How to control heat loss in my MLT

I use a generic 48 qt cooler for my mash tun. My heat loss is generally 2-3 deg per hour. But this past weekend I brewed a 1.035, which obviously had much more head room in the MLT and I consiquently lost about 7 deg in 40 min! I've noticed that the hinge for the top is where most of the heat seems to escape. Can I just cover with a blanket and hope for the best, or is there a better method?

I do the blanket thing and it works fine for me. Others on here have cut a piece of styrofoam to fit inside their mash tuns and placed it directly on top of the mash. Seems to me that would work great, but I haven't tried it.

Are you preheating the cooler?

Between preheating the cooler and wrapping it with a blanket you should be able to have reasonable temp stability even with a generic cooler. I personally wouldn't be too concerned about 2-3 degrees in an hour, though I can seeing being upset by 7.

I don't even lose 7F in my sanke MLT with two layers of reflectix.

Big10Seaner said:

Are you preheating the cooler?

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Yeah, I preheat.

NateKerx said:

I personally wouldn't be too concerned about 2-3 degrees in an hour, though I can seeing being upset by 7.

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I'm not concerned about the 2-3, but yeah, the 7 bugged me. Especially since it's a Scottish style, so I need it to be less fermentable.
I have heard of the foam idea, and would like to give that a try. I'm just not too sure on how to fit it, or pull it out without breaking it.

If I were going to do th foam idea, I would affix some stick on velcro on the underside of the cooler lid, and also to the cooler lid shaped cut of rigid core foam board (probably the foiled wrapped stuff).

I think that if you were using 1 or 1.5" foam core you might want to stack 2 or more layers, as the idea here is not only increasing the insulation value of the lid, but also reducing the volume of the container.

With this rig you could attach the lid supplement for smaller beers which tend to lose more heat, and detach the foam and eat the 2-3 degrees for a normal batch

Bobby_M said:

I don't even lose 7F in my sanke MLT with two layers of reflectix.

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Bobby,
Would you please comment on your experience with your mash-tun with the Reflectix insulation. Show a picture if you can so others can learn from what you have done using a keg/mash-tun.

How much temperature do you loose per hour if not heated during that time?