What am I calculating wrong?

[Smellyglove]

I did a high gravity beer yesterday and diluted it to a target OG after boil.

This is my second attempt where my OG is low. I can't figure out why.

I use beersmith. I've taken my equipment-profile and copied it and adjusted some numbers for HG-batches.

I basically doubled the batch size, and added top up water to be half the batch into fermentor.

My target preboil SG yesterday was 1.086. I hit 1.086, maybe one point over. I'm 100% sure I did not mess up any readings on the low side. The OG was def at least 1.086.

I missed my preboil volume by about 0.3L. I didn't worry about it. So preboil was 17.9L

Post boil was 1.096.

The Target OG for the batch was 1.052. So in my mind 52*2= 104. Dillute with 50% water and we're down to 1.052.

Here comes the boil off:

17,9L preboil volume as measured just before boiling temps. SG 1.086
16,0L, pre chill. OG 1.096

Do it backwards: (17,9*86)/16 = 96. My OG was 1.096
When I look at these numbers it seems like I boiled off more than calculated, anyways, let's continue.


What beersmith calculated:

(18,17*86)/16,67 (this is pre chill volume) = 97.

97/2 = 48.5

The OG in Beersmith was set to 1.052.


Disclaimer: I've broken my sight glass, but I have marked fermentors. I'm always way inside the ballpark when it comes to boiloff.

Anyone see where I could have gone wrong? Or is there a bug in BS? s there something I didn't think about? I'm curious about the numers BS gave me.

I have "loss to trub and chiller" 2L
Batch Size 28L
Top up water 14L
Boil off 1.5L/hr

 

[FunkedOut]

A few thoughts that might help you sort this out...

Top up water should be added after boil.
Top up water for kettle should be added before boil.

With such a large top up water volume, boil off rate errors are magnified.

Boil off rate in BS (1,5) does not match your actual rate (1,9).
Adjusting that should raise the predicted OG a bit.

Adjust your BH efficiency to get it the rest of the way there.
With all system losses held constant, and BH efficiency changes should result in mash efficiency changes.

 

[Smellyglove]

This makes it even more funny. Then I boiled off more than what Beersmith predicted, and still I was low on OG, even though higher boil off should leave me with a higher OG. I did for sure not boil off less, as I'm having problems boiling off less than my normal boil numbers (i tried to boil off 1.5L comparing to normal 1.7-1.75L for this one) The top off water should be correct as I have those numbers dialed in "top up water" (into fermentor).

 

[FunkedOut]

I’m not sure I follow.
Would you mind posting a screenshot of your sessions tab for that recipe?

 

[histo320]

Are you adjusting your hydrometer reading for the temperature of your sample?

 

[BLL]

Your efficiency is almost always going to drop with an increase in grain mass. If you're averaging 80% with worts in the 1.050 to 1.070 range then I'd anticipate around 75% for a wort that is approaching 1.100, maybe even less.

 

[Smellyglove]

Your efficiency is almost always going to drop with an increase in grain mass. If you're averaging 80% with worts in the 1.050 to 1.070 range then I'd anticipate around 75% for a wort that is approaching 1.100, maybe even less.

I hit my preboil SG. Boil off was more then BS predicted. So, I should have a higher OG wort comparing to what BS predicted.

The question is am I overlooking something obvious, or the the calculation I wrote above how I believe BS calculates this wrong?

 

[Smellyglove]

Are you adjusting your hydrometer reading for the temperature of your sample?

Yes and yes to all other questions regarding "obvious measurement stuff"

One lab grade hydrometer, one digital refractometer, one "analog" refractometer. 1.086.

I just cant get the BS calculation to add up.

 

[chickypad]

I can't follow you either. As mentioned it might be helpful to post screenshots of your recipe and volumes page.

 

[Smellyglove]

 

[BLL]

I hit my preboil SG. Boil off was more then BS predicted. So, I should have a higher OG wort comparing to what BS predicted.

The question is am I overlooking something obvious, or the the calculation I wrote above how I believe BS calculates this wrong?

It's not uncommon for preboil gravity measurements to be misleading, especially in bigger batches since you've got a runoff outlet feeding wort that is of a substantially lower gravity and temperature into a large volume of higher gravity, higher temperature wort. All of this contributes to a condition called stratification which means due to varying densities and temperatures you cannot expect the wort to be completely homogenized. Stratification is common in production settings where you're dealing with many hundreds, if not thousands of gallons of wort at once and the best way to make sure you're getting a gravity measurement that is accurate is to stir and take multiple readings.

 

[Smellyglove]

It's not uncommon for preboil gravity measurements to be misleading, especially in bigger batches since you've got a runoff outlet feeding wort that is of a substantially lower gravity and temperature into a large volume of higher gravity, higher temperature wort. All of this contributes to a condition called stratification which means due to varying densities and temperatures you cannot expect the wort to be completely homogenized. Stratification is common in production settings where you're dealing with many hundreds, if not thousands of gallons of wort at once and the best way to make sure you're getting a gravity measurement that is accurate is to stir and take multiple readings.

I don't even sparge. SG-numbers are correct. If they are not correct it's most likely only one point off.

 

[Smellyglove]

double.

 

[Smellyglove]

To do a recap on the number so you don't have to look for them:

Preboil SG 1.086
Postboil SG: 1.096

Since I dilute with the same amount of water as I have wort, I'm guessing the post boil SG should be 1.104 since my target OG was 1.052.

When doing the estimated numbers from beersmith:

Preboil Volume: 18.17L
Preboil SG: 1.086
Post boil volume (pre chill): 16.67L

=

(18.17*86) / 16.67 = 94 ish. And since I dilute with equal amounts of water as I have wort.. this does not add up to me.

 

[BLL]

Preboil gravity could've been off due to stratification, postboil could've been off due to temperature.

If there's no question in your mind your gravity readings were correct then you're just going to have to chalk it up to a miscalculation in beersmith. That could be because you've input some information incorrectly in your equipment profile, it could be because it's just beersmith and it's not perfect. All beersmith does is pump out numbers based on what you put in it. It doesn't brew beer.

Ultimately you came up a little bit shy of you're target, but not by much. You win.

 

[chickypad]

I think this looks like it calculated right, you said it estimated 1.097 post boil prior to topping off, right? That should be the post chill volume of 16L. So:

Preboil 18.17L at 1.086
Post chill 16 L at 1.097
top off with 14 L to 30 L to get 1.052

Doing it be calculations:
(86*18.17)/16 = 97.6
(97.6*16)/30 = 52

 

[Smellyglove]

Preboil gravity could've been off due to stratification, postboil could've been off due to temperature.

If there's no question in your mind your gravity readings were correct then you're just going to have to chalk it up to a miscalculation in beersmith. That could be because you've input some information incorrectly in your equipment profile, it could be because it's just beersmith and it's not perfect. All beersmith does is pump out numbers based on what you put in it. It doesn't brew beer.

Ultimately you came up a little bit shy of you're target, but not by much. You win.

I posted my numbers in the screenshots above. I'm wondering if there's something I've missed/misunderstood. Or if there is a bug in Beersmith. I'm guessing the first, but I can't figure out where I've missed.

 

[Smellyglove]

I think this looks like it calculated right, you said it estimated 1.097 post boil right? That should be the post chill volume of 16L. So:

Preboil 18.17L at 1.086
Post chill 16 L at 1.097
top off with 14 L to 30 L to get 1.052

Doing it be calculations:
(86*18.17)/16 = 97.6
(97.6*16)/30 = 52

Ah! But I also have loss to trub in there which is 2L. So I blend 14L wort with 14L water to get 28L into fermentors. Dang that I dind't think twice about why I had to stop at 12L instead of 14L to get to my OG.

So, It's kind of misleading, I guess? I leave 2L behind, as stated in the loss to trub and chiller, and top off "into fermentor". Batch size is also set to 28L. But Beersmith calculates that I'm using these 2L to blend. Does it sound reasonable?

In other words the loss to trub and chiller parameter is not in the equation when topping off into fermentor?

 

[Smellyglove]

So. Instead of trying to manipulate BS (it's a mess, since all numbers follow). The easiest will be to just set it to a normal batch size, but twice the OG, then dilute it.

 

[chickypad]

Yeah I think that's the answer, it's probably counting as top off first then lose the 2L to trub. I don't run into this generally because I just pour everything into the fermenter, with no trub loss it seems to calculate the top off for me fine.

 

[FunkedOut]

the top up water value is calculated by beersmith to be added to the kettle before transferring to the fermenter.

I’d advise this strategy if possible, as it will dilute the sugars before leaving your loss to trub and chiller behind, improving brewhouse efficiency.

if you’re set on adding the water to the fermenter, zero out the top up water value, and set your batch size to half the desired at twice the gravity.
I don’t see a way for BS to calculate this scenario.
(you still need the keep the loss to trub and chiller value, as you need to make this wort if you’re going to leave it in the kettle)

 

[rocketpants]

the top up water value is calculated by beersmith to be added to the kettle before transferring to the fermenter.

I’d advise this strategy if possible, as it will dilute the sugars before leaving your loss to trub and chiller behind, improving brewhouse efficiency.

if you’re set on adding the water to the fermenter, zero out the top up water value, and set your batch size to half the desired at twice the gravity.
I don’t see a way for BS to calculate this scenario.
(you still need the keep the loss to trub and chiller value, as you need to make this wort if you’re going to leave it in the kettle)

Or double the kettle loss to take the extra sugar loss into account when doing double batches

Sent from my Pixel using Home Brew mobile app

 

[Smellyglove]

I guess this phrasing is where I had it wrong:

 

[Smellyglove]

Or double the kettle loss to take the extra sugar loss into account when doing double batches

Sent from my Pixel using Home Brew mobile app

Wouldnt this offset it even more? Dilute with less sugars when Im already low on sugars?

 

[FunkedOut]

I guess this phrasing is where I had it wrong:

View attachment 566886

That phrase does seem to say the complete opposite of what I wrote above.

I found this blog about creating a profile:
http://beersmith.com/blog/2015/08/02/creating-an-equipment-profile-in-beersmith/

Post Boil Additions and Losses

Now that we’ve got the target batch volume, we’re going to work backwards to determine how much water is needed in the boil to get to our target batch volume. The next section in the wizard shows the post-boil additions and losses.

The first field in this section is Top Up Water. Top Up Water is water added after the boil, usually by extract brewers. Many extract brewers brew with a smaller stove-top pot of 3-4 gallons (12-16 liters) and then add 2+ gallons (8+ liters) or more water after the boil to bring their volume up to the desired level in the fermenter. This added water is the Top Up Water.

All grain brewers usually work with larger full volume boils, so they rarely need any top up water. So if you are an all grain brewers the top-up water should be set to zero.

The next number shown is the Loss to Trub and Chiller. This is the volume of wort lost to the sediment (called trub) left in the bottom of the pot after the boil as well as any losses from the use of a chiller or losses in transferring the wort. For a typical 5 gallon (19 liter) batch its not unusual to have 2 quarts (2 liters) or more of loss to trub, though it can be more or less depending on your brewing technique and how you manage your grain and hop additions.

Below that you will see an estimate for Post-Boil shrinkage – since water volumes shrink by about 4% as the water cools. And finally you will see an estimate for the post-boil volume needed for your equipment setup. This is simply the sum of the target batch volume plus trub loss minus any top-up water. Its an estimate of how much wort you need to have when you finish the boil to hit your target batch volume into the fermenter.

Although the top up water section is not 100% on where to added the water, the fact that we are “working backwards” and top up water comes before loss to trub and chiller, makes me think that it calculates dilution after the loss.

 

[Smellyglove]

That phrase does seem to say the complete opposite of what I wrote above.

I found this blog about creating a profile:
http://beersmith.com/blog/2015/08/02/creating-an-equipment-profile-in-beersmith/


Although the top up water section is not 100% on where to added the water, the fact that we are “working backwards” and top up water comes before loss to trub and chiller, makes me think that it calculates dilution after the loss.

The two beers I made with the HG/dilution process did end up perfectly with the "error", so it can't calculate the loss in the equation. I had to make 2x13L batches instead of 2x14L batches, those 2L is in the loss.