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First BIAB - Help me understand the numbers

Post #1 made 11 years ago
by SilentBob
So yesterday was my first BIAB attempt and I think it mostly went to plan..Did the All Amarillo APA
Did a 90 min mash, stirred while bringing up to 78 degree mash out then a 90 min boil.

Few areas where i missed the mark, but only slightly so I think it went well..
Any thoughts on the following (BIABacus file attached with these points noted):

Overshot on my strike temp a little with the mash starting around 67/68 (started at 67 but after wrapping the urn up the temp rose another degree).. so ended up with a 90min mash going from 68 down to about 66.5 degrees.. So, will know for next time to try a little lower on my start temp.. My insulation + sleeping bag around the urn definitely kept the heat in..
- Will a slightly higher mash temp have any negative effects? I

My evaporation was less than the BIABacus predicted with only around 4.3 litres lost from my starting 'Volume into Boil' (VIB) instead of the esimtated 6.18..
This meant I ended up with an OG of 1.050 instead of the predicted 1.056 and an extra couple of litres above the estimated 'Volume of Ambient Wort' (VAW)
- Is a lower level of evaporation an issue? Im using a Birko 40L urn so the wort was definitely boiling but was not a vigorous boil..

Dumped the liquid into a no chill cube for pitching next weekend (fermenting fridge is currently crash chilling something else), so won't know the exact volume into the fermenter until then..
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Post #2 made 11 years ago
by mally
Well done SilentBob :clap:

I have had a quick look and there is nothing that jumps out to me as being a problem to worry about.

If your mash liquor has pockets or uneven heat in it, just give it a good mashing before raining in your grain. Using a masher is much better than a paddle as you are mixing the liquor in an up & down movement not rotational. Check if the temp has changed and adjust accordingly.
However, I would "guess" that the few degrees of difference you have measured will have very little effect on your brew.

For your evaporation. what I would suggest is to leave your settings as is and do a few more brews before trying to elucidate info from it. We very rarely hit our numbers exzctly every time.

doing a quick calculation you got 1.050 (50 gravity points) with a VAW of 25.44? (50x 25.44) = 1272 "sugar units". The BIABacus predicted VAW of 23.31 x 58 = 1352 "sugar units".
There is a discrepancy here, ideally they should be a little closer, but as I said just do a few more brews, and take the same measurements and see if it is a pattern or just a one off.
G B
I spent lots of money on booze, birds and fast cars. The rest I squandered
I've stopped drinking, but only when I'm asleep
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Post #3 made 11 years ago
by PistolPatch
Congratulations Bob - good on you :clap: :salute:,

Totally agree with mally. There is nothing to analyse/worry about here as yet. You have done a great job at collecting volume figures but there is only one gravity reading. On the next brew, try and get a gravity reading into the boil and, next weekend, after you have agitated/aerated the wort before pitching, take another gravity sample then. You can't trust numbers from a single brew let alone one gravity reading form a single brew.

The auto-estimate by the BIABacus of evaporation rates is currently based on kettles ranging from small urns to 100 litre kettles but very few brewers had an urn or 100 litre kettles so we need more info. In fact, it looks like this thread is well-overdue for a bump. The existing formula, from memory, over-estimates small diameter evaporation and under-estimates large diameter kettle evaporation. The only way to know for sure is to collect your figures and hopefully contribute them to that thread. I wouldn't be too scared though at lowering the default in Section X in your case. It is much better to have a lower estimate than a higher one.

It is also important to get that boil vigour happening so buy a stainless steel bowl to float on top of your wort for the next boil. I'd guess at getting a bowl that will reduce the surface area of your wort by about 25% if you had it boiling but not vigorously so. (Just had a play here and you want a bowl that when floating will cover about an 18cm circle of your wort.)

Hope you had a fun/rewarding day Bob. Good job again Bob :),
PP
Last edited by PistolPatch on 31 Aug 2014, 20:19, edited 1 time in total.
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Post #4 made 11 years ago
by SilentBob
PistolPatch wrote:
Totally agree with mally. There is nothing to analyse/worry about here as yet. You have done a great job at collecting volume figures but there is only one gravity reading. On the next brew, try and get a gravity reading into the boil and, next weekend, after you have agitated/aerated the wort before pitching, take another gravity sample then. You can't trust numbers from a single brew let alone one gravity reading form a single brew.
Thanks, and half way through the boil i realised i only took a volume measurement and not a sample for a gravity measurement...
PistolPatch wrote: I wouldn't be too scared though at lowering the default in Section X in your case. It is much better to have a lower estimate than a higher one.
So I should be lowering it, or wait for more 'attempts' and then adjust after that..
Having a lower estimate would mean I end up with more wort as opposed to not enough?
PistolPatch wrote: It is also important to get that boil vigour happening so buy a stainless steel bowl to float on top of your wort for the next boil. I'd guess at getting a bowl that will reduce the surface area of your wort by about 25% if you had it boiling but not vigorously so.
Thanks... had a hop bag hanging into the urn for the boil but a bowl on top would be an easy addition to try and increase the boil vigour..
Last edited by SilentBob on 02 Sep 2014, 16:25, edited 1 time in total.

Post #5 made 11 years ago
by PistolPatch
SilentBob wrote: So I should be lowering it [evaporation rate], or wait for more 'attempts' and then adjust after that..
Having a lower estimate would mean I end up with more wort as opposed to not enough?
All this can get a little confusing. Even I have to stop for a second when reading things like the above to make sure I haven't made a mistake :P.

If you lower your evaporation rate in the BIABacus, what will happen is your Total Water Needed will drop as well. So you will start with less water and your wort should be more concentrated. Have a play and watch Section K.

So, it won't do any harm lowering your evaporation rate. It is much better being in the scenario when pitching to be diluting a high gravity wort a little than trying to strengthen a low gravity wort.

Main thing for you though is to get that boil invigorated! :)
Last edited by PistolPatch on 02 Sep 2014, 16:40, edited 1 time in total.
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Post #6 made 11 years ago
by SilentBob
PistolPatch wrote:
SilentBob wrote: So I should be lowering it [evaporation rate], or wait for more 'attempts' and then adjust after that..
Having a lower estimate would mean I end up with more wort as opposed to not enough?
All this can get a little confusing. Even I have to stop for a second when reading things like the above to make sure I haven't made a mistake :P.

If you lower your evaporation rate in the BIABacus, what will happen is your Total Water Needed will drop as well. So you will start with less water and your wort should be more concentrated. Have a play and watch Section K.

So, it won't do any harm lowering your evaporation rate. It is much better being in the scenario when pitching to be diluting a high gravity wort a little than trying to strengthen a low gravity wort.
Thanks... in my head thats kind of what I assumed you meant.. less water with the same grain bill = higher OG wort (and therefore can water down if needed)..probably just didnt come out like that on the keyboard ;)
PistolPatch wrote: Main thing for you though is to get that boil invigorated! :)
Noted..and on the to-do list for the next one (which isnt for a couple of weeks due to other commitments )
Last edited by SilentBob on 02 Sep 2014, 17:45, edited 1 time in total.
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