new all grain brewer here. i was amazed how far off my BS specifc heat estimates were according to the attached spreadsheet. BS estimates my igloo cooler 10 gal tun at .30, i got .17 almost half that amount! i haven't brewed yet with the new numbers but i would imagine this would have to change some things. you might want to check your numbers with it too. (if you don't have MS office it runs fine on the free openoffice). weigh your mash tun, put in however many gallons you want (1-2 gallons is easier/faster to heat, i checked it with 1 gallon and 3 gallons and got the same numbers). it will automatically calulate the weight for the gallons you put in. have your tun at room temp is easiest, put that in for tun temp. you don't need to boil your water, i used mash temps (160F)