Author Topic: Calculating gravity on partial mash and extract batches incorrectly?  (Read 2838 times)

Offline h22lude

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Going to be doing a few extract and steeping grain batches to show some friends. Trying to remember how to calculate gravity for extract. I'm using BeerSmith and it doesn't seem like he calculates it correctly.

For volume, my post-boil will be 6.5 gallons and wort into fermentor will be 5.5 gallons. BeerSmith calculates OG by using the into fermentor amount. For example, 1lb of DME has 43 points per pound per gallon. So BS calculated it as 43 points x 1lb DME / 5.5 gallons to get about 1.008. Shouldn't the volume used be post boil (6.5 gallons), since at that point the gravity of the wort won't change? Whether you put all 6.5 gallons into the fermentor or leave 3 gallons in the kettle, that wort will have the same gravity.

Also, I'm using steeping grains which I know adds a little sugar. I'm using 2oz black patent, 6oz chocolate wheat, 8oz carafoam, 8oz C10, 8oz flaked oats and 1lb C60. BS is only giving a total of 2 points for all those grains (and as above, is using 5.5 gallons to calculate it). Using John Palmer's grain list (http://howtobrew.com/book/section-2/wha ... alt-yields), I get a little over 6 points when using 5.5 gallons as BS would use. If I use 6.5 gallons, like I think I should, I get a little over 5 points which is still higher than the 2 BS calculates.

Am I missing something or is BS wrong?

Online Oginme

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Re: Calculating gravity on partial mash and extract batches incorrectly?
« Reply #1 on: October 18, 2019, 04:35:45 PM »
I have created an extract recipe using DME and my standard batch size.  So I have 1 kg of DME with a potential of 1.045 (45 points) in a 10 liter batch size with 1 liter of trub.  The program calculates out the OG in the fermenter as 1.034, which is correct for 11 liters at the end of the boil.  If the program were to calculate the gravity based upon the batch size (10 l) then it would give me a gravity of 1.037 as my target.  Seems to me that the program is doing the calculation correctly.

For the above, I changed the recipe type to 'extract' in order for the program to use the proper set of equations to calculate out the OG value.

For the steeping grains, you are comparing the settings in BeerSmith where the steeping extraction is set for 15% of the available sugars from that grain to a figure in Palmer's book which lists an unknown potential for the grain with an unknown steeping efficiency.  Until you actually do the recipe and see where your values come out, you are really just chasing numbers that you have no basis for comparison.  I can tell you that when I make extract plus steeping grains, I ended up increasing the the steeping efficiency to 19% because every system is different and that is what my system produced.  It has worked reliably and predictably since I made that change.

The program is a set of calculations.  The tools are embedded within the program for users to customize the expected results for them to make the program match what their system gives you. 
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Offline GigaFemto

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Re: Calculating gravity on partial mash and extract batches incorrectly?
« Reply #2 on: October 18, 2019, 07:54:53 PM »
Beersmith 2 and 3 calculate gravity incorrectly for all-grain batches with large amounts of extract. For the grain contribution the final amount of sugar in the fermenter uses the trub loss to calculate the percentage. It takes the cooled volume in the kettle and assumes that the percentage of sugar that makes it into the fermenter is: (batch volume)/(cooled volume) =((cooled volume) - (trub losses))/(cooled volume). However, BeerSmith 2 and 3 incorrectly assume that trub losses of ZERO apply to the DME contribution, so all the sugar from DME makes it into the fermenter. For small amounts of DME this is not a big deal, but if you are using significant amounts, the OG calculations are wrong unless you actually do have trub loss of zero (i.e. you dump the whole kettle into your fermenter). Also, BeerSmith 2 and 3 don't account for the volume of the DME. The recipe tab will list the volume of the DME but the calculations on the volumes tab don't take this into account (?? this boggles my mind). Again, for small amounts it doesn't matter, but when you start adding several pounds to a 5 gallon batch it is significant. My mash tun is too small to handle more than about 13 pounds of grain, so for high-gravity beers I add a lot of DME to get the OG up. I have two stouts coming up that will have several pounds of DME in them and I have had to calculate gravities and volumes myself because BeerSmith is just wrong. I complained about this in BeerSmith 2 and was greatly disappointed to see that BeerSmith 3 did not fix these problems. it isn't a big deal for me because I know the issue and when to do my own calculations, but it is an ongoing source of confusion to others.

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Offline h22lude

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Re: Calculating gravity on partial mash and extract batches incorrectly?
« Reply #3 on: October 19, 2019, 06:17:14 AM »
I have created an extract recipe using DME and my standard batch size.  So I have 1 kg of DME with a potential of 1.045 (45 points) in a 10 liter batch size with 1 liter of trub.  The program calculates out the OG in the fermenter as 1.034, which is correct for 11 liters at the end of the boil.  If the program were to calculate the gravity based upon the batch size (10 l) then it would give me a gravity of 1.037 as my target.  Seems to me that the program is doing the calculation correctly.

For the above, I changed the recipe type to 'extract' in order for the program to use the proper set of equations to calculate out the OG value.

For the steeping grains, you are comparing the settings in BeerSmith where the steeping extraction is set for 15% of the available sugars from that grain to a figure in Palmer's book which lists an unknown potential for the grain with an unknown steeping efficiency.  Until you actually do the recipe and see where your values come out, you are really just chasing numbers that you have no basis for comparison.  I can tell you that when I make extract plus steeping grains, I ended up increasing the the steeping efficiency to 19% because every system is different and that is what my system produced.  It has worked reliably and predictably since I made that change.

The program is a set of calculations.  The tools are embedded within the program for users to customize the expected results for them to make the program match what their system gives you. 

I started off using extract setting.  That does calculate the extract gravity correct using the post boil volume.  I don't feel like it calculates steeping grains correctly.  So I switched to partial mash which was calculating it a little better but that is where it doesn't calculate extract correctly.  If you enter just extract and use partial mash setting, BS uses into fermentor volume.  I'm not sure why it would do that.

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Re: Calculating gravity on partial mash and extract batches incorrectly?
« Reply #4 on: October 19, 2019, 07:41:45 AM »
With a partial mash setting, the program will treat your steeping grains as if they were a base malt and possibly calculate to extract more sugars than they contain. 

It is your choice in how you want to use the program, but manipulating it to match what you "think" it should give you for output without some basis in what your process will actually produce is setting yourself up for disappointment and/or frustration if you don't achieve those values.

« Last Edit: October 19, 2019, 08:38:17 AM by Oginme »
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Offline h22lude

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Re: Calculating gravity on partial mash and extract batches incorrectly?
« Reply #5 on: October 19, 2019, 12:39:34 PM »
With a partial mash setting, the program will treat your steeping grains as if they were a base malt and possibly calculate to extract more sugars than they contain. 

It is your choice in how you want to use the program, but manipulating it to match what you "think" it should give you for output without some basis in what your process will actually produce is setting yourself up for disappointment and/or frustration if you don't achieve those values.

I agree things might change based on my system but I feel it is safer to go with what Palmer has stated than the 1 gravity point BS is spitting out.  There is no mash efficiency with steeping grains.  The starches have already been converted to sugars.  I just need to rinse them out.  I will definitely get more than 1 point from these 3 pounds of grains.

Offline BOB357

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Re: Calculating gravity on partial mash and extract batches incorrectly?
« Reply #6 on: October 19, 2019, 01:02:15 PM »
With a partial mash setting, the program will treat your steeping grains as if they were a base malt and possibly calculate to extract more sugars than they contain. 

It is your choice in how you want to use the program, but manipulating it to match what you "think" it should give you for output without some basis in what your process will actually produce is setting yourself up for disappointment and/or frustration if you don't achieve those values.

I followed this person's same subject thread on Reddit. No matter what you try to tell him he'll argue that he's right and nobody understands what he's doing. You're wasting your breath.
Bob

Offline h22lude

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Re: Calculating gravity on partial mash and extract batches incorrectly?
« Reply #7 on: October 19, 2019, 01:21:03 PM »
I followed this person's same subject thread on Reddit. No matter what you try to tell him he'll argue that he's right and nobody understands what he's doing. You're wasting your breath.

Please tell me what I've said that is wrong.  Give me just one thing.

People understand what I'm talking about.  Those people understand how to calculate gravity when using extract.

Offline BOB357

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Re: Calculating gravity on partial mash and extract batches incorrectly?
« Reply #8 on: October 19, 2019, 01:41:28 PM »
I don't waste my words on those who refuse to listen to good advice. Hope you achieve whatever it is you want.
Bob

Offline h22lude

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Re: Calculating gravity on partial mash and extract batches incorrectly?
« Reply #9 on: October 19, 2019, 02:07:16 PM »
I don't waste my words on those who refuse to listen to good advice. Hope you achieve whatever it is you want.

I did listen to good advice.  Someone on the Reddit thread and Oginme in this thread said to look at the steeping grain efficiency.  That fixed my issue.  Still doesn't answer why partial mash doesn't calculate extract additions correctly though.

You post saying no matter what people tell me I will argue that I'm right.  But then when asked to post where I was wrong, you say you don't want to waste your time...but you spent the time to come here and say I'm argumentative.  This is a typical response when you have no proof that I was argumentative.  Usually coming from someone that was proven wrong but can't admit it.

Offline BOB357

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Re: Calculating gravity on partial mash and extract batches incorrectly?
« Reply #10 on: October 19, 2019, 04:16:15 PM »

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Re: Calculating gravity on partial mash and extract batches incorrectly?
? Reply #5 on: Today at 12:39:34 PM ?

Quote
Quote from: Oginme on Today at 07:41:45 AM
With a partial mash setting, the program will treat your steeping grains as if they were a base malt and possibly calculate to extract more sugars than they contain. 

It is your choice in how you want to use the program, but manipulating it to match what you "think" it should give you for output without some basis in what your process will actually produce is setting yourself up for disappointment and/or frustration if you don't achieve those values.


I agree things might change based on my system but I feel it is safer to go with what Palmer has stated than the 1 gravity point BS is spitting out.  There is no mash efficiency with steeping grains.  The starches have already been converted to sugars.  I just need to rinse them out.  I will definitely get more than 1 point from these 3 pounds of grains.

Bob

Offline h22lude

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Re: Calculating gravity on partial mash and extract batches incorrectly?
« Reply #11 on: October 19, 2019, 06:26:00 PM »

BeerSmith 2 Rocks!
 
 
Re: Calculating gravity on partial mash and extract batches incorrectly?
? Reply #5 on: Today at 12:39:34 PM ?

Quote
Quote from: Oginme on Today at 07:41:45 AM
With a partial mash setting, the program will treat your steeping grains as if they were a base malt and possibly calculate to extract more sugars than they contain. 

It is your choice in how you want to use the program, but manipulating it to match what you "think" it should give you for output without some basis in what your process will actually produce is setting yourself up for disappointment and/or frustration if you don't achieve those values.


I agree things might change based on my system but I feel it is safer to go with what Palmer has stated than the 1 gravity point BS is spitting out.  There is no mash efficiency with steeping grains.  The starches have already been converted to sugars.  I just need to rinse them out.  I will definitely get more than 1 point from these 3 pounds of grains.

This post just proves to me that you don't understand the problem and are just posting to be deviant for no reason.  You blindly following a product and when someone questions whether the product is working properly, for some reason you get butt hurt.

If you took the time to read what I'm saying the problem is, maybe you would understand.  If you don't want to learn or help others learn, you should just stay away from forums and stop trying to be a troll.  If you care to learn, go look at my post in the Beersmith Mobile sub forum.  That may help you understand.  If you don't care to, then continue to blindly use products without questioning whether they are right or not.  Even if I'm wrong, I at least try to learn.  You just post nonsense.

Offline BOB357

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Re: Calculating gravity on partial mash and extract batches incorrectly?
« Reply #12 on: October 19, 2019, 07:14:17 PM »
This would be funny if it weren't so pathetic. You actually believe that you're right and everyone else is screwed up, don't you? Have fun with yourself.
Bob

Offline h22lude

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Re: Calculating gravity on partial mash and extract batches incorrectly?
« Reply #13 on: October 19, 2019, 07:23:26 PM »
Nope I don't think I'm right, I know I am.  You have yet to give me one example of why I am wrong but I figured that would happen.  You don't understand the calculations so you just say I'm wrong.  I get it.  It is a very human thing to do.  Say someone is wrong because you don't understand.

I probably shouldn't egg you on anymore but just in case a small part of you actually wants to learn.  This is my post from the mobile sub forum and explains why the extract addition calculation within BS is wrong.

The constant variables are...
1) Post boil volume is 6.5 gallons
2) Into fermentor volume is 5.5 gallons
3) 5lbs of DME at 45ppg
4) How to calculate gravity...points per pound per gallon X pounds of extract / gallons

When using the extract setting type, the gravity that BS calculates is 1.034.  This is correct.  Using the equation from #4, 45ppg X 5lbs / 6.5 gallons = 34 points (which is 1.034).  Sugar is added to a volume of water.  Some of that water evaporates during the boil.  After the boil, we are left with 6.5 gallons of water (wort at this point).  That volume and the sugar concentration in that volume will never change going forward.  If you take 5 gallons from that or you take 1mL, the gravity will always be 1.034.

When using all-grain and partial mash setting type, the gravity that BS calculates is 1.041.  This is not correct.  When using all-grain and partial mash, BS calculates the gravity of the wort when using extract by using the into the fermentor volume even though that sugar was put into the post boil volume.  45ppg X 5lbs / 5.5 gallons = 41 (which is 1.041).  Changing BH efficiency does not change that gravity figure.  I have it set at 1% and then changed it to 100%, the gravity figure stays the same at 1.041.   I also changed between all-grain and partial mash.  Still 1.041.  I changed to boil off amount from .9 gallons to 1.5 gallons.  That also didn't change the gravity, which it shouldn't so that is correct.  Changing the Loss to Trub and Chiller also doesn't change the gravity (which it should because now the post boil volume will be higher).  Changing the batch size (which is into the fermentor volume) does change the gravity for both all-grain and partial mash.  I agree that changing the batch size will change the gravity but that is because it will also change the post boil volume (which is what we use to calculate gravity of extract additions).  The reason the gravity changes in BS when changing the batch size is because it uses batch size to calculate gravity of extract additions.

I then added grains into the equation.  I added 8lbs of pilsner.  Using partial mash and all-grain, BS calculates the gravity for just those grains to be 1.038 for a 5.5 gallon batch with 6.5 gallon post boil volume.  I agree with that calculation.  I then added the same 5lbs of DME.  The gravity now is 1.079.  The difference between the gravities is 41 points.  If you remember from my DME only example above, 41 points is what we get when using the batch size (into fermentor volume).  So even with all-grain and partial mash using DME and grains, BS is still using batch size to calculate extract additions.  I changed my BH efficiency from 72% to 1%.  This did change the gravity but only from the grains.  At 1% I got a gravity of 1.001 for just the grains.  When I added the DME back in, I got 1.041 (which is 1 point off but that is probably due to rounding).

When using all-grain or partial mash and you have an extract addition during the boil, BS does not calculate the gravity correctly.  It should use BH efficiency for sugars from grain and post boil volume for the extract addition.

Let's think about this another way.  Let's say we mashed in with the 8lbs of pilsner malt and boiled for 60 minutes.  Our post boil volume is 6.5 gallons and our gravity is 1.038.  Now we add 5lbs of DME to the 6.5 gallons post boil.  The DME adds 34 points (45ppg X 5lbs / 6.5 gallons).  So we have 1.038 from the grain and 1.034 from the DME giving us 1.072.  We now drain 5.5 gallons into our fermentor.  That 5.5 gallons in our fermentor is still 1.072 BUT the way BS calculates this we are getting 1.079.  How can transferring wort from the kettle to the fermentor increase gravity?

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Re: Calculating gravity on partial mash and extract batches incorrectly?
« Reply #14 on: October 19, 2019, 07:27:23 PM »
OK, let's try looking specifically at the partial mash setting.  This means the program is using not only the extract addition but also the mash setting *Including any mash tun losses* and the Brew House efficiency on the grain portion of the malt bill.  If you are steeping grains, you do not have the losses for the mash tun so this setting should not be looked at or compared to any other setting.
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