For this brew method I used an 8.5 US gal. pot with a false bottom suspended 3 inches above the source of the heat. I filled the pot with approximately 5.5 gal. of cold water and brought to a temperature of 130 degrees F. I then filled the bag with the grains (see recipe) and stirred until temperature stabilized at 128 degrees. This temperature was held for 20 minutes.
The mash was heated to 156 degrees over 15 minutes. It was held at this temperature for 1 hour. The mash was then heated to 170 degrees over 22 minutes. Finally, the bag was raised out of the pot and rinsed with 170 degree water to 6 3/4 gals.
It took over an hour to raise the wort to boiling. In the process the wort was reduced to 6 gallons before the bittering hops were added. The wort was boiled for 45 minutes and the aroma hops were added. By this time there was just less than 5 gals. in the pot, which was topped with boiled water to bring it to 5 1/4 gals.
The wort was cooled quickly to 64 deg. F. using a reverse-flow cooler. After aeration the yeast was pitched. The SG was measured at 1.059 at 64 deg. F., resulting in a mash efficiency of 86%!
A note on the recirculating pump:
A pump was used at the outset to take the wort from the bottom of the pot and bring it to the top of the grains. While the outflow tube was submerged in the mash, a foam developed which led me to believe that hot-side aeration was occurring. I dismantled the pump set-up at this point and relied on frequent stirring instead.
Beer Profile After Adjusting for Efficiency
The profile after adjusting for the measured efficiency of the method is as follows:
Bitterness 39.1 IBU
Colour 11.2 SRM
Est Alcohol by Volume 5.5%
This is wonderfully close to the specs for Worthington White Shield!
The batch is now fermenting at 65 deg F. in the primary fermenter.