Originally Posted by SCUD_Brew
just pre-heat your tun and set the values to 0 (no thermal loss).....good to go and very accurate this way.
+1 to this. ProMash has been right on for strike temp and mash temp. I generally preheat the water to 175F and transfer to the mash tun for heating and measure the water temperature periodically until it's down to the strike temperature.