[quote=“dannyboy58”]Very timely post for me as I plan to do my first BIAB early next week. Crusty, the overview of your brew day was quite helpful and lined up with things I’ve gleaned from Denny and some others in these forums.
Couple questions though… I have a 9 gallon kettle and have been doing full boil extract batches beginning with about 6.6 gallons to get something like 5.25 going into the primary. Should I expect about the same or a little more boil down?
I ordered grains from NB and asked them with a note on my order to double crush the grains. Does anyone have experience with that? Should I expect that they’ll double crush them or no?
Does everyone use something like a false bottom in their kettle to keep the bag off the bottom? This just occurred to me in reading Crusty’s post.[/quote]
Boil off will depend on your kettle set up. A shorter wider kettle will boil off slightly more than a taller thinner kettle. This also depends on what you use to boil, gas or electric & ultmately, how hard you drive the boil. In the past, I boiled fairly hard & would lose 8 litres in an hour with my 32jet Mongolian burner. These days, I boil in an electric urn & my boil is very tame & I typically lose 10% over an hour. With a 29-30 litre pre boil, I lose approximately 3 litres. You can double crush your grains & milling the grain a tad finer is ok with Biab. We don’t need to worry about a stuck sparge. Milling too fine will just result in more trub loss so not too fine. Some guys here in Australia that use round stock pots use a round cake cooling rack to keep their bags off the bottom when heating. Make sure the grid is fine enough that the bag wont slip between the grates in the cooling rack.
As far as sparging goes with Biab, I found it a complete waste of time & an unnecessary step. Sparging is simply rinsing the grains & works well with a traditional 3 vessel set up but not as effective with Biab. Simply sacc resting for 90mins followed by heating to 78degC for the mash out will be more than adequate to release those trapped sugars. When I hoist my grain bag via a pulley system, I squeeze as much wort from the bag as possible & then drop the bag into another vessel & squeeze some more. I then add this back to the urn for boiling.