Author Topic: measuring efficency  (Read 1955 times)

Offline micsager

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measuring efficency
« on: December 06, 2012, 10:13:43 AM »
I see many posts regarding homebrew efficiency.  I'm wondering how many folks really go to all the hassle to accurately measure efficiency.  At least I think I wonder.  I remember a BrewStrong episode where the crew was explaining how to accurately measure one's efficiency, and IIRC it was quite involved with exact potential of grains, and very spcific water volumes. 

Or is there an easier way?  I have beersmith set at 75% efficiency, and I always come close to the estimated OG.  (1.065 on BS, and I'll hit 1.060) I suppose I could adjust the efficiency in BS to the point where I'm right on, and figure that is my efficiency. 

How do you all measure your efficiency?

Offline Joe Sr.

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Re: measuring efficency
« Reply #1 on: December 06, 2012, 11:01:20 AM »
I pretty much do what you do.  Sometime I hit it right on.  Sometimes I'm a bit off.

I only get pissed when I'm significantly off, but that's not happened recently and is likely attributable to inaccuracies in measuring sugar, DME, honey or other sugar additions.
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Offline anje

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Re: measuring efficency
« Reply #2 on: December 06, 2012, 11:08:25 AM »
Similarly, I'm curious how you all measure volumes accurately, particularly for top-offs, post-boil, etc. Clearly you'll need this for efficiency calculations.

I've been going by the graduations on my fermenter buckets as best I can, but I can't even pretend that those are particularly accurate. Is there a preferred way?
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Offline weithman5

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Re: measuring efficency
« Reply #3 on: December 06, 2012, 11:09:11 AM »
i tend to rough it.  i use my ibrewmaster now as a general guideline but fundamentally i figure what i should get based on the grains i use (roughly) based on their potential. then i figure what my og  gravity is at ferment temp before pitch.  kind of a rough brewhouse total.  quite honestly unless my og or fg are way off from my predicted i don't get bent out of shape.
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Offline rjharper

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Re: measuring efficency
« Reply #4 on: December 06, 2012, 11:15:31 AM »
Similarly, I'm curious how you all measure volumes accurately, particularly for top-offs, post-boil, etc. Clearly you'll need this for efficiency calculations.

I've been going by the graduations on my fermenter buckets as best I can, but I can't even pretend that those are particularly accurate. Is there a preferred way?

I calibrated each of my primaries when I got them.  Some of the buckets were close, others off if the printing wasnt right.  I also calibrated and etched my glass carboys.  My boil kettle and HLT have sight glasses that I calibrated too.

Or is there an easier way?  I have beersmith set at 75% efficiency, and I always come close to the estimated OG.  (1.065 on BS, and I'll hit 1.060) I suppose I could adjust the efficiency in BS to the point where I'm right on, and figure that is my efficiency. 

How do you all measure your efficiency?

Same here.  I know my system is ~67-70% so I set my recipes to 68, then compare the predicted to measured FG.  You have to accurately know the dead volumes in your mash tun, brew kettle etc, and your final volume to fermenter to be accurate.

That said, it's less about knowing your exact efficiency, and more about making it reproducible so that you can hit your targets when you design a recipe.
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Offline Joe Sr.

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Re: measuring efficency
« Reply #5 on: December 06, 2012, 11:20:21 AM »
Similarly, I'm curious how you all measure volumes accurately, particularly for top-offs, post-boil, etc. Clearly you'll need this for efficiency calculations.

I've been going by the graduations on my fermenter buckets as best I can, but I can't even pretend that those are particularly accurate. Is there a preferred way?

I calibrated each of my primaries when I got them.  Some of the buckets were close, others off if the printing wasnt right.  I also calibrated and etched my glass carboys.

I did this with my carboys and better bottles, too, ages ago.  I know it's lazy, but with the last two better bottles, I just put them side by side and marked the volumes from the old bottle.

I fill my kettle from jugs that hold 2.5 gallons so I have a good idea how much water is going in.  Not completely accurate but for the most part I get repeatable results.
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Offline Kaiser

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Re: measuring efficency
« Reply #6 on: December 06, 2012, 11:23:33 AM »
I think there is some value in keeping track of efficiency. At least at the stage at which you care for it. I measure post boil volume and gravity, but am mostly interested in gravity since I always brew more than I can fit in the fermenter.

I also tend to keep track of conversion efficiency since at this point may still be able to fix it.

On the topic of accurate measuremets, you may want to play around with my efficiency analysis spreadsheet (http://braukaiser.com/documents/efficiency_calculator.xls) it allows for input of measurement errors and does a full error propagation to the result.

with these errors:

grain weight +/ 10g
grain extract potential +/- 2%
gain moisture +/- 1%
wort volume +/- 0.2 l
gravity +/- 0.2 Plato

I get an average error of a little less than +/- 3 percent points for the efficiency of a standard 5 gal batch.

Kai

Offline mtnrockhopper

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Re: measuring efficency
« Reply #7 on: December 06, 2012, 11:24:22 AM »
I calibrated my carboys using jugs and I'm pretty sure their accuracy is questionable. I calibrated my kettle by weight (8lb / gallon), which I think is better. It is only as accurate as the scale though.
 
I don't calculate efficiency. I just note if the OG is off and adjust over time. Beersmith is set at 70% which seems to be working. I don't try to fix it and just buy a little more grain.
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Offline goschman

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Re: measuring efficency
« Reply #8 on: December 06, 2012, 12:15:49 PM »
The buckets that I use are not calibrated over 5 gallons and I normally get a post boil volume of about 5.5 gallons. Efficiency has been bugging me a lot lately. Since I don't get a very accurate post boil volume reading, I have decided to take pre boil gravity readings since I know what my beginning volume is. If I have accurate grain potentials then my efficiency should be pretty accurate.

I can then use the post boil gravity reading to calculate my post boil volume. For instance, a preboil gravity reading was 1.048 for 6.5 gallons but the post boil reading was only 1.052. I ended up with a post boil volume of 6 gallons which seemed about accurate after looking at the level on the bucket. In the past I would have put 1.052 for 5.5 gallons which would have significantly lowered my efficiency.

Is this a decent method to use?

Offline a10t2

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Re: measuring efficency
« Reply #9 on: December 06, 2012, 12:28:18 PM »
Is this a decent method to use?

I don't think there's anything wrong with it, but what purpose does it serve? If you've hit the target OG and you have enough volume in the fermenter to net your desired packaging volume after losses, what else matters?
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Offline goschman

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Re: measuring efficency
« Reply #10 on: December 06, 2012, 12:31:42 PM »
Is this a decent method to use?

I don't think there's anything wrong with it, but what purpose does it serve? If you've hit the target OG and you have enough volume in the fermenter to net your desired packaging volume after losses, what else matters?

I just like track my efficiency to ensure that it is reasonably consistent. I didn't hit my desired OG. I would have liked a higher OG in the example given but somehow I had less boil off than usual. It was good to know that my lower OG was due to that instead of low efficiency

Offline neemox

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Re: measuring efficency
« Reply #11 on: December 06, 2012, 02:35:24 PM »
Or is there an easier way?  I have beersmith set at 75% efficiency, and I always come close to the estimated OG.  (1.065 on BS, and I'll hit 1.060) I suppose I could adjust the efficiency in BS to the point where I'm right on, and figure that is my efficiency. 

How do you all measure your efficiency?
I have been doing a lot of efficiency measuring recently just trying to get into the ballpark. After listening to the advice of others, I'm never going to worry about the difference between 72% and 75%, but I was having really low and inconsistent efficiencies. To try and pinpoint what is/was going on in my system and get consistent, I've been measuring all of the components off of Kai's spreadsheet that he linked.

The biggest things I have either measured or started recording that have helped have been the dead space in my MT (very easy to measure, add water to cover the outlet, drain, measure remaining water using something calibrated), which in turn has allowed for measuring my mash volume. This can also be done just by measuring the volume in your boil kettle after collecting (but then you are missing some information about grain absorption). Measuring the run-off gravities (at the correct temp) and the volumes in the MT, kettle, and fermenter have all helped me greatly.

I measure volume in my kettle using a meterstick, multiplying by the surface area of my cylindrical pot, and converting milliliters to gallons. My fermenter is marked and I just trust it enough for my rough calculations.  I calibrated the 1/2 gallon pitcher I use on brew day using a pyrex measuring cup, which so far is working fine for my calculations. Again, not worrying about the 3% difference that will take my beer up or down a couple of points, I'm worried about the 10-20 point variations. All in all, the measurements I take on brew day now add an extra 10 minutes or so, but the information I get from calculating the efficiency has already helped my consistency greatly. Totally worth it to measure the variables, even if you don't need to calculate the values later on. If you end up with the right volume of the right gravity, then your efficiency was pretty damn good. But if not, it's going to be really hard to go back and collect the data you need once the beer is in the fermenter.

Offline malzig

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Re: measuring efficency
« Reply #12 on: December 06, 2012, 07:04:35 PM »
I measure my volumes with a dipstick, using the radius of my kettles to calculate the volume by depth (V=3.14r2h).  Smaller volumes I measure in a Nalgene 5L graduated cylinder (looks a lot like a narrow and tall pitcher).  I've worked in a lab for what has now been most of my life, so I'm more comfortable knowing I'm taking accurate measurements, than winging it.

I buy my base mats by the sack, so I use the grain analysis to adjust my potential for each new lot.  Specialty malts I just go by what BeerTools Pro defaults to.

Long ago, I calculated my efficiency to be 87% for an average gravity beer, batch sparged, and it is rare that that isn't predictive within a point or two.  When I plan on making a low or high gravity beer, I use Kai's Batch Sparge Simulator spreadsheet to predict what the efficiency will be, and it has proven accurate for me.