Insulating my Mash Tun

My setup is a single tier, 2 pump Brutus style system with HLT, Mash and Boil keggles with 3 wok burners (2x175,000 btu and 1x150,000 btu).

I've been trying to find a good way to insulate my mash tun in order to maintain my mash temp and not have to apply heat as often. I have tried reflectix and am now using armaflex. Armaflex is a great insulator and will maintain temp without having to apply any heat once I hit mash temp. The problem is when I have to apply heat to the mash tun. I have taped off the bottom of the armaflex (or reflectix when I used it) with silver tape (and the vent holes) and put sheet metal on the stand around the keggle, but when I apply even a small flame, hot air flows around the outside of the keggle and up the sides deforming the armaflex (or reflectix).

Is there a another material that would be a good insulator AND be impervious to the heat? Thanks for the suggestions folks!

David

Rock wool or mineral wool insulation is completely fire proof, and water proof.
I wrapped mine in 1" rock wool, then wrapped that in SS sheetmetal. Works pretty good, but I still use HERMS to maintain the temp.
Keggles are not good at retaining heat.

Thanks acidrain. After I posted this I found a long thread that Bobby M. started a few years ago where he encapsulated mineral wool in sheet metal and sealed it, much like your system. I would think that would be a pretty good project, especially with 2 valves and a thermometer. I'll bet your ss was fun to work with! He doesn't remove his. Do you know what the R value of the rock wool/mineral wool is?

In that post, Bobby talks about either encapsulating in sheet metal or a welding blanket. I think I have a thick piece of fiberglass blanket insulation around somewhere, so I could pick up a welding blanket (Harbor Freight has em for $20). I'm assuming that the fiberglass blanket won't burn.

Anyway, appreciate any other suggestions/ideas.

The fiberglass blanket won't burn, but it does scorch and turn black a bit. That is where I started... I was trying to wrap fiberglass insulation with a fire proof blanket... it didn't work.
Not sure about the r value of the rock wool, and I didn't seal the ss to the keggle. The flame will actually go up between the keggle and the outer shell, but no problem. It doesn't hurt a thing.

Did you wrap the fiberglass blanket in a welder's blanket? When you said it didn't work, did you mean it didn't insulate adequately or it was hard to pull tight around the keggle or what?

I found my fiberglass blanket. Forgot how much I hate working with fiberglass. Geez, I'm still itching.

Do you have some pics of your current setup? Thanks for the info!

I tried to cut the fiberglass blanket. It was one of the tan ones you can get at Harbor Freight.
Once the hems were cut, it just unraveled. I tried to sew hems in it, but it just pulled and unraveled. It was a nightmare.
I don't have current pics, but I will get some when I get home.

Hmmm. I think I have a different form of fiberglass than you had. I'm attaching a pic. It's 1" thick. I'm wondering if I can cut/sew/tape a welding blanket?