missing OG by 2-3 points everytime?

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shaunpycroft

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Hi there, Im trying to nail an issue thats bugging me. Ive been using beersmith for a good few years now and Im pretty confident ive got used to it and nailed in everything for my system. Ive very carefully measured all volumes, losses etc, efficiency settings have been tweaked. I always seem to hit expected SG pretty much bang on everytime but the OG is always down by 2-3 points?? I have checked and measured boil off a few times and its perfect. I really cant see where im not getting whats expected? Any help appreciated folks Thanks
 
If your volumes are right on target, then the issue comes with your brew house efficiency.  You are just not drawing as much sugar from your mash as your efficiency calls for.  Check your recently brewed recipes and on the session tab, left side you will see the calculation of actual BHE versus the target.  If you average the results of a few recipes and change your equipment profile to this value, it will bring you closer.

Remember that when you change your equipment profile, you must update your recipes with this new profile in order for it to take effect. 
 
Would love to see a few recipes with your session data to make it a bit easier to see where the issue may lie.

you say you hit expected sg but miss og, at what points are you hitting/missing?
 
Thanks for the replies chaps. I noted my brew house efficiencies for my last 7 brews and i am regular under my 70.5%. I will change that. it may help. I also noted the difference between my expected attenuation and actual. I am over attenuating on every brew. I must need to re calibrate my mash temp sensors. i am obviously hitting lighter body than intended every time even though my probes say its bang on. For info I run a herms system with my own built control panel. do you think different body, ie different types of sugars, would affect og after boil?
 
not to my knowledge. It only effects the way the starches are converted.

I've got a 32g eHERMS, and would gladly offer any help. Having a .bsmx of a recipe with session data may help establish what your issues with gravities may be. usually it's something simple, feel free to upload a recipe and I know i'll gladly look it over, and i'm sure others would chime in as well. It's hard(impossible) to try to troubleshoot an issue without the data thats obtained.

If you're hitting your Pre-Boil gravity and volume EXACT, (making sure your volumes and gravity readings are correct and calibrated)

then the issue is in your boiloff rate, or loss to trub. I've found that with a rigorous boil i get 3.5g boil off per hour, but with a boil that i then drop down to 80% on my controller after the boil has started i only boil off about 2.5g in an hour. this extra gallon could change the reading quite a bit.

taking precise measurements is always key. If you're using a hydrometer and measuring hot liquor than you need to be sure you're correcting for temperature. for example a reading of 1.050 at 170F is actually 1.076 but if its read at 80F than it's 1.052

As another aside, i use weight to get my volumes. I've got a scale i bought off amazon that measures up to a couple hundred pounds, so i just put my vessel im transferring to on the scale and use that as my measured batch size into fermenter.
 
When you say you are over attenuating, is that straight from your actual final gravity as compared to the target FG?  If you are low by a two to three points, you can expect that your FG will be lower as well. 

On the apparent body of the beer, check the calibration of your thermometer or if you are relying on the thermocouple or thermistor in your HERMS system then I would recommend checking the actual temperatures against a calibrated thermometer.  I've done a lot of tuning of control circuits on thermistors and thermocouples to be wary of their accuracy.
 
dtapke said:
not to my knowledge. It only effects the way the starches are converted.

I've got a 32g eHERMS, and would gladly offer any help. Having a .bsmx of a recipe with session data may help establish what your issues with gravities may be. usually it's something simple, feel free to upload a recipe and I know i'll gladly look it over, and i'm sure others would chime in as well. It's hard(impossible) to try to troubleshoot an issue without the data thats obtained.

If you're hitting your Pre-Boil gravity and volume EXACT, (making sure your volumes and gravity readings are correct and calibrated)

then the issue is in your boiloff rate, or loss to trub. I've found that with a rigorous boil i get 3.5g boil off per hour, but with a boil that i then drop down to 80% on my controller after the boil has started i only boil off about 2.5g in an hour. this extra gallon could change the reading quite a bit.

taking precise measurements is always key. If you're using a hydrometer and measuring hot liquor than you need to be sure you're correcting for temperature. for example a reading of 1.050 at 170F is actually 1.076 but if its read at 80F than it's 1.052

As another aside, i use weight to get my volumes. I've got a scale i bought off amazon that measures up to a couple hundred pounds, so i just put my vessel im transferring to on the scale and use that as my measured batch size into fermenter.
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I will happily share a file if I knew how?? lol ill look into that
 
Oginme said:
When you say you are over attenuating, is that straight from your actual final gravity as compared to the target FG?  If you are low by a two to three points, you can expect that your FG will be lower as well. 

On the apparent body of the beer, check the calibration of your thermometer or if you are relying on the thermocouple or thermistor in your HERMS system then I would recommend checking the actual temperatures against a calibrated thermometer.  I've done a lot of tuning of control circuits on thermistors and thermocouples to be wary of their accuracy.
Click to expand...
Its more from the expected attenuation percentage than fg which says im lighter body than it should be. I will this week calibrate my temp probes
 
shaunpycroft said:
I will happily share a file if I knew how?? lol ill look into that
Click to expand...

To share the recipe file, click once on the recipe in the folder to highlight that recipe without opening it.  Now click on 'file' > 'export selected' and save as a .bsmx file.  Now you can attach it to a message and post it.
 
Oginme said:
shaunpycroft said:
I will happily share a file if I knew how?? lol ill look into that
Click to expand...

To share the recipe file, click once on the recipe in the folder to highlight that recipe without opening it.  Now click on 'file' > 'export selected' and save as a .bsmx file.  Now you can attach it to a message and post it.
Click to expand...

ok lets try this, now you can tell me where im going ridiculously wrong ha ha
 

Attachments

I am not sure you are so very far off.  You are a point high on your mash gravity, a point low on your OG.  How accurate are your volume measurements?  How much trub did you have left over after transferring the wort to the fermenter? 

As far as your FG reading, the model for fermentability within BeerSmith does not do well at predicting FG for mashes with multiple saccharafication steps as does any software model.  Your apparent attenuation of 84% does seem a bit high, especially for WY2124 which I use quite a bit.  I just checked a Marzen made with WY2124 which I bottled the other day and calculated 79.3% apparent attenuation, and that was made with similar 147F-158F saccharafication steps. 

Remember that the software is a model of what is happening in your system.  I put in a lot of work making sure that I have lot analysis of my main malts, measure my volumes to within 0.2L, and have a pretty tight process and am pretty happy with results like you just achieved.  Boil off rates change slightly with the ambient temperature and humidity, so don't sweat it unless you find you are consistently ending up with results like you just attained.

I keep a running spreadsheet of volumes and gravity readings from which I calculate water absorption, boil off rate, and trub loses for each recipe I brew.  Typically, I only make changes to my equipment profile about once a year and usually they are minor updates from my tightening down my process more than changes in the actual values. 
 
Thanks for looking at that. I might put a different recipe up that didn?t use a step mash. That pils is in fermenter at moment so it?ll be interesting to see how it ends up. Ones where I?m only single infusing seem further away. Volumes into kettle are bang on, I will double double check into fermenter, more so what?s left in kettle. I know I always get my stated 27 litres into fermenter when it?s emptied the kettle to its outlet point. I have, when setting the equipment up, measured the capacity to the outlet point. Thanks 👍🏻
 
Forgive me, for I may go back and forth from american stupidity and metric systems, i'll try to stick with metric if thats what you're using.

if we use the boil off tool, you'll find that if we enter 43.5L of 1.038 wort for a 90 minute boil at a boil off rate of 5L per hour (how your equipment profile is set up) we should get 34.55L of 1.047 wort, yet your batch size is listed as 27L of 1.045 wort

this tells me something we already knew, you're running into an issue between mashing and fermenting. Now you've got a boil off rate of 5L/hour which seems reasonable. but you also have a loss to cooler and trub as 7.5L. I think this is where we're running into an issue.

now, boil off rate and time is where you get gravity readings. if we address that first, than your boil off rate is a bit off. IF you boiled for exactly 90 minutes, you can change your boil off rate to 5.2L/hour and you'll find that you get 34.24L of 1.047 wort, so we can try making that change to get your Gravity on track and assume that your volume is a hair off as far as loss to cooler and trub.

I would say the first thing you need to change would be boil off rate if you're constantly not hitting the post boil gravity, as boil off is the only thing that can effect post boil gravity.

other than that i would definitely do something to address your cooler/trub loss, you're losing a 12 pack of beer there bud. who cares about a few gravity points when you're tossing a 12 pack down the drain every time you brew. I've gotten my cooler/trub loss down to a half liter.
 
dtapke said:
Forgive me, for I may go back and forth from american stupidity and metric systems, i'll try to stick with metric if thats what you're using.

if we use the boil off tool, you'll find that if we enter 43.5L of 1.038 wort for a 90 minute boil at a boil off rate of 5L per hour (how your equipment profile is set up) we should get 34.55L of 1.047 wort, yet your batch size is listed as 27L of 1.045 wort

this tells me something we already knew, you're running into an issue between mashing and fermenting. Now you've got a boil off rate of 5L/hour which seems reasonable. but you also have a loss to cooler and trub as 7.5L. I think this is where we're running into an issue.

now, boil off rate and time is where you get gravity readings. if we address that first, than your boil off rate is a bit off. IF you boiled for exactly 90 minutes, you can change your boil off rate to 5.2L/hour and you'll find that you get 34.24L of 1.047 wort, so we can try making that change to get your Gravity on track and assume that your volume is a hair off as far as loss to cooler and trub.

I would say the first thing you need to change would be boil off rate if you're constantly not hitting the post boil gravity, as boil off is the only thing that can effect post boil gravity.

other than that i would definitely do something to address your cooler/trub loss, you're losing a 12 pack of beer there bud. who cares about a few gravity points when you're tossing a 12 pack down the drain every time you brew. I've gotten my cooler/trub loss down to a half liter.
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Hi there and many thanks for looking.
I think the cooler trub loss is because im leaving 6 litres in the bottom of my kettle as it a stainless keg system which has a round bottom and when im transferring to fermenter and it stops emptying at the tap outlet there is 6 litres left in along with trub and hops etc etc. I also use a plate heat exchenger and pipework so that allows for the rest, roughly.
If I try changing the boil off rate to a higher rate then surely the system will expect me to have created an even denser wort but my main problem is its always under? Should I maybe drop the boiloff rate?
 
LOL you got it. yes, I misspoke because i was doing a few things at once.

you started at 1.038 and got to 1.045 which would mean you're close to a 3.5L boil off rate. which is a VERY soft boil likely, or your time was off, did you boil for a full 90 minutes for sure?
 
I'll add to this, i use a pretty massive plate chiller, when i'm done draining my kettle (leaves 4oz behind) I then remove the hose from the kettle, hook an Oxygen tank to it, and crank it up. this pushes all the remaining wort out of my cooler, pump, hoses, etc.

I end up with another 4-6oz of liquid in those remaining hoses and the chiller.

fwiw its a Duda 60 plate 20" chiller. the thing could probably hold 2 gallons by itself if i didn't do that lol.

I'd see if you can find a dip tube, or even custom make one to get to the bottom of that kettle. I'd have a heck of a time worrying about a few gravity points when I'm leaving behind that much.

with the right measurements, these guys could get a diptube and hopstopper that would help you keep more beer in your fermentor and less in the drain:
https://shop.theelectricbrewery.com/collections/hop-stopper
 
dtapke said:
LOL you got it. yes, I misspoke because i was doing a few things at once.

you started at 1.038 and got to 1.045 which would mean you're close to a 3.5L boil off rate. which is a VERY soft boil likely, or your time was off, did you boil for a full 90 minutes for sure?
Click to expand...

It was a viorous boil and bang on 90 minutes timed with an ezboil pid. backed up by the laptop running beersmith timer just incase!
 
how are you measuring gravity? hydrometer or refractometer?
is it properly temperature calibrated?


a vigorous boil in a 10-15g pot should boil off 5-7LPH

I get around 10LPH in my 32G electric brewery. Boiling with a 5800w element on full.
 
dtapke said:
how are you measuring gravity? hydrometer or refractometer?
is it properly temperature calibrated?


a vigorous boil in a 10-15g pot should boil off 5-7LPH

I get around 10LPH in my 32G electric brewery. Boiling with a 5800w element on full.
Click to expand...
Its a digital refractometer designed for beer with atc. I factor in the loss to kettle so shouldnt make a difference to the gravity should it?
 
from the start of the boil to the end of the boil the concentration of sugar and volume lost to the air is the only thing changing.

I'd make a minor tweak to boil off rate and see what it gets you, maybe drop from 5 to 4.5/hr and see if you're closer to your numbers on the next run.
 
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