Brewmate Water Calculations

[mikec]

OK kicked off the second attempt at first BIAB on the weekend. Got the grinding, mashing etc down pat this time.
So I thought I would familiarise myself with BrewMate, plug in the numbers I'm achieving, and work backwards to calculate my brewhouse efficiency and so on.

In the pic below you see my grain bill, final volume, SG. 10.2L of cooled wort at 1.055.
Ignore the yeast attenuation & FG, I'll know these when the ferment is finished. Ignore also that the OG is too high for a CPA, I later watered it down to 1.048. The point of this exercise is simply to plug in my results, and work backwards from there.

The next shot is the "Brew Day" page.
The figures on the right are pretty much spot on. The SG before boiling, final volume, pre-boil volume, evap rate, etc - all pretty much on the money. All good right? Wait, why on the left does BrewMate tell me I need to start with 15.07L? Where does the other 1.27L go to?

Thoughts:
- A little bit will be absorbed by the grain. But not this much. I started with only 14L and had a pre-boil volume of just under 14L. I drained that grain good.
- Is the "Total water rqd" and "Strike Water" figures based on cold water or hot? Water will expand when heated from 25 to 70 degrees. But I wouldn't think by this much.

What says the collective?

 

[nala]

OK kicked off the second attempt at first BIAB on the weekend. Got the grinding, mashing etc down pat this time.
So I thought I would familiarise myself with BrewMate, plug in the numbers I'm achieving, and work backwards to calculate my brewhouse efficiency and so on.

In the pic below you see my grain bill, final volume, SG. 10.2L of cooled wort at 1.055.
Ignore the yeast attenuation & FG, I'll know these when the ferment is finished. Ignore also that the OG is too high for a CPA, I later watered it down to 1.048. The point of this exercise is simply to plug in my results, and work backwards from there.

The next shot is the "Brew Day" page.
The figures on the right are pretty much spot on. The SG before boiling, final volume, pre-boil volume, evap rate, etc - all pretty much on the money. All good right? Wait, why on the left does BrewMate tell me I need to start with 15.07L? Where does the other 1.27L go to?

Thoughts:
- A little bit will be absorbed by the grain. But not this much. I started with only 14L and had a pre-boil volume of just under 14L. I drained that grain good.
- Is the "Total water rqd" and "Strike Water" figures based on cold water or hot? Water will expand when heated from 25 to 70 degrees. But I wouldn't think by this much.

What says the collective?

You have an evaporation figure of 23% on your brewday sheet, probably double mine (12.6%)
maybe this is where your problem is.
The standard should fall between 5-15%.

 

[mikec]

You have an evaporation figure of 23% on your brewday sheet, probably double mine (12.6%)
maybe this is where your problem is.
The standard should fall between 5-15%.

The numbers on the right are pretty much what I experienced. Started with just under 14L, ended with 10.2 after cooling.
I've managed to get the figures to match what happened.
So unless I'm WAY off with my measurements, 23% is what I got.\

Edit: Also the SG before boil and after boil are in line with the high rate of evaporation.

 

[iralosavic]

You're BIABing, so you need to "strike in" with the full mash volume, which in your instance is 17.18L. Your evaporation rate should be below 15%, even if you're blasting the crap out of it. So it would appear you've miscalculated along the way. Probably linked with using the wrong initial volume?

 

[BobtheBrewer]

[You have set 0.6 as your absorption rate. That means that you will lose 1.27 ltrs to absorption. If you are not losing that much you need to change your absorption rate.

 

[mikec]

[You have set 0.6 as your absorption rate. That means that you will lose 1.27 ltrs to absorption. If you are not losing that much you need to change your absorption rate.

Ah ha! Problem solved, cheers Bob.

 

[mikec]

You're BIABing, so you need to "strike in" with the full mash volume, which in your instance is 17.18L. Your evaporation rate should be below 15%, even if you're blasting the crap out of it. So it would appear you've miscalculated along the way. Probably linked with using the wrong initial volume?

Absorbtion rate setting was wrong as above.I did definitely use 14L of water, 10.5 for mash and 3.5 for sparge.I guess it is possible my measurements were off slightly - higher absorbtion rate, less in kettle pre-boil, lower evaporation rate, would give the same end result. Measuring the kettle volume using a ruler, so possible to be out a little, but probably by no more than half a litre.