Fri Jan 11, 2013 10:00 am
After reading through the posts here there is a lot of good information to consider when deciding on a mash tun type or sparge method, but I have a few additional bits of information to consider ... plus my .02 cents.
One of the most common flaws that I see from all grain brews is a lack of body/mouthfeel. I am convinced that this comes from homebrewers often not performing a mash-out step to fully denature the Alpha and Beta amylases. The typical process that, I believe, is at fault for this phenomenon is as follows. Brewers complete there mash and sparge with 170 degree water which will never get the grain bed up to the enzyme denaturing temp of 168. The collected wort sits in a secondary container for often an hour + during the sparge and slowly cools down enabling the various enzymes to continue their work and negating all the brewer's efforts to maintain a 156 degree mash resulting in a highly fermentable, dry, and low bodied beer.
Your particular set-up will determine how the mash-out can be performed. If you have a set-up with enough space to add enough hot water to bring the grain bed up to 168 degrees, then you are golden. From there you simply proceed to the sparge, after a 10-15 minute rest/vorlauf, with 168 -170 degree water. The second option (also they option I use), design your set-up to sparge with your 170 degree water to slightly raise the grain bed temp (ensuring that the grain bed does not drop below mash temps) and collect the wort in a kettle. Once a couple of gallons are collected, low heat can be applied which basically performs the mash-out enzyme denaturing as the wort is being collected. Planning for this mash-out step as you choose your mash tun would be recommended ... at least my me.
Sparge method fly vs batch: You can make good beer either way and it just depends on your preferences and set-up, but it does take a bit more caution on the brewer's part to not screw up while fly sparging. You just need to keep a few things in mind (fly sparge):
1) Make sure to run-off slow as efficiency lowers with faster run-off speeds.
2) As you near your batch volume, be sure to check the gravity of your, well mixed, collected wort to see if continued sparging is even necessary.
3) As you near the end of the sparge, be sure to check the gravity of the run-off as you don't want that to drop below 1.012. Once the gravity drops below 1.010, that is the point when the pH in the mash has risen to undesirable ranges and tannin extraction becomes a problem. (Batch sparging does not have this issue of pH "creep").
Fly sparging does give you better control over your starting gravities. For my fly-sparge process, I consistently get ~82-83% efficiency but calculate my grain bill for a 78% efficiency. This effectively gives me:
1) a little wiggle room in case I screw up somewhere and have a lower efficiency mash/sparge on any particular batch.
2) gets me to the desired surgar content in my collected wort faster (i.e. I have all the sugars I need for an 11 gallon post boil batch by the time I have collected 10 gallons of wort ... quicker to collect 10 gallons of wort than 13+ gallons). Once I have all the necessary gravity point I dilute up to pre-boil volume with filtered water and start the boil. Equation (using just the number after the decimal point (i.e. 1.064 is 64)): Post boil gravity=Gravity of collected wort * Volume of collected wort / post boil volume.
3) Naturally keeps me away from the tannin extraction "danger-zone" as my run-off is usually around 1.020 by the time I have all the needed sugars. (granted I am wasting some grains, but also preventing brew day headaches).
Hope that all makes sense.
Cheers!
Eagle Dude
On Tap: Barrel Fermented Berlinerweisse 3.2%; American Pale Ale 6.3%, Amarillo Blond 5%
Aging: Flander's Red in a 60 gallon Merlot barrel
Fermenting: Robust Porter 6.5%
. The others have no taste. 
BN Army // 13th Mountain Division 
