Efficiency Adjustments for Size of Grain Bill/Gravity

I currently have 36 recipes in my database. I brew 5.5 gallon batches & now have my own mill so I can get a consistent crush every time I brew. However, my recipes range from a 4.2% 8 lb grain bill (Southern English Brown) to a 12.9% 27 lb grain bill (Belgian Imperial Stout).

I've only used my mill for one brew so far & got a solid 72% efficiency with a higher gravity 19 lb grain bill. How much do you think my efficiency would change with an 8 lb grain bill vs a 27 lb grain bill based on the principle that the higher the gravity/grain bill, the lower the efficiency?

I'm interested in this thread...subscribed

Slight side question...I have a 48 qt cooler mash tun and a 35qt kettle, how many pounds of grain could I realistically fit?

CTownBrewer said:

I currently have 36 recipes in my database. I brew 5.5 gallon batches & now have my own mill so I can get a consistent crush every time I brew. However, my recipes range from a 4.2% 8 lb grain bill (Southern English Brown) to a 12.9% 27 lb grain bill (Belgian Imperial Stout).

I've only used my mill for one brew so far & got a solid 72% efficiency with a higher gravity 19 lb grain bill. How much do you think my efficiency would change with an 8 lb grain bill vs a 27 lb grain bill based on the principle that the higher the gravity/grain bill, the lower the efficiency?

Click to expand...

In a perfect world and with identical, perfect process your efficiency should be a constant, mathematically speaking because your recipe/grain bill is always 100%. All water volumes, temperatures, etc are scaled directly to the size of your grain bill and process.

This is strictly my opinion as, while I have done many AG brews, I too have experienced higher or lower efficiencies with both big and small grain bills.

While I have often wondered why there is a difference, I have come to the understanding that there are too many variables in the process to really want to lose sleep over it.

All it really takes is a change in weather, vigor of boil, 1 degree of mash temp, time of mash, and so on and your efficiency can change as a result.

I too will tune in to see if a more experienced brewer can chime in.....

I'm just thinking if I have a 20+ lb grain bill, it's going to be much more difficult to prevent dough balls & get every single grain wet, so sugar extraction will go down. If it's only 8 lbs, I can much more easily mix the grain & strike water to ensure all the grain is saturated & the maximum amount of sugar is extracted.

I just don't know how much of an adjustment I should make. I've got a Belgian Tripel & Hefeweizen on deck, which have grain bills on opposite ends of the spectrum.

I can fit 25 lbs of grain at a ratio of 1.25 qts/lb in my 10 gallon cooler mash tun. If I'm doing a 90 minute boil, I need to start with about 7.75 gallons in the kettle to end up with 5.5 gallons of beer after fermentation. 7.75 gallons in my 10 gallon kettle gets pretty close to the rim when boiling, so I can't go much more than that.

You could probably fit a little more grain in your mash tun, but depending on your boil off rate & duration of boil, your kettle could be what limits you. That's something that will be unique to your set-up that you'll need to find out.

jeffdill said:

I'm interested in this thread...subscribed

Slight side question...I have a 48 qt cooler mash tun and a 35qt kettle, how many pounds of grain could I realistically fit?

Click to expand...

CTownBrewer said:

I'm just thinking if I have a 20+ lb grain bill, it's going to be much more difficult to prevent dough balls & get every single grain wet, so sugar extraction will go down. If it's only 8 lbs, I can much more easily mix the grain & strike water to ensure all the grain is saturated & the maximum amount of sugar is extracted.

I just don't know how much of an adjustment I should make. I've got a Belgian Tripel & Hefeweizen on deck, which have grain bills on opposite ends of the spectrum.

Click to expand...

When I have done things that large I have had a friend help with the dough in and we add grain-water-grain-water so we are mixing and stirring as we go. This always seems to help, I also tend to add 1 or 2 more stirs into my mash schedule to reduce hot/cold spots when doing bigger grain bills.

I always get between 78% and 83% efficiency (sometimes higher, but it's abnormal) with my typical 10-13lb grain bills for 5g batches.

When I tried a 10g batch, with some 21lbs of grain, I could only hold so much grain and water in my pot so my mash was thicker, harder to stir because of lack of room and sheer heft of the wet grain. Harder to drain out (I BIAB), etc. I wound up with 63% efficiency.

I'd expect if you can truly scale up everything in the same fashion, like wind up with the same water:grist ratio AND can truly stir it properly and mix it well enough, you should get the same, but I do think there is a point where it sort of slides down a bit.

Expect 10% less is my thought. If you do better, awesome, dilute it down a bit and get more beer from it.

The only reason I can think of that would cause a lower efficiency in bigger grain bills is due to using a lower sparge amount.

What I mean is this- in a 10 pound grain bill, with a boil volume of 7 gallons, you are running 2.8 quarts of water through the grain (plus some for absorption- so call it 3 quarts, or the maximum you should). That would maximum the efficiency.

With a 30 pound grain bill, and a boil volume of 7 gallons, you're putting less than 1 quart of water per pound of grain through the grain (again, add a bit for absorption, so call it 1 quart). That will reduce efficiency.

Still it shouldn't be more than a small amount. I get 72% with small grain bills, and 68-69% with huge grainbills.

CTownBrewer said:

You could probably fit a little more grain in your mash tun, but depending on your boil off rate & duration of boil, your kettle could be what limits you. That's something that will be unique to your set-up that you'll need to find out.

Click to expand...

Could I boil with the first runnings for an hour or so, then add the second runnings and start the normal boil? Is there harm in some of the wort boiling for 2+ hours?

I would think that could work if you're concerned with your end volume of wort. However, you could run into a few issues by doing it this way...

- The longer you boil the more kettle caramelization you could get, possibly even scorching the wort, so I wouldn't boil too long just to reach a certain volume
- Your hop utilization will be off since the hops wouldn't be in contact with the second runnings at all until you add it
- It would be a lot more difficult to predict your gravities & IBUs

Personally, I'm not too concerned about my final volume of beer I end up with. I'd gladly take 5 gallons of great beer over 6 gallons of decent beer.

jeffdill said:

Could I boil with the first runnings for an hour or so, then add the second runnings and boil more if boiloff is my only goal?

Click to expand...