I have a pretty typical converted keg mash tun. Over the course of a sixty minute mash it loses 8-10º F. My previous mash tun, a converted cooler would only drop a few degrees and I would like to be able to maintain a consistent temperature. Instead of direct-firing, running the pump, wasting propane, overshooting the temperature and potentially scorching the wort, I want to insulate the tun.


  • The insulation should be able to take the heat of a burner
  • It should be easy to clean
  • The temperature of my mash should only drop a few degrees in an hour

How can I better maintain my mash temperature?


Mash Tun

  • Dean do you recirc during the entire mash? I am building a tun like this soon and was going to do a direct fired set up with pump. I wonder what the heat loss is with a small flame and recirc?
    – brewchez
    Commented Mar 5, 2010 at 12:28
  • No, only when heating. I'd rather save the propane. Commented Mar 5, 2010 at 13:35

2 Answers 2


I also use a converted keg for my mash-tun and swear by Reflectix foil coated bubble insulation. This stuff comes in rolls from the big box hardware stores, isn't too expensive and the 24" roll is exactly the right width to be wrapped around the keg multiple times.

I cut slits in it to account for the thermometers and valves and also have a couple of disks of it to go over the lid.

Best of all, I can quite easily remove it to clean the mash tun and it will take a little bit of heat if you direct fire, although it will melt at the bottom if you apply too much heat. Hopefully by insulating, you won't need to apply much if any heat during a 60 minute mash. One roll is usually enough to insulate two kegs so I replace mine about once a year once the holes start to get over-enlarged or I apply too much heat to the bottom.

  • I tried some of this and it started to melt & curl when I applied heat. Granted, I rested it on the grill so it was in direct contact with very hot metal. Commented Feb 15, 2010 at 17:51
  • @Dean, yes this certainly seems to happen but wrap my keg above the skirt so I have about 3 inches of clearance. despite this if I only heat gently it seems to hold on and not spread beyond the lower inch or so although I did have one catch fire once... but that's another story. Commented Feb 15, 2010 at 22:38

You can get a whole bunch of armaflex and wrap it around the mash tun.


I think the stuff looks cool to and plan I using it for my hot liquor tank.

  • 1
    Lame: "Not available in your currently localized store." Commented Feb 17, 2010 at 15:57

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