I'm wondering how to account for the deadspace in the mash tun. I'm told they have about .3 -.4 gallons space.
So if for instance I want to mash 1 qt/Lb and I have 10 Lbs, do I mash with 10 qts, or do I add in the .3 gallons? I ask becuase I did my first Chaos brew Sat. and lost more temp than the software calculated. Maybe this is the reason or is that something else?
The temp loss may e accounted for by the starting grain temp. It was cold that day and the brewhouse was cold as well, the strike water temp is usually calculated based on an ambient grain temp of 70 degrees. If your grains were in your car or sitting in the brewhouse for any length of time they may have been less then that, thereby soaking up more heat than originally accounted for. Beersmith has a box to change your starting grain temp, not sure if other programs do. I had that problem earlier this winter when I left my grain in my car overnight in freezing temps. In the winter now I keep the grain on the passenger seat floor and blast them with the heater on my way in then I get down to business as soon as possible once I get to the brewhouse.
In addition to accounting for grain temp, boil two gallons of water and add to the empty tun for at least ten minutes before you start your mash. This will condition your mash tun and help it to retain temperature. (Discard the boiling water, it's not part of the mash.)
I did pre-warm it, but I think I only used one gallon.
My house temp (where I kept the grains) was 69 overnight, but I realized I left them next to a window, so they may have been cooler than the 70 I calculated for. Thanks guys!