Efficiency Questions

[Nola_Brew]

How do you guys calculate batch efficiency? I follow the instructions and enter what is called for but my numbers seem to be off. My brewhouse efficiency rarely gets over 70.
Conversion efficiency on my last batch was 101. how can it be over 100?
* I take the gravity once mash is complete and use total strike volume. Last batch the gravity was 1.045 and used 6 gallons strike water.
*Pre boil efficiency was 86%>>preboil gravity would be the same as mash complete gravity? I then measure the wort in the kettle which was 5.5 gallons.
* Ending Kettle>> post boil gravity was 1.059, I then measure the volume in the kettle, which was 4.6 gallons. 91%
* Brewhouse>> post boil gravity then fermentor volume which is 3 gallons. 69%.

I mill my own grain and the setting is .030-.031.

Do these numbers seem right?

 

[J A]

* Ending Kettle>> post boil gravity was 1.059, I then measure the volume in the kettle, which was 4.6 gallons. 91%
* Brewhouse>> post boil gravity then fermentor volume which is 3 gallons. 69%.

Where did the other 1.6 gallons go? Hops can account for up to a pint or so and if you leave the break material out of the fermenter that can be as much as a gallon. Over a gallon and a half seems like a lot of wort is going somewhere other than the fermenter.

 

[Nola_Brew]

Where did the other 1.6 gallons go? Hops can account for up to a pint or so and if you leave the break material out of the fermenter that can be as much as a gallon. Over a gallon and a half seems like a lot of wort is going somewhere other than the fermenter.

boil off was approx. .9 gallon so that accounted for part of the 1.6 gal- the rest was trub and excess wort. Normally I only have about a half gallon or less of wort/trub left but the last two brews it was very humid and my boil off was less than expected. My fault for not accounting for that.

 

[J A]

boil off was approx. .9 gallon so that accounted for part of the 1.6 gal- the rest was trub and excess wort. Normally I only have about a half gallon or less of wort/trub left but the last two brews it was very humid and my boil off was less than expected. My fault for not accounting for that.

Your boil off accounts for going from 5.5 to 4.6 and then the 1.6 loss to get to the 3 gallons. Of that you probably lost a half gallon to hops and break material. Seems to me that you had somewhere around a gallon of extra usable wort. If you could have put in a fermenter but didn't, it shouldn't go against your efficiency.
Your batch size into the fermenter is 3 gallons. Starting from there and working backwards, accounting for hops, break, boil-off, maybe you could have started with less wort to begin with (and less grain to get the wort you need).
If you're getting 90 percent kettle efficiency and tossing wort out, I'd get a bigger fermenter.

 

[TheZel66]

J_A is right... if you dump "extra" volume after the boil, you losing gravity points in the lost volume; hence a lower efficiency.

 

[Nola_Brew]

Lately, from batch to batch my boil off varies. Sometimes it's right at 1 gallon, then under a gallon up to 1.2 gallons.
the batch before this one I used 5.5 gallons of strike water and I overshot my OG- so I added a half gallon more and it was too much. Same batch size just a different recipe.
Next batch I'll go with 5.5 gallons and see what happens.
I use priceless brewing calculator but don't really care for it since they made changes. So I also use a BIAB calculator and both come up with different strike water volumes.

 

[J A]

As long as you know you have enough capacity in your mash tun (or pot) for your preferred mash thickness, you can use the Mash Calculator in the Tools tab. I've used it exclusively since I got my bigger pot and I don't have to worry about holding enough water during rests and mash-out.
The way I've had best success is to really get a handle on my grain absorption rate and add the absorption volume from my total desired pre-boil volume to get total volume of mash and sparge. Then I calculate mash/strike water volume and temp at 1.25 to 1.5 quarts per lb, calculate mash out volume (boiling water), add those up and make up the difference in sparge water to get to my total volume of water needed.
That still leaves variables in boil-off, but at least you can top up as needed if absolutely necessary (use the Dilution and Boiloff Calculator in the Tools tab).
After a few brews of honing in on my mash efficiency, I can now hit my OG within a very small margin of error as long as my post boil volume is pretty close and by making sure that I'm boiling vigorously the whole time, I can get a good, predictable boil-off.

Best of luck with it!