Direct Fire MLT Insulation Project

[Bobby_M]

I'd say you can skip it. I have NEVER taken the assembly off the keg so the whole purpose of the adhesive has been negated.

 

[mlafnitzegger]

Bobby, I know this thread is old but hows the insulated mlt working? Anything you would do differently if you were to build it today? Also how did you install the thermometer? did you extend it out with a nipple or coupler?

 

[Bobby_M]

The insulation is still like new. I wouldn't do anything differently. My thermo coupler was already sticking out from the keg by about 3/4" so it cleared the wrap by a bit already.

 

[Jewrican]

i put mine together last week and brewed on Sunday. I was very happy with it. Seems to hold heat much better than my jacket that I had before.

I think we went about 30 or 40 minutes in about 35 degree weather before we needed to heat it at all. It was the smoothest mash i have had yet on this system.

 

[30Bones]

i put mine together last week and brewed on Sunday. I was very happy with it. Seems to hold heat much better than my jacket that I had before.

I think we went about 30 or 40 minutes in about 35 degree weather before we needed to heat it at all. It was the smoothest mash i have had yet on this system.

Do you recirc your mash also?

 

[Jewrican]

i decided i was loosing too much heat doing so. I only did after i turned the burner on to keep from scorching it

 

[30Bones]

Building my first system and am unsure if I want to insulate, but do plan to recirc either way

 

[mlafnitzegger]

His directions are very good. I used .032 sheet metal and was able to install with ratcheting straps which makes it very easy. Instead of using latches, I just riveted the seam. If need to take apart I will have to drill them out but people have stated they have not ever taking apart.The hardest part was the fittings and making sure they dont leak.

 

[Bobby_M]

That's a beautiful piece of art right there. It also makes beer.

 

[freshhoarse]

Yes it is! Nice work.

Sent from my SCH-I535 using Home Brew mobile app

 

[Eugenio]

Reanimate the dead!

Anyone know if the original images live somewhere? Would love to see this project

 

[Stealthcruiser]

P. M. "BobbyM", the thread starter.

 

[Bobby_M]

I just put some of them back, I need to really think about how to restore all of them

 

[Eugenio]

That is really cool, thank you. I wanted to insulate my kettle, but was concerned about using any meltables or fabrics...ive actually used Mineral Wool on a few 3B buildings now, its great, non combustible stuff! Ill be going this route, thanks again for showing this.

 

[mlafnitzegger]

I built this direct fire MT last winter. I was fairly easy following the post here. The main issue I had was making sure the bulkheads didn't leak. It took some time and fun discovery finding leaks during water tests and then after using a few times. The bulkheads would move depending on outside temp and just not paying attention.

This winter I decided to check insulation. I removed the sheathing and found that the insulation held up well but was obvious that there had been leakage. The main evidence was the rusting on the wool.

I bought some new rockwool from McMaster ($7). I also decided to add a layer of ceramic insulation and find some bulkheads that would ease my paranoia. I found new bulkheads at brewhardware. Bobby pretty much guarantied that you could crank these down and they would not leak. Sold. SO purchased them and cranked them down and did leak tests. NO LEAKS and tight. They will not budge when connecting and disconnecting the quick connects. Awesome product - True Weldless Bulkheads. (https://www.brewhardware.com/product_p/truebulkheadfem.htm)

Here are some photos:

 

[mlafnitzegger]

More pics...

I will test heat retention this weekend.

 

[mlafnitzegger]

It looks like over kill but I wanted to make sure I never have to do this again. Things I learned...
- The bulkheads need to be tight as with it extending out as much as it does it doesn't take much to loosen outside bulkhead nut. Solution was to buy BobbyMs True Weldless bulkheads available at brewhardware.com
- I found that heat in old MT be uneven after applying heat. This was due to the bottom not being properly shielded and where the hole are on the bottom would allow more heat the where I had shielding. Solution was to make sure to heat shield the outside of keg well. I also used a tube of Furnace Cement and Fireplace Mortar from Menards. Heat resistant up 2000 degrees
- I did have to replace the sheathing as it was 1/4 inch to short with added ceramic blanket. I used the old sheathing as a fireshield on would stand. I also had enough sheathing to put top on stand above burners
- I also used screws to attach sheathing instead of rivets. Just easier to remove if required

 

[tally350z]

mlafnitzegger, what was your process and product for finishing the top and bottom around the insulation?

 

[mlafnitzegger]

mlafnitzegger, what was your process and product for finishing the top and bottom around the insulation?

My old MT I used aluminum color pure silicon caulk on top and white pure silicon on bottom (I had white lying around and it's on the bottom). The top help up well. The bottom was ok but charred.

The new MT I had to replace the sheath so I went with 21.5" width and 69" length. This gave me extra space on top and bottom between insulation and top of sheathing. I taped the top outside edge of sheathing and a line on keg. I filled up the top with aluminum caulk. Did it in two layers as it's a good 1/2" deep. Let it cure for 24hrs between layers. I used a cheap plastic brush bar from Menards and cut it to use as a jig to smooth the caulking out as best I could. Smooth out to the tape on keg. Let dry for 5 minutes or so and remove tape. Use your finger carefully to smooth out any gaps left by removing tape. Let cure and try not to poke it until after first brew. It's very tempting to poke just because...

The bottom was the same procedure except I used gray fireplace & mortar cement. It has dried pretty good but I haven't brewed with it yet. It is supposed to get rock hard and resist heat up to 2000 degrees. Shouldn't have to worry... ever. Just make sure to clean up any mess before it dries as it will not come off easy I suspect. Purchased caulking at Menards.

 

[mlafnitzegger]

Update after two brews;
1st the furnace cement is weird and did drip. I would go back to silicon
2nd No leaks with True bulkheads from Brewhardware.com
3rd the temp retention is great, lose about 1.5 degrees in an hour mash at 55 degrees ambient temp and no wind.
I transfer 176 from hlt to mt which is at 169 when transfer is complete and I wait 10 minutes for temp to equalize. I then mash in for 10 minutes and end up with 152.5. At the end of an hour the temp was 151 with no heat added during mash

The new design work great other then the cement around bottom. The cement still protects the insulation and is rock hard.

 

[jaginger]

man that looks flat awesome. nice work!

 

[Bobby_M]

Nice!

 

[aangel]

Have you tried boiling using that setup? I'd like to know what the time difference and boil intensity is like. I'm considering using it on my kettle.

 

[jtlambert]

I haven't tried boiling using it. I only use it for my Mash Tun, and I don't fire the burner under it very often, although I could. I just built a RIMS tube for my mash.

 

[mlafnitzegger]

I wouldn't use it as a boil kettle. The insulation will break down faster and the silicon will eventually fall apart.

 

[aangel]

Why would the insulation break down? It can't handle those temps? I'm looking at doing something similar but with steel top/bottom instead of silicone.

 

[BazzookaBuddy]

Why would the insulation break down? It can't handle those temps? I'm looking at doing something similar but with steel top/bottom instead of silicone.

It's not the mineral wool itself that breaks down. It the binder of the insulation that I would worry about. The binder will evaporate around 275 Celsius. It will then evaporate some nasty fumes, but once they have evaporated it will never happen again.

I wouldn't worry as long you have something that keeps the insulation in place. Like sheet metal for instance.

 

[FLJohnson]

Considering the original design, would there be an advantage to bending the metal skin as shown in cross section in the attached image to hold the mineral wool and to protect the mineral wool on the top from liquid and on the bottom from heat?

 

[Stealthcruiser]

Considering the original design, would there be an advantage to bending the metal skin as shown in cross section in the attached image to hold the mineral wool and to protect the mineral wool on the top from liquid and on the bottom from heat?

Looks like it would have some definite advantages.

Curious as to how you'll roll it, if for a round mash tun.

 

[FLJohnson]

Shaping it to the mash tun could certainly be a problem. I thought of that, but I thought I'd like to hear from others about the advantages or disadvantages to this before pursuing it.

I have a brother-in-law who is a professional machinist with equipment like you wouldn't believe. I thought I might tap him for the shaping, but only if the design was a definite improvement.