What is the formula to calculate the temp of the sparge water needed after the 1st runnings have been drained from the mash tun so that the sparge temp is 168? I'm familiar with the strike water temp formula -
Strike Water Temperature Tw = (.2/r)(T2 - T1) + T2
r = The ratio of water to grain in quarts per pound.
T1 = The initial temperature (¡F) of the mash.
T2 = The target temperature (¡F) of the mash.
Tw = The actual temperature (¡F) of the infusion water.
Last batch, I measured the temp of the grain in my mash tun after mashing out and draining the first runnings as 161 degrees. I wanted to sparge with water hot enough to raise the temp to 168 and guesstimated 176 degrees. It got me close (164ish) and fortunately below 168, but now I'm curious if there's a formula that will relieve me of guessing.