Comparison of mash tun insulation methods

[applescrap]

I just picked up a new Brewer's Edge Mash & Boil (No, I haven't actually brewed with it yet), but since I knew I'd need some form of insulation, I experimented with a few different kinds of insulation. Even though I used the Brewer's Edge as the test bed, the results should apply to any mash tun / electric kettle.

The quick and dirty results are the following from best to worst, out of the methods I tried:

1. Stock
2. Cotton based water heater insulation
3. 3 layers of Reflectix
4. Sleeping bag

Yes, the least high tech, ended up being the best.
Here is a graph of temps through a simulated mash range (water only).

If you want the full run down and more graphs and info, check out the post:
http://fermware.com/mash-tun-insulation-comparisons/

Hah, cool. I enjoyed this very much. I really appreciate the actual data. I've had discussions on this before and do enjoy them but I think this is the first time I've actually seen data. I saw a picture once of a guy who used a big old winter coat. Well I happen to have an old huge double extra large down jacket. And it keeps I think about three degrees as you found with sleeping bag. 155 to 152. Test after test showing it doesn't matter I'm dwindling in caring. Ultimately using a cooler and a boil vessel seem like a good idea if you really want better control and or recirculation. Lined cardboard box over sleeping bag? plastic Bag over sleeping bag?

 

[hausofstrauss]

I just made a cylinder out of reflectix a couple inches wider than the keggle, taped it with aluminum foil tape, and then cut out a circle for the top from reflectix and taped it to the cylinder.

I have the keggle setting on some pink styrofoam building insulation.

I mash in, then put the reflectix cone on top of the keggle.

Interesting approach and I think a good one based on some of my current thoughts. I might try to whip one up and make that my last set of addendum tests.

 

[yags]

I usually check it at the top of the grain, stir the grain and then check it again.

 

[hausofstrauss]

Looking at the photos in your blog post, it looks like you wrapped the reflectix tightly around your kettle, with no air space.

From what I've read, that's the exact wrong way to install reflectix.

Beertastic,
Can you describe your exact method? Gap distance, layer count, etc. I'm trying to make sure I replicate the insulation path as best as possible, or be able to understand any differences.

 

[yags]

There wasn't much science to my design. The reflectix I bought was 24 inches tall, so that was the basis of my design.

Cut a square 2 ft x 2 ft.
From that square, cut a circle that is 2 ft in diameter. That is the top.

The circumference around the top is pi*d or 2*pi*r, so 24 * 3.14159 = 75.39 in, or roughly 75 and 3/8.
Roll the side piece into a cylinder.
Tape up the vertical seam.

Put the top on the cylinder. Use some mashing tape to help hold the shape.
Seal the top with foil tape.
I ran the tape around the top of the cylinder all the way around about half the width of the tape. (Let half the tape exposed)
Then cut vertical slits in the tape every couple of inches and fold the tape over to the top piece.
Work you way all the way around until the top is sealed.

Originally for the base, I did the same thing. A 2 foot circle and sides that were about 2 inches high. I would set the keggle in the base piece, then slid the top over and tuck it into the side of the base piece. However, I found I kept damaging the base piece. Also, this does not give an air gap of the bottom.

Now I just have a piece of pink styrofoam insulation board from home depot for my base.

It is important to have some type of thermal barrier for the base; styrofoam or reflectix. Heat will be lost from keggle contact to the ground or whatever you have it in contact with.

It is just tall enough to give you an inch or so airgap on the top. If you wanted to wrap a second layer of insulation around the first, I would do it a few inches lower so that the overall height is increase a couple of inches.

But for starters, I would recommend just doing a single layer and then adding a second layer at a later time if you think you need it.

 

[TennBrewer]

Where was it 152F? At the top of the grain, in the center, at the bottom? I have a Stout 20G mash tun and I find that my temps vary based on where I am measuring UNLESS I do a recirculation with heat and a PID temp controller. I also find that my temps vary greatly depending on the ambient temperature. For instance, in the winter my mash tun temps drop significantly more compared to the summer months.

I start with the probe in the center, then slowly move it around and up and down. After mashing in with a good stir, the temps are pretty much equal all around, only varying by 0.1 or 0.2 degrees which is close enough for me.

 

[SlitheryDee]

My first mash I used a single layer of reflectix and it seemed to make so little difference I went without insulation at all while simply applying heat occasionally on my next try. On my next one I think I'm going to go with a sleeping bag given how easy and effective that appears to be. It would be nice to not have to turn the flame on during the mash.

 

[yags]

How are you sealing off the mash tun if you are applying heat from a burner?

If you don't have the bottom of the tun insulated, then heat is escaping from the bottom. If you have the tun setting on a burner stand, you have good thermal conductivity path from the mash tun to the burner stand to lose heat.

The reflectix is only good if you are making a big bubble around the entire tun. If you have an exposed base or even worse, uninsulated contact with the tun to a metal heat sink, you will lose any benefits of the reflectix.

 

[Stepp2]

After looking at the data I tried the sleepingbag technique. I wrapped two 15 gal boilermakers with no sparge volumes (12.5#'s grain/9g of H2O) They only dropped temp 1 degree. That's close enough for me. Thanks for the work you put into your experiment.

 

[SlitheryDee]

How are you sealing off the mash tun if you are applying heat from a burner?

If you don't have the bottom of the tun insulated, then heat is escaping from the bottom. If you have the tun setting on a burner stand, you have good thermal conductivity path from the mash tun to the burner stand to lose heat.

The reflectix is only good if you are making a big bubble around the entire tun. If you have an exposed base or even worse, uninsulated contact with the tun to a metal heat sink, you will lose any benefits of the reflectix.

Yeah I basically did it all wrong lol. The reflectix was tight to the mash tun and the bottom was uninsulated sitting on the burner. Fashioning an insulating jacket out of reflectix just seems like more work than bungee strapping an old sleeping bag around it though. It's just an added benefit that the sleeping bag is as effective as it is.

 

[anchornm]

Yeah I basically did it all wrong lol. The reflectix was tight to the mash tun and the bottom was uninsulated sitting on the burner. Fashioning an insulating jacket out of reflectix just seems like more work than bungee strapping an old sleeping bag around it though. It's just an added benefit that the sleeping bag is as effective as it is.

If you are worried about losing heat to the heating element, why don't you just turn on the element?

 

[hausofstrauss]

Looking at the photos in your blog post, it looks like you wrapped the reflectix tightly around your kettle, with no air space.

From what I've read, that's the exact wrong way to install reflectix.

Ok, so I finally got around to organizing the data for additional experiments with the Reflectix insulation. It has been suggested that the optimal method when using Reflectix insulation is to have an air gap of about 2 cm (3 layers). I also added another method, where I created a "dome". It was close, but I would consider all methods a statistical tie. It appears that you don't really need to try that hard with Reflectix.
Here is a graph of temps through a simulated mash range (water only). All 3 methods lose less than a 1 degree in the first 15 minutes.

If you want the full run down and more graphs and info, check out the post:
http://fermware.com/mash-tun-insulation-comparisons-part-ii/

 

[augiedoggy]

It would be awesome to try this same experiment but with a constant mash re-circulation running as that causes temps to drop more rapidly.

But why?

Anyone recirculating would also be reheating to maintain or step the mash temps right? Thats kind of the point of a lot of these systems including Rims and Herms... With these insulation is not needed in all but the most extreme cases.

 

[jschein]

But why?

Anyone recirculating would also be reheating to maintain or step the mash temps right? Thats kind of the point of a lot of these systems including Rims and Herms... With these insulation is not needed in all but the most extreme cases.

Very true in my case, I never insulted the mash tun outside in freezing weather. The burner fired up more than it did when the temperature was over 50

 

[jschein]

But why?

Anyone recirculating would also be reheating to maintain or step the mash temps right? Thats kind of the point of a lot of these systems including Rims and Herms... With these insulation is not needed in all but the most extreme cases.

Very true in my case, I never insulted the mash tun in freezing weather. The burner fired up more than it did when the temperature was over 50

 

[oakbarn]

Insulating in the winter would make a difference. I brew in a Barn and have had frozen pipes. Some brews days it can be quite cold.

 

[wilserbrewer]

A mash has different thermal properties than water....take the water only data with two grains of salt.

 

[stopher]

goto thrift store and buy an old wool blanket or wool jacket. sew it up to fit your rig and won't catch on fire. it'll keep 98% heat.

ALSO, ADDITIONAL USE: i put my kegs in a regular cooler with lid open half sticking out of cooler with WOOL blanket over the kegs. retains ice for 2 days.

easy to clean. just drop into wash machine and the shine/paint job on your boilers will look good when not in use.

 

[Izzie1701]

I used spray foam on mine and then wrapped that in tin to seal it from
Anything gross getting on it. Seems to work great. Before I was running HERMs in a 60 minute mash I would only drop 2-3F

 

[Gadjobrinus]

For those of you with pot-style vessels, and not kegs: whatever your system, whether you manually turn the burner on and mix to maintain heat, or recirc your wort as in a HERMS or RIMS (or just a pump going through some hoses and recirc on your MLT) - do you have any issue with scorching?

I ask, because I used to step mash, and I had a very difficult time not scorching if direct firing. This was a keggle, however, and the false bottom was just a disc obtained from St. Pat's. What I have are Spike vessels, so I know we're in an entire other paradigm. Haven't yet brewed on this new system because I'm still gathering things. Just know Wisconsin winter is coming, I'll be outside, and I'd rather not make black patent wort under the false bottom.

Thanks.

 

[akroessler]

For those of you with pot-style vessels, and not kegs: whatever your system, whether you manually turn the burner on and mix to maintain heat, or recirc your wort as in a HERMS or RIMS (or just a pump going through some hoses and recirc on your MLT) - do you have any issue with scorching?

I ask, because I used to step mash, and I had a very difficult time not scorching if direct firing. This was a keggle, however, and the false bottom was just a disc obtained from St. Pat's. What I have are Spike vessels, so I know we're in an entire other paradigm. Haven't yet brewed on this new system because I'm still gathering things. Just know Wisconsin winter is coming, I'll be outside, and I'd rather not make black patent wort under the false bottom.

Thanks.

I direct fire recirculate on my system and as long as you have a temp probe right out of the valve. It doesn’t scorch. My system is direct fire natural gas and it’s on for like 5-10 seconds at a time and then turns off. Never burnt before.