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Efficiency

I use Promash to formulate my recipes, take care of my inventory, and track all my batches. Have for years and years. I’ve been brewing all-grain, nearly all lagers, for over 25 years. So you’d think I’d have it down, right? Here’s my problem:
A few years ago my efficiency started going through the roof. It now ranges between 90% and 100%. I know I’m good, but nobody’s that good. Here are a couple relevant points:

  1. I measure very carefully. From a highly-accurate digital scale to a calibrated measuring stick for the kettle to a hydrometer AND refractometer–I’m a stickler for accuracy.
  2. I do quite long mashes, as long as five hours, so I’ve always gotten pretty high efficiency (not why I do it, but that’s a subject for another post), but this consistent figure of near 100% is new. The only thing different (that I can think of) from the days when I got in the 80s is I’ve converted my setup to electricity.
    The batch I brewed today came in at 99% and I had to fudge a little to keep it under 100%. Any ideas where to look for my mistake? Anybody else have this problem? Thoughts?
    Thanks, Jack.

High efficiency is a nice problem to have. I had the same problem a couple of years ago. Ideas:

  1. If you are now pumping your wort out of the mash tun, is it possible you are sucking more wort out of the grain bed than you would if you were just gravity draining? Could be a pressure thing. Where you were once draining by converting potential energy to kinetic energy from one height to another both at the same atmospheric pressure, now you might have introduced additional force in the form of a vacuum to suck quite a bit more wort out of the same grain bed. This possibility applies a little bit more if you are a batch sparger than if you fly sparge, but in either case it only applies if you are using a pump. If not pumping, then ignore and move on…

  2. You say you measure everything very accurately. How about volume measurements? If you measure everything to a T except for post-boil volume, then your efficiency results are meaningless. There are two essential variables to efficiency: specific gravity and volume, and they are inversely proportional, e.g., if volume goes down, gravity must go up. Failure to recognize this fact could result in inaccurate estimations of your efficiency. Your final post-boil volume needs to be EXACTLY according to recipe, or else your calculation for efficiency is wrong. If your post-boil volume is off a little, this can be corrected through addition of water or through extra boiling, as the case may be. Or, you can use proportionality to calculate exactly what your specific gravity would have been at a different volume, ala GU1(V1)=GU2(V2), where GU1 and GU2 are the gravity units after the 1.0, e.g., GU for 1.065 would be 65, while V1 and V2 are volumes. Once you know your true post-boil gravity, you can then use this to back-calculate your true brewhouse efficiency.

  3. I hope your thermometer and hydrometer or gravity-ma-jig (what are those digital contraptions called again?!) are properly calibrated at the temperature you are using them. If not, then your calculations could be way off.

Those are the biggies. It’s most likely one or more of those 3 things.

Thanks for your considered response.
My volume measurements are, I think, quite accurate. I used a mathematical formula to create a measuring stick for the kettle, and it’s got both hot and cold volume readings. I measure exactly how much I sparge (fly sparge, always, and by gravity) and stop the sparge at 7.8 gallons–I collect 7.8 gallons. I boil for 90 minutes, and with the rate of boil-off, the amount I end up with in the kettle is 6.3 gallons. That is what I need to end up with for a comfortable amount in the fermenter, and it’s the amount my Promash recipe specifies for the batch size–6.3 gallons, measured at the kettle. So, to respond to your points:

  1. I’m not pumping, but even if I were, I would still only sparge to a given volume–in my case 7.8 gallons (which varies a little through the brewing season as the boil-off rates changes. I monitor it with every batch.)

  2. I am quite sure that my post-boil measurements in the kettle are accurate. I turn the burner off, wait until the wort levels, and take my measurement–again with a stick that has been calibrated and has both cold and boiling scales.

  3. Here I suppose I cannot be completely sure. But I will say that I use both a hydrometer and a refractometer. And they agree fairly closely.

Today, for instance:

8.3 pounds of floor-malted Bohemian Pilsner malt
2.25 pounds of Munich malt

6.3 gallons in the kettle at 1.060 (refractometer read a bit higher, over 15)

It seems to me that’s all you need to do an efficiency calculation–amount of malt (the extract potential thereof), volume, and gravity. The above comes out to 99%, accoring to Promash.

What am I not seeing?

Yup, I put that in my brewing spreadsheet and get 99% dead nuts. 6.3 gallons is a lot of post boil volume for a 5-5.5 gallon batch. I do big batches but I shoot for 22 gallons total into the fermenters to fill four kegs.

A few years ago, I bought 8 sacks of Canadian 2-row malt which was giving me a brewhouse efficiency of 94-96% and I too am a stickler for detail and accuracy. Must be good malt as I don’t know how else to explain it.

Saturdays batch was a 1.102 OG big RIS and I got 71% but had to boil for 4 hours to get my target volume and OG. I was shooting for 1.098

I leave a quarter gallon in the kettle and a quarter in the chiller/oxy lines. That leaves 5.8, and after chilling, just over 5.5 gallons in the fermenter.

I like to fill the kegs as full as I can, and I HATE to run out before I do so. :cheers:

Might be a calibration thing. Won’t know until you double and triple check everything.

StrangeBrew software gave me 95% efficiency for that mash at 1.060. But regardless of which software is the most accurate, yeah, you’re definitely in the high 90s. You must be crushing your grains super hard and collecting every last drop of wort from the mash tun. That’s great. But…

Do you notice that your beers taste thin or watery as a result of your super high efficiency, compared to what you used to brew when efficiency was in the 80s? I’m still debating with myself whether super high efficiency has an adverse flavor impact. I have had mixed results when my efficiencies were in the mid-90s. So I decided to open the gap on my grain mill to shoot for more like mid-80s, just to be “safe”. Still need to run some more experiments to know for sure, but I’d be curious to get your perspective on it. The theory I have is that at a certain point, you are squeezing too much sugar out of too little grain. Grain has a lot of delicious grainy flavor that is good to have in your beer, so when you need to use less grain than the average brewer, you get less delicious grainy flavors in your finished beer than the average brewer. Perhaps not a good thing, especially if you are a malthead like me (as opposed to the typical American hophead). The converse is more certainly true – it has long been said by many experienced brewers that you can get improved malt flavors by purposely not sparging and collecting only one batch runnings, at the expense of efficiency which tends to run in the 50s, or 60% maximum, if you don’t sparge. I believe this theory to be true, but have not run enough experiments to prove it to others… yet…

[quote=“MullerBrau”]
A few years ago, I bought 8 sacks of Canadian 2-row malt which was giving me a brewhouse efficiency of 94-96% and I too am a stickler for detail and accuracy. Must be good malt as I don’t know how else to explain it.
/quote]

Another point is that software and spreadsheets assume a points per pound yield of sugars from the grain. If that assumption is low, you are getting more points out of your mashed grains than the computer predicts. I suppose if you wanted to get into it, you could use the malt analysis for the lots of malts in your grain bill to do a better job predicting points per gallon.

Shouldn’t brew house efficiency be measured using the total volume that’s in the fermenter not what’s in the kettle post boil? You efficiency is still gonna be very high but since your leaving .8 gallons in your system you wouldn’t count that. I could be wrong but that’s how I check mine.

[quote=“dmtaylo2”]Might be a calibration thing. Won’t know until you double and triple check everything.

StrangeBrew software gave me 95% efficiency for that mash at 1.060. But regardless of which software is the most accurate, yeah, you’re definitely in the high 90s. You must be crushing your grains super hard and collecting every last drop of wort from the mash tun. That’s great. But…

Do you notice that your beers taste thin or watery as a result of your super high efficiency, compared to what you used to brew when efficiency was in the 80s? I’m still debating with myself whether super high efficiency has an adverse flavor impact. I have had mixed results when my efficiencies were in the mid-90s. So I decided to open the gap on my grain mill to shoot for more like mid-80s, just to be “safe”. Still need to run some more experiments to know for sure, but I’d be curious to get your perspective on it. The theory I have is that at a certain point, you are squeezing too much sugar out of too little grain. Grain has a lot of delicious grainy flavor that is good to have in your beer, so when you need to use less grain than the average brewer, you get less delicious grainy flavors in your finished beer than the average brewer. Perhaps not a good thing, especially if you are a malthead like me (as opposed to the typical American hophead). The converse is more certainly true – it has long been said by many experienced brewers that you can get improved malt flavors by purposely not sparging and collecting only one batch runnings, at the expense of efficiency which tends to run in the 50s, or 60% maximum, if you don’t sparge. I believe this theory to be true, but have not run enough experiments to prove it to others… yet…[/quote]

I’m a malthead, too, and if I don’t mistake, we had this discussion years back. I don’t happen to believe that higher efficiency leads to thin or watery beer. To the contrary, in order to get that high efficiency, while you may be getting every last bit of extract out of the malt, you’re also getting lots of other compounds, compounds you wouldn’t get with a shorter, less-efficient mash. I run my mash for 4-5 hours, and I’ll put my beers up against any beer mashed for 30 minutes.

If you could see me you’d see I’m trying very hard to stay off my soap box, because there are lots of trends that seem to me to be more about saving time than making better beer. But I won’t go there. I’ll just close by saying–there’s a reason why decoction mashing yields that beautiful malt character. Breaking down that malt kernel to its ultimate constituents gives maltiness in the glass.

[quote=“chinaski”][quote=“MullerBrau”]
A few years ago, I bought 8 sacks of Canadian 2-row malt which was giving me a brewhouse efficiency of 94-96% and I too am a stickler for detail and accuracy. Must be good malt as I don’t know how else to explain it.
/quote]

Another point is that software and spreadsheets assume a points per pound yield of sugars from the grain. If that assumption is low, you are getting more points out of your mashed grains than the computer predicts. I suppose if you wanted to get into it, you could use the malt analysis for the lots of malts in your grain bill to do a better job predicting points per gallon.[/quote][/quote]

Yes, while I do my best to insert the specs for each bag of malt into Promash (though I admit to finding it a bit confusing at times), I was wondering if I am just simply getting more out of the malt than the maltster expects. Maybe I should just set my brewhouse effeciency at 98% and forget about it…

I’ll be honest… I have not yet run enough experiments on decoction either to conclude one way or the other as to its benefits… but even if decoction is a farce and no benefit to flavor at all whatsoever, it is at a minimum a fun and educational process, and I choose to utilize it for my own lager beers just in case, and so… I’ll drink to that.

:cheers:

In Promash you select where you take that volume measurement and the software figures it out. Volume in the kettle, at x.xxx OG, made with XX pounds of malt. Seems the simplest way.

But just now looking in the Promash Help for this section, I came across this:

“While we consider the most accurate time to take the “in-kettle” measurement to be immediately before boiling, a brewer can actually record this measurement anytime from pre-boil to the end of the boil, as long as it is taken before any wort is drained from the kettle.”

This doesn’t make sense to me. The gravity is going to change over the course of the boil; the volume too, for that matter.

Cheers, Dave!

In Promash you select where you take that volume measurement and the software figures it out. Volume in the kettle, at x.xxx OG, made with XX pounds of malt. Seems the simplest way.

But just now looking in the Promash Help for this section, I came across this:

“While we consider the most accurate time to take the “in-kettle” measurement to be immediately before boiling, a brewer can actually record this measurement anytime from pre-boil to the end of the boil, as long as it is taken before any wort is drained from the kettle.”

This doesn’t make sense to me. The gravity is going to change over the course of the boil; the volume too, for that matter.[/quote]
It makes perfect sense. The gravity and volume change will be proportional to each other. Efficiency is how much sugar you extract per unit of grain, so all you are really concerned about is how much sugar you get in the kettle based on how much grain you put in the mash tun. The volume measurement is only needed as a way to convert your measurement of concentration to absolute mass of sugar. And as long as it is in the kettle, the sugar mass stays constant.

I think it is time to check the calibration of your measuring equipment. The scale may be highly precise, but it may not be as accurate as you think. Only way to tell is to test it with something of known weight. Same with your hydrometer and refractometer - make a couple of sugar solutions of known concentrations (using your verified accurate scale) and make sure they are spot on. You should also double check the volume measuring stick by using a known volume of water.

Or maybe your kettle has shrunk? It happens to cloths as you get older, why not kettles?

Yes, of course. But the volume must also be measured accurately to calculate efficiency. How does one do that in the middle of the boil?

The question I would like answered is, when Promash specifies a 6 gallon batch @ 1.040, or whatever–where does it reckon that volume measurement (along with the gravity measurement) must be taken? In the fermenter? In the kettle? At the beginning of the boil? The end?

I’ve been setting my recipes for 6.3 gallons and I measure both volume and gravity at flame out. Is this where my problem lies?

Other Promash users?

I don’t use ProMash, but…

I measure the recipe’s volume for input into the software immediately at flameout, and I measure specific gravity after boiling and chilling at between 60-70 F, which is where hydrometers are calibrated. This might not be correct – I have never been certain whether to measure volume while hot at 212 F or after chilling at 60-70 F. However I am certain that the volume must be measured sometime after the boil.

So the point of debate is whether to measure post-boil volume hot or chilled. Honestly, I do not know the “right” answer for this, if there is one, but temperature certainly does introduce a discrepancy of up to 4% efficiency due to the different density of wort when hot versus cold.

To illustrate this point, if you are supposed to measure volume cold but you measure it hot, then your volume measurement for estimating brewhouse efficiency will be too high by 4%. To the software, this is treated just the same as if you hadn’t boiled quite hard or long enough, and should have boiled a few extra minutes to get to the right volume for the software, which would result in an increase in your specific gravity, and thus result in a brewhouse efficiency that is 4% higher than it truly is.

So… if she weighs the same as a duck… er, I mean…

  1. If you are supposed to measure volume cold but you measure it hot, then your calculated brewhouse efficiency is 4% too high.

  2. Conversely, if you are supposed to measure volume hot but you measure it cold, then your efficiency is actually 4% higher than you thought.

I have to admit, I am not certain which of these two conclusions is correct. What I am sure about, though, is that exactly one of them is correct.

I also stumbled upon the idea of chiller volume during this thought process… If you were to mistakenly measure your post-boil volume while a copper coil chiller is still submersed in the wort, then your volume measurement will mistakenly be way too high, as if you had not boiled long enough… thus resulting in an extremely wrongly high brewhouse efficiency calculation. So if you are measuring volume with a chiller in your wort, then you could mistakenly be calculating your efficiency to be higher than 100%, which is totally wrong because you need to get that chiller out of there for accurate volume measurement. So in that case…

Maybe the right answer really is that we should be measuring volume after the chiller has done its job of chilling, and left the wort. We probably really should be measuring volume cold. So conclusion #1 is more likely to be the correct one. Which means that I have been measuring efficiency wrong myself… or should I say, I have been lackadaisical about my volume measurements with respect to temperature. Maybe. But maybe I’m wrong and conclusion #2 is indeed correct. I really do not know.

Okay, enough procrastination… I’d better get back to my real job…

I’m a ProMash user, and I measure efficiency pre-boil. But the fact is, if you ignore the effect of temperature on wort volume (good call Dave, I never considered that*), you should get the same efficiency numbers pre-boil as you would post-boil, assuming nothing has been added or remove from the kettle during that time - except water. Any water gain/loss doesn’t matter because it is taken into account in the calculation. Putting a chiller into the kettle would make a difference, as would adding massive amounts of hops. The reason I take the measurement pre-boil though is just that the efficiency is a measure of the mash/lautering process, not the boiling, and the less that happens between the end of lautering and the taking of the measurement the less chance there is for errors.

  • ProMash does take into account the coefficient of expansion for water when it does water needs calculations, but I’m not sure if it does at other times. I’m guessing no, as there is no way the software would know for example what temperature you are taking a volume reading at to figure efficiency.

So… your pre-boil volume is measured at mash or mashout temperatures between about 145-170 F, correct? This too will mess with the efficiency calculation if it inherently assumes either 60-70 F or 212 F.

The problem with all of this is that there are implicit assumptions, i.e., the software developers probably did not bother to define what temperature the recipe volume should be measured, i.e., even though any use of efficiency calculations requires the temperature variable to be considered, it just plain isn’t, or requires a research project to figure out which temperature was implicitly assumed.

I suppose I’m going to have to Google all this stuff later… I’m too busy at the moment. This discussion is getting into the really deep dirty details, that’s for sure!

You’re right, this is getting into the deep dirty details. But one thing I’m sure of is that volume differences due to water temperature are not responsible for ALL of the problem the OP is asking about. Water takes up about 4% more volume at 212F than it does at 70F. Using a 4% higher volume in the calculation will increase the apparent efficiency by a similar amount, tops. And as the OP said, he may be good, but I don’t believe anyone who doesn’t have a highly tuned professional-grade set-up can regularly get efficiencies above 95%.

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