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Old 09-19-2013, 01:12 PM   #1
Ronkas
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Jul 2012
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Hi guys,
i'm trying to figure out why i've always less wort than expected (1-2L) when I brew my all-grain 5gal bateches.

For calculus and recipe design I'm using BrewMate w/ this (default) settings:
-grain abs rate (L/kg) : 0.90
-sparge deadspace :0L
-evap per hour = 10%
-after cooling loss = 4%
-losses trub/chiller = 0L

I'm doing batch sparging e and i do not use any tools to chill out rapidly the wort.

The only thing i'm thinking about is: how do you count the time on heat between end of mashing/lautering and rolling boil (100C)?
My burner isn't so powerful and it needs some time to reach boiling (30-40mins), for a total time on high heat of 90mins avg.

Are my losses caused by more evaporation than i expected?
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Old 09-19-2013, 01:30 PM   #2
brewmeister13
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Possibly, you need to get to know your system and adjust the default setting to match. If you are always between 1-2L short I would suggest adding trub/chiller losses in that amount to compensate.

 
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Old 09-19-2013, 08:33 PM   #3
acidrain
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your 10% boil-off rate is wrong.
Setting the boil-off rate is critical. I set mine as a constant... it's always 2 gallons per hour regardless of how big the batch is.
I suggest you boil a given amount of water and check the actual boil-off rate for your system.
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Old 09-19-2013, 08:45 PM   #4
feinbera
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Do you know exactly where you're losing the volume?

It could be you're boiling off more than expected, but it looks like you're also assuming no deadspace in your mash tun and no trub losses. Now, this isn't impossible -- you could be doing BIAB and squeezing every last drop outta the bag for zero sparge deadspace, and just dumping the whole cooled kettle into your fermenter after your boil. But most people leave some wort in the mash and some trub in the kettle; if you're one of them, you have to take that into account, too.

 
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Old 09-19-2013, 08:46 PM   #5
LandoLincoln
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Yeah, water doesn't boil off by percentage. You need to carefully measure out a certain amount of water, get it up to boiling, and then time it for 15 minutes, then quickly cool off that water and measure how much you lost. The loss x 4 = how much water you'd lose in a 60 minute boil.
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Old 09-19-2013, 08:51 PM   #6
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Quote:
Originally Posted by feinbera View Post
Do you know exactly where you're losing the volume?

It could be you're boiling off more than expected, but it looks like you're also assuming no deadspace in your mash tun and no trub losses. Now, this isn't impossible -- you could be doing BIAB and squeezing every last drop outta the bag for zero sparge deadspace, and just dumping the whole cooled kettle into your fermenter after your boil. But most people leave some wort in the mash and some trub in the kettle; if you're one of them, you have to take that into account, too.
Also a very good point. Take four cold gallons of water and run it through your whole system, all the way to the fermentation bucket or carboy. Measure how much water is in the carboy. The missing volume is how much water you lose from deadspace / tubing.
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Old 09-20-2013, 01:35 AM   #7
retheisen
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Quote:
Originally Posted by acidrain
your 10% boil-off rate is wrong. Setting the boil-off rate is critical. I set mine as a constant... it's always 2 gallons per hour regardless of how big the batch is. I suggest you boil a given amount of water and check the actual boil-off rate for your system.
Can relative humidity effect boil-off to any appreciable amount?

 
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Old 09-20-2013, 11:16 AM   #8
Ronkas
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Thank you all for all the good replies.

First I'm brewing in a mash/lauter tun made in a 50L inox bucket with copper manifold e ball valve, not BIAB.
I've almost no deadspaces 'cause i've little/no tubing: no chillers. When collecting the wort from the kettle I lost .5 - for trub, but the total is still less than expected (1,5 - 2L less).

The crucial settings in my opinon are:
-Time on the stove when boiling. Finished the sparging and put the wort in the kettle on heat, do you start the boil timer counting propmtly or wait that wort is reaching rolling boil (100C)? Because for now i always started the timer when wort reached 100C, and IMO, i'm missing water that is evaporating in the gap from lautering to reaching boil.
-Grain absorption rate. Because i don't squeeze every grain, it should be a value that integrates the fact that some sparge water is remaining in the m/l tun. Maybe is more than 0.9?
-Evaporation per hour. IMO is surely function of the relative humidity (here is about 80%) and area in contact with air, don't know other variables. Anyway, i'm googled on it and also folks using BrewSmith have set it on 8 - 12%

Also here there's a good article (hope theresn't nothing wrong in linking it)
http://byo.com/stories/item/874-how-...ggressive-boil
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Old 09-20-2013, 11:41 AM   #9
IslandLizard
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You're not that far off, only missing about 10% of your volume. I have the same problem, always coming up a bit short in the fermentor, even after draining my hoses and plate chiller. I keep adjusting to close the gap.

-grain abs rate (L/kg) : 0.90 <== commonly 0.13 Gal/lb = 1.08 l/kg ==> Check your actual absorption: Strike volume - first runnings volume. Divide that number by your grain bill weight.

-sparge deadspace :0L <== you could lose 250ml to a liter there, even when you think it is 0. I don't tip my converted cooler mash tun at the end to prevent sucking in grain bits and flour.

-evap per hour = 10% <== As mentioned already, that is usually a fixed amount. And some evaporation occurs while heating up to boil.

-after cooling loss = 4% <== what is this? contraction (cool water has smaller volume than hot water)?

-losses trub/chiller = 0L <== That could be a significant higher amount, and is never 0. Hops and cold break are like a sponge.

 
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Old 09-23-2013, 08:10 AM   #10
Ronkas
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Jul 2012
Mo, Italy
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Lizard has right.
I'll try to change some values

-grain abs rate : 0.9 L/kg -> 1.08 L/kg
-sparge deadspace : .1 L
-evap per hour (i can't put it as a fixed amount in my tool) : 10%
-losses trubs/chill : .5 L

I'll put the results of the next batch!
Thank you!
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Wine is as good as life to a man, if it be drunk moderately: what life is then to a man that is without wine? for it was made to make men glad. Wine measurably drunk and in season bringeth gladness of the heart, and cheerfulness of the mind: But wine drunken with excess maketh bitterness of the mind, ith brawling and quarrelling.
Sirach 31,27-30

 
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