Calculating Heat Rise from Dough In

[maltoftheearth]

This weekend I am using my 10 gallon igloo cooler as a mash tun. In the past when I used it I never did a dough in at 104 so I just heated water, added it to the cooler to get it to mash temp, then added grain. The heat would drain into the cooler a bit so I would always add about water at about ten degrees above mash temp to get it just right.

Today I always use a dough in at 104 and raise the mash temp from there. Not sure how to calculate the water temp for this addition b/c the igloo cooler can absorb/drain a lot of heat from mash water.

Any suggestions on how to calculate this?


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[gwapogorilla]

I dough in at 104* as well.

I always preheat my mash tun with 2 gallons of boiling water. I put the lid on it and let it set for 10 minutes. I then drain the tun, but leave the amount of water under the false bottom intact.
Then I dough in using .8 of water per lb. of grain. The water temp I use is 99* since the mash tun is so warm. Once I mix in the grains, it comes out to a perfect 104*.

 

[Zepth]

I use this handy calculator. Allows for single infusion, multiple rests, and mash out. I've yet to have any complications from doing exactly as it tells me.