I have a converted keg (legally obtained) mash tun. I’d like to add some insulation to the tun so that it holds temperature longer and more evenly. I heat my strike water directly in the mash tun, so the insulation either has to be removable or fire proof. Any suggestions?
We are fixing to insulate a 55 gallon SS mash tun. Have you tried plain 'ol water heater insulation? That’s what we were planning on trying.
I put some of the bubble foil wrap on my keg mash tun. Wrapped it around twice and secured it with 3 strips of velcro. So I can remove it if I want to direct fire it or for cleaning.
Holds heat pretty well, but not as good as the cooler I use occasionally
I’ve insulated one of my mash vessels as well as my electric keggle with foam insulation wrap from Home Depot…it’s relatively thin and covered with a heavy duty foil material. A couple of layers does the trick nicely…works like a champ.
using it on the mash vessel was a no-brainer, but I put it around the keggle as an afterthought and saw immediate improvement in both the time it took to come to a boil, and the intensity of the boil.
So I assume it is not flammable?
I don’t know if you can assume that since the Prof said he has an electric kettle.
Ahhh - ooops. I saw that but missed the ball completely!
While the bubble wrap insulation from Home Depot won’t go up in flames, it does melt. I used it for several years while brewing in the Michigan winters, and in time I would forget and light the burners while recirculating the mash and…smell something. It never caught fire, but was unpleasent to smell.
I just used masking tape to hold it to the keg, and in time I would punch a termometer through it into the thermo-probe thingy on the kettle. This worked to also keep it in place.
Right. You definitely wouldn’t want to use this stuff where a burner is involved. My home made keggle uses a high wattage, 220V element inside the vessel. That also allowed me to put some insulating material on the bottom as well (another afterthought that made a measurable difference).
I have a 10-gal brewpot that I use for my mash tun. After the infusion (not directly heated), I wrap an old camping sleeping pad around it and keep it in place with bungee cords. I lose barely a degree over the course of an hour.
Isn’t there a fiberglass insulation with a metal/foil outer layer? Find that and some foil aircraft tape and that might work.
I use a jumbo silver bubble insulated car windshield sun blocker, modified with velcro.
Best to remove when direct firing the mash tun, which I rarely do.
I use direct fire kind of… I have a 1/4" steel plate that sits between my mT and the burner, this has help to keep from scorching the wort and I don’t worry so much about the insulation catching fire. I went to HD and picked up a roll of waterheater insullation.
For whatever reason I do not insulate my SS MashTun.
Just a lid and even in a New England winter I do not lose more that 1-3f over a 90 minute period.
So…
Is the insulation really needed?
Alot depends on the pot…I use a 20gal ss. The wall thickness is less than a keg and so depending on the temp in the garage?even with the insulation my temps will drop 5+ degrees in an hr.
X2 on the camping pad insulation. I secure it with a couple quick clamps or a tie down. 10 gallon batches hold temp with in a degree at 60 mins. 5 gallon batches lose a few degrees.
i had planned on making essentially a gigantic tea cozy out of something so that i could just slip it on and off easily. what i haven’t figured out yet is what to make it out of. luckily i have an industrial sewing machine for making boat sails, so i have some options. 
I use 2 layers of the foam camping pad insulation, held on with bunge cords. The left over parts are big enough to put over the lid and add extra insulation there.
Wow… alot of responses. 
I’m in the planning stages of building a Brutus 10 system, so I’ll be swithing from a cooler with a braid to a recirculating system when the Brutus 10 is finished. It’s going to take me a few months to get it all together…meaning the whole system.
I found some neat stuff at Lowe’s in the flooring / carpet section. It’s a pack of interlocking grey squares of ¾” rigid foam used in exercise areas. Interlock together, cut to the circumference of your tun and duct tape the seams to keep it together. You can also but seam and glue with crazy glue- it takes a few tubes. I also put a strip of aluminum sticky tape around the bottom first because I use a propane burner.