Grainfather - Pre-Boil Gravity, Efficiency and ABV Issues

[joegbeer]

I've done about 30 partial mash extract brews over the last 18 months. I just bought a Grainfather and did my first brew. I have a lot of numbers that are not adding up in Beersmith and it's driving me mad.

I manually entered all of the equipment profile stats for the grainfather from the other thread on homebrewtalk found here.

For the recipe I used distilled water. Using Brun's spreadsheet, I was going to add some calcium choloride and gypsum to raise the Calcium and Bicarbonates. I forgot that step, so the water profile was straight distilled.

Here's the recipe:

Recipe: Oatmeal Stout
Style: Oatmeal Stout
TYPE: All Grain

Recipe Specifications
--------------------------
Boil Size: 6.41 gal
Post Boil Volume: 5.75 gal
Batch Size (fermenter): 5.00 gal
Estimated OG: 1.068 SG
Estimated FG: 1.023 (Manually added metric from beersmith recipe profile)
Estimated ABV: 5.9% (Manually added metric from beersmith recipe profile)
Estimated Color: 39.1 SRM
Estimated IBU: 36.0 IBUs
Brewhouse Efficiency: 75.00 %
Est Mash Efficiency: 82.9 %
Boil Time: 60 Minutes

Ingredients:
------------
Amt Name Type # %/IBU
9 lbs Pale Malt (2 Row) US (2.0 SRM) Grain 1 70.6 %
1 lbs Oats, Flaked (Briess) (1.4 SRM) Grain 2 7.8 %
12.0 oz Special Roast (Briess) (50.0 SRM) Grain 3 5.9 %
8.0 oz Black (Patent) Malt (500.0 SRM) Grain 4 3.9 %
8.0 oz Caramel/Crystal Malt - 80L (80.0 SRM) Grain 5 3.9 %
8.0 oz Chocolate (Briess) (350.0 SRM) Grain 6 3.9 %
8.0 oz Crisp Pale Chocolate Malt (250.0 SRM) Grain 7 3.9 %
2.00 oz Goldings, East Kent [5.70 %] - Boil 60.0 Hop 8 36.0 IBUs
1.0 pkg English Ale (White Labs #WLP002) [35.49 Yeast 9 -


Mash Schedule: BIAB, Medium Body
Total Grain Weight: 12 lbs 12.0 oz
----------------------------
Name Description Step Temperat Step Time
Saccharification Add 29.38 qt of water at 161.9 F 154.0 F 60 min


Using Grainfather's formula for water volumes on Mash/Sparge, it recommended a 5.05 gallon mash volume and a 2.5 gallon sparge volume. I don't know why, but I'm positive I started a little high on mash volume at 5.25 gallons.

So after sparging (@168 degrees, took about 25 minutes) I took a wort sample and measured the gravity using a hydrometer when the wort was at 68 degree Fahrenheit. The sample read 1.051.

Beersmith reports my pre-boil volume at 6.4 gallons. Actual was about 6.75 gallons. Beersmith estimates my pre-boil gravity at 1.059 and I measured 1.051. When I plugged the measured pre-boil gravity of 1.051 into beersmith, I saw that the measured efficiency was listed as 57%. I really didn't want this beer to turn out weak on the ABV, so I made a snap decision at this point to dump 1 lb of DME when the boil started. I rushed through a bunch of calculations for adding DME when you miss efficency low and came up with 1lb which was probably a tad bit too much. Why was I so far off pre-boil gravity at 1.051? I understand that being over volume a tad on the mash would have an impact. I understand that the lack of calcium in the water could have an impact. Am I overlooking another reason why the pre-boil gavity turned out so much lower than the beersmith esimate of 1.059?

Calculating pre-boil efficiency obviously depends on the preboil gravity measurement, so the answer to this next question could be related to the previous answer about pre-boil gravity. After the brew out was done, I recognized that the Grainsmith efficiency calculator determined the pre-boil efficiency at 78%. Why is beersmith calculating my efficiency at 57% and the grainfather estimate of efficiency 78% so far apart?

So remember, I measured a pre-boil gravity of 1.051 and then added 1lb of DME. After the boil the volume was about 6.15 gallons After I transfered the wort to the primary and took an original gravity reading, it came out as 1.061. Beersmith had an estimated original gravity of 1.068. How did I miss the original gravity by so much, especially after I added more DME to the preboil volume?

 

[beergolf]

I am assuming that your recipe was for 5 gallons. Your post boil volume of 6.15 is high. For OG gravity reading to be correct the volume must. match what was estimated. The higher volume diluted the wort.

You also need to brew a few times on your systen to dial in the efficiency numbers. But again that is assuming that you get the correct volumes.

 

[joegbeer]

Yes, the intent was a 5 gallon batch.

Agree my volumes were a bit high. Like I mentioned, I did start with about .25 gallons too much at boil time. Not sure I see .25 gallon dilluting the wort by .008 in total.

I agree that I'll need a couple runs to get comfortable with the dynamics of managing the volumes. I tried to just follow the Grainfather volume calculations blindly, but it was bothering me how much the beersmith and grainfather calculations seems to disagree (like the efficiency numbers).

Another question I would have for Grainfather users then is how much do people find themselves deviating from the grainfather volume (mash/sparge) recommendations?

I'm trying to determine what my target should be for pre-boil volume when my goal is make a 5 gallon batch. I think it should be somewhere in the 6.2 - 6.6 gallon range. The three biggest areas of wort loss is going to be evaporation during the boil (.6 gallons), loss to the chiller (??), and deadspace below the pump which includes the trub (cleaning with water, I measured this at .5 gallons). I'm confused by the fact that beersmith equipment profile for the Grainfather has the deadspace listed at .9 gallons)

 

[beergolf]

A couple of things. The Grainfather 78% estimate may be on the high side. Especially if you are using a LHBS crush. Some LHBS crushes are a little on the coarse side. It may take a few brews to get that dialed in. I would set it to 70% and start from there. Then if you are high or low you can adjust again until you get it dialed in. For example using my LHBS crush, I get 70% almost dead on every time. Once I got that dialed in I was able to make recipes that I hit my numbers within a point or two every time.

Your boil off rate needs to be adjusted. You are off on the post boil volume, which will definitely lower your OG. Water evaporates the sugar does not. You should be able to guestimate your volumes from this last brew and adjust accordingly. Once you do then you should be able to hit your numbers pretty easily.

Hang in there. You will get it figured out. A new rig always takes a little to get things dialed in.

 

[joegbeer]

Good comments about the grain crush, that was a detail I left out. I bought a grain mill (Barley Crusher) and set the gap at .38.

I didn't go into this first all-grain batch completely blind (beersmith and grainfather formulas), but I've definitely learned that I need to be very detailed on recording all of the volumes at each step until I've refined/adjusted the process.

I just don't like being off on my metric goals more than a small margin.

 

[beergolf]

You will get there. Dial in your volumes first and then assess where you are on efficiency. Then if you want to try to improve that, then adjust your crush. Remember that changing more than one variable makes it impossible to figure out what variable made the difference.

I am guessing that if you get your volumes figured out , you should get a fairly consistant efficiency. Then if you want to improve that you can tighten up the crush.

 

[joegbeer]

Are your recommending a smaller gap for the crush? I'm not malt conditioning when I crush. I tried to split the difference of what I perceived the popular gap sizes to be in the range of .35 - .40.