recipe and procedure:
8.8lbs 2 row
1.6lbs Caramel 40L
14oz Munich
14oz Victory
9oz chocolate
Hops
1.25oz Northern Brewer-60min
1oz cascade-60 min
1oz cascade-0 min
1oz Saaz-0 mmin
Wyeast 1056
1 oz cascade dry hop 7 days
.5 oz saaz dry hop 7 days
Single infusion med. body batch sparge
Mash in 3.82 gallons at 168/step 156
Drain-sparge 2.07 gal, drain sparge 2.07 gal (15 minutes between)
Grain absorption at 1.42 and .25 dead space
6.25 gallons wort with 1.25 gallon boil off at 60 minutes
(Because we added hot water to raise temp during mash we actually got 6.75 gallons wort, experienced our first boil over but not terrible and still got our 5 gallons of wort)
Total grain bill was 12.2lbs which is why we needed to change tuns as the 5gal was not large enough with the required water to mash, last time we tried something this big the water oozed out when we put on the lid.
We used the same screen and valve for the cooler, no false bottom. Mash was stirred every 15 minutes and temp was checked at the same time, hence the adjustment. Hope all this info helps, I am still thinking the temp variables are to blame.