Adjusting boil off rate?

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obsidian
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Adjusting boil off rate?

Post by obsidian » 1 year ago

Hi

I have a couple of BIAB brews under my belt now (having done a fair bit of kit brewing in the past too). Everything has gone pretty well so far, and I've been hitting pretty close to the biabacus numbers in most areas. The one thing I am slightly concerned about is that my boil-off rate seems to be considerably lower than predictions suggest. I brew fairly small volumes (around 9l) on a stovetop, and my most recent brew I hit all my pre-boil predictions, but I ended up with around 1.5l of extra wort post boil, and therefore OG was also a little low. My first brew was similar.

So, my question here is, what are the variables I should be thinking about here? I can think of:

1) Increasing the vigorousness of my rolling boil to increase evaporation rate
2) Decrease boil off rate in biabacus

Is there anything I've missed? If not, I was thinking of gently decreasing the boil-off prediction downwards for future brews.


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Adjusting boil off rate?

Post by Contrarian » 1 year ago

Brewing inside means that you don't have as many of the atmospheric variables that can impact boil off rate. Mainly temperature, humidity and wind.

Boiling harder will result in more boil off but if you have a good rolling boil going isn't necessary.

On a stove top you probably have more chance of getting a consistent boil from brew to brew than I do so if you have had the same amount of boil off over 5-6 brews then change it in the biabacus.


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Post by PistolPatch » 1 year ago

Contrarian wrote:Boiling harder will result in more boil off but if you have a good rolling boil going isn't necessary.
Obsidian, I know we have touched on this issue in other threads but, a an update for you ;)...

a) Contrarian's quote above is correct. Don't try and match the BIABacus's estimates. In addition to what Contrarian mentioned...

b) On small or extremely large kettle sizes, the BIABacus estimates become less reliable so...

In your case, I think you can over-ride the BIABacus default immediately, not even gradually.

Hopefully, even after over-riding the default, you will still end up with a slightly higher gravity wort than estimated which is what you want.

:peace:
PP
Last edited by PistolPatch on 08 Jun 2016, 22:37, edited 1 time in total.
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Post by obsidian » 1 year ago

Great stuff, thanks for the info!

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