Brewfather & Smallbatch BIAB

[HemanBrew]

I'm having hard time to configure my equipment profile in brewfather.

I have a 7 litre kettle.

I star brewing by heating 6.4 litres of cold water. After adding water additions I separate 1.4 litres to another kettle (for dump Sparge later). So now my volume is 5l in main kettle.
I heat that to strike temperature and ad grains (1kg).

After mash I squeeze the biab-bag and dump the grains to the Sparge water. Then I squeeze again so that I can get every drop out of the grains. The bag with drained grains weights now only about 11g more than before putting them to mashwater.

I combine the liquids and now my hot preboil volume is about 6 litres.

Boil off is about 1.6 litre / hour (measured for hot to cooled wort).

After all I have about 4.3 litres to fermenter (basicly every drop from kettle).

I have tried to find a way to make this as a profile to brewfater but somehow it's too complicated. Any help would be priceless. Thanks.

 

[VikeMan]

I heat that to strike temperature and ad grains (1kg).

The bag with drained grains weights now only about 11g more than before putting them to mashwater.

There's something wrong with that 11g number.

BIABers who squeeze might get a grain absorption of, let's say, 0.05 gallons per pound, which translates to 0.417 liters per kilogram. So with one kilogram of malt, you'd have something like 417 grams of retained water, not 11 grams. If you assume 11 grams, I'd expect your finished volume to come up about 406 ml short.

ETA: The numbers I typed above are way oversimplified, and won't give the right answer. Don't try this at home.

 

[HemanBrew]

There's something wrong with that 11g number.

BIABers who squeeze might get a grain absorption of, let's say, 0.05 gallons per pound, which translates to 0.417 liters per kilogram. So with one kilogram of malt, you'd have something like 417 grams of retained water, not 11 grams. If you assume 11 grams, I'd expect your finished volume to come up about 406 ml short.

I mean that with exact measured numbers the malts weighted 980g and after the mash and squeezes the bag weighted 991g.

Of course there are more water than the 11g because the grains gave up the sugars... Right?


I believe it is easyer o squeeze more out of 1kg than for example 20kg bag.

 

[VikeMan]

I mean that with exact measured numbers the malts weighted 980g and after the mash and squeezes the bag weighted 991g.
I believe it is easyer o squeeze more out of 1kg than for example 20kg bag.

If you say so. Personally, I'd measure it again.

 

[HemanBrew]

If you say so. Personally, I'd measure it again.

I'll take your advice and measure this next brew again.
But is the formula like this:
Weight of (wet) grains after mash and squeeze - Grains before mash = Grain absorption rat*e (l/kg?

 

[VikeMan]

I'll take your advice and measure this next brew again.
But is the formula like this:
Weight of (wet) grains after mash and squeeze - Grains before mash = Grain absorption rat*e (l/kg?

Really, the right way to do it is to measure the pre-boil volume of the wort and subtract that from the total water volume (mash plus sparge). Then divide that by the kilograms of grains.

In reality, there's more water than that left in the grains, because the grains have lost most of the carbs, which increases the kettle volume. But the volume contribution of those carbs lost from the grains, when dissolved, is less than the volume of the same weight of water.

But using a "net" volume loss number by comparing liquid in to liquid out works, and it's what software is expecting. You could estimate your "net" absorption (i.e. the value the software wants) by measuring wet and dry grain weights, but it would take some math gymnastics (and some more info, like your mash efficiency) to get there.

 

[HemanBrew]

Really, the right way to do it is to measure the pre-boil volume of the wort and subtract that from the total water volume (mash plus sparge). Then divide that by the kilograms of grains.

In reality, there's more water than that left in the grains, because the grains have lost most of the carbs, which increases the kettle volume. But the volume contribution of those carbs lost from the grains, when dissolved, is less than the volume of the same weight of water.

But using a "net" volume loss number by comparing liquid in to liquid out works, and it's what software is expecting. You could estimate your "net" absorption (i.e. the value the software wants) by measuring wet and dry grain weights, but it would take some math gymnastics (and some more info, like your mash efficiency) to get there.

Oh no!
So it's something like this:
(6.4l - 6l) / 1xkg = 1.066kg/l

 

[VikeMan]

Oh no!
So it's something like this:
(6.4l - 6l) / 1xkg = 1.066kg/l

(6.4 L - 6 L) / 1 kg = 0.4 liters per kilogram

 

[HemanBrew]

(6.4 L - 6 L) / 1 kg = 0.4 liters per kilogram

Man I should have been wake in a maht class. So this starting to make more sense now.

 

[HemanBrew]

(6.4 L - 6 L) / 1 kg = 0.4 liters per kilogram

One more stupid question : is the preboil volume in BF the volume after the mash and squeeze?

Somehow those calculations in BF gives me too small boiloff rate...

 

[VikeMan]

One more stupid question : is the preboil volume in BF the volume after the mash and squeeze?

I don't use BF, but it should be whatever liquid you have left before boiling.

Somehow those calculations in BF gives me too small boiloff rate...

So, boil off rate and grain absorption are completely different and separate. Whatever software you're using, the boil off is something you should measure and input, i.e. I wouldn't rely on any default value, even if that default value is part of some pre-populated equipment profile.

 

[HemanBrew]

So, boil off rate and grain absorption are completely different and separate. Whatever software you're using, the boil off is something you should measure and input, i.e. I wouldn't rely on any default value, even if that default value is part of some pre-populated equipment profile.

I know. In BF there is possibility choose that do you insert the preboil volume (FB calculates boil off) or do you insert boil off (FB calculates pre boil volume).

And with all the info it calculates the total water amount needed.

And I can't get these match unless I enter some variable that I don't have. For example "mash tunn loss 0.2l" seems to work....

 

[HemanBrew]

I actually would like to be able to choose and lock the total water amount used and then chance the other values after that. But I guess that's not possible.

 

[HemanBrew]

Ok. I think I found my remaining problem. I didn't calculate the temperature expansion to boil off. Before I compared preboil to cooled wort. When comparing preboil to cooled wort*1.04 I get about the right numbers.... I think...