Brewhouse efficiency

[slackerlack]

I need some help figuring out my brewhouse efficiency. I used the calculator at brewersfriend.com, but I have mixed results. Should I be entering my pre-boil volume and pre-boil gravity or post-boil volume and post-boil gravity?

Grain bill:
9 lbs 6 oz (9.38 lbs) - Muntons Maris Otter Pale Ale Malt
15 oz (0.94 lbs) - American Carapils/Dextrine
5 oz (0.31 lbs) - American Black Patent

6.5 gallons pre-boil
1.046 pre-boil gravity

4.5 gallons post boil
1.052 post-boil gravity

 

[hamiltont]

Did you adjust for the temperature when you took the gravity readings?

 

[hamiltont]

Your post boil gravity should have been around 1.066 based on the numbers provided. Something is amiss...

 

[je52rm]

just over 66% efficiency if my math is correct

actually i figured that for 5 gallons accidentally. For 4.5 gallons its around 59% efficiency

 

[slackerlack]

Yes. Those are my readings after temperature adjustments.

 

[chickypad]

Your post boil gravity should have been around 1.066 based on the numbers provided. Something is amiss...

hamiltont is right, one of those readings must be off (edit: or your volume measurements are off)
6.5 x 46 = 299 gravity pts
299 / 4.5 gal = 66, or 1.066 post boil

I get about 78% efficiency if that's the correct one

 

[hamiltont]

I get about 78% efficiency if that's the correct one

77.68% to be exact... Based on the mash tun efficiency A.K.A. Preboil.

 

[hamiltont]

5.5 gallons at the post boil would get you into the 1.054 range???

 

[chickypad]

Correct.
oops, thought you were the OP for a second!

so even with cooling issues wouldn't be that off, that's like 20% off

 

[slackerlack]

Unfortunately, I forgot to measure the post boil volume. So that number I gave you is actually what made it to the fermenter.

 

[je52rm]

Efficiency =

(OG - 1) x gallons water / lbs. grain
(grain gravity - 1)

 

[hamiltont]

Unfortunately, I forgot to measure the post boil volume. So that number I gave you is actually what made it to the fermenter.

Are you using a bucket? I found a couple of mine were off by up to 1/2 gallon based on their markings on the side. That coupled with what was left in the BK could get you to the 5.5 gallons post boil?? Cheers!!!

 

[slackerlack]

No. It went straight into my glass carboy. I have markings on the carboy that I measured a while ago. I think what was left in the chiller and the brew kettle was probably about a half gallon or more.