Water loss to absorbtion and evaporation.
« Reply #6 on: March 19, 2011, 01:27:15 AM »
"How would I calculate the amount of water needed for a given recipe"

You can work this backwards and get in the ballpark for water needed(remember, you'll have H20 losses during the whole process):

5.5 gallons of wort in the fermentor(after fermentation using a racking cane you'll leave a quart to a 1/2 gallon behind)

+ amount of grain in recipe X .12 i.e. absorption

+ evaporation of boil (you can start with ~ 1.25-1.5 gallons per hour)

+ dead space losses depending on your equipment configurations.(you can figure this by using just water and see what's left in the brewing vessels after draining via valves etc.)

Should give you a ballpark of total water needed. It will be up to you to decide how much in mash kettle and sparge. Usually you go with the larger quantity in the mash tun. Anywhere between 1.3 quarts per lb up to 2 quarts per lb once again depending on your recipe and your equipment specs and limitations. Take good notes so you can adjust and "dial in" your system until it becomes "old hat"

hth

Offline oscarvan

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Re: Water loss to absorbtion and evaporation.
« Reply #7 on: March 21, 2011, 08:18:51 AM »
"How would I calculate the amount of water needed for a given recipe"

You can work this backwards and get in the ballpark for water needed(remember, you'll have H20 losses during the whole process):

5.5 gallons of wort in the fermentor(after fermentation using a racking cane you'll leave a quart to a 1/2 gallon behind)

+ amount of grain in recipe X .12 i.e. absorption

+ evaporation of boil (you can start with ~ 1.25-1.5 gallons per hour)

+ dead space losses depending on your equipment configurations.(you can figure this by using just water and see what's left in the brewing vessels after draining via valves etc.)

Should give you a ballpark of total water needed. It will be up to you to decide how much in mash kettle and sparge. Usually you go with the larger quantity in the mash tun. Anywhere between 1.3 quarts per lb up to 2 quarts per lb once again depending on your recipe and your equipment specs and limitations. Take good notes so you can adjust and "dial in" your system until it becomes "old hat"

hth

That jives with what I do.....

So to work a 10 pounds of grain and 60 minute boil example.....

5.5 + (10*.12) = 5.5 + 1.2 = 6.7 + 1.25 (evap) = 7.95 + .55 (arbitrary loss number) = 8.5 (nice round number)

Now since the infusion has the grain loss I would use 5 gallons for the infusion, and then 3.5 for the sparge.

BUT, all the math aside, the easy way is to take your spoon, or similar and stand it straight up in the brew kettle and add water, one gallon at a time to make a measuring scale. Do a 5 gallon infusion and then you measure and KNOW how much wort you end up with after the infusion. Now, all the absorption is done, as well as system loss. So now you know how much more you need and you make the sparge that large.

If all else fails and you have a little too much, boil a little longer, or, if you are a little short, add some water when you're all done.

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« Last Edit: March 21, 2011, 10:11:51 AM by oscarvan »
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Re: Water loss to absorbtion and evaporation.
« Reply #8 on: March 21, 2011, 12:22:58 PM »
I hadn't been brewing for a couple of years and just got back into it again this weekend. 

I think I neglected to account for how much water the mash would soak up - and how much I'd lose to evaporation.  I was shooting for a 10 gallon batch, but I think I wound up with a little under 9 gallons.

The VERY basic run-down of the process I used to brew this batch can be seen HERE - video coming later for those interested...
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Offline Beer Monger

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Re: Water loss to absorbtion and evaporation.
« Reply #9 on: March 22, 2011, 08:07:19 AM »
The video of my brewing session on Sunday is up - for those interested in taking a look.  It's a 15 minute video and covers the whole brew process, from start to finish. I hope you enjoy it. 

This was my first attempt ever at videoing myself while brewing.  Clearly, I enjoy the word "OK" too much.  lol  I'll try to make sure I don't start each segment with "OK" next time.  ;) 

Also, I was alone this time, so much of the video is from a tripod.  I'm hoping to have a 'cameraman' with me next time, to get some better shots. 

http://www.youtube.com/watch?v=ql8bYJ8Zi4Q
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