Beersmoith: hot or cold preboil wort (in relationship to volume)?

I pump my wort to the BK during a continious sparge, and also ramp the temp of the BK to follow the volume to reach boil quickly, so the wort is on the brink of boiling all the way until my BK is full. So the wort is expanded...

My post-chill volume is 1L less than pre-chill. Should I pump close to 1L more to preboil?

I guess BSs numbers are with cold wort? Can it be that im boiling close to 1L less than I actually should?

Are your gravities correct? Or are they a little high? If the latter, then yes, a little more water in the kettle is called for.

Your preboil and post boil kettle volumes are measured hot in BeerSmith. In your equipment profile, you can adjust the expansion to fit the temperature you're measuring at. 4% is the default.

If you're gravity and expansion numbers are correct, you need to look for other physical loss. This should be accounted for in "Loss to Trub & Chiller" found in the equipment profile.

They are a little high yes. And even though I feel I get the planned volume into the fermentor, I sort of have to work to fill it up, so I've been boiling almost a litre to little.

The loss to chiller is pretty much spot on. I lose about a litre after chilling, which is the 4% set in Beersmith.

I shot Brad a mail, and he agreed that I should pump one more litre into the BK, as (as I understood it from his answer) beersmith does not account for expansion going into the BK preboil.

I just got a new reply from Brad and he told me the preboil volume is a hot measurment. So now I'm confused. I feel like I lack one litre, but my boil off rate is pretty correct.

Hmmm, I asked the specific question on the Beersmith forums "Estimated pre-boil volume...at what temperature" and got a relatively non-specific answer which seems to contradict what Brad Smith is now telling you:

http://www.beersmith.com/forum/index.php?topic=7249.5

Seems like there is a pretty simple resolution for this.

In your equipment profile, if you select "Calculate Boil Volume Automatically" and then change the cooling shrinkage number, does the pre and post boil volume change?

I believe it does. That would indicate the numbers are measured hot.

brewfun said:

Seems like there is a pretty simple resolution for this.

In your equipment profile, if you select "Calculate Boil Volume Automatically" and then change the cooling shrinkage number, does the pre and post boil volume change?

I believe it does. That would indicate the numbers are measured hot.

Click to expand...

I think this might have been a recent change because I'm pretty sure I too recall the pre-boil volume not accounting for expansion, though now it does seem to (though not really, more on that later). I did a little tinkering to try and figure things out and sadly it may have raised more questions than answers.

0% Cooling Loss:

Total Mash Water: 16
Grain Absorption: 6.76
Water Avail From Mash: 9.24
Sparge Vol: 15.19
Kettle Top Up: 0
Est Pre-Boil Vol: 24.43
Boil Off: 4.43
Post Boil Vol: 20
Cooling Shrinkage: 0.00
Pct Cool Loss: 0.00

Now with 4% Cooling Loss:

Total Mash Water: 16
Grain Absorption: 6.76
Water Avail From Mash: 9.24
Sparge Vol: 15.99
Est Pre-Boil Vol: 25.23
Kettle Top Up: 0
Boil Off: 4.43
Post Boil Vol: 20.80
Cooling Strinkage: .83
Pct Cool Loss: 4.00

So changing Pct Cooling Loss resulted in a change to Est Pre-Boil Vol, Post Boil Vol and the Sparge Vol. Hmmm. I started to write up how these numbers are calculated and figure out the assumed Pre-Boil temperature, but then I realized I was trying too hard (in that I was trying to do it accurately). It turns out Beersmith just works backwards and simply hides the expansion difference in the sparge volume. A batch size of 20L means an Post Boil Vol of 20.80L that extra .80L is curiously also how much Est Pre-Boil Vol and the Sparge Vol increase by. Measure pre-boil and sparge volume at temperature would be the correct way to do it, but that's not what's going on here because changing the sparge temperature doesn't change the volume and the percentage difference between the 2 sparge volumes in the above example is > 4%. I didn't look at how kettle top up works, but I suspect there is similar hand waving going on. Am I wrong in saying that this is broken?

Robert

The difference between your two preboil volumes is .177%. Which happens to correspond to the expansion expected for 22C (72F) water. That seems to be the "cold" temperature reference point.

Your point about the sparge volumes is correct, though. The sparge volume is tied to the expansion rate in the equipment profile rather than the sparge temperature. You're also correct that the sparge expansion rate is greater than what's entered in the equipment profile.

I've made the point on the BeerSmith forum that sparge water seems to use more expansion than needed. The error ranges from 11 to 18%. What I got back was an explanation about grain absorption. Which doesn't make any sense since the grain is already saturated.

The most accurate way to account for water in brewing is with weight. But, that'd require a wholesale shift in home brewing techniques. That just isn't going to happen. So, we're left with relative volume/temperature measurements. I'd be happier with an error range <5%, though.