Author Topic: Low OG - Excess Water from AG Batch Sparge  (Read 6676 times)

Mij

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Low OG - Excess Water from AG Batch Sparge
« on: September 20, 2008, 04:32:26 PM »
Hello guys,
I really need some help with this one...  I'm all grain, performing batch sparges.  I've attached my recipe for your perusal :)

Here's my problem - I ALWAYS end up with too much water and low pre-boil gravity after sparge.  Today, for example (and why I'm writing this post), I did the attached recipe.  My boil volume should have been 30.90 liters, however, I wound up with 33 liters instead.  My pre-boil OG should have been 1.049 but was 1.040...  I'm SO discouraged.

I have lowered my "Batch Efficiency" to 65% in BS, it used to be 70% but I'm trying to get it "closer" to what reality happens to be.

I'm in the process of defining each step of my process; things like getting my exact evap rate (4 liters/hour), batch sparge temp, etc.  I'm stuck, however, on why I keep getting more wort than I should when I perform my sparges...

To the best of my ability, I believe that BS uses something like .455 liters of water per pound as the grain absorption rate - but I am getting way less than that.

I perform my own grain crush, Barley Crushed with about .36 +/- on the rollers.

I perform batch sparge:  2 step, both equal size.  I add the water, stir for 2 minutes then let it rest for 5 minutes.  Perform my vourloff (sp?) and let it drain.

Guys, can anybody help me understand what's going on?  Am I really getting a grain absorption rate around .3 liters/pound?  Can that be improved?

Mij

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Re: Low OG - Excess Water from AG Batch Sparge
« Reply #1 on: September 21, 2008, 08:32:47 AM »
Update #1

I've become somewhat convinced that my grain absorption rate is MUCH lower than the rate used in BS.  I really do think that I'm around the .08gal/lb...  Here's a link to Ken Schwartz's page on batch sparging  http://home.elp.rr.com/brewbeer/files/nbsparge.html

"Also, you'll need to pick a number representing the absorption of liquid by the grain.  A well-drained mash will hold about 0.08 gal./lb ((0.67 l/kg), but you may want to consider using a larger figure so that you won't have to wait all day for that last drop of wort to find its way out of the mash tun.  Also, depending on your mash tun design, you may not be able to recover all the liquid no matter how long you wait, and so a higher absorption value is required.  A figure of 0.13 gal/lb (1.08 l/kg) or one pint per pound is a pretty good compromise between time saved and grain wasted."

I use a false bottom on a 10 gal rubbermaid tun and it really does drain well...  When I'm done at the end of the brewday, there is little water 'cept what's in the grain itself...

I've seen that there have been request to change the grain absorption rate, but I guess it's not available yet.  Does anybody know of a good workaround?  I'm thinking if I just reduce my water by 1 liter for the 1st sparge and 1 liter from the 2nd sparge that just might be close enough...

OR, if there is a setting that I can change, please let me know!!!

Thanks!
Jim

Offline UselessBrewing

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Re: Low OG - Excess Water from AG Batch Sparge
« Reply #2 on: September 22, 2008, 10:30:07 AM »
Here is my understanding:
The water absorption rate for grain is a fixed number because the absorbency of all grains are different. The setting in beersmith is close enough for almost any situation.

I believe your issues stem from your equipment setup incorrectly. Here is the official equipment setup site: http://www.beersmith.com/equipment_setup.htm. You might also find this helpful: http://www.beersmith.com/forum/index.php?topic=1749.0.

After I got my equipment dialed in I find, I'm usually in the mid 70's and sometimes in the 80 percentile on efficiency. I wrote a small blog about it here http://uselessbrewing.com/?p=61. Hope this helps.
Cheers
Preston
The woodpecker pecks, Not to annoy, But to survive!

Mij

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Re: Low OG - Excess Water from AG Batch Sparge
« Reply #3 on: September 22, 2008, 10:55:15 AM »
Useless Brewing,
Thanks for the response.

I'm working on a couple of things; understanding the impact of each type of sparge action and understand how BS determines water/gravity estimates.

To the first, I have not been performing a mash out step as I've simply used the BS basic batch sparge mash profile.  Perhaps that will make a shift in efficiency :)

The 2nd however is really my bigger concern:  water addition and calculations.  I have brewed my last 4 batches and kept pretty decent notes on what I put in at each step (just as the BS recipe dictates).  I'm SURE I was accurate as I couldn't remember the number from the 5th batch ago and then started keeping better notes!!  So, over the past weekend, I added the water and got just way too much pre-boil volume.

That's why I'm not entirely confident that my equipment setup is really throwing off the numbers:  there is really only a single variable - mash tun loss (I measured 1 liter) - which impacts how much pre-boil water is affected.  This is why I keep coming back to the grain absorption rate calculation in BS, that's the only variable left that would impact having too much water - right?

Off topic, I'm really considering going back to fly-sparging.  Not that it would solve this issue, but I'm seeing more and more time performing batch sparge activities (like considering a 3rd run-off for large grain > 15lbs batches).

Thoughts?

Mij

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Re: Low OG - Excess Water from AG Batch Sparge
« Reply #4 on: September 25, 2008, 06:21:01 AM »
Bump.

Guys, any help with recommendations on reducing the pre-boil water?

Offline UselessBrewing

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Re: Low OG - Excess Water from AG Batch Sparge
« Reply #5 on: September 25, 2008, 03:11:42 PM »
Sorry its been a little hectic at work lately, No play time for me latley. I believe that doing a mash out will help with efficiency, as far as the pre-boil volume. If you add X amount of water to the grain and you are getting a different amount in the kettle than expected, then either your measuring device is incorrect, or the amount of water absorbed by the grist differs from batch to batch. Currently there is no changing the water to grain absorption rate. The fact that this is a variable that changes from batch to batch to me means it is one of those "Close Enough" settings that we have to deal with.

Can you tell us what your equipment settings are for the following. Lauter tun Deadspace, top up Water for Kettle, check mark in Calculate boil volume automaticly, Evaporation Rate, Lost to Boil Trub and Chiller, Top up water, Cooling loss Pct, and Final Volume. You may be asking yourself why would he want boiler information, the reason is because this affects how much water will be boiled out of the kettle.

Here are my settings: Lauter tun Deadspace .25G, top up Water for Kettle 0G, check mark in Calculate boil volume automatically Yes, Evaporation Rate 15%, Lost to Boil Trub and Chiller .5G, Top up water 0G, Cooling loss Pct 4%, and Final Volume 5.5G.

Personally I'm not bothered by an extra 2 liters/.5G for me that's close enough.  DWHAHB. Either way you are making beer, so you get a few bottles more than expected. Thats not a bad thing. For instance it equates to about less than half a % abv. I always make my batches 5.5 because I like to leave a buffer when I transfer out of the primary.

We may have to wait for the next release for this feature to be implemented. If it is implemented at all.

Cheers
Preston
The woodpecker pecks, Not to annoy, But to survive!

Mij

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Re: Low OG - Excess Water from AG Batch Sparge
« Reply #6 on: September 26, 2008, 08:13:11 AM »
Batch Size: 21.00
Mash Volume: 37.85 L
Boil Volume: 30.90 L
Mash Tun Weight: 4.08 kg
Evaporation Rate: 13.00 %
Mash Tun Specific Heat : 0.300 cal/g-deg C
Boil Time: 90.0
Mash Tun Deadspace: 1.00 L
Top-up for Boiler: 0.00 L
Equip Hop Utilization: 100.00 %
Losses to Trub/Chiller: 3.00 L
Cooling Loss (%): 4.00
Top up water for Fermenter: 0.00 L


I think we're pretty much the same along the thought/process lines - I also like to leave 5.5 (21L) of wort to get into the fermenter...

I hope those following the thread don't misunderstand - of ALL the brew products out there, I CLEARLY believe BS is the best!  Hands down - I get the "process" and design of the tools and can really appreciate them.

My primary goal is to make my process MATCH what BS is telling me (and the other way around too).  I hear you about the 2 liters worth of difference; yes, I can boil for another/extra 30 minutes - but the point is I don't want to!  I want to NAIL the H2O numbers!

Ok, let's assume that BS will not change the default grain absorption rate anytime soon (if at all) - do you (or anybody else) have any suggestions on the "BEST" way for me to "correct" for this?

Offline UselessBrewing

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Re: Low OG - Excess Water from AG Batch Sparge
« Reply #7 on: September 26, 2008, 12:04:00 PM »
Ok, let's assume that BS will not change the default grain absorption rate anytime soon (if at all) - do you (or anybody else) have any suggestions on the "BEST" way for me to "correct" for this?
I would say change the evaporation rate down to 10% and Losses to Trub/Boiler -1L and you are there.

Hope this helps

Cheers

Preston
The woodpecker pecks, Not to annoy, But to survive!

Mij

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Re: Low OG - Excess Water from AG Batch Sparge
« Reply #8 on: September 26, 2008, 01:17:19 PM »
Ah, but BS is Too Smart for that!  It automatically reduces the pre-boil amount to reflect that change :)

I think that I'm just gonna try the following:

  • Let BS build my recipe (let's use 10 lbs of grain)
  • Compute the H2O Requirements
  • Determine how much water BS Calculates:  # of grain x 0.13 = 1.3 gallons
  • Determine how much water I think I use:  # of grain x 0.08 = 0.8 gallons
  • Subtract my amount of water from the BS amount of water:  1.3 - 0.8 = 0.5 gallons
  • Subtract 0.5 gallons from the sparge water (using a single infusion sparge)

The challenge now is when do I get to brew another batch!!!  ;)

 

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