Hello out there!
I have been BIAB sparge brewing snice I went AG. I have done about 15 batches and have my process down pretty good. Recently, I upped the ante and started brewing in 2 seperate pots to make 5.5+ gallon batches, as I got tired of putting in all that work for 3-4 gallons when I could do the same work for more volume.
Well, my efficiency has always been 75% pretty much spot on. However, my last 2 brews I got 85% +... unexpectedly. I realized why during my last brew. Since using the 2 brew pots I have been getting higher starting mash temps due to rejigging my process. So, I have been stirring like hell to lower to my target temp. I mean stirring my mash for like 5 minutes straight, hitting my target temp, and lidding it. It must be the stirring that has raised the efficiency so high.
High efficiency is good or bad depending on how you look at it, but this finding is significant for me and I hope it helps other BIAB spargers. Stir your mash like hell, break up all those lumps. Heck, use a whisk!