So I brewed a batch of DFH 60 min IPA last night with my newly sewn BIAB. I'm calculating my efficiency and found a discrepency between the pre-boil and post-boil efficiencies. Let me know if you see anything that looks funny
12lbs American 2-rom (double crushed)
0.75lbs Crystal 60L (Double Crushed)
Mash temp 154F for 90min (end temp ~150F), Mash Vol ~8gal.
Pulled the grain bag with squeezing and measured 1.050 OG in 7.2 gal
Post Boil ~5.25gal @ 1.064
2-Row 12 x 38 = 456
Crystal 60L 0.75 x 34 = 25.5 + 456 = 481.5 / 7.2gal = 66.8 ~ 1.067
50 points / 67 points = 74.6% yield
Post Boil extraction:
5.25gal x 64 points = 332 / 481 = 69.1% yield
Both the Pre-boil and post-boil Hydrometer readings were taken with the wort around room temp. I only mixed the mash once during the 90min hold to retain heat. I know the sugars don't evaporate, so I'm guessing it was either my temp was higher than I thought when I measure the post-boil (thermometer read around 70 though), or were a lot lower for the pre-boil reading (taken outside in the cold).
I'm not really upset about the efficiency since I was targeting 1.064 for the postboil OG. Is there another reason why these numbers would be off?