Efficiency

Kai Troester has this to say on his braukaiser website at http://braukaiser.com/wiki/index.php?ti … Efficiency:

“When measuring volumes on brew day, the temperature based expansion of water should be taken into account and all measured volumes should be corrected such that they represent the volume at room temperature. Since wort is mostly water, what is true for water is also true for wort. At 100 C or 212 F a given amount of water/wort has about 4% more volume than at room temperature. This means that 25 liters or quarts of wort at 100C/212F are actually 24 liters or quarts. This is a difference of 1 liter or quart and fairly significant for precise efficiency calculations. Because it results in more volume than actual, it results in a higher than actual calculated efficiency.”

So, yep, I was right. Without temperature correction, the brewhouse efficiency might be too high by 4%. Okay, I feel like this horse is finally dead.

I think I mentioned earlier that my method for measuring volume does take into account wort expansion. It’s a stick with two scales, one calibrated for room temp, the other for boiling. The scale I use to weigh malt has been checked with a known weight–and with another scale. So, checked and double-checked.

Today I brewed and found a small difference between what my refractometer measured (usual method) and my hydrometer. The latter read 1.050 on the button, while the former read about 12.8 degrees (1.052). Calculating efficiency with the hydrometer reading gives 92%; with the hydrometer it’s 95%.

Not a huge difference, but enough to keep track and maybe shop a new refractometer.

I wish we could have answered more definitively when and where these measurements should be taken in Promash for best accuracy–though when I find myself fixating on this issue I remind myself that it’s just beer, not the amount of fuel needed to reach Mars. On the other hand, it would be nice to know whether it’s 5% ABV or 6%.

I’ll continue to measure the volume and the gravity at flame out–until I hear why I shouldn’t.

I am a little late to the conversation but ProMash has a “Hydro Adjust” feature for temp correction. If you have a 1.050 reading @ 180 degrees it is actually 1.079. It is because the wort is thinner, not because of the expansion. I never considered the 4% expansion in any of my volumes. I was happy if my margin of error was within 4%.

Also you said you used a mathematical formula to create a measuring stick to check your volumes. You may want to double check your stick by actually measuring out gallons of water and adding them to your kettle.

P.S. I am just getting back into brewing after a few years hiatus so take this info for what it may (or may not) be worth. :cheers:

I would never attempt to measure the gravity at anything like 180 degrees. I take gravity readings after chilling (for me, that’s in the 50s); with the refractometer, the temp doesn’t really matter.

The stick has two scales–one at room temp, the other at boiling. And, yes, they jibe with known volumes.

But to update: I’ve brewed three times since my last post and found discrepancies of .4, 1.28, and .9 degrees brix. Using a trusted hydrometer I’ve gotten 92%, 91%, and 91% efficiencies with those three batches.

The plan is to set 91% at my brewhouse efficiency and toss the refractometer.

[quote=“Steverino”]I’ve brewed three times since my last post and found discrepancies of .4, 1.28, and .9 degrees brix. Using a trusted hydrometer I’ve gotten 92%, 91%, and 91% efficiencies with those three batches.

The plan is to set 91% at my brewhouse efficiency and toss the refractometer.[/quote]

Interesting result! And probably considered blasphemous by many folks who love their refractometers! I have always used a hydrometer so I guess I wouldn’t know any better, other than the general advice to ensure your measuring equipment is all calibrated. I’m not sure what the error rates are on each type of equipment but based on the limited data above, it does seem wise to rely on the steady result and ditch the one that’s off by as much as 0.005 SG.

:cheers:

I think the thing about refractometers is that they’re easy to use and a snap to clean up. You don’t have to wait for the wort to chill–just a drop or two on the glass, take the reading, and you’re done. Maybe there are better ones out there, but I’ve always suspected mine–it’s hard to read and not entirely consistent measurement to measurement.

I used (and quit using) my refractometer for the same reasons you are describing. I am going to take mine to the brew shop and trade it for something.

:cheers:

Here is the key fellers.

DIGITAL Refractometer.

Have a good day.

Do you use one? Can you recommend one?

Not sure if this is relevant to your problem, but a few years ago I modified my process to get more consistent, repeatable results with my refractometer. I was taking a sample with an eyedropper, walking into the house (winter brewing in freezing weather) and taking a measurement. Every time I tried to take a second measurement to confirm the results, I got a lower Brix reading. Turns out the problem was the portion of the sample at the end of the eyedropper was seeing enough evaporation as it cooled to change the reading. Now I squeeze out 3-4 drops into the sink immediately before placing some on the refractometer glass. Much better.

[quote=“Steverino”][quote=“ITsPossible”]
DIGITAL Refractometer.
[/quote]

Do you use one? Can you recommend one?[/quote]

Check your PM