An efficiency observation....

[smizak]

I just figured out an efficiency issue I was having, and didn't see my particular problem ever discussed on this forum.

Ever since going all-grain, I noticed that I would "lose" about 3-4% efficiency from pre-boil gravity readings to fermenter readings. I brew 6 gallon batches and boil down from about 7.5 gallons. It happened again this sunday. A little over 7 gals. in the kettle read 1.052 which gave me 84% extract efficiency. Boiled down to 6 gals and cooled read 1.061 which gave me 80%. It was driving me nuts, because I know the sugar didn't freakin evaporate, and I don't add any additional water to dilute wort.

What never occurred to me was that when pulling my sample from the kettle, the wort was near boiling, around 190-200F. Accounting for the thermal expansion, my 7.1 gals of 200F wort was actually around 6.8 or so gals. of 60F wort. This accounts perfectly for the missing efficiency points.

Anyway, thanks for reading about me understanding brewhouse efficiency better, and I hope this helps someone else somehow.

 

[brewmasterpa]

you also have to temperature correct your gravity reading as well.

 

[smizak]

Yeah, I should have made it clear I cooled the sample before I took a reading. Both readings were at 60F exactly.

 

[Bobby_M]

I know that beertoolspro software accounts for thermal expansion of 212F wort. That's why the preboil gravity (based on assumed efficiency) is clearly displayed at a certain preboil volume at boiling temps. Certainly if you work it out by hand you'd need to account for it.

 

[smizak]

I use Beersmith, and I'm not sure that it accounts for thermal expansion, which led to my confusion about my readings. The brewhouse efficiency tool in Beersmith only accounts for top-off water and mashtun deadspace, etc. Or maybe there's something I'm missing in Beersmith?

 

[usurpers26]

In your equipment setup - it deaults to 4% for expansion. Whether or not it uses this when calculating brewhouse efficiency, I'm not sure. (I would guess that it does though)

I use Beersmith, and I'm not sure that it accounts for thermal expansion, which led to my confusion about my readings. The brewhouse efficiency tool in Beersmith only accounts for top-off water and mashtun deadspace, etc. Or maybe there's something I'm missing in Beersmith?

 

[SpanishCastleAle]

Ever since going all-grain, I noticed that I would "lose" about 3-4% efficiency from pre-boil gravity readings to fermenter readings. I brew 6 gallon batches and boil down from about 7.5 gallons. It happened again this sunday. A little over 7 gals. in the kettle read 1.052 which gave me 84% extract efficiency. Boiled down to 6 gals and cooled read 1.061 which gave me 80%. It was driving me nuts, because I know the sugar didn't freakin evaporate, and I don't add any additional water to dilute wort.

What never occurred to me was that when pulling my sample from the kettle, the wort was near boiling, around 190-200F. Accounting for the thermal expansion, my 7.1 gals of 200F wort was actually around 6.8 or so gals. of 60F wort. This accounts perfectly for the missing efficiency points.

Maybe my math is bad but if you have 6 gal. of 1.061 wort then you have 6*61=366 total points. If you were @ 80% eff. then you should have a theoretical max 366/.8=457.5 points.

7.1 gal. of 1.052 wort equals 7.1*52=369.2 points (very close to the 366 points from above). 369.2/457.5=80.7% efficiency...pretty darn close.

6.8 gal. of 1.052 wort is only 353.6 points (not as close to the 366 points from above). 353.6/457.5=77.3% efficiency...not as close as 7.1 gal. @ 1.052.

So it looks like you were closer the first time. What am I missing?

EDIT: I totally agree with accounting for the volume difference when hot...I just don't understand the numbers.

 

[smizak]

Whoa! Math police!!!



Just checked my notes. Pre-boil reading was 1.054, not 1.052.

Sorry.

 

[Superman3278]

Your loos of liquid condenses the wort to a higer number wich is the FG target for Post Boil. If you mesure after lautering you are mesuring the gravity of wort @ pre boil thus the number should be 4-6 % lower than target FG.

 

[smizak]

Your loos of liquid condenses the wort to a higer number wich is the FG target for Post Boil. If you mesure after lautering you are mesuring the gravity of wort @ pre boil thus the number should be 4-6 % lower than target FG.

Yeah I know this.

I was losing a couple points in efficiency. The efficiency number shouldn't change after you mash. Using my brewing process, the extraction efficiency should equal the brewhouse efficiency. It wasn't, and I figured out my error, which was not compensating for the volume of the wort increasing due to thermal expansion.

 

[Jolly McStanson]

I use Beersmith, and I'm not sure that it accounts for thermal expansion, which led to my confusion about my readings. The brewhouse efficiency tool in Beersmith only accounts for top-off water and mashtun deadspace, etc. Or maybe there's something I'm missing in Beersmith?

Beer Smith has hydrometer adjustment tool. You punch in the temperature of the liquid and the reading your getting. You also tell Beer Smith what temperature your hydrometer was calibrated at.

Beer Smith recalculates to the correct reading.

 

[SpanishCastleAle]

The efficiency number shouldn't change after you mash.

That's not so I don't think. For example, if you use a bunch of whole hops those hops will absorb some wort. Less wort at the same gravity is less efficiency.

I always lose eff. points from kettle to fermenter (I always use whole hops) even when accounting for the volume difference of hot wort.

 

[smizak]

That's not so I don't think. For example, if you use a bunch of whole hops those hops will absorb some wort. Less wort at the same gravity is less efficiency.

I always lose eff. points from kettle to fermenter (I always use whole hops) even when accounting for the volume difference of hot wort.

Well, yes and no.

If you lose wort you intended to collect, and don't hit your volume, then yes; you have lost brewhouse efficiency points.

I shoot for 6 gals. with the intention of collecting 5.5 into the fermenter. I assume a loss of 0.5 gals. to trub and hops. It should be the same efficiency number, unless the hops absorb sugar more than water or something, and I haven't noticed that.

 

[SpanishCastleAle]

I shoot for 6 gals. with the intention of collecting 5.5 into the fermenter. I assume a loss of 0.5 gals. to trub and hops. It should be the same efficiency number, unless the hops absorb sugar more than water or something, and I haven't noticed that.

That trub and hops is a loss and reduces your efficiency. I agree that you can account for it so that you hit your volumes/gravity but it's still a loss and affects efficiency.

When you devise a grain bill it has a theoretical maximum yield...in total points. That represents 100% efficiency. Any points lost along the way (no matter how) are an efficiency loss whether you account for it or not. The amount of points you get divided by the theoretical max equals your efficiency.

 

[Kaiser]

I had a similar problem. But I was correcting for the temperature based volume change. Turns out my problem was cooling the preboil sample in a large open bowl. This caused enough water to evaporate to drive the gravity up by a few points. Now I always chill samples in a closed jar.

BTW, you would not have to account for the change in volume if you would take the gravity reading at the same temp that the wort is at. Because then the correction factor (4%) is accounted for in the gravity which will be about 4% lower. But measuring the gravity at or near boiling is impractical as your hydrometer is likely to break in the process. So because we correct the gravity to 60F we also need to correct the wort volume to 60F.

Kai

 

[smizak]

It's a loss if I calculate efficiency for my actual batch size. I don't. I calculate for more. This way my efficiency calculation is simply my extraction efficiency.

Does that make sense?

I think I know what you mean, but I don't factor in the wort I'm leaving in the trub as a loss, just as a portion of the batch I'm not using. It's still the same gravity as the wort in the fermenter.

 

[smizak]

I had a similar problem. But I was correcting for the temperature based volume change. Turns out my problem was cooling the preboil sample in a large open bowl. This caused enough water to evaporate to drive the gravity up by a few points. Now I always chill samples in a closed jar.

BTW, you would not have to account for the change in volume if you would take the gravity reading at the same temp that the wort is at. Because then the correction factor (4%) is accounted for in the gravity which will be about 4% lower. But measuring the gravity at or near boiling is impractical as your hydrometer is likely to break in the process. So because we correct the gravity to 60F we also need to correct the wort volume to 60F.

Kai

This is precisely what I determined myself. I actually searched your Wiki for a quick reference, but didn't see anything immediately. I admire your work on that, BTW, thanks.

 

[SpanishCastleAle]

It's a loss if I calculate efficiency for my actual batch size. I don't. I calculate for more. This way my efficiency calculation is simply my extraction efficiency.

Does that make sense?

I think I know what you mean, but I don't factor in the wort I'm leaving in the trub as a loss, just as a portion of the batch I'm not using. It's still the same gravity as the wort in the fermenter.

I think of efficiency as the percentage of the max theoretical yield. The grain bill has a max theoretical yield but whatever you actually get...well that's all you got. What you got divided by the max yield equals efficiency. 'What you got' doesn't all have to go into the fermenter...but it's still a part of the efficiency equation.

I found out not long ago that when we (i.e. homebrewers) say 'efficiency' we may not always be talking about the same thing. The way I do it there is no fudging numbers or estimating this or that...it's simply: What I got (measured grav and volume) divided by Max Theoretical Yield.

Even though folks may do it differently...we all seem to be able to brew good beer.

 

[smizak]

I think of efficiency as the percentage of the max theoretical yield. The grain bill has a max theoretical yield but whatever you actually get...well that's all you got. What you got divided by the max yield equals efficiency. 'What you got' doesn't all have to go into the fermenter...but it's still a part of the efficiency equation.

I found out not long ago that when we (i.e. homebrewers) say 'efficiency' we may not always be talking about the same thing. The way I do it there is no fudging numbers or estimating this or that...it's simply: What I got (measured grav and volume) divided by Max Theoretical Yield.

Even though folks may do it differently...we all seem to be able to brew good beer.

I know. We are talking about different things. If I do it your way with my porter which we talked about, my brewhouse efficiency, by the books, is 66.6%. That's for the real 5 gals. that will end up in bottles. However, using that number and calculating method makes it a pain in the a$$ to determine what the actual gravity of my beer will be. It's easier to just know what the extraction efficiency is and boil down.

I know what you meant, I was just trying to explain my method so I could be clear in how I solved the volume problem.

 

[brown_dog_us]

I focus mainly on my brew house efficiency. I take a gravity reading right before I pitch and note the total volume in my fermenter. I feel like I need to get that % to being consistent so I can accurately concoct my recipes. I still take a reading of my preboil wort just to make sure I haven't screwed up the mashing, but as long as it is in line I don't pay a lot of attention to it.

 

[bandt9299]

This subject is important to me because recently for the first time I made a big beer and was 11 points low on my OG, I want to be able to adjust for this if it ever happens again by adding some DME during the boil, to get me where I want to be, so from now on I will take a gravity reading pre boil as well as pre pitch.

 

[smizak]

For whomever's reference, I just checked the Beersmith brewhouse efficiency numbers and it definitely does not account for thermal expansion. Hm, I'm liking that Beer Tools has that, I may look into that software.

This subject is important to me because recently for the first time I made a big beer and was 11 points low on my OG, I want to be able to adjust for this if it ever happens again by adding some DME during the boil, to get me where I want to be, so from now on I will take a gravity reading pre boil as well as pre pitch.

That's why I do it as well. I like to know where I'll end up.

 

[Kaiser]

For whomever's reference, I just checked the Beersmith brewhouse efficiency numbers and it definitely does not account for thermal expansion.

Because it doesn't assume that you measure the "batch size" while the wort is hot.

Kai

 

[nosmatt]

crap.
you can measure anything too much, right?


so, i measure my possible points, and then my OG into the fermenter for my efficiency...

yep, i might miss somethng for mash efficiency and all that. but take into account your thermal losses, barometric pressure, trun losses, obama losses..... too much!

my obama losses are far, far more costly than any other losses, and we should all be happy we have jobs still (those of us who do), and just measure efficeincy the old fashoined way!


sorry, had to throw a little politcal crap in there, cuz, some of you voted the WRONG way, and now you realize it!

anyway, i am stoked with my best of 80.1%, and i am hoping to beat it this weekend. this thread has given me several ideas on how to do so.

analyzing trub losses, and thermal expansion, gravitational losses, quantum particle gain, and, or loss...... you can get a bit too extreme in this, no?

 

[Superman3278]

Smizak, what have you learned? seems to me you are making a mole hill into a mountain. Your grain bill did not compensate for your losses, excuse my bluntness but thats the reality. Often newcomers to all grain did not research this fact. In reality, a tested true recipe performed exactly, does not require calculations for humidity, barometric pressure, or such. My gosh man it is beer not puff pastry science, so adjust and try again. Let us know how it works out.

 

[SpanishCastleAle]

Some people just like to brew as simple as possible. Others go to the other extreme and analyze everything. Most of us are somewhere in between. We all do this for personal enjoyment more than anything so whatever gets you that personal enjoyment is a good thing. Analyzing one's efficiency and isolating/identifying losses is never a bad thing imo.

I always measure pre-boil and into-the-fermenter volumes and gravity. If something went wrong or I miscalculated my grain bill or something, I'll know pre-boil and can add DME or water to compensate. If I added water I'll have some leftover wort for starters or something. An example would be when I tightened the gap on my Barley Crusher...efficiency went up but it was expected and easy to compensate for, pre-boil.

 

[smizak]

Smizak, what have you learned? seems to me you are making a mole hill into a mountain. Your grain bill did not compensate for your losses, excuse my bluntness but thats the reality. Often newcomers to all grain did not research this fact. In reality, a tested true recipe performed exactly, does not require calculations for humidity, barometric pressure, or such. My gosh man it is beer not puff pastry science, so adjust and try again. Let us know how it works out.

There's no issue for me. It's all good!

I just wanted to share what I observed about hot pre-boil volume affecting efficiency numbers. I certainly don't stress out about my beer, I hit 85% extraction efficiency on my last batch, 80% on this one. No big deal, I'm not trying to get dead-on consistency.

 

[smizak]

Because it doesn't assume that you measure the "batch size" while the wort is hot.

Kai

That's what irks me. If I was designing the software, I should assume that a brewer lets his wort cool to room temperature after the mash before he measures it? Who does that? It's not a big deal anyway, I can manually factor in volume losses, but I think it is an oversight. According to BobbyM, Beertools apparently accounts for it.

 

[Kaiser]

Beersmith’s definition of brewhouse efficiencty is based on batch size and it assumes that you consider the amount in the fermenter as the “batch size”. I don’t agree with this either as I’d like to consider the amount in the kettle as being the batch size and would like to see brewhouse efficiency being the efficiency in the kettle. But that’s called efficiency into kettle in Beersmith. When I still used this program I considered the chilled volume in the kettle as the batch size.

Kai

 

[smizak]

That's how I run my numbers in beersmith as well. As SpanishCastle alluded to, the definition of efficiency is different for a lot of brewers. I think I'll just say kettle efficiency from now on.