Brew in a Bag Efficiency

I did my second AG batch yesterday, making some modifications to the method I used in the first.
The first time, I went with 4 gallons of water, and then did a sparge with an additional 2.
I ended up with about 3 gallons of wort when all was said and done.

I read about more people having success just going with the full amount at mash in, and letting ‘nature’ take care of the rest - so I started last night off with 6.2 gallons of water at mash in for an hour at 153 degrees, and then pulled the bag out drain.
I added what drained off in my barrel back to the wort, and continued my boil. When I finished that one, I (again) had just over 3 gallons.

My OG at the start of the boil was 1.010, and when it was done, I had the right OG of 1.050 (Stout)…

So I have to figure out the best way adjust in order to get a full 5 gallons at the end of my boil with as close to my target OG as possible.

By the way… I’m using a 7.5 gallon kettle for my Brew in a Bag.

A 7.5-gal kettle is too small to do a no-sparge and end up with five gallons post-boil. Take a regular recipe, then mash with as much water as you can in the kettle, pull the grain, and sparge with the remaining water to top up the kettle to 6.5 gallons for the boil.

do a google search for “BIAB calculator”. There’s a nice one someone made to be able to calculate the max amt. of water you can mash with based on your capacity and lbs of grain. that way you can use the most possible for your mash. Could be your boiloff is more than you thought.

It sounds like you’re limited due to your kettle size so you’ll need to do a sparge. I personally do small BIAB on the stove top and like adding a tad more grain and doing no sparge but it seems that is out of the question for you. As for your pre-boil gravity did you adjust that for temp? Just curious because that is crazy low.

+1 - If you’re an iPhone user, theres a nice app out there for measuring the max amount of water your kettle will hold. Its free.