BIAB Mash Efficiency Question

This past weekend I brewed my second 5 gal batch of beer using the BIAB method.  I added a recirculating pump which took the water from the bottom of the pot back to the top of the grain bag  I did a batch sparge/rinse at the end of the mash. 

The Method:

Step 1 - dough in with 14 qts of water to 7 pounds of grain - 125 deg/10 min
Step 2 - raise temp to 156 deg/40 min
Step 3 - raise temp to 168/15 min
Step 4 - rinse bag of grains in secondary pot with remainder of water (about 3 gal) 172 deg/45 min

When I measured the SG after the boil (which included 12 oz of Lyle's syrup) - I calculated (using BeerSmith 2) a mash efficiency of 98.6%!

I double checked all measurements because I didn't believe the results.  The problem is that rather than have a Special Bitter, I now have an Extra Special Bitter, and the IBU's fall lower than I wanted.  I need to know whether it is reasonable to change the brewhouse efficiency for future recipes so that I stay in the range of what I am intending to brew.

Suggestions?

That is not unusual for a good biab setup.  They can be extremely efficient, especially if you go to the lengths that you did.  Good show.

If you plan on this same routine, you would want to change your efficiency to be able to get accurate recipes, but  once you set it up there, you will have to maintain the same protocol in future brews. If I had such a good result, I would probably go with 90% for my next starting point, after recalibrating all my measures twice to be sure I was not missing something.

Normally, biab is done with a longer (60-90 min) mash, with less time spent rinsing the grain.  That way you can do the whole thing in a single vessel, rather than having a second one for rinsing (it is not really a sparge when it takes that long).


Keep experimenting

I just want to chime in here--a little late--that this has been my experience now with four BIAB batches.  The efficiencies, which I was told would be lower, are actually much higher than I ever achieved with fly sparging.  The best I could get with that method was 70%.  I've ranged from 85% to 90% every time I have used BIAB. 

I also run the wort through a pump for the entire 75 to 90 minutes, and then rinse with just a 1/2 gallon.  But I found on the last brew day, that rinsing made no difference whatsoever in my OG.  So I'm just going to skip that step.

Given this experience, I'm unclear why everybody doesn't use this method.  It's so much simpler and so much more efficient.  Granted, I prefer 3.25 gallon batches, as I like to brew a lot and I don't drink that much beer!  I could see where a 10 gallon batch would be a problem. But I would think a 5 gallon batch wouldn't be a problem.

"I double checked all measurements because I didn't believe the results.  The problem is that rather than have a Special Bitter, I now have an Extra Special Bitter, and the IBU's fall lower than I wanted.  I need to know whether it is reasonable to change the brewhouse efficiency for future recipes so that I stay in the range of what I am intending to brew."

I usually check the gravity and volume of the wort before boiling, then adjust my numbers in BS to reflect or adjust that pre-boil gravity. It lets me adjust my hops or increase my boil time/add water to get the desired gravity and hopping level going into the fermenter. A refractometer makes it quick and easy, but a hydrometer will work. It only takes a couple of minutes at the computer to make the adjustments.

That has given me pretty good results. Am I missing some important point here? Maybe over-simplifying?

Dan

Great job bcull!  I agree with you about everyone at least trying the BIAB method to see if they like it.  The problem I've seen is it's a close line to telling people how to brew and this hobby is all about finding your way.  *shrug*.

Regarding your efficiencies, that is truly amazing.  My first 10 or so batches used two pots and the dunk sparge method you described.  My efficiencies haven't been as good since I moved to the single pot "no sparge" method, but it works better for me because I'm doing 10 gallon batches and I want cleanup to be as easy as possible.

Cheers!

TK