Author Topic: Brew house efficiency revisited  (Read 655 times)

Offline BrewBama

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Brew house efficiency revisited
« on: February 01, 2015, 06:02:27 PM »
I am brewing an Irish Red Ale today and I'm in Brew Smith looking at the numbers.  If everything goes 100% to plan, I'll get a 1.056 OG which is 70% brew house efficiency using my equipment profile and batch sparge.  ...but so many others here report higher efficiency ...in the 80+% range.

If I increase the OG in Beer Smith, I get higher brew house efficiency.  OR  If I increase the amount of wort that enters the fermenter I get higher brew house efficiency.

So... for those getting in the 80+% range when batch sparging my question becomes: a) Do you have near zero loss to trub and dead space in the boil kettle? or b) Are you getting more OG from your grain?

I can see how "a" would be accomplished: simply dump everything into the fermenter and voila - more efficiency.  I have about a gallon of dead space where the trub rides below what I consider usable wort that exclude from the fermenter.  When I deduct this dead space and loss to trub to my equipment profile and get the desired OG from the grain bill I get 70% brew house efficiency.

But I cannot see how "b" would be accomplished.  With a given mash Ph and water chemistry, a grain bill is going to give you the same OG as it will me ...won't it?

In other words, when you say you're getting 80% and I am saying I get 70%, are we talking apples and oranges, or are we measuring the same way?
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Offline Wort-H.O.G.

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Re: Brew house efficiency revisited
« Reply #1 on: February 01, 2015, 06:08:22 PM »
read this-might help differentiate for you the mash efficiency from brewhouse efficiency.

http://beersmith.com/blog/2014/11/05/brewhouse-efficiency-vs-mash-efficiency-in-all-grain-beer-brewing/
Ken- Chagrin Falls, OH
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Offline mchrispen

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Re: Brew house efficiency revisited
« Reply #2 on: February 01, 2015, 06:25:36 PM »
Quote
So... for those getting in the 80+% range when batch sparging my question becomes: a) Do you have near zero loss to trub and dead space in the boil kettle? or b) Are you getting more OG from your grain?


First, I hope you are not getting all caught up in chasing efficiency. That said - what Wort posted should help.


You should really take a look at your Equipment profile in BeerSmith and make sure it is adjusted appropriately such that your volumes are accurate. If you have that gallon of deadspace, then you should compensate for it. I seriously doubt that anyone is getting higher levels of extract, rather simply being efficient and accurate in volumes.


IMO the real goals should be to have a reasonable extract efficiency, and repeatable volumes and target SG's into the boil and fermenter. That allows your recipe creation to be far more accurate and your brewing to be repeatable with consistent results.


I have to admit that I don't leave behind much in the BK. I try to get as much of the hop matter out as possible, but if it passes into the fermenter, it will fall out. I have a keggle with a false bottom that just catches a portion of the trub and any whole hops I use.

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Re: Brew house efficiency revisited
« Reply #3 on: February 01, 2015, 08:09:54 PM »
I will be the first person to tell you that I have little to no use for efficiency percentages.  In the grand scheme of things, what does an efficiency percentage really tell a brewer?  An efficiency percentage is an abstract value that is difficult to translate to pounds of grist necessary to hit a target O.G. at a given volume without significant computation.  To further complicate things, efficiency percentages are based on a static look-up table of theoretical maximum extraction rates that may not bear any direct relationship to the actual bag of malt being used in the girst.  Efficiency percentages did not play much of a role in practical home brewing until brewing software became common place, and home brewers were still able to calculate accurate batch-to-batch original gravities.

Let's ask ourselves a question, what is the goal of calculating an efficiency percentage?  If that goal is something other than bragging rights, then we need to eliminate the abstraction and switch to a system of direct measurement;  namely, points per pound per gallon (PPG) or points per kilogram per liter (PKL).  Both of these measurements give us directly usable numbers.  PPG and PKL were common place measurements before the introduction of brewing software.  These units of measure are still common enough that British maltsters tend to quote extraction rates as HWE (Hot Water Extract) in PKL on their malt analysis sheets, not DBFG (Dry Basis, Fine Grind) percentages.

Now, forum members are wondering how I apply this system to produce accurate values on which to base my recipes.  My system is so simple as to be almost trivial.  First off, after casting out the clear wort to a primary fermentation vessel, I remove the hops and break from my kettle.  I use whole cones almost exclusively; therefore, I squeeze as much liquid as I can from the hops and measure it (this wort does not get added to the primary).  This volume along added to the cast-out wort volume becomes my finished batch volume.  I then multiply the original gravity in points (e.g., 1.052 is 52 points) by the finished batch volume and divide by the weight of the grist, yielding batch points per pound.

batch_points_per_pound = batch_original_gravity_in_points * batch_volume / grist_weight

Now, the next step is to track and sum multiple batch_points_per_pound values and divide by the number of values summed, yielding an average_batch_points_per_pound value.   From here, calculating the standard deviation will tell the brewer how far one standard deviation lies above and below the mean (average).  In practice, we really do not need to calculate the standard deviation.  What will happen is that one will start to categorize "like" grists based on the percentage and type of base malt that is in the grist because the base malt used in a recipe drives extraction rate.  For example, two of my main categories are 90/10 and 80/20, that is, 90% base malt/10% other and 80% base malt/20% other.   Recipes that fall between 80 and 89% malt are clustered together as are recipes between 90 and 100% base malt.

In practice, while clustering allows one to achieve higher levels of accuracy.  One will find that all of one's batches will converge to within a spread of 2 to 3 PPG with the occasional outlier.  I also use a sliding window to track the actual bags of base malt being used because the maximum extraction rate for a bag of grain can vary from year to year and malting to malting (in this context, a sliding window is basically using the most recent batch extraction values in my average batch extraction calculation).  For example, if my recipes have been yielding PPG values between 31 and 33 PPG, I will pick 32 as my PPG value.  If I want to yield a final batch volume of 5.5 gallons of 1.058 wort, I multiply the O.G. in points by the final batch volume and then divide that value by 32, yielding pounds of grist necessary to hit that target O.G.

grist_weight = batch_original_gravity_in_points * batch_volume / batch_points_per_pound

grist_weight = 58 * 5.5 / 32 = ~10lbs

This system can also be used to reverse engineer commercial beers if one knows the percentages of the grist.  For example, it has been claimed that SNPA is composed of 97% domestic 2-row and 3% caramel malt.  We want to formulate a recipe that will yield a final volume of 5.5 gallons.  SNPA has an O.G. of 1.053.

grist_weight = 53 * 5.5 / 32 = 9.1lbs

weight_of_2row = 9.1 * 0.97 = ~8lbs 13oz
weight_of_caramel = 9.1 * 0.03 = ~4.4oz

In practice, I tend to round to even ounces and often to even fractions of a pound if doing so does not alter the grist percentages horribly. If one takes the time to calculate the percentages of grain in any given recipe grist, one can scale that recipe for one's brew house using the system outlined above. 

In the end, whatever system a brewer uses, the primary goal should be consistent batch-to-batch results.  My system has yielded consistent batch-to-batch results since 1993, and it is so simple that the grist for any given wort can be casually penned on that back of a napkin while having a few pints at a local craft beer bar.  There's something to be said about keeping the things that we can control simple.

« Last Edit: February 02, 2015, 01:37:04 AM by S. cerevisiae »

Offline BrewBama

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Re: Brew house efficiency revisited
« Reply #4 on: February 01, 2015, 08:23:35 PM »
I think you're right Matt and Mark.  Thank you both.  I was using brew house efficiency to compare myself to others.  I think I'll quit getting all caught up in chasing efficiency and drink the beer I brew.  After all, it is awfully good.

Having said that, I was not 100% perfect today.  My mill is set to .025 which is the most I can tighten it, I condition the grain prior to milling to keep husks in tact, and I don't get stuck sparges.  With 11 lbs of grain, I hit 1.054 OG with 5 gal in the fermenter and  one gallon left in the boil kettle.  A while back I read somewhere that I should expect 5 points per pound of grain so by this rule of thumb I was 1 point off.  In my opinion that's within tolerance. 

However, 1.054 was 2 points below the Brew Smith estimated OG of 1.056 which resulted in a 67.1% brew house efficiency (per Beer Smith).  ...but if I added the gallon left in the kettle (which I easily could have by simply pouring it in the fermenter), I get 80.5%.

Oh well.
« Last Edit: February 01, 2015, 08:43:49 PM by BrewBama »
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Offline HoosierBrew

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Re: Brew house efficiency revisited
« Reply #5 on: February 01, 2015, 08:56:47 PM »
+1 to everything said.  The difference in getting 70 and 75% efficiency (or 75 and 80, etc.) is maybe a buck or two a batch.  In the scheme of things, irrelevant.  What is important is to dial in your system accurately - draining your mash tun dry with your preboil volume spot on, and hitting post boil volumes consistently. That will give you pretty steady efficiency and therefore the important thing - consistency. A 75% efficient beer doesn't inherently taste any worse than an 80% efficient beer. It's all about consistency.
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Offline BrewBama

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Re: Brew house efficiency revisited
« Reply #6 on: February 01, 2015, 09:28:20 PM »
Good read Ken.  Thanks Jon.  Spot on - both of you!  I am evolving.
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Offline Wort-H.O.G.

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Brew house efficiency revisited
« Reply #7 on: February 01, 2015, 09:41:00 PM »
Good read Ken.  Thanks Jon.  Spot on - both of you!  I am evolving.

Sure thing. Key is just knowing where you are at and planning accordingly. As mentioned, it's ok to try and squeeze the potential yield out-just knowing or doing that that will not make better beer. I just know my system and can easily nail whatever I target.....that's my objective.
Ken- Chagrin Falls, OH
CPT, U.S.Army
https://www.facebook.com/pages/Harveys-Brewhaus/405092862905115

http://braukaiser.com/wiki/index.php?title=The_Science_of_Mashing

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