I've been doing BIAB in a cooler using about 4 gallons of water for around 12 pounds of grain on most of my brews. But last night I decided to give a full volume mash a shot, and just do it in my keggle, there was plenty of space. With my cooler, I heat my strike water to 168 degrees, and the grain and cooler almost immediately eat 12 degrees of heat, leaving me at about where I need to mash my IPAs, around 154-146ish for the majority of the mash. So last night I heated my strike water, 7.8 gallons of it to around 168 degrees, then tossed my grain bag in there. The first thing I noticed is that I did NOT lose 10 degrees immediately. One thing I had not accounted for was that I had much more water now, which obviously helped it lose less heat once I doughed in. First mistake. It was a cold night (For Florida) and I figured I'd lose that temperature quickly, but I ended up mashing fairly high for the majority of the 1 hour mash, probably around 160. Anyway the rest of the process was more or less uneventful. My OG worked out to be 1.058 instead of 1.064 the recipe called for, so my efficiency was definitely lower than usual, as I normally exceed what my recipes from the local shop call for. But it was damn easy, with no extra cleanup, no sparge, and was less temperature loss than I expected. I think I may refine this technique in the future, assuming it doesn't make for a terrible beer. I'm interested to see how the high mash temp correlates to mouthfeel and body once this ferments up. While I was mashing and boiling I had plenty of time to read this forum, and there was plenty of information (as usual) on both sides of the spectrum on why you should or shouldn't do it. Think this beer will suck? 
