What's The Best Way To Post Efficiency On Ahb?

[brendanos]

yes, you've measured both the gravities at the same temp and those by themselves are total comparable. but the point I was getting at is that unless you measure your volumes all at the same temp they are not directly comparable. if you measured pre boil volume at mashout into kettle temps (60-ish), mid volume boil at 100C and post boil in the fermenter (80-ish assuming you're no-chilling) you'd need to know some more constants to draw comparisions. ie. (preboil vol)* (expansion factor @ 60) vs (midboil vol * 1.04) vs (postboil vol)* (expansion factor @ 80)

honestly, I dont measure things with this much accuracy myself yet as my efficiency is still a bit all over the place, but when I'm trying to explain something I like to think about things and an analytical manner

Thanks for clearing that up, I hadn't realised what you were referring to earlier, and yeah it's probable that thermal expansion could account for quite a significant difference in volume (possibly even enough to explain a large part of the apparant 4% variation in efficiency). Volumes were measured after lautering at 80ish and in fermenter after chilling to 22-24C.

Cheers
Brendan

 

[lucas]

If using a refractometer, take a tablespoon of wort, dribble it onto the refractometer and take the reading five minutes later. Write down the Brix reading and multiply it by 4.1 then add 1 unit. e.g a Brix reading of 10.0 would equal 1.041. Post this to 4 decimal figures so people can see that you used a refractometer.

Ok, so I've only read down to here so far (my god you can write PP), but I'll throw in my opinion that people measuring in brix/plato should post their figures in brix/plato. there are several different ways to convert between brix and SG and most of them dont completely agree with one another. I'd leave the conversions up to the reader to ensure that nobody is using a different conversion method without mentioning it.

 

[PistolPatch]

I'm on the phone to Screwtop at the moment but I reckon this thread should favour new brewers. If people follow my decimal point system and the simple multiplication written there then the experienced guys can work back should they want to convert to Brix. Fair enough?

 

[Screwtop]

Ok, so I've only read down to here so far (my god you can write PP), but I'll throw in my opinion that people measuring in brix/plato should post their figures in brix/plato. there are several different ways to convert between brix and SG and most of them dont completely agree with one another. I'd leave the conversions up to the reader to ensure that nobody is using a different conversion method without mentioning it.

I take all measurements in Besser Blocks, can't be bothered with Brix

 

[chris.taylor.98]

I was very confused for a long time over efficiency calculations.

The model that I finally settled on ( that made sense for me anyway ) was to work on a point system, multiplied out by the volume.

The theory behind this system is that if we take a quantity of liquid and measure the density of sugars in suspension ( ie gravity ) for example 2 liters at 1.048, then if we dilute the solution with water ( lets say to 4 liters ) the gravity is reduced by the same amount ( ie it will now be 1.024 ). i.e the density is directly related to the amount of sugars and the volume, and this relationship will not change unless you actually take some of the sugars out of the system.

This way you can calculate the expected gravity of all your run-offs ( if you batch sparge like I do ) and also work out your conversion ratio.

This method is actually very simple when it comes down to it (despite me trying my best to make it long winded and complicated), and takes away a lot of the mystery surrounding the efficiency calculations.

Basically you start with the theoretical maximum gravity that you could get if you had an efficiency of 100%. ( So lets say it is 1.068 for example ) and you factor this with the number of liters that you expect ( assuming that there are no loses to trub or dead spaces etc ) lets say 25 liters. To do this take the last 3 digits of the gravity reading ( lets call it "points" for want of a better term ) and multiply it by the number of liters. In this case:

25 x 68 = 1700

Now this figure represents the theoretical maximum amount of "points" what we are able to extract if we could get 100% efficiency and there are absolutely no losses.

So now to determine our actually efficiency we just calculate the number of "points" that where extracted after sparging, by measuring the gravity of the wort in the boiler ( lets say 1.052 or 52 and 23 liters ) which ends up with:

23 x 52 = 1196

So our efficiency is

1196/1700 = 0.70 ( or 70% )

Now the fun part of this method is that we can even work out an approximate conversion % if you are batch sparging, as well as the expected gravity of each of the batches ... yes I know that brewsmith and all those other tools already do this for you ... but this way you may even get to understand it a bit.

I have a horribly rough spreadsheet that I use to do all this if anyone is interested, might even get around to cleaning it up for mass consumption one of these days

Some other points on efficiency calculations:

i) Its only a theoretical model and will never represent the real world exactly. To start with, if the grain that we are mashing varies from the grain that they used to determine the extract potential, then the calculations are not going to match exactly even before you take into account your process, and your equipment ( ie don't get too carried away about it being spot on to what you have calculated, as this rarely happens ).

ii) Low efficiency is not a sign of lack of manliness, and there is much to say that you might end up with a better beer at the end of it. In fact some brewers have reported good results by only taking the first runnings from the grains, and not adding extra sparge water at all ( about 50% efficiency ). I usually aim for around 70%.

iii) The only real benefit of accurately knowing your efficiency is to be able to plan your recipe to give you the gravity that you need for the beer you are making. Once you can consistently predict this, then you don't really need to worry about it.
The "cost" of not getting that extra 10% out of your system is probably only a couple of dollars in grain, and mostly likely will lead you to doing stupid things like over sparing and ruining many potentially fine batches of beer ( and yes I am talking from experience here ).

Cheers

Chris

 

[bayWeiss]

I think this whole thing is really getting overcomplicated... and it does not have to be.

In regards to the problem question... there is only one question that is being asked.

Where did the sugar go from the time period of "boil begin" to "boil end"? With this being said, grain type used, and absolute efficiency values are irrelevant.

Now, the most controlled way of figuring out what is going on is to have a very controlled test. This means in essence, that you can not brew beer to test this, because there are too many variables and you would probably ruin your beer in trying to test for the "yield = loss of sugar".

As I mentioned above (if you read back some pages) you need to have a test with a controlled sugar solution. The only part that really needs to be controlled, are the measurements of the three variables [volume and gravity and temperature]. This entails homogenous temperature readings and EXACT measure of volume at that particular temperature. Also, the gravity reading needs to be taken at that temperature.

That is it... there are no hops involved, no boilovers, and no volume losses due to break material.

You are only going to get to the bottom of this problem by doing something similar to what I suggest, or, you will need a sample size of 1000 brewers or so to overcome random error creeping in.

cheers!

 

[PistolPatch]

I think this whole thing is really getting overcomplicated... and it does not have to be.

Sorry Chris, I haven't digested your post as yet but will have a look tomorrow.

Meanwhile....

Bayweiss, I don't agree. I spent considerable time tonight converting into words in the technical post above what could be conveyed face to face in five minutes.

Yeah, it is simple but it is also not that simple. There were five or so posts of God knows how many words today just analysing one person's set of figures. This costs both the writers and the readers a heap of time.

I have had a crack at establishing some clear standards to adhere by in taking readings. Is this not a good idea or should we continue taking up time trying to nail down how every individual takes their readings?

Your suggestion of measuring an extract or sugar solution I have already refuted. The stuff has already been boiled so cannot possibly give us an informative answer. The low volumes in the proposed experiment would also create a higher degree of error.

We are dealing with real life stuff and this means grain.

So, I think the technical post above might well be worth a second and very considered look. If anyone can shorten the post, I'm all for suggestions. Personally, I think it would be quite difficult to shorten it to a standard that encompasses everyone.

Spot,
Pat

 

[bayWeiss]

Your suggestion of measuring an extract or sugar solution I have already refuted. This stuff has already been boiled.

We are dealing with real life stuff and this means grain.

...

I better go,
Pat

I am not sure how the argument of whether something has been boiled already or not has to do with measuring sugar in a solution. [you get an accurate volume measurement (means taking temp into account), and an accurate gravity reading] Sugar is sugar is sugar... sure, there are different types of sugar, but I do not see what relevance this has to checking the gravity.

The phenomena should be boil-time invariant. You should be able to perform a test from 60 minutes to flameout, or 45 minutes to 15 minutes. You can determine if it is boil-time variant by taking a large enough sample size of measurement during the boil, and you will see something non-linear.

It is my belief, that the whole thing is random error, and you will not see a pattern... just like I do not see a pattern really of trials from the previous posts.

oh, this is frustrated bayWeiss....

:beer:

 

[PistolPatch]

OK, one last refutation of the measuring sugars idea.

Let's say that we do conduct this experiment.

Regardless of what result it gives, it will not explain why Trent, I and at least another two get the readings we do when making an all-grain brew. Exactly the same instruments are being used in either test.

If anyone can argue against that logic then they have me buggered.

Doing such a test does however have some merit. It would establish if there is a difference between measuring previously boiled sugar solutions and real life grain solutions.

This would be very interesting but still doesn't solve our problem.

Anyway, I'm out of here for a few days. Hopefully I'll be coming back with a big smile on my face - say your prayers guys

 

[bayWeiss]

In all honesty PP if you are troubled with the idea of sugar or extract, then you can do the experiment with a small pilsner mash or something...

I just suggest you keep the water volumes low for ease of handling, and quickness of cooling/measuring. Also, keep the hops out of it, and mix the cooled wort before taking measurements to keep sugar water stratification non-existent.

cheers!

 

[PistolPatch]

I have a horribly rough spreadsheet that I use to do all this if anyone is interested, might even get around to cleaning it up for mass consumption one of these days

That was an interesting post Chris and I'd certainly like a look at the spreadsheet. Thought your comments at the end were very good too.

I was hoping that a few people may have brewed yesterday and added some figures. All we have so far are Hogan's and mine. I've converted these figures to and posted them below using the standard I proposed in Post #59 - the one that no has read

Figures to Date

Brewer: PistolPatch
Grain Bill Weight: 3.78kg

Volume at Beginning of Boil = 32.4lts
Gravity at Beginning of Boil = 1.0295

Final Volume = 25.8lts
Gravity at End of Boil = 1.0336

Efficiency Into Boiler = 80.1%
Final Efficiency = 72.6%

Brewer: Hogan
Grain Bill Weight: 4.77kg

Volume at Beginning of Boil = 32.5lts
Gravity at Beginning of Boil = 1.0370

Final Volume = 24.0lts
Gravity at End of Boil = 1.0500

Efficiency Into Boiler = 79.9%
Final Efficiency = 79.7%

 

[Corny]

For those using a dip-stick to measure volume: TEMPERATURE

Made a dip stick by adding 5L at a time to my vessel and marked the stick. Then made a really nice job of it all sealed and laquered. Filled the HLT to the required level/amount. Heated my strike water and checked the volume - had an extra litre - of course expansion.

 

[lucas]

Brewer: Lucas
Grain Bill Weight: 6.17kg

Volume at Beginning of Boil = ~ 31.5lts
Gravity at Beginning of Boil = 10.75P = ~ 1.043

Final Volume = ~23.0 - 25lts (couldnt measure it very accurately yet due to hop sock, just below the seam of the keggle)
Gravity at End of Boil = 14.75P = ~ 1.060

edit: looking at the numbers some more I seems to have defied physics in the opposite way to you PP That said, my measuring stick is only calibrated in 2L increments so I'm welcome to the possibility my measurements are crap

 

[Thirsty Boy]

A couple of quick points. Not really any answers but some things to think about.

Measuring

Dipsticks - It seems that a lot of people are measuring with dipsticks. There has been a lot of talk about thermal expansion of wort at different temperatures. But none about thermal expansion of dipsticks, or of kettles. Calibrate that dipstick with cold water and then stick it into boiling wort... not gonna be accurate anymore. Your kettle is also going to expand and contract. Dont know the amounts, dont know what effect it would have. But i bet it has one, and we are only talking a couple of % here and there for our mystery figures. Hell, what th dipstick is made of will make a difference from brewer to brewer.

Calibraton - Learned this lesson the hard way. The set of measuring jugs I bought was out of whack and by a good 15% too. I ended up having to calibrate my whole setup using a 500ml measuring cylinder. In this thread so far, different people to different degrees, seem to be mixing up their measuring tools. To be consistent, everything you use needs to be calibrated from the same base measuring device. Kettle, Dipstick (which is probably a bad tool for accuracy in the first place) measuring jugs, fermentor.... the lot. If you want consistency AND accuracy, better make the base measuring device a peice of lab equipment. Better yet, a really accurate set of scales and 100 litres or so of distilled water.

Reading - When you are taking your volume reading etc. How accurately can you read your intruments, even if they themselves are accuarate? I've used a dipstick a few times and just to see how accurate it was, I did a rough experiment. with the liquid on the 5litre mark I added 100ml and asked my wife to tell me the volume in the kettle -- 5litres, and thats what I would have said too. So I played around using random volumes in and out, and the wife could not tell volumes with any better accuracy than + or - 100ml (and thats being generous) Thats a 200ml range on a measureing device with a gradiation at 1000mls. That means that my measurements are really only accurate to within + or - 10%. That error flows accross to everything else you are calculating. Your figures can only be as accurate as the LEAST accurate figure you obtain. And I dont know about you, but when I read my hydrometer, anything more accurate than 1.041 , 1.042 is just kidding myself and when we are talking the difference between readings of say 1.038 and 1.035 the inability to read down to the 4th and 5th point becomes really significant.

Potential Extract - You cant just quote weight of grain bill. Potential extract can have a real effect on final figures. assume 1.038 and its not, then your figures will be out. At work our extract figures can vary by several % from batch to batch of the same grain from the same maltster. You have to quote your expected efficiency for the grain you actually used. If a recipe recipient uses different grain, its just going to be different and they need to take it into account.


But, to not just point out negatives - I will do the controlled experiment that has been suggested. I will however do it with AG wort to avoid the "boiled or not" issue. I will use volumes that are small enough so that they can be fully decanted into vessles calibrated with lab equipment in order to work out volumes; and all the samples will be taken to work and run through our digital density meter.

I will also ask one of the brewers if its possible to lose extract during a boil just to see what he says.

Like I said, no answers, but a few more things to think about before any conclusions get drawn.

BTW. IMHO - efficiency into the kettle is the thing to consider. Thats what pro brewers use if they are swapping recipes, thats what BYO and Zymurgy use. A lot of brewers get recipes from those sources, I think we should stay consistent with them. My $.02 anyway.

Thirsty

 

[PistolPatch]

LOL Lucas Yeah I noticed that! If you did end up with 23 litres then you would have had no efficiency drop. If 25, then you would have had an efficiency increase! You never know, you mightn't be the only one who gets this - lol. Did you work out your final volume in the end BTW? If so we can whack your figures into the list. Thanks mate.

Ah Thirsty! So well-written mate but unfortunately you must have missed a few critical posts. Oh well, you get that

I think everyone here would be happy to use Efficiency Into Boiler figures as a standard but a few of us are finding our efficiency dropping during the boil by up to 10%.

Hence, what we are trying to gather now are some figures to try and see how many people are having this problem and then hopefully discovering why. For the purposes of determining this, potential SG is irrelevant and the 1.038 has been picked arbitrarily just to make it quicker to see if peopole are getting a drop or not.

A lot of points you mentioned others have brought up already but the thermal expansion of dipsticks and kettles is a new one. Unfortunately this point doesn't help with the problem either. We would need a contraction to occur at high temps not an expansion. Would have been nice if that was the answer but it's not.

Be great if you can throw in your figures though. We certainly need a lot more and I think these are the key to this thread for the moment.

I'm going back to bed now with my flu which is the only thing I've been in bed with this weekend.

<_<
Pat

 

[Trent]

Gday all
Just spent the weekend at a mates house, and he is a full time brewer. He was telling me that when he brews at home, he gets 90% efficiency into the kettle, and his overall brewhouse efficiency (postboil, and taking into account the trub, etc..) is usually between 72 and 75%. That is the efficency he quotes when people ask, and that is the way I base my eff. too. I think that is probably the easiest way to quote it, as it will obviously be the lowest number, but feel free to quote preboil eff (mash efficiency) as the way to go. I will just keep basing all my stuff on brewhouse effiency, as that it what allows me to work out my recipes. At the end of the day, thats the only reason we need to use efficiencies anyway.
All the best
Trent

 

[Thirsty Boy]

Pat,

I understand that the potential SG has nothing to do with the amazing shrinking efficiency problem. But it does have to do with the ability to translate recipes from brewer to brewer. I made that point more towards the original question posed in the thread, rather than the perplexing side issue.

On the perplexing side issue however.... Actually I didn't miss the points you mentioned. I know a number of the things I talked about have been covered, I just dont think that a lot of them have been as well addressed as you say they have.

I have seen a few posts where calibration was mentioned, but no one has made a comprehensive statement that convinces me that their setup has been really well calibrated. Not saying they aren't, I just haven't seen anything that says they are. I also haven't seen anyone talk about the accuracy with which they can read their instruments, not just how accurate their instruments are. The ability to factor in consistent margins of error is critical in any scientific experiment.

I mentioned, I am unable to read my dipstick to a certainty of more than +/- 100ml or my hydrometer to better than 3 figures;

so to make an example: Lets say I read my pre-boil volume to be 23litres @ 1.038 That gives me 874 points of extract. BUT in reality I have 22.9 litres at 1.0375 for 859 points of extract.

I conduct my boil and at the end should still have 859 points of extract, so I take my measurements to see. In reality I have 20.1 litres at 1.0427 (859 points) but what I read is 20.0 litres at 1.042 for 840 points of extract.

So I have magically lost 34 points of extract in the boil. Thats 3.9% Reverse when I read the highs and lows and I am working with an accuracy of around +/- 4%.

Add in measuring pre-boil with my dipstick that is calibrated to read ever so slighlty high and then measure my post boil in my fermetor that reads ever so slightly low... and suddenly 10% variations dont look that far out of the ball park.

Thats not being unrealistic either, the figures I quoted are pretty close to the BEST I could do for accuracy.

The +/- factor, that could be caused by a number of things, is my main point. Not if the expansion or the mis-calibration effects the results in any particular way, but that the expansion/contraction or whatever introduces uncertainty that needs to be accounted for.

You are of course right when you say that we need more numbers to help figure this out, but to be honest, I just dont think that the majority of homebrewers out there are measuring things in an accurate enough way that you are going to get conclusive results with the sort of sample size you are likely to get.

I really tend to believe that the shrinking efficiency is a matter of systemic error in measurment. Sorry.

To be less of a party pooper though. I am happy to help prove myself wrong.

Next time I brew my house ale, I'll make the batch a bit bigger so I have 4 litres of AG wort with which to conduct as tightly controlled an experiment as I can. I will heat it to nearly 100C and tap it off into a small no-chill. After I have finished my regular brew day, I'll geek out on the 4 litres.

-Everything calibrated from the same schot duran measuring cylinder.

-All volumes taken at the same temperature and measured by fully decanting the whole kettle into the measuring container

-All gravity samples taken to my work and run through the serious arsed desktop density meter

I still doubt if I'll be able to get any better than +/- a couple of percent, but I will do my best.


I will also go talk to the guy who runs our lab brewery (mate, I drool when I see that lab brewery, it is every hombrewers wet dream made real) and find out whether dissapearing extract is possible in his view. His whole job is to conduct mashes, boils and fermetations to 3 decimal places in accuracy and consistency. If it happens, he'll know about it and be able to tell us how to calculate it.

Dont hold your breath waiting for me though, its gonna be weeks at least till I brew again and I wont be on the right shift to talk to the lab guy for a couple of weeks either. Sorry.

Damn.... I write posts longer than Pat does.

Thirsty

 

[lucas]

Did you work out your final volume in the end BTW? If so we can whack your figures into the list. Thanks mate.

It's in a nochill cube with the sides compressed still cooling. probably wont have a free fermenter for it until the weekend, or maybe early next week so no final volume measurement until then

 

[Trent]

Thirsty,
You DO write longer posts than Pat! It looks like we are going to get some definite answers one way or another, with all the people doing experiments and stuff. I am happy to agree it could be me reading stuff wrong, though I am a little doubtful (as I am very anal about measuring my grain, and the amounts of water I add), but happy to be proven wrong. Pat wanted me to add that full time brewer is working in a micro, and I hold his advice very highly, but at the end of the day, it appears that at least a few of us are victims to the disappearing sugars, we just need to work on our final figures rather than anything else, and the rest of it (reading mistake or otherwise) is superfluous. I will be interested in reading hte results as they come in, but will be surprised (based on most peoples experiences) if any of them have the drop in efficiency.
All the best (and I will try not to post too much more here!)
Trent

 

[PistolPatch]

You know the funniest thing? I actually started this thread to take a break from writing on AHB. My posts were getting longer and poorer in proportion to the long hours I've been working recently. So I thought I better stop answering questions and just ask a couple of quick ones that I had.

This thread was my first quick question. LOL!

Back on Topic. This thread is currently stuck. No one has been able to answer the following question as yet...

I have done efficiency measurements using two different sets of instruments and calibrations for both volume and gravity and the figures have matched. I repeatedly get about a 10% drop in efficiency during the boil. So do some others. Why?

How About A New Poll?

It looks like it's going to take a while for everyone to throw some figures in this thread so in the meantime, how about we do a new poll to determine how many people are actually having the same problem as Trent, myself and the couple of others (including a microbrewer!)?

Writing such a poll well so as to get the most info possible is not a 5 minute job so if anyone has any ideas on how it should be written then throw them in here. (That's you Thirsty Old Boy )

Here's my huge effort so far - lol

Poll: Does your efficiency drop during the boil?
Yes
No

Obviously a little more thinking is needed A poll title for a start. Here's a few other things that come to mind...

The first post should also explain that trub losses should be added etc. Paragraph 4 of this post would help put the purpose of the poll in context. A link to this thread would be of value in getting a few more people to throw their figures in here using the template I wrote up the other day. People could also add any theories here. Might as well have one big mess rather than than two

So, if you think a new poll would be worthwhile please fire away with some suggestions and maybe we can whack one up tomorrow evening.

By the way, once we have all this sorted, I'll put a huge edit into Post #1 here with our conclusions and maybe links to some of the top stuff that you guys have written. This way no other poor bugger will have to go where we have gone!

I must say I don't think I have ever seen a thread with such long posts (besides mine). Amazing!

Spot ya,
Pat