This assumes 15% boil off/hr during boil and 0.1gal/lb of loss in grain absorption (after squeeze).
FOR THIS RECIPE
Grain absorption: 1gal
Boil off 90min: 1.5gal
Expected efficiency: 70%
Target fermentor: 5gal
So the volumes needed:
Mash: 6gal
Fly sparge: 1.5gal
Boil: 6.5gal (90min)
Process for BIAB:
-heat 6gal in brewing kettle to 160F with upside down colander on bottom.
-add grains in bag
-heat side pot with 1.5gal of water to 170F.
-after 1hr mash at 150F, take out bag, place different colander on top of brew pot (we fix it with hooks, so it is like a lid on the pot) and place the bag into that colander so it drains into the brew pot
-pour the 180F water over the bag to rinse, then squeeze bag to get your boil volume of 6.5gal
-boil 30 min to boil off pilsner DMS before starting the hop schedule (90min boil time total)
-after 2 week OG was 1.018
-after 4 week OG was 1.018
= Yeast attenuation was only 65%
Priming for bottling using Gyle:
want 2.2 CO2 in 4 gallon:
save 1.3 quarts of unfermented wort (freeze)
add 4.5 gallon to fermenter (excluding what you took for gyle and what was left over in brewing pot)
-cold crash in fridge for 48 hours before bottling
based on:
http://brulosophy.com/2016/02/08/fermentation-temperature-pt-4-lager-yeast-saflager-3470-exbeeriment-results/