Filling the air space in a cooler

[emoutal]

I have a coleman extreme 52 qt cooler with stainless steel braid as a MLT and for the most part it works great. However, the other day I brewed a mild with only 7 pounds of grain so there was obviously a lot of air space.

I don't normally have a problem, but this time I lost a couple degrees during the mash. I brought it back up with some boiling water, but it was quit a hassle.

I was thinking that I should fill the air space with something. What would people recommend. Is styrofoam food safe at those temps, because that would probably be the easiest method.

 

[TipsyDragon]

if your not already preheat your cooler.

 

[emoutal]

I do preheat.

It has been fine other times when I have more grain. But with less grain it means more air space and less thermal mass.

 

[malkore]

get some of that pink foam insulation, like 1.5" thickness. cut a circle to fit inside the MLT.
cover it with a few layers of aluminum foil (really just to protect the wort from the insulation...no idea how food safe it is).

some people get the spray insulation for windows and doors (so it doesn't expand as much) and fill the lid with that, since the lid isn't insulated..just a hollow plastic disc.

 

[david_42]

You want a piece of closed-cell foam, cut to fit on top of the mash.

Consider doing a thinner mast when you don't have much grain. I have a 48 qt Ice Cube and I never use less than 2 gallons of water, even for a mini-mash.