Author Topic: Trub Loss Issues  (Read 1127 times)

Offline gizzygizmo

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Trub Loss Issues
« on: March 12, 2020, 11:12:10 AM »
I've noticed trub loss is decoupled from batch size when calculating OG.   You have a choice:

1) just ignore the slight variation, it's usually only 2-3 points off OG
2) Set trub loss to 0, set batch size to actual ending kettle, set BH eff to Mash Eff sinze you now have 0 losses

How to repeat:
1) Create new recipe of 5g batch size
2) zero out shrinkage, boil off rate, and trub size
3) Add 5 lbs of D-180 or other 1.032 PPG sugar

You're OG is now 1.032 which is correct in a perfect world.  Expand your trub loss to 1 gallon now.   Notice your Post boil volume is now 6 gallons to account for the 1 gallon of loss into the ferment.

However, the OG has stayed at 1.032.   You can change trub loss to 0 and make batch size 6 to see the correct 1.027 OG.

Offline brewfun

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Re: Trub Loss Issues
« Reply #1 on: March 13, 2020, 02:02:49 AM »
The issue is how you're looking at Brewhouse Efficiency vs Mash efficiency. Brewhouse Efficiency (BHE) is the percentage of sugars that make it to the fermenter.

As soon as you add trub loss, there is a percentage that is left behind, so, BHE has to be less than 100%. The only place that the sugar can come from is your sugar source, which is why BeerSmith increases mash efficiency to account for it. If the mash efficiency is over 100% clearly your BHE is too high.

In your example, you need to lower BHE to 83% to account for your gallon of trub loss. That would adjust the gravity downward.

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Offline gizzygizmo

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Re: Trub Loss Issues
« Reply #2 on: March 16, 2020, 01:05:01 PM »
I'll play along... i lowered my BHE to 10% just to see how much it'll lower the OG once we've taken into account the new lower brewhouse efficienty. 

The OG is 1.032 still.

The bug here is that trub loss is not tied to BH eff in any meaningful way.  It's actually tied to Mash eff ... the mash eff is calculated using the BH eff, trub loss, etc.  Those volumes are user editable fields and not linked directly, they all adjust mash eff up/down to make "bh eff" equal the losses you've inputted.

I bet the addition of sugar is using a mash eff of 100% because it's extract and the efficiency is not variable.   Then the PPG is calculated with the batch volume and not the total ending boil volume. 

I'd be further curious if PPG for grains is being calculated off batch volume and not ending boil volume... because most people just adjust BH eff number until their preboil OG matches what they got brewday and assume that's their mash eff.

This theory can be tested... substitute your 5lbs sugar for 5lbs 2row at 1.036 PPG.  Your OG is 1.036 at 100% BH eff.   I noticed my mash eff jumped is 200% which is impossible, and makes sense here because i need to extract 10g of wort to have a 5 gal batch and 5 gal of trub loss.  But to keep a 100% bh eff i'd need to get twice as much sugar out of those grains than possible.    DRop BH eff to 50% and my mash eff goes to 100% and my OG is back at 1.018 which is what i'd get if i diluted the wort with double the water.  This all seems to check out, because Bh eff is tied to the volumes and mash eff. 

For sugar, we have no variable mash eff.. it's 100%.  So if we add trub loss we need to drop the PPG gained from the sugar.   Rather, not drop the PPG.. but divide the PPG we got from the sugar over the volume... we get less points as we dilute it away with extra 'trub loss'.  I can't  lower the BH eff number because it'll jack with my mash eff on the grains in the recipe.   Plus, the BH eff adjustment doesn't affect OG with sugar ... I really just need the points calculated for the lbs of sugar and divide by the total ending volume.  There's not really a way to link BH eff into that...   

Suggested fix -> use ending volume for calculating PPG by sugar unless I specify adding to "secondary" or something later when the volume will match the batch volume.  If i'm adding 5 min into the boil it should be based off "ending boil volume" which includes trub losses that i'll suffer as i drain into the fermenter

Workaround -> Do the math yourself for PPG ... or just live with it.  You'll only be off by a percentage (the percentage difference is post-boil volume vs batch size)
« Last Edit: March 16, 2020, 01:22:41 PM by gizzygizmo »

Offline Oginme

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Re: Trub Loss Issues
« Reply #3 on: March 16, 2020, 01:45:01 PM »
I have been through the math many, many times with BeerSmith and I think you are missing something. 

If you take your sugar replacement of the grains, for example.  To do this properly and have the program treat the sugar as the extract that it is, then you also need to change the recipe type to 'extract'.  Otherwise, the program does not know sugar from grain and calculates a mash efficiency which will include the losses due to mash tun loss and trub to chiller and kettle losses. 

The program works based upon volume into the fermenter (batch size) as the set volume for output and the brew house efficiency (BHE) for the sugar output. 

It works the volumes backwards through the process to give you your starting volumes, taking into account any volume losses which you have in your equipment profile. 

For the extracted sugars, it works them back by taking the amount of possible sugars in the grist and applying the BHE to that potential to give you your sugar content in the fermenter.  It calculates backward with the volume losses to give you an estimate of mash efficiency, which can easily be over 100% if you have not set or adjusted your BHE properly to take into account trub losses.  This is where the program uses your trub amount to calculate the loss of sugar in the process.  This is what Brewfun was describing.

You appear to be applying the BHE to the end of boil volume and this is not how the program works. 
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