Direct Fire MLT Insulation Project

[rudu81]

Would building a shell like Bobby's and using spray foam insulation be a viable solution?

Product states it can handle temp to 240 F

 

[klyph]

For electric, spray foam would work, but not for direct fired vessels. Spray foam is flammable.

 

[rudu81]

For electric, spray foam would work, but not for direct fired vessels. Spray foam is flammable.

That's what I figured. I also wasn't sure if using the flashing would act as a good shield from the burners.

 

[matiasek]

Did anyone try the aluminum flashing? Was it thick enough in single ply or was 2 required?
Anyone have any thoughts on what guages would be acceptable for any metal material? I see bobby used 16 guage (1.5mm) and that the aluminum flashing is around (.0092mm), this is quite a range! I have never worked with the flashing, can you tear it by hand on accident or is it tougher than that?

 

[Bobby_M]

I could probably start my own thread, but Bobby maybe you can answer this. I've got an E-HERMS and want to insulate my mash tun. My three options are:

1. Your aluminum armored insulation
2. Reflectix
3. the adhesive backed foam insulation from McMaster

What would you recommend as my best option? The vessel is a keggle.

I think I'd go with the adhesive backed foam rubber. It's not shiny, but it's really simple to do and seems a lot more robust than glorified bubble wrap. If my vessel was electric, I'd never go through the trouble of what I did.

 

[Bobby_M]

Flashing does come in different gauges but most of the stuff you find would be hard to tear by hand. Maybe if you got a cut started with snips, you'd be able to keep it going by hand. Another way to describe it is that a pair of kitchen grade scissors will cut it pretty easily. The primary reason I advocated doubling up is so you can clamp it tightly without tearing the machine screws out.

 

[Dog House Brew]

I know some people that have used underhood auto insulation. Double wrapped it would be 3/4" thick. Just an idea, I've never used it, but they are susing a similar product on all their vessels.

http://www.sportcompactonly.com/Insulation/Interior/part_c-106_pl-2611_p-12011.htm

 

[boldham]

That is a sweet setup! I checked the "metal by the inch" website and their prices are reasonable, but a little pricey to ship. Bobby, do you recall the dimensions of your aluminum sheet? Does 19" X 55" sound about right? I'm looking at thinner gauge so I could always fold over ends if 55" is too long.
Thanks for any help!

 

[matiasek]

It's holding up like a beast. Honestly the most wear and tear it has seen so far is the random interested party poking at the silicone seal at the top to try to figure out what it is. My previous solution was doubled reflectix with velcro but even thought it was easy to remove didn't mean I'd remember to remove it when the flame was lit.

I have not removed the insulation or metal wrap since it was installed as I've always just cleaned in place. It doesn't appear that the silicone seal has been compromised at all and I don't think the wool has gotten wet. The silicone smelled solventy when it was first applied but it was gone within a week. I don't notice any smells at all during heating. The very bottom layer of wool is exposed to the heat but it doesn't flinch or smolder.

So I just finished my own version of this and did a test run warming up water. I used about 24 guage aluminum sheet, and the mineral wool from mcmaster, and silicone along the top and around the fittings. I was disappointed to see that I got smoking and smelly solvents shortly after firing up. I let it run for about 15-20 min hoping it would burn off but the smoking seemed to be getting worse. The outside aluminum layer was too hot to touch even when the water is only 110-120F inside. There appears to be a lot of conductive heat coming up along the outside. I have 2 thoughts as to what could be going wrong: 1) the adhesive is burning off. 2) the drain holes on the lower skirt (right next to the burner), are allowing direct fire onto the wool and adhesive. I actually only put the adhesive spray on the outside of the wool, the side that touches the aluminum.

Bobby, did you cover up those drain holes on the bottom skirt? If so what did you use? I had looked briefly at JB weld and other like compounds at that hardware store and none of them seem to be temp resistant enough. I could just slip in a piece of aluminum flashing to see if that helps, or I have a TIG welder friend who could seel them up for me. Any thoughts?

For now, I will just use it like a plastic cooler, and use my HLT heat exchanger to recirculate and maintain temps, but I was hoping to be able to direct fire.
thanks for your advice!

 

[Bobby_M]

I didn't block off the lower drains at all. What kind of burner are you using? It sounds like the flame is rocking too hard. Honestly, I'm stumped. My setup never smelled funny or smoked.

 

[matiasek]

I am using a propane burner, similar to this:
http://bayouclassicdepot.com/1114_stainless_steel_propane.htm
and it is rigged to a 20 psi regulator... pretty standard as far as I can tell.

So I slipped folded over squares of aluminum flashing under the insulation on the outside of the keg to block the lower drain holes, which seemed to help a bit. I also constructed a rudimentary heat shield out of of the aluminum flashing as well. Now it has stopped smoking at least but it is still a little stinky. The smell is low enough that I will give it a go on a brew day but I will reevaluate as I go. I wonder if it is the type of spray adhesive I used that is causing the problem: I ended up getting: super 77 which is not the most temp resistant one in the line of 3m adhesives. I will try to spray some adhesive on a piece of flashing and warm it up on the burner and see if that is the same smell I am getting.

Otherwise, some lessons learned for others:
Probably not important to run the insulation over the lower skirt of the keg, if you can stop it right at the water line, the temp the insulation and adhesive experiences should be much lower. Similar the aluminum does not need to go so low, I ran mine to 1/2 off the bottom. Since it is so close to the heat there that it is conducting heat up the side of aluminum making the outside pretty dam hot to the touch.

Here is a pic of the heat shield I came up with on the fly: not permanent yet but a good enough for now to see if it can help. I had tried a couple different diameters, but the widest one, the one in the pic is the one I liked the best and had the least impact on O2 availability for the flame.

 

[ghart999]

Any chance you can repost that picture matiasek?

 

[ghart999]

Bobby or others, would it be possible to use Hot Dipped Galzanized Flashing instead of aluminum flashing to cover the wool? I was at Lowes to pick up the aluminum and man it was thin. But next to it was the glazanized stuff for the same price and at least twice as thick. I just didn't know if this stuff is toxic when it gets heated up or anything.

Thanks.

 

[Bobby_M]

Don't do it: http://www.anvilfire.com/iForge/tutor/safety3/index.htm

I actually found that link after I finished mig welding some galvanized unistrut into a brew stand in my garage. I never had any symptoms that I can tell but it's still a scary situation.

 

[matiasek]

Any chance you can repost that picture matiasek?

Sorry I am not sure why the pics are not going up? Do I need to be a paying member to post pics?

 

[klyph]

That should work.

 

[ghart999]

Thanks for posting the pic. That helps.

 

[ghart999]

Well I just ordered all the stuff for this including a 19" x 55" piece of 20 gauge aluminum sheet from metalbytheinch.com. I hope this works....

 

[matiasek]

I would try to avoid using the spray adhesive if possible. Thats my only beef with the original design. It has been a little stinky when direct firing the mash tun but manageable.

 

[ghart999]

Thanks matiasek. I will avoid this unless I find I can't keep the thing from sliding around or something.

 

[matiasek]

I think the key is to get the aluminum "pre-bent" as best you can. Every time you bend the insulation around the kettle it breaks down a little, and this will be more so without the adhesive. I kept having to enlarge one of them to get it to fit. So I would pre-bend the aluminum around the keg with the straps as bobby showed in his pics, but first without the insulation. This should make it easier to be gentle when you do the final assembly with the insulation in place. I had a bunch of trouble getting my holes drilled in the right place for all three of my mash tun ports. There is probably a more elegant way to measure, rather than just holding the aluminum sheet up against the ports and trying to make markings... perhaps drill one hole and then measure with a string to the second hole so that you get a good measure of circumference. The problem is that the spacing of the holes will vary depending on how far you are from the keg surface. The good thing is that it does not need to be perfect, and making the holes a little bigger than they need to be will not hurt your efficiency. Best of luck!

 

[Gridlocked]

I just insulated mine with this stuff http://www.acousticalsurfaces.com/quiet_duct_wrap/quiet_duct_wrap.htm?d=26 I work at this place, so I figured I'd bring some home and give it a shot. Hit me up if you have questions, I'd be happy to help.

I've only used it for one batch and so far the only complaint that I have is that it's easy to puncture the foil facing. I double-wrapped mine and used standard foil-tape to encapsulate all of the cotton fibers. An aluminum wrap/casing would be SWEET. I wonder if I can have a buddy fab one up for me...

 

[ghart999]

Yeah I expect drilling the 3 holes to be lots of fun too. I imagine you have to do this based on the diameter with the insulation on since it should be wider than without it.

Good advice on pre-bending the aluminum as best as I can before the insulation.

Thanks.

 

[EarthBound]

How much time and money did all this take?
Did you do all this just to save money on gas?
Now that it has no handles, is it not a PITA to move?

 

[Stankonia]

I'm planning on doing this, but with aluminum flashing instead. All the holes are already drilled on my MLT.

Does anyone have any tips for drilling the holes through the aluminum and insulation? Since I'm using flashing I imagine I might be able to poke something through it from the inside of the keg to at least leave a mark I can see from the outside surface.. Bobby, what did you do for this? I couldn't find anything you said about it specifically

 

[matiasek]

I used my biggest drill bit to cut through the aluminum, then used a grinding attachment on my drill to grind it our to the appropriate size. This was much cheaper than buying a larger drill bit.

The handles are not covered on my version of this, I only ran the insulation and aluminum to just beneath the handles.

Lastly, at least for me, this was not designed to save gas necessarily but rather to get the mash tun to hold its heat better so that mashing requires less fuss... meaning I have to add heat less frequently making mashing the mash process simpilier. I still need to heat it, but usually only 1 time in the summer, and 2 times in the winter.

 

[Bobby_M]

How much time and money did all this take?
Did you do all this just to save money on gas?
Now that it has no handles, is it not a PITA to move?

I don't move my vessels as I clean in place but in the rare case that I do, I can still grab the rolled edge from inside. This was done to hold mash temp more consistently as I don't constantly fire the burner or run an automated temp maintenance system. This basically turns a direct fire tun into a metal beverage cooler (almost). Money? All the money is in the metal wrap. If you can get a piece for free or scrap prices, it's very cheap. My time is free right? ;-)

 

[mux]

Mineral wool insulation cones in round pieces. I found 16" round pipe fire retardant insulation. Mineral wool panels won't last long after it's bent.

 

[Bobby_M]

You'd be a lot more helpful by posting a link or source for the insulation you found.

 

[mux]

http://www.amerisafe.net/en/Mineral...-PIPE-INSULATION-16-IPS-X-2-THICK-/12681.aspx