Post boil calculations

Discussion in 'General Brewing Discussions' started by getack, Oct 28, 2016.

  1. getack

    getack New Member

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    Good day all.

    I want to brew a larger batch using my limited kettle. Normally I can get about 15 liters into the fermentor but this time I want about 30 liters so that I can keg and bottle the remainder.

    It seems that the best option is to brew a higher concentration wort and then just dilute before pitching the yeast.

    It looks like I have two options when it comes to doing this in the Brewer's Friend framework:
    • I can set up a 15 liter batch that will end up with an estimated OG and IBU that is double what I want in the end and then I just dilute. I did this by simply setting up the recipe for 30 liters and then in stead of scaling I just changed the target volume to 15liters. The ingredient amounts stayed the same as for the 30 liter batch but the OG and IBU's obviously increased.
      • The problem with this is Brewer's Friend thinks that I'm making something way out of style and it complains thus.
    • My other option is to set the Target Volume to 30 liters in the fermentor and leave the boil volume about 20 liters. It seems like the OG and FG matches up for the final product, but when I want to brew it it wants me to sparge with almost 20 liters so that I get a pre-boil volume of about 40 liters (which is impossible, my kettle is only 20l in volume). It seems like it's ignoring the 20liter boil volume I set in the recipe.
      • Can I just ignore this mash issue and just mash with whatever's needed to result in 20 liters pre-boil? Will the IBU calculations work out after I top-off with fresh water before pitching yeast?

    Is it even a sound idea to dilute with 1:1 water?

    Thanks for any and all help with this!
     
  2. Mark D Pirate

    Mark D Pirate Well-Known Member

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    how big is your boil kettle ?
    what method are you using ? ie extract , all grain ?
    What is your target OG ?

    i do 23-25 litre batches (AG) with a 22 litre pot every brewday and that does take some serious juggling .
    keep in mind that with an extremely high gravity boil like that would take for me i would need to add a load of extra hops to hit my IBU as put simply the wort can only absorb so much .
    also seriously doubt i could get enough grain into my tun

    there's a process called the " texas 2 step " it's simply 2 mashes , both added to FV before pitching
     
  3. Trialben

    Trialben Well-Known Member

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    Yep go linger behind your local pub and thank them for that sly keg gone sideways opps! Na I got mine on the cheap! If it makes any difference get a bigger brew pot I've herd aluminium transfers heat twice as quick and is all good after a few brews when it develops some scaling. I'm not your guy on this thread mate but Mark is onto it cheers!
     
  4. getack

    getack New Member

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    Sorry for leaving out some vital info, Mark.

    I am brewing all-grain, my kettle is a ~20 liter aluminium pot heated over gas.
    Typically to be safe I brew no larger than 15 liters in the fermentor to avoid boil overs and such.

    This time I want to brew a 30 liter batch so that I kan fill a 20 liter keg and have a respectable amount remaining to bottle.

    I think my plan of action is to brew a high concentration brew such that I reach my target numbers after diluting it.
    I want the final product to be 30 liters at 1.040 with around 14.3 IBU's

    According to my calculations if I want to brew 15 liters (and dilute with another 15 liters of water) I will need to hit 1.087 and around 26.5 IBU's.

    I got the gravity by using the dilution calculator on Brewer's Friend and I got the IBU's from a formula I found online (initial IBU x (original volume / final volume)

    I was just hoping there is a way for Brewer's Friend to factor this dilution into the recipe without doing funny stuff.
     
  5. jmcnamara

    jmcnamara Well-Known Member

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    i think the calculator (set to the right parameters) takes into account dilution. like, if your boil volume is 10 liters, but you set the amount going into the fermentor as 20 liters, it knows that the extra 10 liters has to come from adding water post-boil

    fwiw, i BIAB and for the longest time i had my profile set as such. this made my water calcs a bit weird, which i just ignored. however, i also sparge to some degree, so i should have picked the All Grain option for my profile. after doing that the water amounts seemed to line up a bit better with what i was actually doing

    is there any reason you can't do 2 separate batches to get the final amount you want?
     
  6. jeffpn

    jeffpn Well-Known Member

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    Is it possible to calculate a final IBU the way you're hoping? I thought there was more to it than multiplying by a fraction to adjust for an increase of water.
     
  7. Mark D Pirate

    Mark D Pirate Well-Known Member

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    With a boil gravity that high the hop utilisation will be dramatically reduced , also you have almost no chance of getting enough grain in the pot .
    The 2 step mash or adding malt extract are the only options I can think of
     
  8. getack

    getack New Member

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    I don't really have the time! I've tried doing two batches in one day before and I was nearly dead afterwards. Not a fun experience. Boil kettles are really expensive where I come from. So have only the one pot. So mashing the second batch while boiling the first is out because there is no vessel available to heat the water in.

    In the end I went ahead as planned and brewed 15 liters, diluted with 15 liters water and pitched yeast.
    I will update with results when it's packaged.
     
  9. Mark D Pirate

    Mark D Pirate Well-Known Member

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    with the 2 step both mashes can be on different days , chill first mash and pitch yeast
    mash second batch next day , chill and pour over the first ....yeast will think that somebody upstairs really really loves them
     
  10. Trialben

    Trialben Well-Known Member

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    Go grab yourself a keg getack it will fit all your mash volume in heck you can even do a full volume mash for 30lt of wort you've already got the gas burner it's just a small step forward to more convenience and saved time:). A 50lt brew keg is a cheaper option in my opinion than a 50lt stainless steel pot and a good quality one at that I think the steel thickness on the keg is like 3mm so great quality and will last you a lifetime!
     
  11. jmcnamara

    jmcnamara Well-Known Member

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    Haha, yeah I've had a few doubled up brew days. feels like I went to work after its all over.
    On the brightside, sounds like you know what works and what doesn't with your setup. always a plus
     

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