Thermal Conduction and Cooler Systems

[toddilgen]

I just completed my three tier gravity system by moving up to the ten gallon tun and sparge arm. The bigger tun did not hold a steady temp as effeciently during rest times as the five did and i do preheat them before i mash. Are there any tricks to get it to hold temp. more consistent? Should i increase strike temp.? Lids are on during rest.

 

[brewmadness]

I just got a 10 gallon round cooler to use as a mash tun. I haven't used it yet to see how it holds temp, but I had thought of getting a piece of 2" rigid insulation and cutting it to fit snuggly down in the cooler just above the water level, thus eliminating head space. Maybe others will chime in that have tried this?

 

[najel]

It seems the issue a lot of the time is that the cooler is fairly well insulated at the bottom and sides, but not the top. This is fine if you are trying to keep stuff cold, but when trying to keep stuff warm, you want the top insulated better.
I lose about 3 or 4 degrees over an hour in my rectangular cooler, I believe a lot of that is because the lid is very thing and not insulated at all. Well, I guess there is air in it, but that does not seem to do much.
Some people have sprayed that window insulating foam into their lids, but that is questionable because it doesn't seem to expand well in there. There are a few threads about that on here.
I think what I will try with mine is simply cut a piece of styrofoam to size and glue it to the bottom of the lid, so it fits into the cooler.