BeerSmith calculations

[Black n Tan]

Crusty, could you have the boil duration set incorrectly in the recipe? To get from a pre-boil gravity off 1.033 to a post-boil gravity of 1.042 is a 21% boil-off which is in-line with your equipment profile for a 1 hour boil. To get a 1.049 post boil gravity your pre-boil gravity should be about 1.039 for a 1 hour boil. To get to 1.049 post-boil from 1.033 pre-boil would require a 33% boil off which would take 90 minutes if your equipment profile is correct. This suggest to me that you may have your boil duration in the recipe incorrectly set to a 90 minute boil but you are really only boiling for 1 hour.

 

[Barge]

Original called for 1049 post boil & 1033 pre boil. I got 1033 pre boil bot only 1042 post boil, volumes correct.

To get "1049 post boil & 1033 pre boil." is a massive boil off , at 45%, and would over caramalise the wort

Not sure I can find where he said that he hit his pre-boil efficiency?? I have already made a comment about the pre-boil and post-boil above (post#2).

Don't even need a calculator to see that 1.033 to 1.049 requires a decent boil off. This is the problem with calculators, it stops people from thinking.

33 to 49 is a change of 16 gravity points. 16 is about half of 33 so a boil off of half the final desired volume is required. ie, starting with 30L and boiling off about 10L to be left with about 20L. This is then a 33% boil off as 10L was boiled off from 30L. As the boil was a 90 minute boil, that works out to a bit over 20% an hour.

The problem here is, is that the OP says he hit his pre-boil and post-boil volumes (29L and 20L) and his pre-boil gravity (1.033). I think the only way this can be explained is that there is an error in measuring volumes and/or gravity.

You may need to check how you measure volumes and s.g. Particularly considering temperature. Do you use a hydrometer? Did you allow the sample to cool? Could you have misread one or both figures?


OR WHAT B&T SAID ABOVE. Didn't think of that h34r:

Yet another edit. Not sure that a 60 minute boil explains it if Crusty hit his post boil volume of 20L. Unless he was initially expecting 23L and then changed the profile but forgot and thinks 23L was the desired final volume after all.

 

[Crusty]

This is the recipe & expected figures. My actual figures are in the bottom right corner so my eff for this recipe in actual numbers rounded off is 70%. Take note of the preboil gravity which was 1.033. I got 1.033 using a refractometer. Actual numbers 1.042 instead of 1.049.



Now, if based on the actual result, I now scale the same recipe rounded off to 70%, you can see more grains are in my recipe to get me to my expected 1.049. What confuses me a bit is my preboil gravity is still 1.033 & that's a long road to 1.049. I assumed by preboil would be up into the 1.040 range at least.



Drinking & posting questions is probably not a good idea but from my original recipe, how do I scale, fix or alter that recipe to get me the 1.049 I was expecting. Maybe the flaked wheat came into play with this particular recipe. I've always entered a recipe as is into BeerSmith & simply scaled it to my 78% eff & 20lt batch size & have been pretty spot on but the Wit beer fell short on gravity..

 

[Barge]

Forget efficiency for the time being. If you had 29L in the kettle at 1.033 and boiled it down to 20L (including shrinkage) then the gravity would be 1.049. End of story.

However, if you boiled it down to 23L in the kettle but only got 20L into the fermenter then your post boil gravity would be closer to 1.042.

If you are confident that you had 29L in the kettle at the start of the boil and 20L at the end then one or both of your gravity readings are wrong.

If both your gravity readings are correct then your volumes are wrong.

It's as simple as that.

 

[Black n Tan]

There is something wrong with either the BS recipe or the BS equipment profile you have used for this recipe. It is indicating that you will get a 33% boil off which is not right. If you have used the equipment profile as shown in post #6, then I suspect your boil duration is incorrectly set in the recipe. Check you have selected the right equipment profile and the boil duration in your recipe and let me know.

 

[TheWiggman]

Your boil off is set at 6l/hour. From what I can see with a quick web search your boiloff should be 5.5 - 6l for 90 minutes. Hence, change that value (6) to 4l/h and that should address many issues.

Changing this number will give you a higher pre-boil gravity if your OG remains the same.

 

[Black n Tan]

I also use a BM and have the boil off set to 5L/hr, so 6L/hr is not that dissimilar. Previously he hits his numbers using this equipment profile, so I am not sure changing this will solve his problem.

 

[Crusty]

Your boil off is set at 6l/hour. From what I can see with a quick web search your boiloff should be 5.5 - 6l for 90 minutes. Hence, change that value (6) to 4l/h and that should address many issues.

Changing this number will give you a higher pre-boil gravity if your OG remains the same.

I did a test run on the BM & boiled for an hour & lost 6lt to evaporation & that is set as an hourly rate in BS. ( 9lt for 90mins )
I'm not sure what caused the shortfall but with those ingredients, the efficiency is basically 70%.
I'll scale it to 70% which will give me more grain next time round so that should get me to my expected 1.049.
Thanks for the tips guys.
Cheers

 

[Mardoo]

Be interested to hear how it ends up. Hope you'll post results.

 

[Crusty]

Be interested to hear how it ends up. Hope you'll post results.

It's just going to be 3.9% instead of 4.9% but I'm sure it will still go down just fine.
It's fermenting away @20deg at the moment & it really didn't taste too much of anything going into the fermenter.
It had a really nice aroma from the coriander seed & bitter orange peel & there was a slight peppery zest to it but very mild.
Looking forward to pouring a glass actually.

 

[TheWiggman]

I stand corrected, too late to edit.
Edit: can edit this one though. So you say you got a pre-boil of 1.033, 29l, then boiled off 9 litres and didn't get 1.047? As per Barge, there's an error with your measurement somewhere. Either you only boiled of 6 litres or you didn't measure gravities right.

 

[Crusty]

I stand corrected, too late to edit.
Edit: can edit this one though. So you say you got a pre-boil of 1.033, 29l, then boiled off 9 litres and didn't get 1.047? As per Barge, there's an error with your measurement somewhere. Either you only boiled of 6 litres or you didn't measure gravities right.

It has to be the 1.033 because the volumes were right. I got my 20lt into the fermenetr.

 

[TheWiggman]

If you had 29l of 1.033 pre-boil, then your OG would have been 1.047 if 20l went in the fermenter.
If you had 20l of 1.042 OG, then for 29l pre-boil your gravity would have been 1.029.
If neither of these, your boil-off rate mustn't be 6l/min.

 

[Barge]

It has to be the 1.033 because the volumes were right. I got my 20lt into the fermenetr.

What were the pre boil and post boil volumes in the kettle? How much do you lose transferring to the fermenter?

 

[Crusty]

What were the pre boil and post boil volumes in the kettle? How much do you lose transferring to the fermenter?

I don't measure my pre boil volume anymore as I always get my volume & OG into the fermenter.
I leave around 2lt of trub in the BM after transfer.

 

[Black n Tan]

I don't measure pre-boil volume often either. Did you check the boil time at the top of the recipe as there is clearly something wrong with the BS recipe?

 

[Crusty]

Yep!
90min boil.

 

[Barge]

 

[Black n Tan]

Hi crusty, I have a given this some more thought and have a few points:

1/ a 90 minute boil on a Wit is too long, go for 60 minutes. It will add too much colour and you want a Wit to be very pale.
2/ you should consider incorporating a beta-glucan (40C/20') and protein rest (55C/10-15') into your schedule because of the unmalted barley. This will likely improve your efficiency.
3/ I cannot reconcile why beer smith is estimating a pre-boil gravity target of 1.033 to hit post-boil gravity of 1.049. Based on your equipment profile (20% boil-off per hour) and boil duration (90 mins), 1.033 pre-boil will give you 1.047 post-boil (however it is not too far off).
4/ Based on the figure you provide your equipment profile should be updated: 1.033 pre-boil to 1.042 post-boil is a 21% boil off in 90 minutes or 14% in 60 minutes. So I would update your equipment profile to reflect this (14% boil-off in 60 minutes) and also update 'loss to trub/chiller to 2L (you indicated that you leave 2L in BM when to transfer to fermenter; this is where this figure should go).
5/ For you next Wit I would expect your efficiency to be better, lets guess 74% (split the difference of what you normally achieve and your efficiency for the last Wit). So increase the grain to achieve this but do not add any more water. Your target pre-boil gravity should be about 1.042 for a 60 minute boil, dilute if higher.

With any luck this should largely fix your problems.

 

[Crusty]

Hi crusty, I have a given this some more thought and have a few points:

1/ a 90 minute boil on a Wit is too long, go for 60 minutes. It will add too much colour and you want a Wit to be very pale.
2/ you should consider incorporating a beta-glucan (40C/20') and protein rest (55C/10-15') into your schedule because of the unmalted barley. This will likely improve your efficiency.
3/ I cannot reconcile why beer smith is estimating a pre-boil gravity target of 1.033 to hit post-boil gravity of 1.049. Based on your equipment profile (20% boil-off per hour) and boil duration (90 mins), 1.033 pre-boil will give you 1.047 post-boil (however it is not too far off).
4/ Based on the figure you provide your equipment profile should be updated: 1.033 pre-boil to 1.042 post-boil is a 21% boil off in 90 minutes or 14% in 60 minutes. So I would update your equipment profile to reflect this (14% boil-off in 60 minutes) and also update 'loss to trub/chiller to 2L (you indicated that you leave 2L in BM when to transfer to fermenter; this is where this figure should go).
5/ For you next Wit I would expect your efficiency to be better, lets guess 74% (split the difference of what you normally achieve and your efficiency for the last Wit). So increase the grain to achieve this but do not add any more water. Your target pre-boil gravity should be about 1.042 for a 60 minute boil, dilute if higher.

With any luck this should largely fix your problems.

Thanks for the tips but a few points on your reply.
1. The colour in this recipe for a 90min boil compared to a 60min boil is zip. No difference at all according to BeerSmith & with flaked Wheat & Pilsner, I'd be surprised if there was any colour difference at all. The wort was extremely pale going into the fermenter.
2. I mash in @50 & did a 52deg rest for 5mins before 90mins @63deg. I also added a glyco protein rest at 72deg for 20mins followed by the usual 78deg for 10mins for the mash out.
3. I have no idea why BeerSmith is calculating 1.033 either but for those ingredients, 70% eff is more like real world figures for that recipe. Scaling it to 70%, I should get 1.033 pre boil but BeerSmith still reckons 1.049 into the fermenter?
4. Are you suggesting that my 2lt that I leave behind goes into the loss to trub & chiller column under Fermenter/Bottling volumes instead of Lauter Tun deadspace? I have allowed for a 1lt loss in the fermenter loss column.
Keep in mind that up until now, my volumes & efficiency have been pretty bang on for the last couple of years brewing on the BM but this Wit was my first discrepancy in SG compared to anything I've made in the past.
Can you post an equipment profile of your BM?
Cheers