Big Beers vs. BrewEasy

[Gravitationally Gifted]

So I've taken the plunge in the last couple of years into all grain and to do so I created a BrewEasy clone using a 15 gallon brew kettle and a 20 gallon mash tun from Spike. Add a pump and a propane burner and voila, a BrewEasy knock off! I've brewed about 5 batches of beer with it (all 10 gallon batches) and have found my efficiency varies greatly depending on the OG I'm shooting for. My one attempt at a smaller beer gave me a BH efficiency (BHE) of 75%, but every time I shoot for a 1.1 OG my efficiency takes a nose dive to about 56% and i miss my target by around 0.018 . This is an issue because i can only fit so much grain in my tun and really don't want to have to buy a bigger tun so was hoping you guys could help me diagnose why i'm getting such a crummy BHE so i can spend money on grain and not new equipment. I did notice that using lactic acid on the smaller beer upped my BHE, but it could also be that it's a smaller OG that is contributing to that. I also noted that i'm missing my pre-boil gravity in the few times i've measured that since i bought a refractometer. I'm at a loss and can't wait to hear what you have to say. I've attached my notes below.

Batches	lbs
lmperial Stout (Tom Mik's clone)
Grain	39
Candi Sugar	1
Pre-boil gravity (refractometer)	NA
Mash temp	153
Predicted Pre-Boil Gravity	1.083
Measured Pre-Boil Gravity	NA
Predicted OG	1.1
Measured OG	1.079
Difference	0.021
Measured FG	1.024
Predicted ABV	9.80%
Actual ABV	7.22%
BH efficiency	58.43%
Belgian Dubbel
Grain	28.3
Candi Sugar	1.7
Lactic Acid	.5 Tbs
Pre-boil gravity (refractometer)	NA
Mash temp	155
Predicted Pre-Boil Gravity	1.066
Measured Pre-Boil Gravity	1.055
Predicted OG	1.071
Measured OG	1.066
Difference	0.005
Measured FG	1.0000
Predicted ABV	7.30%
Actual ABV	8.66%
BH efficiency	75%
Experimental Imperial Stout
Grain	43.1
Candi Sugar	1
Lactic Acid	none
Pre-boil gravity (refractometer)	NA
Mash temp	152
Predicted Pre-Boil Gravity	1.089
Measured Pre-Boil Gravity	NA
Predicted OG	1.095
Measured OG	1.077
Difference	0.018
Measured FG	1.02
Predicted ABV	9.60%
Actual ABV	7.48%
BH efficiency	58.50%
Double IPA try #1
Grain	40
Corn Sugar	1
Lactic Acid	none
Pre-boil gravity (refractometer)	NA
Mash temp	152
Predicted Pre-Boil Gravity	1.094
Measured Pre-Boil Gravity	NA
Predicted OG	1.1
Measured OG	1.082
Difference	0.018
Measured FG	1.001
Predicted ABV	12%
Actual ABV	10.89%
BH efficiency	51.02%
Double IPA try #2
Grain	40
Corn Sugar	1
Lactic Acid	none
Pre-boil gravity (refractometer)	NA
Mash temp	152
Predicted Pre-Boil Gravity	1.094
Measured Pre-Boil Gravity	1.07
Predicted OG	1.1
Measured OG	1.084
Difference	0.016
Measured FG	TBD
Predicted ABV	12%
Actual ABV	TBD
BH efficiency	57.27%

 

[doug293cz]

Efficiency (specifically lauter efficiency) drops as the amount of grain increases for the same pre-boil volume. This is because the more grain you have the more wort (and sugar) gets left in the spent grain mass. Sparging increases lauter efficiency vs. not sparging, but will not make up for the increased grain absorption.

Here's a chart that shows this effect for batch and no-sparge processes. Fly sparging (if done well) will have a few percentage points higher lauter efficiency than a triple batch sparge at 0.12 gal/lb absorption rate.

Mash efficiency is conversion efficiency times lauter efficiency. You can improve lauter efficiency by doing more aggressive sparging, but you will always have losses during lautering, as shown above. If your conversion efficiency is not close to 100%, then your mash efficiency will be reduced.

In order to diagnose efficiency issues, you need to know if your conversion efficiency is lower than it should be, or if you lautering process is giving lower than the theoretical best given by the chart.

You can calculate conversion efficiency just by knowing the grain total weight, the weighted average extract potential for the grain bill, the strike water volume, and the SG of the wort in the MLT at the end of the mash. I give the details here.

Then you calculate your lauter efficiency by dividing the mash efficiency by the conversion efficiency.

Brewhouse efficiency is just mash efficiency * volume in fermenter / post-boil volume. If your mash efficiency is already high, then you can increase your brewhouse efficiency by leaving less wort behind in the BK while transferring to the fermenter.

You can predict your mash efficiency for a given recipe by using my spreadsheet.

If you want other people to help you diagnose your efficiency issues, you should collect and report the following values:

• Grain bill weight, and weighted average extract potential
• Strike water volume, and temp at which volume was measured
• SG of wort in MLT at end of mash
• Pre-boil volume, and temp at which volume was measured
• Pre-boil SG (temp corrected)
• Post-boil volume, and temp at which volume was measured
• Post -boil SG (temp corrected) - i.e. the OG
• Volume to the fermenter, and temp at which volume was measured

Accuracy of the above data is critical, as the accuracy of the calculated values can be no better than the accuracy of the input data.

Since you didn't provide any volume measurements, there is nothing we can say about your efficiencies.

Brew on

 

[Gravitationally Gifted]

Doug that is awesome! I look forward to some "light" reading this weekend.

 

[Beholder]

With a Breweasy type setup myself, aside from working through above, I can suggest a few additional tips.

Water chemistry and achieving pH around 5.2 is helpful. Raking top half of grain bed is helpful. Last suggestion is to share your mash tun / false bottom details, just to confirm you don’t have channeling. When you dough in, you mix as you add slowly to avoid dough balls?

 

[doug293cz]

With a Breweasy type setup myself, aside from working through above, I can suggest a few additional tips.

Water chemistry and achieving pH around 5.2 is helpful. Raking top half of grain bed is helpful. Last suggestion is to share your mash tun / false bottom details, just to confirm you don’t have channeling. When you dough in, you mix as you add slowly to avoid dough balls?

pH within the range of 5.2 to 5.6 will give good results, but even a little outside this range will work. In general people prefer the lower end of the range for lighter colored beers, and the higher end of the range for darker beers. In any case, a pH that is way out of whack would affect the conversion efficiency, but not lauter efficiency, so is something to consider if your conversion efficiency is low.

Dough balls also affect conversion efficiency, but not lauter efficiency. So again, low conversion efficiency would mean that you need to rule out dough balls.

However, the most common cause of low conversion efficiency is too short a mash time for the coarseness of the crush. The coarser the crush, the longer conversion takes, because complete gelatinization of all of the starch takes longer. Starch has to be gelatinized before it can be hydrolyzed (converted to sugar.) If you have low conversion efficiency, you should look at going to a finer crush (usually requires your own mill.) Ability to lauter will limit just how fine you can crush. Once you have gotten to the finest crush you can use, then you need to look at extending your mash time, if conversion efficiency is still significantly below 100% (95% or less.)

Channeling during fly sparging, due to a poor false bottom design, sparging too fast, or any other cause, will show up as a lauter efficiency significantly below the upper solid line in the chart I posted above. Channeling is the most common cause of low lauter efficiency when fly sparging.

Channeling does not affect batch or no-sparge processes. Low lauter efficiency for these processes is due either to inadequate mixing prior to run-off, or not draining long enough after each run-off.

The above examples show how knowing whether conversion efficiency or lauter efficiency is lower than they should be can help you determine what the cause of low mash efficiency is.

Brew on

 

[deuc224]

You know what i dont understand? When people say they cant hit a starting gravity Why not just brew a bigger batch and boil off more liquid to concentrate the wort and get the starting gravity you are really aiming for? i do this all the damn time lol. Now yeast starter to eat all that sugar is a whole other story.

 

[Velnerj]

Lower efficiency for bigger gravity beers is unavoidable. It's simple science of diffusion. Outside of the enzymatic activity in the mash what is taking place is simple diffusion, a higher concentration diffusing to a lower concentration.

The grain contains a high concentration of sugars and our water has none. The water will only draw out the sugars until there is an equalibrium betwee the grain and the water. Therefore the more sugar in the mash, the less sugars will be drawn out of the grains.

So to overcome this you will either need a lot more volume of water in mash/sparge and boil longer or supplement your boil kettle with sugars (malt extract or other forms of sugar).

 

[McMullan]

I'd add collision theory to the mix. Higher grist: liquor ratio means more particles in suspension. More particles in suspension means a drop in the rate of successful collisions between enzymes and their substrates. As @doug293cz noted above, increasing mash time is the solution, to a level. To minimise dough balls forming it's important to work against the low wettability of the grist. First, thoroughly mix a cup or two of the grist in the mash water, which makes subsequent grist additions more wettable. Then start mashing in slowly. I add about 1/3 each time and mix slowly for 2-3 minutes. About 10 minutes total. If I'm short of my target OG, and I insist on reaching it, I'll add some brewing sugar. It works just fine.