Author Topic: Not hitting Est OG / Trub & Chiller Losses bug?  (Read 4093 times)

Offline Gutpunch

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Not hitting Est OG / Trub & Chiller Losses bug?
« on: May 17, 2015, 04:10:37 PM »
Hi all,

I'm having trouble hitting the Estimated OG for my All Grain brews.  I've searched around the forum and kind of wonder if this is just one of the many bugs haunting the program, but I'm more inclined to suspect that I must be doing something wrong.  Hopefully somebody can help me see the error of my ways.

If I tweak my Brewhouse Efficiency to make my Est Mash Eff match my Measured Mash Eff, the OG climbs higher than I can reliably hit.  Yesterday's brew was especially off -- I missed the Est OG of 1.068 with my measured 1.062.

But I noticed something weird.  I don't understand why, conceptually, the "Loss to Trub and Chiller" field in the Equipment Profile has anything to do with OG.  Once the wort is chilled to pitching temp, OG isn't going to change no matter if I leave a quart or a gallon in the kettle, but this loss reduces the batch size which boosts the estimated OG.  So I went into the Equipment Profile, zeroed the Loss to Trub and Chiller, added it to my total batch size (leaving total water volumes unchanged), and voila, my Estimated OG was dead on.  But then my Est Mash Efficiency dropped 7%.

What am I missing?  Thanks.

Offline brewfun

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Re: Not hitting Est OG / Trub & Chiller Losses bug?
« Reply #1 on: May 18, 2015, 06:04:25 AM »
The similarity is that both are based on the total percentage of sugars available. The difference is where that total is measured.

Mash Efficiency: The sum of conversion efficiency and sparge efficiency into the kettle.

Brewhouse Efficiency: The percentage of total sugar that makes it into the fermenter.

With brewhouse efficiency, if you say you'll get 80% efficiency, you're saying that; of the total sugar available, even with losses, that's how much gets to the fermenter. That means that if you add losses to trub, you still have 80% going to the fermenter and will maintain the same gravity. Therefore, the ONLY place you can gain that sugar is with increased Mash Efficiency.

If you're measuring your batch volume in the kettle, then zero loss to trub is appropriate. But, your batch volume needs to be equal to the post boil kettle volume. Zero loss to trub makes Brewhouse and Mash efficiency the same.

If you're measuring your batch volume in the fermenter, you can start with lowering Brewhouse Efficiency by the same percentage as the loss to trub. When you brew, just accurately record your volume and gravities. In the Fermentation Tab, you'll see the estimated and actual (Measured) Brewhouse Efficiency totals. You can use the Measured total for your equipment profile.
Beer Appreciation is the space between pints.

Offline Gutpunch

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Re: Not hitting Est OG / Trub & Chiller Losses bug?
« Reply #2 on: May 18, 2015, 06:37:51 PM »
Thanks for the reply.  That makes sense enough that I think I see how to unearth an accurate Est OG, but it seems like the same basic problem remains.  There doesn't appear to be a way to tease BeerSmith into accurately identifying both my Est Mash Efficiency and Est OG at the same time without fudging other numbers.

Let's say I anticipate a particular mash efficiency, and I want to know what OG to expect.  I measure just about everything things days -- pre-boil volume, the post-boil volume in the kettle, as well as my losses so I can calculate the volume that goes into the fermenter.  I track all those numbers, and can predict them with reasonable accuracy.  Lately, when I'm designing a recipe, I plug those volumes into my equipment profile and adjust the brewhouse efficiency until the Est Mash Eff matches my target, but I know the Est OG will be too high.  Is there a way to set things up so that both Est Mash Eff and Est OG can be accurate?

If I'm understanding this correctly, right now it seems like I have two options to get accurate Est OG, but they both require manual adjustments and render the Est Mash Eff inaccurate:
- I can calculate the percentage of expected loss to trub and scale back my brewhouse efficiency by that percentage.
- Or zero out my loss to trub and add it to my batch size.

Is this correct?  Is there no way to make BS handle this automatically?
« Last Edit: May 18, 2015, 06:50:44 PM by Gutpunch »

Offline brewfun

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Re: Not hitting Est OG / Trub & Chiller Losses bug?
« Reply #3 on: May 19, 2015, 03:39:35 AM »
- I can calculate the percentage of expected loss to trub and scale back my brewhouse efficiency by that percentage.
- Or zero out my loss to trub and add it to my batch size.

Is this correct?  Is there no way to make BS handle this automatically?

If you've lined up your losses and accurately weighed your grain, then the Brewhouse Efficiency will give you an accurate OG and Mash Efficiency. Make sure that the extract potential of your grains are accurate for the manufacturers you use. I've found they can have a lot of variation, but are often closer to 36pppg than the 38pppg that a lot of grains are set to in the program. BeerSmith calculates the potential of each grain individually, then sums the total.

Also, make sure that you're measuring the preboil volume at the same temperature and the same point in time of your brewing process.

I measure pre and post boil volumes at about 200F, which gives me a consistent heat expansion number. I've adjusted my shrinkage number to 3.25% to compensate for the lower apparent volume. A quart of difference is 5% in a 5 gallon batch and that can knock a few points off your efficiency estimates.

Beer Appreciation is the space between pints.

Offline Gutpunch

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Re: Not hitting Est OG / Trub & Chiller Losses bug?
« Reply #4 on: May 23, 2015, 02:42:37 PM »
Okay, I brewed again yesterday with a pretty simple recipe.  I did a SMASH with 16 lbs of Vienna (never tried it before and this seemed like a good excuse) which I thought might simplify things, but I couldn't figure out how to determine pppg from the info I downloaded from Weyermann, so I stuck with BS's 38.  I used a digital scale at my LHBS to weigh the grain, so I'd like to assume that's accurate.

Basically the same thing happened.  When I plugged in pre-boil volume and gravity, adjusted my brewhouse efficiency to make those estimates match my measurements, and then plugged in my final volumes, Est OG was way higher than the measured OG (1.092 / 1.082) unless I lumped the trub losses with the total batch size, in which case it was a near match (1.083).

One thing I do want to take a closer look at is how I measure my volumes with regard to temperature (I measure 1st and 2nd runnings separately, usually in the 130-140F range, that I combine for my pre-boil volume), but it seems unlikely that would be solely responsible for such a large discrepancy.

Now that I'm seeing how the trub losses are factored in, at least I have a workaround that I can use for the future, so that's good.  However, the way BS appears to work, I'm having a hard time imagining a set of profiles and measurements where it would even be mathematically possible for a single brewhouse efficiency number to accurately predict both mash efficiency and Est OG without trub losses being lumped into total batch volume.

I really want to understand this.  Clearly it works perfectly for you and others, so what am I missing?

Offline brewfun

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Re: Not hitting Est OG / Trub & Chiller Losses bug?
« Reply #5 on: May 23, 2015, 04:05:10 PM »
When you plug in all of your losses and your actual gravities, what does the "Measured Efficiency" number say? It's on the Fermentation Tab, right next to the Fermentation graph.
Beer Appreciation is the space between pints.

Offline Gutpunch

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Re: Not hitting Est OG / Trub & Chiller Losses bug?
« Reply #6 on: July 11, 2015, 09:12:53 PM »
I've been tinkering with this for a while and found little consistent relationship between the Measured Efficiency percentage and the estimated numbers.  The discrepancies are especially pronounced if a recipe involves any additional sugars.  I have a workaround that gets the job done, so I've given up trying to solve this.  But thank you very much for trying to help.