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Double batch help.

Post #1 made 11 years ago
by nicko
So my first batch was here http://www.biabrewer.info/viewtopic.php ... start=1900 and it was a single batch with a TWN of 38.51L.

So I've been told my 70L kettle is big enough for a double batch, but based on that TWN doubled for a 46L batch into fermenters, I'd need 77.2L, or doesn't it work like that?
Last edited by nicko on 14 Jul 2014, 18:03, edited 1 time in total.
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Post #2 made 11 years ago
by PistolPatch
Your kettle is big enough for a 'double batch' but it depends on what is meant by double batch. For example, your kettle will handle not a pure full volume mash.

For example if you did a 1.050 OG brew and wanted 38 litres into the fermentor, a 70 litre kettle will double batch you. If you wanted 38 litres into the packaging, then it won't. Same if you wanted a higher gravity brew. With that in mind...

Your kettle is the same as mine. If the BIABacus throws you a red warning, then in your case, all you need to do is go to Section W and put around 10 litres into the 'Water Added Before the Boil' field. Try different numbers there until the warning disappears.

You'll also see that the amount you type into that field increases the amount of grain you will need but, in your scenario, it should not be by much. (The podcast I mentioned in the other post might help explain why you will need more grain otherwise search here for "Sweet liquor shop posts".

;)
PP
Last edited by PistolPatch on 14 Jul 2014, 18:41, edited 2 times in total.
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Post #3 made 11 years ago
by nicko
Thanks Pat, makes sense, remove grain, add more water!

The initially scary BIABacus really rocks! :clap: :salute: :champ: :thumbs: :party:

I'll get there mate, might not be overnight but it will happen.
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Post #4 made 11 years ago
by Rick
I also have the same size kettle (75qt, which is about 71L).

Around 1.050, you'll have no problems with typical 41.64L VIF at all. My kettle efficiency has been 82-85% in this range. I don't reserve water for these, but I also only tend to do 60m boils for my lighter beers since I don't really use pils malt. For the ideal 90m, you will have to reserve a bit.

For 1.070 I put it down to 38L VIF (always 90m boils here), and reserve adding 3.8L/1G to the mash, then dump it back in just before the boil. I've only done a single brew up in this range, and it was 75% kettle efficiency. This actually works out, because I tend to need the extra head space for fermenting bigger beers.
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Post #5 made 11 years ago
by nicko
Rick wrote:I also have the same size kettle (75qt, which is about 71L).

Around 1.050, you'll have no problems with typical 41.64L VIF at all. My kettle efficiency has been 82-85% in this range. I don't reserve water for these, but I also only tend to do 60m boils for my lighter beers since I don't really use pils malt. For the ideal 90m, you will have to reserve a bit.

For 1.070 I put it down to 38L VIF (always 90m boils here), and reserve adding 3.8L/1G to the mash, then dump it back in just before the boil. I've only done a single brew up in this range, and it was 75% kettle efficiency. This actually works out, because I tend to need the extra head space for fermenting bigger beers.
Ok great thanks Rick! I'll try a double batch next brew of Dr Smurtos GA, I'll have a crack in BIABacus and see how it goes, thanks!
Last edited by nicko on 14 Jul 2014, 19:54, edited 1 time in total.
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Post #6 made 11 years ago
by JackRussel
For a double batch, your TWN will not double because the evaporation will stay the same. If you've got a 71L pot then evaporation is roughly 10L for a 90 minute boil. 10L evaporation whether the kettle has 60L in it or 30L. This is also the reason that grain amounts might more than double, because double batches actually see less water.
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Post #7 made 11 years ago
by nicko
JackRussel wrote:For a double batch, your TWN will not double because the evaporation will stay the same. If you've got a 71L pot then evaporation is roughly 10L for a 90 minute boil. 10L evaporation whether the kettle has 60L in it or 30L. This is also the reason that grain amounts might more than double, because double batches actually see less water.
That makes sense thanks Jack. I'll have a crack in BIABacus sometime and see how i go. Thanks.
Last edited by nicko on 15 Jul 2014, 02:47, edited 1 time in total.
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Post #8 made 11 years ago
by nicko
PistolPatch wrote:Your kettle is big enough for a 'double batch' but it depends on what is meant by double batch. For example, your kettle will handle not a pure full volume mash.

For example if you did a 1.050 OG brew and wanted 38 litres into the fermentor, a 70 litre kettle will double batch you. If you wanted 38 litres into the packaging, then it won't. Same if you wanted a higher gravity brew. With that in mind...

Your kettle is the same as mine. If the BIABacus throws you a red warning, then in your case, all you need to do is go to Section W and put around 10 litres into the 'Water Added Before the Boil' field. Try different numbers there until the warning disappears.

You'll also see that the amount you type into that field increases the amount of grain you will need but, in your scenario, it should not be by much. (The podcast I mentioned in the other post might help explain why you will need more grain otherwise search here for "Sweet liquor shop posts".

;)
PP
It was a very interesting podcast too thanks Pat, I'll never look at my jeans the same way ever again! I also read the sweet liquor shop posts, also very interesting and well explained thanks.
Last edited by nicko on 06 Aug 2014, 20:21, edited 1 time in total.
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