The other thing I'm thinking of, and sorry for bringing an older thread back from the dead, is that even if you put in cold water (sub 100f) that you'll get a equalization from the residual grain heat. So it's not going to be
that[/] cold. I'm thinking of doing this and just adding another pound of grain for the extra points instead of buying an HLT.
However, I always thought it was sugar/water solubility that was the reason for sparging with 165-170f water. Not to extract anything else, but as described it seems it does. So maybe a cold water sparge may benefit from a 90 min mash to help with complete conversion. Palmer describes how you get some benefit from the extra 30 minutes and could explain the added points. I bet you could correlate that to the extra mash time and sparge temp.
We'll see what happens with my next brew I'll be batch sparging too.