Help with Brewhouse Efficiency

[Cookiedds]

I brewed an oatmeal stout today that ended up being an Imperial Oatmeal Stout. My calculated Brewhouse Efficiency according to Beer Smith clocked in at 90.39%. Every time I've brewed I tweak different areas of my system (finer gap in Barley Crusher, stirring the mash, adding a beta rest, etc.) and each time the efficiency goes up which I shouldn't be complaining about but it's hard to dial in my recipes so far.
I personally don't even think 90.39% is possible but that's what the calculations came up as. I measure each step with as much precision as possible. I gun for 6+ gallons at the end of the boil so I have 5.5 going into primary. Today my pre boil volume was 7.5 gallons at 1.057 and my OG was 1.079 with 5.5 into the primary. Here's my recipe, let me know where I'm screwing up.
Thanks for the help, I love this forum.

Recipe: Captain Oats
Brewer: Christian Claeys
Asst Brewer:
Style: Oatmeal Stout
TYPE: All Grain
Taste: (35.0)

Recipe Specifications
--------------------------
Batch Size: 6.00 gal
Boil Size: 7.83 gal
Estimated OG: 1.066 SG
Estimated Color: 29.1 SRM
Estimated IBU: 38.5 IBU
Brewhouse Efficiency: 75.00 %
Boil Time: 75 Minutes

Ingredients:
------------
Amount Item Type % or IBU
1.00 lb Rice Hulls (0.0 SRM) Adjunct 6.45 %
8.00 lb Pale Malt, Maris Otter (3.0 SRM) Grain 51.61 %
1.00 lb Caramel/Crystal Malt - 60L (60.0 SRM) Grain 6.45 %
1.00 lb Golden Naked Oats (15.0 SRM) Grain 6.45 %
1.00 lb Oats, Toasted (3.0 SRM) Grain 6.45 %
1.00 lb Victory Malt (25.0 SRM) Grain 6.45 %
1.00 lb Wheat Malt, Ger (2.0 SRM) Grain 6.45 %
0.50 lb Cara-Pils/Dextrine (2.0 SRM) Grain 3.23 %
0.50 lb Chocolate Malt (350.0 SRM) Grain 3.23 %
0.50 lb Roasted Barley (300.0 SRM) Grain 3.23 %
3.00 oz Williamette [4.70 %] (60 min) (First WortHops 38.5 IBU
1.10 items Whirlfloc Tablet (Boil 15.0 min) Misc
2.00 items Vanilla Bean (Boil 5.0 min) Misc
3 Pkgs London Ale III (Wyeast Labs #1318) Yeast-Ale


Mash Schedule: Single Infusion, Medium Body, Batch Sparge
Total Grain Weight: 15.50 lb
----------------------------
Single Infusion, Medium Body, Batch Sparge
Step Time Name Description Step Temp
30 min Step Add 12.40 qt of water at 126.0 F 116.0 F
60 min Mash In Add 10.85 qt of water at 204.9 F 153.0 F

 

[davesrose]

http://beercalculus.hopville.com/recipe

If I completely plug in your grainbill, I get 84% effeciency for 5.5 gallons. It is a big grain bill if you factor all the malt (not just the Marris Otter).

 

[JuanMoore]

I think you may be overestimating how much wort you're losing to trub. If you boil 7.5 gal of 1.057 wort, you have to boil off a full 2 gallons to concentrate it enough to read 1.079. If we use 5.5 gal for the batch size (7.5 minus 2) beersmith gives an efficiency of 82-83%. It looks like you're collecting a lot of wort, and have a higher than usual boil-off, which would lead to higher than average efficiency.

 

[ajf]

I put the recipe into Promash and came up with an efficiency of 81% using your figures.
One thing you may want to do is to adjust the potential SG for UK Pale Malt in Beersmith from 1.036 to 1.038 (which is more typical).

-a.

 

[Cookiedds]

I already have the MO in at 1.038. I actually had just over 6 gallons left before I went into the primary and ended up with 5.5 minus the trub.

By the way, I checked the primary before bed and it had a nice krausen going. Checked it first thing this morning and my floor and wall have a nice krausen on them Once I got the blow off hooked up the bucket looks like my daughter making bubbles in her milk, it is literally going crazy. Go yeast:rockin: I threw the vanilla beans into the primary when I pitched the yeast. Wonder what kind of 1.079 OG Oatmeal Stout this is going to turn out to be?

 

[a10t2]

I actually had just over 6 gallons left before I went into the primary and ended up with 5.5 minus the trub.

In that case your gravity readings don't really match up. 7.5 gal at 1.057 would boil down to, say, 6.1 gal at 1.070. How are you taking those readings?

 

[Sawdustguy]

I always take efficiency claims with a grain of salt. I have seen guys on the forum claim better than 100% with no sparge, no crush and no brew.

 

[JuanMoore]

I actually had just over 6 gallons left before I went into the primary and ended up with 5.5 minus the trub.

Then either your volume measurements or gravity measurements are off, because the math doesn't add up. You'd have to add a lot of sugars to get 7.5 gal of 1.057 wort to equal 6+ gal of 1.079 wort.

Are you correcting the volumes for temperature? Have you read Kaiser's wiki article about measuring accuracy?

 

[Cookiedds]

I have my brew pot, 6.5 and 5.5 gallon carboys and gallon measure "dip sticks" all calibrated and marked on the side of the carboys and kettle. The kettle is also engraved on the inside. I calibrated them all by volume and by weight to double check (using distilled H2O). I take my gravity readings with a hydrometer in a glass graduated cylinder spinning it, waiting, and rechecking 10 minutes later. I adjust the gravity readings for fluid temperature at the time of measuring and read the bottom of the miniscus with all readings. My grain scale is calibrated and extremely accurate and I take all measurements in grams then convert to std units for the recipe (just to keep it simple for folks on this side of the pond).

I am definitely not bragging about efficiency here, on the contrary, I'm upset by my lack of consistency. I'm all about the final product and I'm not concerned with cost/gallon ratios of my brew. I'm happy to bone up for a couple extra pounds of grain to get the best quality possible. If I had 60% efficiency and excellent beer I'd be a happy brewer.

Hope this info helps to clarify a bit.

 

[Got Trub?]

OK then with the information you have now given it is unlikely to be a volume problem - except you need to adjust your total preboil volume for temperature. At 212 this would be off by about 4% so 7.5g would in fact be 7.2g once cooled to room temperature. As pointed out the math doesn't work so one of your SG measurements is off. If you assume the first one is accurate then you started with 57*7.2=410.4 gravity points. This translates into 6g of 1.068 SG wort at the end of your boil. That is within the margins of homebrewing error of the 1.066 you targeted with an efficiency of 75%. I think the SG you measured at the end was inaccurate. How hot was the wort when you took the SG hydrometer reading? In my experience the correction factor doesn't work well if the temperature is far off from the calibration temp of your hydrometer.

GT

 

[Chuck_Swillery]

75+% efficicency is something to be proud of! Well done...

 

[Cookiedds]

My preboil volume measurement was taken at 165 degrees F. My SG measurement (before pitching yeast) was 1.079 at 64 degrees F. I pulled the sample from the 6.5g primary just before I dropped my airstone in to aerate the wort. I get the wort down 2 degrees below my target fermentation temp before I put it in primary, aerate and pitch my starter. My hydrometer is calibrated to 60df, so with the sample at 64df I just fudge the miniscus about 1/4 point higher SG.

 

[Yooper]

My preboil volume measurement was taken at 165 degrees F.

That's way too high. Even with the correction tables, a sample of over 100 degrees or so is notoriously inaccurate. Next time, cool your sample to 90 degrees before taking the reading. It's easy with a pitcher and an ice bath. I stick some ice and water in a tall round pitcher and place the test jar in it. It cools within a few minutes and you can get a more accurate reading.

That's the only reason I bought a refractometer- I hated messing with chilling the samples but found that there really isn't an accurate way to take a good SG reading when the sample is over 100 degrees.

 

[JuanMoore]

My preboil volume measurement was taken at 165 degrees F.

Was that the temp you took the pre-boil SG reading at? You really need to be within about 30F of the hydrometers calibration temp to be at all accurate. For future reference, your temperature corrected starting volume would be about 7.275 gal. Did you read the link I posted earlier? It explains all of this better than I can.

 

[ajf]

A lot of good information has already been posted about temperature and volume corrections, and this would indicate that your pre-boil readings are suspect; but have you checked your hydrometer for accuracy? It is not uncommon for hydrometers to read a few degrees high or low. It should read 1.000 in water at close to the calibration temperature. If it reads 1.003, then simply subtract 0.003 from all gravity readings. If it reads 0.998, then add 0.002 to all gravity readings.

-a.

 

[davesrose]

Is this thread going off track from the initial post? It seems we're now talking about proper measurement of pre-boil SG, and the descrepency between pre-boil gravity vs post boil gravity. Chances are the gravity reading for the pre-boil gravity isn't accurate (because of temp). I thought the OP was asking why they were getting an OG reading of 1.079 with the posted grain bill. Seems like it's quite possible to get that from the grain bill at a 81-83 percent effeciency (depending on particulars of actual grain extraction). The main point here is that there is actually quite a bit of grain in this bill, so I would have expected a OG gravity within the 1.07+ range (if you get an effeciency above 70%).

 

[Cookiedds]

That's way too high. Even with the correction tables, a sample of over 100 degrees or so is notoriously inaccurate. Next time, cool your sample to 90 degrees before taking the reading. It's easy with a pitcher and an ice bath. I stick some ice and water in a tall round pitcher and place the test jar in it. It cools within a few minutes and you can get a more accurate reading.

That's the only reason I bought a refractometer- I hated messing with chilling the samples but found that there really isn't an accurate way to take a good SG reading when the sample is over 100 degrees.

I think you misread my last post. My SG sample temperature was taken at 64 degrees. It was my preboil volume measurement that was taken at 164 degrees, I hope your not suggesting I chill the wort out of the mash tun just to measure volume before I boil it?

 

[Cookiedds]

Was that the temp you took the pre-boil SG reading at? You really need to be within about 30F of the hydrometers calibration temp to be at all accurate. For future reference, your temperature corrected starting volume would be about 7.275 gal. Did you read the link I posted earlier? It explains all of this better than I can.

Nope. The VOLUME measurement was taken at 164 degrees. The SG measurement was taken at 64 degrees (which is within 4 degrees of the calibration temperature for my hydrometer). I tried to be very clear and specific with this in my previous posts but a lot of folks are getting confused or are just reading over it.

 

[Cookiedds]

A lot of good information has already been posted about temperature and volume corrections, and this would indicate that your pre-boil readings are suspect; but have you checked your hydrometer for accuracy? It is not uncommon for hydrometers to read a few degrees high or low. It should read 1.000 in water at close to the calibration temperature. If it reads 1.003, then simply subtract 0.003 from all gravity readings. If it reads 0.998, then add 0.002 to all gravity readings.

-a.

Yep, I calibrated my hydrometers in plain old tap water and also in distilled water, both at 60 degrees and they are pretty much spot on. I'm a dentist and kind of a detail freak so I have 4 calibrated thermometers and two hydrometers in order to double, triple and quadruple check against.

I could have solved the whole problem by watering down the whole batch of wort to get my target OG but that is not what I'm after. I would like to get to the point where I'm brewing off my recipes and be within a reasonable margin of error varience.

I guess I'm just not wording my questions and answers clearly. I am certain of my grain bill measurements, pre boil SG(into the kettle) and of my OG(into the primary) measurements. I think the problem is in the crush, the mash or the sparge (the schedule was listed in the original post).

 

[a10t2]

I think you misread my last post. My SG sample temperature was taken at 64 degrees. It was my preboil volume measurement that was taken at 164 degrees, I hope your not suggesting I chill the wort out of the mash tun just to measure volume before I boil it?

So what temperature was the 1.057 SG measurement taken at?

I think people are belaboring the point because at least one of the four numbers (1.057, 7.5, 1.079, and 6.something) has to be incorrect, and you won't get the kind of consistency you're looking for until you can find the reason.

You don't need to chill the entire volume down, just compensate for the density. At 164°F, that means multiplying by 0.978 - 7.5 gal is actually about 7.3 at room temperature. Which puts your mash efficiency at about 80%, FWIW, assuming the 1.057 SG reading is correct.

 

[JuanMoore]

Nope. The VOLUME measurement was taken at 164 degrees. The SG measurement was taken at 64 degrees (which is within 4 degrees of the calibration temperature for my hydrometer). I tried to be very clear and specific with this in my previous posts but a lot of folks are getting confused or are just reading over it.

Accurate volumes are critical for calculating efficiency. 6.0 gal at 164F is about 5.8 gal temp corrected, which would give ~86% efficiency by my math. Still doesn't explain the SG readings 100%, but it's much closer.

 

[Cookiedds]

So what temperature was the 1.057 SG measurement taken at?

I think people are belaboring the point because at least one of the four numbers (1.057, 7.5, 1.079, and 6.something) has to be incorrect, and you won't get the kind of consistency you're looking for until you can find the reason.

You don't need to chill the entire volume down, just compensate for the density. At 164°F, that means multiplying by 0.978 - 7.5 gal is actually about 7.3 at room temperature. Which puts your mash efficiency at about 80%, FWIW, assuming the 1.057 SG reading is correct.

The 1.057 pre boil gravity number was taken at 60 to 65 degrees. I always cool to this range before taking a hydrometer reading just to keep things consistent. It's as easy as putting my glass graduated cylinder in warm or cool water to get it to the temp desired (made easier by the fact that my hydrometers also have thermometers built in).

 

[Cookiedds]

Accurate volumes are critical for calculating efficiency. 6.0 gal at 164F is about 5.8 gal temp corrected, which would give ~86% efficiency by my math. Still doesn't explain the SG readings 100%, but it's much closer.

The volume measurement taken at 164 degrees was the pre boil 7.5 gallons collected directly from the mash tun. All other volume and gravity readings were taken between 64 to 68 degrees. I posted all of this earlier but it is still getting confused. The pre boil volume is the only measurement I take at a higher temp as it would be impractical to chill 7.5 gallons of wort out of the mash tun to take a volume measurement just to turn around and bring it to a boil. Volume into the primary and all SG readings were taken at temperatures between 64 and 67 degrees. I hope this clarifies a bit.

 

[JuanMoore]

The volume measurement taken at 164 degrees was the pre boil 7.5 gallons collected directly from the mash tun. All other volume and gravity readings were taken between 64 to 68 degrees. I posted all of this earlier but it is still getting confused. The pre boil volume is the only measurement I take at a higher temp as it would be impractical to chill 7.5 gallons of wort out of the mash tun to take a volume measurement just to turn around and bring it to a boil. Volume into the primary and all SG readings were taken at temperatures between 64 and 67 degrees. I hope this clarifies a bit.

I think the real issue is that you want consistent, repeatable results, but as you mentioned you keep tweaking your process, which is going to change your efficiency every time. If you keep using the same process and methods of measurement, the actual volume or efficiency won't really matter, because you'll end with predictable results. The simple answer is to stop tweaking the process, keep measuring things the exact same way, and figure your efficiency at the 90% you calculated using that process.

If you really want the math to add up, it sounds like you need to re-evaluate your volume measurements. My first attempts at marking volumes were way off because I assumed that my kitchen measuring cups were close to accurate. I eventually used a graduated cylinder to get accurate marks on all of my equipment.

 

[Cookiedds]

I calibrated the volume measurements by density/weight as it is much more accurate than anything but laboratory equipment. I was amused by how inaccurate a half dozen volume measuring containers I had around the kitchen both under and over actual volume.

 

[cookietruck]

I think you misread my last post. My SG sample temperature was taken at 64 degrees. It was my preboil volume measurement that was taken at 164 degrees, I hope your not suggesting I chill the wort out of the mash tun just to measure volume before I boil it?

yooper is sayin exactly that. if you want an accurate preboil gravity measurement then you have to chill it.
i do the same thing if i take a measurement, right as i'm starting the boil i stir the wort well to mix the first and second running. then i dip a glass in the kettle for the reading. let the glass sit in a bowl of ice water while i'm dumping spent grain in compost or whatever...then take a reading after it's chilled.

sometimes i'll take wort from the kettle right as i end the boil and stick it in ice water in a bowl to chill...that way i don't have to worry about sanitizing wine thief...

 

[JuanMoore]

yooper is sayin exactly that. if you want an accurate preboil gravity measurement then you have to chill it.
i do the same thing if i take a measurement, right as i'm starting the boil i stir the wort well to mix the first and second running. then i dip a glass in the kettle for the reading. let the glass sit in a bowl of ice water while i'm dumping spent grain in compost or whatever...then take a reading after it's chilled.

sometimes i'll take wort from the kettle right as i end the boil and stick it in ice water in a bowl to chill...that way i don't have to worry about sanitizing wine thief...

I think both you and Yooper are misreading his post. He's referring to volume measurment, not SG.

 

[JuanMoore]

I calibrated the volume measurements by density/weight as it is much more accurate than anything but laboratory equipment. I was amused by how inaccurate a half dozen volume measuring containers I had around the kitchen both under and over actual volume.

Well then I'm at a loss. As stated before, at least one of your 4 measurements is off (7.5, 6.1, 1.057, 1.079), because the math doesn't compute. I think it's up to you to figure out which one/ones, because I have no idea from you've told us.

Edit:
I had a thought. Were your first runnings (higher SG) mixed well with your sparge runnings (lower SG) before you pulled the first sample? As many people have found out doing a partial boil with extract and then topping off with water, it takes a lot to thoroughly combine the two liquids of different densities. Your first sample may have been mostly sparge runnings, which would throw off your reading.

 

[Yooper]

I think you misread my last post. My SG sample temperature was taken at 64 degrees. It was my preboil volume measurement that was taken at 164 degrees, I hope your not suggesting I chill the wort out of the mash tun just to measure volume before I boil it?

I think both you and Yooper are misreading his post. He's referring to volume measurment, not SG.

I read him to say that the preboil SG was at 164. Sorry about that!

 

[Cookiedds]

yooper is sayin exactly that. if you want an accurate preboil gravity measurement then you have to chill it.
i do the same thing if i take a measurement, right as i'm starting the boil i stir the wort well to mix the first and second running. then i dip a glass in the kettle for the reading. let the glass sit in a bowl of ice water while i'm dumping spent grain in compost or whatever...then take a reading after it's chilled.

sometimes i'll take wort from the kettle right as i end the boil and stick it in ice water in a bowl to chill...that way i don't have to worry about sanitizing wine thief...

Again, ALL of my Specific Gravity readings are taken at temperatures between 60 to 68 degrees, always have and always will chill or warm the wort/beer to that range before pulling out the hydrometer.

It is the full pre-boil VOLUME measurement that I do not chill before Measuring the VOLUME. Does anyone actually chill 7 to 15 gallons of wort down out of the mash/lauter tun just to get a precice VOLUME measurement? I can't be any more clear on the subject. Of course I would never take a specific gravity reading at 100+ degrees, I ONLY measure SG at a temperature between 60 and 68 degrees.