DIY Homebrew Projects  Homebrew How-Tos

Insulate Your Mash Tun with Reflectix

Chris Jensen · July 25


Hitting and maintaining your mash temps is one of the most critical steps to producing a good beer. Unfortunately, metal mash tuns (including keggles) are not particularly good at maintaining temperatures with out an external heat source. So, many brewers choose to insulate their mash tuns to help maintain a consistent temperature throughout your mash schedule.

For the first few years of my current mash tun's life, I used a long sheet of foam rubber with bungee cords. It was cheap, easy, and maintained temps relatively well. It also looked atrocious and was susceptible to heat from my burners on either side.

So, a few months ago I decided to upgrade to Reflectix insulation. Designed properly, I have found that I can hold a temp within a degree or two over the course of an hour, it's easy to take on and off and it looks outstanding. Here's a photo illustration of how to insulate your mash tun using Reflectix.

Here's what you'll need:

  • Reflectix. I recommend a 24-inch by 25-foot roll, which is perfect for a keggle. If your kettle is shorter than 24 inches, use a narrower roll
  • Straight edge (a level works well)
  • Sharpie marker
  • Scissors
  • Hot glue gun

Here's how to do it (see illustrative photos below):

  1. Tightly wrap the Reflectix roll around your kettle 5 times and clamp it on either side of the point at which it begins its 6th layer. If you have fittings in the kettle, wrap the insulation just above those
  2. Carefully (so you don't loosen your wrap) remove the insulation from the kettle. The Reflectix should form a cylinder which can stand independently
  3. Using a straight edge, mark a vertical line where the Reflectix begins making the 6th wrap, then cut down the line to remove the extra insulation. Set that aside, you'll use it for the lid.
  4. At this point, you should have one clamp on either side of the start and end points to the wrap. Gently pull back the edge of the Reflectix on the interior of the cylinder, and apply a liberal amount of hot glue 1/2" - 1" from the edge all the way down the length. You might find it easier to do this by placing the cylinder horizontally
  5. Do the same on the exterior edge of the Reflectix. For good measure, add a few drops of glue at random points between each of the layers within the Reflectix to increase stability and durability
  6. Once dry, slide the cylinder back over your kettle, and pull down to the fittings
  7. With your Sharpie, mark the location of each fitting on the Reflectix. Measure the distance from the top and bottom of each fitting to the bottom of the kettle, and mark those locations on the Reflectix so you can make the appropriate cut-outs
  8. Make a vertical slit through all 5 layers at the horizontal location of each fitting. Then, carefully cut a hole at the actual fitting location through each layer (you'll probably need to do this one by one) so it is large enough to accommodate the fitting
  9. Test your fit by sliding the Reflectix down over the fittings. In order to minimize heat loss, it should fit snugly with little to no exposure on any side
  10. Next, you'll want to insulate your lid, otherwise all the heat will just escape through the top. Begin by outlining the circle that you'll cut to affix to the lid. To do this, I found it easiest to attach a Sharpie to a string the length of my desired radius. I then used that as a compass to draw the circle on the Reflectix
  11. Cut out the circle, then trace it a few more times on your remaining Reflectix to create additional layers. 4 layers are ideal, but you'll need to plan carefully to get this much out of the remaining material. You may need one layer with 2 halves.
  12. If your lid has a handle, cut a slit in the layers to accommodate
  13. Glue the layers one by one onto the lid. Ensure that the lid still fits well on your kettle. If any of the layers is too big, trim to fit

That's it! It's a very easy project if you plan each step carefully. Expect to spend at least an hour on the project.

Mash on!




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