Up until my last brew (10x all grain IPA brews), I have only used single-run batch sparges (mash-out->drain->add hot water->wait->drain), and through experience have been able to dial-in my sparge water temperature. (alternately, by now knowing my mash tun heat loss, can use the Mash Calculator to calculate varying strike water vs grain volumes) My latest brew will hopefully become a barley wine and is my first *higher* gravity beer (OG = 1.086), which is indirectly the cause of some of the difficulty I had while brewing yesterday evening. Due to limited mash tun space (~30l. total volume), I decided on a 2:1 H2O-grain ratio and 2 batch sparges to achieve my goal of ~20l. of wort @1.085-1.090 SG. 9.2kg of grain + 18.4l. strike water = mash tun @ just under capacity + mash temp @ 67°C (so far so good!) 1st sparge w/ 9.2l. of boiling water = mash tun @ capacity + sparge temp @ 73°C (bit low, but acceptable. Sparge water hotter than 100°C isn't possible, and more than 9.2l. won't fit in my mash tun) ...now comes problem... 2nd sparge w/ 9.2l. of H2O @ 85°C = mash tun @ just under capacity + sparge temp @ 74°C!! I would like to have had a sparge temp closer to 78-80°C, but had no way of calculating the temperature for 9.2l. of sparge water ahead of time. The Mash and Infusion Calculators here only calculate Xl. of H2O @ 100°C, not Xl. of H2O @ Y°C, where X is variable but pre-defined. I probably just missed it while searching, but does anyone know of a way to calculate the temperature of X amount of water needed to raise Y amount of mash(grain+water) Z degrees? e.g. I had 9.2kg grain + 13l. H2O (absorbed in the grain, of course) in my mash tun @ 73°C, and needed to add 9.2l. H2O to raise the temp to 78°C. What temperature should the 2nd 9.2l. H2O have been? PS, the good news is...I ended up with 23l. of wort (actually recovered more than expected) @ an SG of 1.086, so I am pretty stoked that everything worked out regardless of temp, and I even achieved my best brew house efficiency to date.