Est Pre-Boil Volume vs Meas Pre-Boil Volume

I am consistently getting more volume out of my mash tun than BS2 is estimating but I cannot figure out what I can change.  My last Est Pre-Boil volume was 8.56 gallons and get 9.5 gallons in my brew kettle. Can anyone give me an idea of where to look?

Thanks!

Is your tun deadspace value correct in the equipment profile?  Have you put water in it and let it drain completely, then measuring what was leftover?  Mine was too high and I was surprised by how little water was left behind when I measured it.

+1  BeerSmith defaults to values that may be very different from what you actually have, so you'll need to tweak your Equipment Profile to match what you're using. Deadspace and boil-off are things which can change the pre-boil volume dramatically. Trub Loss is another variable that will change your pre-boil volume, but that opens yet another can of worms here...

Long story short; I brew 5-gallon batches, and after much tweaking I've pinned my Trub Loss at 0 and upped my Batch Size to 6.00 Gallons for hoppy beers (lots of trub) and 5.75 or 5.50 Gallons for less-hoppy beers to get the 5 to 5.25 gallons I want into the fermenter (I don't like to drain a lot of gunk into my fermenter so I leave it behind in the kettle.)

Based on my Equipment Profile, my calculated pre-boil volume for a 6-gallon batch is 7.44 gallons, and that's just about on the money with what I get in my kettle BUT; I stop draining the tun when it gets to that point so of course I'm nailing that number every time. What changes is the efficiency number, which I can deal with (just add another Lb of grain or so...)

When you run it down to 1.020 or 1.010 SG (to maximize extract efficiency), if the volume calculations are not all perfect, you will end up with a little more or a little less in the kettle. If it's volume you're after, stop draining the tun when your volume has been reached. If you want every little bit out of the grain, let the volume go higher and boil longer and/or more vigorously to hit your finishing volume target.

Thank you for the replies.  My tun deadspace was set to zero but my trub loss was 1.3 gallons.  I will take the trub loss to zero and see how that goes.  During my initial investigation it looks like that will work.

Thanks again,
Doug

+1  Take accurate measurements and fine-tune after each batch.  You're on the way already.  But specific to hitting the pre-boil volume, the secret is to close the valve. 

When you hit the pre-boil volume you want, just stop collecting.  Just because you're learning your system does not mean that extra water put into the MLT needs to be allowed into the boiler.  That just dilutes the SG of the wort, and adds volume that you must either boil off, or accept a weaker SG beer than you wanted. 

And knowing/hitting the pre-boil volume is a quick path to start dialing in on the boil-off rate to hit the desired post-boil volume.  Once you understand your evaporation rate, then you're going to get close to the OG after the boil that you wanted.

Read this thread:    http://www.beersmith.com/forum/index.php/topic,5140.0.html

so before I changed my Tub Loss to 0 for 1.3 gallons BS2 gave me the following mash information:

Single Infusion, Medium Body, Batch Sparge
Mash In: add 8.21 qts of water at 165.9F
Sparge: Batch sparge with 2 steps (3.02gal, 4.28gal) of 168F water
Est. Pre-Boil Vol: 8.56gal
MEAS Pre-Boil Vol: 9.50gal

After I set my Tub Loss to 0 BS2 gave me the following mash information:
Single Infusion, Medium Body, Batch Sparge
Mash In: add 8.21 qts of water at 165.9F
Sparge: Batch sparge with 2 steps (2.34gal, 3.60gal) of 168F water
Est. Pre-Boil Vol: 7.20gal
MEAS Pre-Boil Vol: 8.20gal

I am still off by 1gal and I am wondering how I can effect the Sparge Water?

If you attach your recipe, I will look it over to see if I can find out what's going on. PM me if you need additional guidance.

I have attached both recipes, with Trub and without the Trub.

The modified version of your recipe tells me you are putting 2.05 gallons in the mash, and draining about 1.26 gallons out (grain absorption accounts the the missing 0.79 gal). Your mash profile tells me you are going to add 2.34 gallons followed by another 3.60 gallons for the sparge. With the grain already holding water, that 5.94 gallons should drain right through to your kettle.

Add that amount to the initial mash-in volume less grain absorption and you should have 7.2 gallons in your kettle. Your tun deadspace is set to zero, so I will assume you've made the measurement - deadspace would subtract from the available water in your kettle anyway, and this doesn't seem to be a problem here.

If you do not add any other water to your mash tun other than that which is stated above (and in your recipe), the volume you see in your kettle after sparging should be 7.2 gallons.

Double check the volumes of your water additions at each step (use a measuring cup or other suitable method) and be sure you are not doubling-up or adding too much.

dbendinger said:

so before I changed my Tub Loss to 0 for 1.3 gallons BS2 gave me the following mash information:

Single Infusion, Medium Body, Batch Sparge
Mash In: add 8.21 qts of water at 165.9F
Sparge: Batch sparge with 2 steps (3.02gal, 4.28gal) of 168F water
Est. Pre-Boil Vol: 8.56gal
MEAS Pre-Boil Vol: 9.50gal

After I set my Tub Loss to 0 BS2 gave me the following mash information:
Single Infusion, Medium Body, Batch Sparge
Mash In: add 8.21 qts of water at 165.9F
Sparge: Batch sparge with 2 steps (2.34gal, 3.60gal) of 168F water
Est. Pre-Boil Vol: 7.20gal
MEAS Pre-Boil Vol: 8.20gal

I am still off by 1gal and I am wondering how I can effect the Sparge Water?

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The "Est." fields are calculated by BS2, based on your inputs.  It went down 1.36 gal.

The "MEAS" fields are actuals, measured and entered by the brewer.  In this case, from one brew, that number should not change. 


Big picture, you enter your best-guess estimates before the brew, and then enter your actual results in the Measured fields and BS2 calculates the efficiency (for that brew) based on those differences. 

Let's say 7.20gal Pre-Boil is correct, and you actually hit 7.20 (by closing the valve at 7.20).  Your volumes are perfect (to the forecast), and all that remains is measuring and entering the SG you got.  If you hit that SG forecast, then you achieved the efficiency you had forecast you would hit.  (And that efficiency could be high or low - you merely hit it.) 

If you hit Pre-Boil volume and still have lots of wort/water in the MLT, then the Equipment Profile has some excess losses somewhere that you can gradually reduce until one day, you will hit the Pre-Boil volume just as the MLT is gurbling and sputtering. 

Thanks!  I am going to run it again to confirm the water numbers going onto the mash.  I currently measure it gallon by gallon so I don't expect it to change but a confirmation will not hurt.  If it does not then there must be a loss being added in I will need to try and find.

MaltLicker said:

If you hit Pre-Boil volume and still have lots of wort/water in the MLT, then the Equipment Profile has some excess losses somewhere that you can gradually reduce until one day, you will hit the Pre-Boil volume just as the MLT is gurbling and sputtering. 

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