Without a herms setup whats the best way of raising the mash out temp of a DP recipe. My gut reaction is to flood the mash with a calculated volume of warmer Liquor to reach 77c
as i fly sparge i just raise my sparge liquor to between 80 and 85'c then run a bit of it into the tun while recirculating... it doesn't quite get the mash up to 76/77'c at first, but over the course of the sparge it does
i'm not sure if that's good enough but it seems to work for me and only ever had sparging problems once.
beersmith tells me that if you've got 5kg of grain in 12.5L of water at 65'c, you'd need 4.62L of boiling water to raise it to 76'c.. of course you'd need to mix it and have to let the grain rest a bit longer before recirculating and sparging so that you get clear runnings.
I was thinking along the lines of using beersmith and 90c liquor to thin the thicker Mash and let it sit for the half hour The DP recipe calls for. Bugger it im going to give that a go