I spent most of yesterday reading up on BIAB techniques, equipment, etc., and this thread has been by far the best primer I've seen. Thanks for the great picks! I'm convinced that as I go AG in the next couple of months, I want to use a BIAB system.
Here's my dilemma, though, and it's about the opposite of C-Rider's: I'd like to be able to brew more than 5 gallons at a time. It seems like for BIAB you need a kettle roughly twice the volume of your final brew volume (after trub loss, evaporation, grain absorption, etc.). For a 10 gallon brew then, it seems like it would make sense to get something like this (82qt SS kettle with steamer insert):
http://www.bayouclassicfryers.com/index.php?l=product_detail&p=203
But what if I only wanted to brew a 5 gallon batch? Would all that extra headspace make it even tougher to keep the mash temp? I've heard of people putting in foam inserts to take up space, but that might be a ton of foam spacers to use. Am I better off going with a 62qt kettle and at least having 7.5 gallon functionality with much less headspace if I were to brew a 5 gallon patch?
Any thoughts?