General Category > Extract/Partial Mash Brewing

Partial Mash Extract Efficiency & Brewhouse Efficiency

**bbump22**:

I have moved on from Extract brewing into Partial Mash brewing and have done several batches now. The first few, I didn't measure my pre-boil gravity as I was using recipes from BYO and it didn't mention anything about pre-boil gravity...I would still hit the Target OG within a few points. Recently, I have been using the trial version of Beersmith to generate my own recipes. The first batch I brewed, I successfuly hit the target OG beersmith estimated assuming the default brewhouse efficiency of 75%...honestly, I think I just got lucky.

On my next batch, I generated a recipe in the same manner (assuming 75% Brewhouse Efficiency), but missed my target OG by about 12 points...After entering in my pre-boil gravity, pre-boil volume, batch volume and actual OG measurements, beersmiith spit out a brewhouse efficiency of 52%...When I did the calculations by hand, I calculated an Extract Efficiency of 74% and Brewhouse efficiency of 68%. So my question is why would Beersmith give me an efficiency % so much lower than what I calculated by hand if I used the same numbers I plugged into Beersmith? I am sure it's probably something I am overlooking, but I can't quite figure it out. I've spent the last 2 days at work searching the forum's but couldn't find anything that gave me a clear reason as to why there would be such a variance.

Below is the grain bill, measurements, and calculations I generated on my own...If one of you experts could help me out so I can get better brewhouse efficiency allowing me to use beersmith to generate a recipe I would be very greatful!

Target OG based on 75% brewhouse efficiency 1.065

Actual Original Gravity 1.053

Est. FG 1.013 - 1.018

Grain Bill: Lbs

US 2-Row 4.5

Crystal 60L 1.5

Carapils 0.5

Rye 0.75

Liquid Malt Extract 2.5

Extra Light Dry Extract 1 (Added for the last 15 minutes of the Boil)

Calculate Estimated Original Gravity

Grain Malt PPG Malt Lbs Total Available Gravity Points

US 2-Row 37 4.5 166.5

Crystal 60L 34 1.5 51

Carapils 33 0.5 16.5

Rye 29 0.75 21.75

Liquid Malt Extract 36 2.5 90

Extra Light Dry Extract 44 1 44

10.75 389.75

Original Gravity Calculation (SGP) assuming 75% Brewhouse Efficiency

=((4.5*37*0.75)/5) + ((1.5*34*0.75)/5) + ((0.5*33*0.75)/5) + ((0.75*29*0.75)/5) + ((2.5*36*1)/5) + ((1*44*1)/5)

65.1625

SGP = 1.065

Caclulate Extract Efficiency

TGP (Total Available Gravity Points)

Grain Malt PPG Malt Lbs Total Available Gravity Points

US 2-Row 37 4.5 166.5

Crystal 60L 34 1.5 51

Carapils 33 0.5 16.5

Rye 29 0.75 21.75

Liquid Malt Extract 36 2.5 90

9.75 345.75

Maximum Specific Gravity

=TGP/Collected Volume in Gallons

=(345.75/3.5) 98.78571429 1.099

Extract Efficiency (EE) 74%

=(Measured SG/Maximum Specific Gravity in Points) * 100

=(73/99)*100 0.737373737

Calculate Brewhouse Efficiency

Grain Malt PPG Malt Lbs Total Available Gravity Points

US 2-Row 37 4.5 166.5

Crystal 60L 34 1.5 51

Carapils 33 0.5 16.5

Rye 29 0.75 21.75

Liquid Malt Extract 36 2.5 90

Extra Light Dry Extract 44 1 44

10.75 389.75

Maximum Specific Gravity

=TGP/Collected Volume in Gallons

=(385.75/5) 77.95 1.078

Brewhouse Efficiency 68%

=(Measured SG/Maximum Specific Gravity in Points) * 100

=(53/78)*100 0.679487179

So that's what I did to figure out Extract Efficiency and Brewhouse efficiency. I mainly want to know how to improve efficiency or at least make it consistent so that I can develop recipes and hit my target OG or at least within a few points. Again, thanks for any help you can offer!

**tygo**:

I'm having a little trouble following your calculations. What was the volume you collected from the partial mash and what was your boil volume?

**hokerer**:

--- Quote from: tygo on March 09, 2010, 07:46:24 PM ---I'm having a little trouble following your calculations. What was the volume you collected from the partial mash and what was your boil volume?

--- End quote ---

Yeah, did you actually measure your volumes? It looks like you used 5 gallons in some of your calculations but did you actually measure it? True volumes are critical to calculating efficiency.

**bbump22**:

Sorry fellas, I should have provided more background info...but yea, i did measure my volume...I had collected 3.5 gallons at pre-boil. After a 60 minute boil, I had 3 gallons remaining in my kettle at which point I added 2 gallons of bottled water to the fermenter, the added the remaining 3 gallons to the fermenter bringing the total batch volume up to 5 gallons.

Also, I mashed with 10 quarts for 60 minutes with a step temp at 154, losing 2 degrees over the course of the mash. Then I batch sparged with 7 quarts with a step temp of 165. (Added water at 186 and then stirred gently and let it sit for another 15 before draining).

I calibrated my hydrometer and thermometer and used measurements on my kettle to measure the pre-boil volume. I took a sample directly from the kettle after incorporating the 2.5 # of LME and adjusted my hydrometer reading for temperature.

Let me know if you need any other background info and thanks for looking into this with me.

**a10t2**:

When calculating your conversion efficiency, use only the grains, not the extract. Otherwise you'll get a different result every time the proportion of extract changes. I'm guessing that's why Beersmith is giving you different numbers.

Since you collected 3.5 gal at 1.073, that's 255.5 point-gal. Factoring out the extract:

(255.5 - (90 + 44))/(389.75 - (90 + 44)) = 0.475, about 48% efficiency. The discrepancy is probably due to slightly different potential extract figures.

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