Efficiency numbers, I'm confused

I just finished a batch of some pale ale and am a little confused about my efficiency. After collecting my sparge runnings, I had about 8 gallons. A bit much I know but I ended up adding some boiling water because I undershot my mash temp and my sparge temp. The theoretical yield for 8 gallons was 1.047 and I measured 1.042. Unless I'm confused, that means I got 89%! I was stoked. Then I took a gravity reading post boil (5.5 gal) and it was 1.051. The theoretical yield post boil was 1.068, so that gives me 75% efficiency right? So which efficiency calculation is right? Is one maybe "mash efficiency" and the other "brew-house efficiency" or what. And why would the efficiency change through the boil? I would appreciate if someone could please help clear this up for me. Thanks

Either way, I'm sure it will still be some tasty beer!

I get a bit confused on the effciency reference also. As you said, one efficiency for mash and one for brewhouse which is how Beer Smith describes them. So which are people refering to when they talk about efficiency and when recipes show assumed effciency of 70% is that mash or brew house effciency?

Edit: Or do you just average the two and call that your efficiency?

brewhouse efficiency is what i have in mind when i say efficiency, this is what count for me, its amount of grain i start with and amount of wort at certain OG in fermenting bucket but actually it should be amount of beer in keg/bottles at the end of the process to calculate efficiency of the whole process
Barnstormer, looks like you lost a lot of wort during transfer from boiling kettle to the fermenter, over 30% of volume decrease in 60min boil and transfer is a lot

You're right - boiling shouldn't change your efficiency. Unless you add fermentables, your total gravity should remain the same.

Preboil 8 gallons x 42 gravity = 336 total gravity
Postboil 5.5 gallons x 51 gravity = 281 total gravity
Those two numbers should be equal, ceteris paribus

Did you adj. your hydrometer readings for temp change?

What's your grainbill & water volumes (mash & sparge)?

My thinking is probably wrong, somebody please correct me.

Would the brewhouse efficiency be better on a 10 vs 5 gallon batch since the evaporation and trub losses would be the same for both? I've heard people refer to less efficiency with large amounts of grain and wonder if they are talking about mash efficiency.

Evaporation shouldn't affect efficiency. Efficiency is the ratio of actual dissolved sugars to potential sugars from the grain. Evaporation increases your concentration of sugars, but does not change the total sugars.

You're right with the mash efficiency - with more grain, you have less water to rinse each piece of grain. Think of the extreme case - if you used 4 gallons of water for a cup of grain, you'll almost certainly get all the sugars out. Conversely, if you only collect a cup of water for 10 pounds of grain, you'll get close to 0 efficiency.

TyTanium said:

Evaporation shouldn't affect efficiency. Efficiency is the ratio of actual dissolved sugars to potential sugars from the grain. Evaporation increases your concentration of sugars, but does not change the total sugars.

You're right with the mash efficiency - with more grain, you have less water to rinse each piece of grain. Think of the extreme case - if you used 4 gallons of water for a cup of grain, you'll almost certainly get all the sugars out. Conversely, if you only collect a cup of water for 10 pounds of grain, you'll get close to 0 efficiency.

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Just trying to get my head around this.

I get the part about the dissolved sugars, but that only has to do with the mashing process doesn't it?. Evaporation and boil kettle loss are how I understand brewhouse efficiency. Or maybe brewhouse efficiency is a combination of mash efficiency, evaporation, boil kettle, and fermenter losses?

Dan said:

Just trying to get my head around this.

I get the part about the dissolved sugars, but that only has to do with the mashing process doesn't it?. Evaporation and boil kettle loss are how I understand brewhouse efficiency. Or maybe brewhouse efficiency is a combination of mash efficiency, evaporation, boil kettle, and fermenter losses?

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You are correct. Brewhouse efficiency is the combined, overall efficiency of your brewing system. It includes cooling loss as well.

Reelale said:

You are correct. Brewhouse efficiency is the combined, overall efficiency of your brewing system. It includes cooling loss as well.

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Oh that's right. I forgot about cooling loss.

My preboil sample was cooled to 60 and I suppose my post boil sample was about 75 degrees. I didn't have any spills or boil overs either. The only place I can think of any loss would be about 10-15 ounces (just a guess) in the bottom of the kettle that my siphon didn't get. I let it go because there was quite a bit of junk in it. Is that enough to make up the difference? Also, what is cooling loss? I'm not familiar with that.

Barnstormer said:

My preboil sample was cooled to 60 and I suppose my post boil sample was about 75 degrees. I didn't have any spills or boil overs either. The only place I can think of any loss would be about 10-15 ounces (just a guess) in the bottom of the kettle that my siphon didn't get. I let it go because there was quite a bit of junk in it. Is that enough to make up the difference? Also, what is cooling loss? I'm not familiar with that.

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I believe it is simply the measure of the loss of liquid volume going from boiling to pitching temperature (due to expansion/contraction). I think the default in Beersmith is 4%, I've never changed it. And there is also a little wort left in the hoses/counterflow/plate chiller and the pump.

Edit: ^^^^ beat me to it

Somebody will probably explain cooling loss better but when the wort is very hot it expands, as it cools it shrinks. I believe the average number is 4 percent loss in volume. At least that is what BS has set it at so for 8 gallons you would lose around a third of a gallon

Thanks for all the good insight! I guess I will just have to be a little more diligent on getting every drop of wort to the fermenter. I guess I will just have to keep practicing... a good problem to have.

Barnstormer said:

My preboil sample was cooled to 60 and I suppose my post boil sample was about 75 degrees. I didn't have any spills or boil overs either. The only place I can think of any loss would be about 10-15 ounces (just a guess) in the bottom of the kettle that my siphon didn't get. I let it go because there was quite a bit of junk in it. Is that enough to make up the difference? Also, what is cooling loss? I'm not familiar with that.

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I believe it is simply the measure of the loss of liquid volume going from boiling to pitching temperature (due to expansion/contraction). I think the default in Beersmith is 4%, I've never changed it. And there is also a little wort left in the hoses/counterflow/plate chiller and the pump.

So how are my numbers? 75% in the fermenter seems pretty average. I thought 89% mash efficiency seemed pretty good for a new AG brewer.

To the OP, sounds like you had a false reading somewhere. Your OG should have been higher than that if you had 8 gallons of preboil wort at 1.047. You cooled the wort before measuring the gravity so, that should have been pretty close. Next time, make sure you are accurately measuring your volume, that might be the problem. Also, if you use whole hops they will absorb wort and lower your OG.

Sounds pretty good to me. Congrats! Do you batch sparge or fly sparge?

Assuming your'e using a hydrometer and not temp adjusted refractometer your post boil gravity of 1.051 adjusted for 75 degrees is 1.052. Not much a diff but SG reads lower at higher temps than it actually is. For example, if wort temp was 100 and read 1.051, it would actually be 1.057. So temp is fairly important to take into consideration when determing specific gravity.

Cooling loss shouldn't affect efficiency - you have the same amount of sugars before & after cooling. You have less volume, but more concentrated so higher gravity.
The only losses that matter are when you leave sugars behind - stuff that's not siphoned out of the BK, liquid in trub that's filtered out or stuck in tubing or spills. Changes in volume to evaporation or cooling do not change the total sugars in the wort.

Mash efficiency: Conversion of starches to sugars
Mash/lauter efficiency: Sugars extracted into wort (pre-boil volume x gravity)
Brewhouse efficiency: Same as mash/lauter efficiency, less losses stated above.

BBL_Brewer said:

Your OG should have been higher than that if you had 8 gallons of preboil wort at 1.047.

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1.047 was the theoretical yield for 100% extraction that I figured out, I used John Palmers forumula. I measured 1.042.

Dan said:

Sounds pretty good to me. Congrats! Do you batch sparge or fly sparge?.

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I batch sparge right now. I've only got a 5 gallon MLT so I have to split it in two sparges but it seems to work okay. I do use a hydrometer calibrated for 60 degrees.

Barnstormer said:

1.047 was the theoretical yield for 100% extraction that I figured out, I used John Palmers forumula. I measured 1.042

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My bad, didn't catch that in your first post. That sounds more like it.

TyTanium said:

Cooling loss shouldn't affect efficiency - you have the same amount of sugars before & after cooling. You have less volume, but more concentrated so higher gravity.
The only losses that matter are when you leave sugars behind - stuff that's not siphoned out of the BK, liquid in trub that's filtered out or stuck in tubing or spills. Changes in volume to evaporation or cooling do not change the total sugars in the wort.

Mash efficiency: Conversion of starches to sugars
Mash/lauter efficiency: Sugars extracted into wort (pre-boil volume x gravity)
Brewhouse efficiency: Same as mash/lauter efficiency, less losses stated above.

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Cooling loss does figure into brewhouse efficiency.

Efficiency as Calculated from Actual Volume - The actual brewhouse efficiency calculated using the actual batch volume and actual OG into the fermenter. This corresponds to your actual measured efficiency for the entire batch.

Semantics, I know. But volume is important in figuring brewhouse efficiency.

Reelale said:

Cooling loss does figure into brewhouse efficiency.

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for me this is incorrect. you see, when i bring 7.5 gallons of cool water to a boil i do not call it 8 gallons. i call it 7.5 gallons even though it may be ocuppying 8 gallons in my kettle. so, if i never had it, i never lost it.

^^Good point

Reelale said:

...This corresponds to your actual measured efficiency for the entire batch.

Semantics, I know. But volume is important in figuring brewhouse efficiency.

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Good clarification. If you use volume in the BK before cooling, your efficiency calc will be off. So, cooling doesn't affect efficiency, per se, as you're not adding or removing sugars; rather, it affects measurement of efficiency. As you said - total volume & total gravity into the fermenter is what counts.

carrolte said:

for me this is incorrect. you see, when i bring 7.5 gallons of cool water to a boil i do not call it 8 gallons. i call it 7.5 gallons even though it may be ocuppying 8 gallons in my kettle. so, if i never had it, i never lost it.

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As long as you account for it, sure. My point is 8 gallons on a sight glass at boiling does not equate to 8 gallons at pitching temperature, and consequently into the fermenter. And volume measures are used for total brewhouse efficiency, at least in Beersmith.

Agreed. Because if you use SG x 8g at boiling, you'll overstate your total gravity & efficiency. In reality, it'd be more like SG x 8g x (1-.04).

TyTanium said:

Agreed. Because if you use SG x 8g at boiling, you'll overstate your total gravity & efficiency. In reality, it'd be more like SG x 8g x (1-.04).

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Yup.

This could just be wort stratification related. You have to really mix the pre-boil wort otherwise it may not be homogenous. This could lead to errors in your pre-boil readings.

Here's my question:

Lets say you have four lbs of grain. If you would hypothetically remove all the sugars with say four gallons of water, then using more sparge water after this lowers your specific gravity obviously, because there is no more sugar to be extracted from the grain bed. In this case, isn't "efficiency" 100%, especially so, since you removed all the sugar you could. You just boil down the wort to reach your desired gravity. Do any of these calculations account for this? In my mind, if you want efficiency, you should just figure how much starch is in each kernel, measure the conversion rate to sugar, and then the amount of sugar being released during the mash/lauter.

Can someone direct me to a thread on how to do calculations on paper? I looked at the various software, but none of it made any sense. I'm a pen and paper guy

At 100% Converion Efficiency you will have a certain amount if extract in your mash. Your lautering/sparging process will allow you to harvest some but not all of it

Understanding Efficiency - German brewing and more

Phenphen - you're exactly on the right track. The maltsters give us the total potential sugars - what 100% efficiency would look like.

For example, 1 pound of American 2-row in 1 gallon of water at 100% efficiency would have a gravity of 1.037. If you mashed & sparged 1 pound of grain, boiled down to 1 gallon and had a gravity reading of 28, you'd know you hit 75% efficiency (28 actual / 37 potential)

Obviously you're doing more than a pound and more than a gallon, so you just have to scale the math accordingly. Let's take a 10lb grainbill of just 2-row.

First, calculate your total potential gravity (i.e., 100% efficiency):
37 gravity pounds per pound x 10 pounds = 370 total potential gravity

Next, take your pre-boil readings. Say 6 gallons at 1.047. How'd you do? 6 gallons x 47 gravity points = 282 total gravity. 282 actual / 370 potential ~ 76% mash/lauter efficiency.

Finally, into the carboy goes 5 gallons of wort at 1.056. 56 gravity points x 5 gallons = 280 actual gravity points. 280/370 ~ 75% brewhouse efficiency. Notice the pre & post boil total gravity are the same, unless you spill / lose some sugars.

Alternatively, lets say you have a target gravity in mind. Let's say 1.050. You know from your pre-boil readings you have 282 total gravity. Well, 282 gravity / 50 gravity points = 5.64 gallons. So you know you need 5.6 gallons into the carboy to hit your gravity target.

TyTanium that was very helpful.

I may be over simplifying, but I believe your problem is your wort was not mixed well (first runnings and second runnings) giving you a higher pre boil reading. I have seen this before. The accurate number is your post boil reading in this case.

+1
I actually usually take a gravity reading of 1st & 2nd runnings separately to "gut check" my combined pre-boil reading. But I'm a nerd and I love the math part of it.