Comparison of mash tun insulation methods

[hausofstrauss]

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/

 

[ZebulonBrewer]

mmmmmmm, Hard Data. The best kind. Even better, your data was taken inside in (what I assume are) consistent conditions. I've been thinking of putting together a reflectix wrap for my 40qt kettle. Lower gravity beers lose quite a bit of temp over 60 minutes and I usually re-heat (while stirring!!!) about halfway through.

Cool website, too. It's the first time I've seen it.

 

[hausofstrauss]

mmmmmmm, Hard Data. The best kind. Even better, your data was taken inside in (what I assume are) consistent conditions. I've been thinking of putting together a reflectix wrap for my 40qt kettle. Lower gravity beers lose quite a bit of temp over 60 minutes and I usually re-heat (while stirring!!!) about halfway through.

Cool website, too. It's the first time I've seen it.

Yes, it was in my basement, which was at a pretty constant 65 degrees.

I've got some other fun experiments planned, but I've still got to get some stuff ready.

 

[beertastic]

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.

 

[mhochman]

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.

This is great, thank you for sharing and taking the time.

To all: am I correct in assuming that if grains are in there instead of just water, the temp would probably no drop as much? I'm wondering if the same test would show less relative drop off with the three insulated methods.

 

[hausofstrauss]

I've still got my test rig set up, so hopefully I can run another test this weekend with an air gap.

 

[hausofstrauss]

This is great, thank you for sharing and taking the time.

To all: am I correct in assuming that if grains are in there instead of just water, the temp would probably no drop as much? I'm wondering if the same test would show less relative drop off with the three insulated methods.

Theoretically, the combined specific heat capacity of the grain/water mixture is lower and will this cool at a very slightly greater rate. I plan to test this as well, because theory is, well theory. This is why I kept the testing to just straight water.

 

[mhochman]

Sorry, computer glitch; duplicate post.

 

[owmatooth]

Thank you for running these. I may or may not choose to do anything, but with this data, at least I know exactly what I'm missing. Well done!

 

[owmatooth]

Fwiw, I'll be getting out a sleeping bag today

 

[owmatooth]

View attachment ImageUploadedByHome Brew1495210686.188320.jpg
Well I was too lazy to get a sleeping bag out, but wrapping it with a cushion from our patio furniture seems to be helping. 45 min into mash and have had heater come on once.

 

[wilserbrewer]

Theoretically, the combined specific heat capacity of the grain/water mixture is lower and will this cool at a very slightly greater rate. I plan to test this as well, because theory is, well theory. This is why I kept the testing to just straight water.

I have found water to cool a fair amount quicker than a mash.

I suspect the water is more free flowing than a mash.

Wouldn't the mash have greater density than water, and greater specific heat?

Been a very long time since I cracked the books...

 

[Island_Dan]

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.

 

[hausofstrauss]

View attachment 401057
Well I was too lazy to get a sleeping bag out, but wrapping it with a cushion from our patio furniture seems to be helping. 45 min into mash and have had heater come on once.

Whatever gets the job done!

 

[hausofstrauss]

I have found water to cool a fair amount quicker than a mash.

I suspect the water is more free flowing than a mash.

Wouldn't the mash have greater density than water, and greater specific heat?

Been a very long time since I cracked the books...

Yes, I'm doubting my own comment. I've always had the feeling that a mash/water mix holds temp much better too, but is it the additional mass or the specific heat capacity?

 

[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, I've just started a test with a 2.0 cm (3 layer) air gap. Once that is complete, I'll start a test with a 1 layer air gap and we'll see what happens.

 

[ZebulonBrewer]

I have found water to cool a fair amount quicker than a mash.

I suspect the water is more free flowing than a mash.

Wouldn't the mash have greater density than water, and greater specific heat?

Been a very long time since I cracked the books...

You're on the right track, but I remember looking in an old thermo book and seeing that most foods (I may dig this out to check it) have a LOWER specific heat than water. Water is pretty awesome as far as specific heat is concerned. A reason for it to retain heat longer would be due to the higher total mass of the system (water+grains). The mash would have a higher total thermal mass/intertia (E=m*Cp*T) than just the water (likely higher Cp but lower m).

(note! If you wish to do those calculations, metric is waaaay better. Mass is dumb in english/american units. Also, T must be Kelvin or Rankine unless you're dealing with differences in temp and then it doesn't matter as long as you're consistent)

 

[UnBrewsual]

I am using a cooler mash tun. I put a heating pad under the cooler and leave it on low. It seems to hold its temp just fine that way.

 

[TheBrewBag]

I've been using furnace duct insulation - the tube style - laid flat and cut to measure then taped with aluminum around the kettle and a pillow cut out of the same material for the top. Draped with a moving blanket - no matter the ambient temp in my garage - the loss over 60 minutes is ~2º. This have been proven over 75 + batches. I have never fired up and I never lift the lid. This stuff - http://www.homedepot.com/p/8-in-Dia-R-6-Ductwork-Insulation-Sleeve-INSLV8/100396954

 

[akroessler]

Just out of curiosity, who here has played with the wood insulation on their tuns? I've done a small amount of research and wood holds heat very well. And on top of that, makes your tun look damn good. Here's a pic of what I've found.

This photo is not mine

 

[Ozzfan666]

so if I live in Phoenix and the outside temp is between 120 and 130, will that slow down my heat loss?

 

[eodell48]

I have found water to cool a fair amount quicker than a mash.

I suspect the water is more free flowing than a mash.

I think that's the key reason for the difference right there. A mash inhibits circulation, so that the outside layer in contact with the vessel cools down and doesn't circulate as much back into the center of the vessel, as compared to plain water. As this outer layer cools, along with the vessel itself, the rate of cooling drops, because that rate is proportional to the temperature difference between the vessel wall and the outside environment. Meanwhile, the center of the mash stays much warmer. OTOH, the free circulation of plain water will bring warmer water from the center to the outside, keeping the temperature of the outer layer and of the vessel wall warmer. Thus the rate of heat loss to the outside environment, and the total integrated amount of heat lost in the end, will be higher.

I suspect differences in heat capacity play a minor role at most.

(I'm glad my classes in thermal and statistical physics were good for something.)

 

[rycollier]

Maybe look into a continuous filament synthetic fiber. This is what is used in sleeping bags.

 

[Michigan_Wolfman]

I've been window shopping for an all grain set up for awhile. Still haven't pulled the plug and bought one, but I'm liking what I'm seeing with the Brewer's Edge Mash and Boil. Budget wise, it looks to be right what I'm looking for.

 

[finsel]

Hi,
That is a nice information!!!
I have here a Cotton canvas with silicone. It is possible you test this too to get this into your graphic?

How I made is:
used this: https://cdn.shopify.com/s/files/1/0300/1493/products/canvas2_1024x1024.jpg?v=1465676142

with both sides covered with liquid silicone ( with most flexible):
http://artificial_stone.china-direc...ilicone_for_large_artificial_stone_molds.html

and my aluminium tun keeps the temperature for long period..

tks!
( my equip. is under finselBR channel - youtube).

 

[BrewKaiser]

@hausofstrauss great data and info. I applied Lizardskin (thermal insulating ceramic paint) to my keggles and HEX. Wish I had done a before and after so I could verify the results. What I do know is that I can put my hand on the outside of my BK during boil for 10 seconds without getting burned.

It's more expensive, permanent, and likely performs less than the other methods you tested, but it is a valid alternative and provides a unique aesthetic.

 

[Ozzfan666]

[/IMG]

Just out of curiosity, who here has played with the wood insulation on their tuns? I've done a small amount of research and wood holds heat very well. And on top of that, makes your tun look damn good. Here's a pic of what I've found.

This photo is not mine

 

[Bigstaubbie]

Sorry all you hi-tech guys. I think brewing is supposed to be fun. I have way too much real world stuff to worry about. I just wrap two beach towels around the keggle mash tun. Drink a couple HB's and don't worry about the 4 degree drop. Oh, I do start 2 degrees warm. I'm at 136 brews of all sorts of different styles. One of these days, I think I wanna brew a tripel.

 

[anchornm]

I know that this reply doesn't match the original concept (put a bunch of heat into a bunch of mass, then insulate to keep it there), but...
What I do, is to add heat as needed to maintain the temperature. No insulation, just a very accurate sensor, and a PID to regulate the element. Now, my next statement (given that the solution is proposed to be insulation), what do guys that take this approach do to step-mash? I just turn up the PID, hold for a given time, then turn it up again (repeat as needed). Need an acid rest, a protein rest and then hold the mash at 147 overnight --- no problem...

 

[stonebrewer]

Interested in the Reflectix info. I only have one wrap around my tun and it is not as effective as I would have hoped. Might be because a) I need more wraps and b) I have it too tight around the tun. Thanks for putting this info out there! Also interested in any data you collect on recirculation losses!

 

[yags]

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.

I loose about 1 degree in an hour mash with reflectix. I have a 2 in air gap around the sides and top of the keggle for the mash tun. Tape the reflectix with aluminum tape.

 

[oakbarn]

I loose about 1 degree in an hour mash with reflectix. I have a 2 in air gap around the sides and top of the keggle for the mash tun. Tape the reflectix with aluminum tape.

How do you get the gap? I have a roll just waiting to wrap my MLT. I use a modified HERMS with a Radiator Element controllled by a BCS 462 and a Chillzilla and two pumps. It maintains the temp fairly good but I think insulation would be better (in the winter it can get quite cold in my Barn/Brewery.

 

[RichBenn]

I just want to add a couple "lurking variables" that could skew these results for other systems:
1. Heat rises. Alot. Those of us that do re-circulation know that the top of the vessel to the bottom can easily be 10 degrees difference, when just water is used. Once grain is well stirred, the grain tends to maintain a much smaller and more even temperature gradient. But there will still be some differences throughout the mash.
2. Insulating the top is crucial for holding that heat in. if your vessel is narrow and tall, then the sides become as or more important.
3. Grain has a great deal of heat capacity. While it's absolutely great that the OP has done some actual experimentation, there will be very different results with grain involved. That said, the relative merits of different insulation will be the same or similar.
4. Finally, R-values can be looked up. The bigger the R-value, the better.

 

[hausofstrauss]

I just want to add a couple "lurking variables" that could skew these results for other systems:
1. Heat rises. Alot. Those of us that do re-circulation know that the top of the vessel to the bottom can easily be 10 degrees difference, when just water is used. Once grain is well stirred, the grain tends to maintain a much smaller and more even temperature gradient. But there will still be some differences throughout the mash.
2. Insulating the top is crucial for holding that heat in. if your vessel is narrow and tall, then the sides become as or more important.
3. Grain has a great deal of heat capacity. While it's absolutely great that the OP has done some actual experimentation, there will be very different results with grain involved. That said, the relative merits of different insulation will be the same or similar.
4. Finally, R-values can be looked up. The bigger the R-value, the better.

Thanks for bringing up some discussion points.
1. Test on that upcoming
2. Yes, and sealing all gaps as well. Even though I didn't make a completely sealed top, I repeated one of the gap tests for the Reflectix just to ensure there were no gaps and it made a measurable difference.
3. See note 1 regarding tests with grain and exactly why I used water as the medium and well known and accepted specific heat properties. It's comparing only the insulation method on the same kettle geometry. Honestly, I think even better that the Brewer's Edge has a larger height to diameter ratio, so that most of the surface area is on the sides.
4. From what I've read on the internet, and we know the internet is truth, R-values should be calculated from a formula, but it appears they can be cheated somewhat.

I finished the test on the Reflectix gap, but need to prep for the next round of tests and also need some more time to make the results presentable and complete the write up.

 

[hausofstrauss]

Interested in the Reflectix info. I only have one wrap around my tun and it is not as effective as I would have hoped. Might be because a) I need more wraps and b) I have it too tight around the tun. Thanks for putting this info out there! Also interested in any data you collect on recirculation losses!

Data will be coming.

Also, I do not currently have a recirculation system and honestly don't plan to just yet. On one hand, it's one more thing to clean. On the other hand, it might actually aid in cleaning, so the jury is out. Unless someone wants to donate one for the test...

 

[TennBrewer]

I have a 15G Spike Mash Tun w/false bottom. Today I brewed a 10G batch with 20# of grain in 6.5G water. I nailed the strike temperature of 152*F and put the cover on. I checked back in 45 minutes and it was still 152*F.

 

[therev71]

I did this with the water heater wrap but I bought double sided velcro to get it on and off easier and not have it rip when taking off the tape.

 

[yags]

How do you get the gap? I have a roll just waiting to wrap my MLT. I use a modified HERMS with a Radiator Element controllled by a BCS 462 and a Chillzilla and two pumps. It maintains the temp fairly good but I think insulation would be better (in the winter it can get quite cold in my Barn/Brewery.

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.

 

[stonebrewer]

I have a 15G Spike Mash Tun w/false bottom. Today I brewed a 10G batch with 20# of grain in 6.5G water. I nailed the strike temperature of 152*F and put the cover on. I checked back in 45 minutes and it was still 152*F.

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.

 

[oakbarn]

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 have a 40 gal stout and Winter vs Summer is the main reason I am looking at some insulation. As in the previous post, I use a Chillzilla as a HERMS and in the Summer I can be right on for the most part. In the winter there is a greater variance.

I measure Wort Out (MLT Out)just past the Outflow of the MLT and the also measure the HERMS Out (MLT In) just prior to the return of the Wort after the Chillzilla. I use a BCS 462 to control an element inside a small 9 gal Stout Electric BK that I use for the HERMS bath. In the summer I can maintain the Mash at 152 if I want 152. In the Winter. I have to heat the HERMS Out (MLT In) to about 154 for the WORT Out to be at 150. I am chasing it sometimes a little more in the Winter.

The BCS 462 will control the Water bath within 0.1 degrees so it is system loss.