Insulating my kettle what material?

[user 25501]

As I do, I've trawled the web but I would still like to start another debate on this topic.
I've recently bought an aluminium chef inox 50l pot to do a stove top BIAB. That method failed. I then purchased 2200w element from KegKing had that fitted to my new pot. I decided to measure my evaporation rate and water heating times prior to my next brew day/night. I setup my pot outside on 2 x 4x2's balanced on 2 "A" table supports. It was a chilly 10o. I used QldKev's water heating calc which was spot on at arriving at 70o. But by no no fault of Kev's calcualator it took an additional 12min to arrive at close to boil. Which I suspect was my un-insulated aluminium pot impeding the progress. In that cold night I could only achieve a very slow boil. I measured the water at 97o. So my debate is.....

Do I

1. insulate with a couple of camping mattress's that I have.
2. insulate with 13mm Airflex Nitrile Rubber. Anyone know where I can purchase this? Clark rubber don't have it.
3. Insulate with 10mm Formshield. Clark Rubber do have this but would be interested in another supplier in the Eastern burbs of Melbourne. ($27/m or $40/m with adhesive back)
4. or What else do you suggest for an easy non mechanical solution.

I did look into Air-Cell but many seem to advise against this for good reason. I welcome your views.

On another note, as I boiled outside I noted a massive concern was boiling under a flouro light. The bugs.

Thanks for any opinions.

Damn

 

[Black Devil Dog]

I use a big piece of black geotextile material that I may or may not have allegedly "taxed" from a job that I was working on. It's like a big black blanket. I've folded it a couple of times and wrapped it around my urn, then I wrap one of those thin foam mats around that and secure it with an elastic cord. On the top of my urn I have 2 big thick cheap towels and I tuck the sides into my foam mat. Works for me, others use sleeping bags, rugs, etc.

A couple of cheap blankets or sleeping bags from an op shop would do the job as good or better and at a fraction of the cost of some of those things you mentioned.

 

[woodwormm]

I have no experience yet, but i'll be in the same boat soon I expect, outside under 'buggy' lights, i guess they hopefully don't make it through the hopscreen?

i'm also keen to see the insulation answers, i'm gas fired so i expect i need to be careful insulating for boil too close to the bottom of the pot in case flames lick up the sides!

 

[technobabble66]

I beat you to it by a month or 2. Again w much reading & hunting

I went with the 10mm Formshield from clarke rubber around my Birko - too hard to resist the shiny silver-backed foam!

I agonised for a while on whether it should face shiny side in or out. I went with it facing out. No idea if i was right or wrong, TBH. It seems to work well, though i've noticed after a while the side feels warm - so maybe some leaking heat. I have a second piece (i bought 1.2m x 1m width, that i then had to cut in half to fit it) so i'll probably wrap the second piece around it to make sure. I also used a sleeping bag on top during the mash, though i probably could've cut out a piece of Formshield to fit the lid.

I then found the heat loss through the top to be a major problem. I could get it to a boil quickly, but once the lid came off, it gradually reduced to a slight simmer at best. 2 little tins floating in the wort seems to solve that problem nicely, though.

Blankets/towels &/or sleeping bags certainly work for the mash. Not sure about the boil. Definitely could be the cheapest option compared to what i did. But less style: more ghetto, not as shiny...

 

[wbosher]

I have no experience yet, but i'll be in the same boat soon I expect, outside under 'buggy' lights, i guess they hopefully don't make it through the hopscreen?

i'm also keen to see the insulation answers, i'm gas fired so i expect i need to be careful insulating for boil too close to the bottom of the pot in case flames lick up the sides!

Shouldn't have any issues with gas, depending on how may rings and pot size obviously. I use a 3 ring gas burner and have no trouble boiling 35L on a chilly 5 degree night with no insulation.

For the mash blankets do the trick.

 

[431neb]

Did you say insulate your kettle?

 

[djar007]

That's awesome neb. It would make a handy bed when the brewing day was done.

 

[431neb]

For those times when it's safer to sleep in the shed.

 

[KingKong]

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IMG_2424.jpgDid you say insulate your kettle?

Is there any insulation against the concrete its sitting on?

 

[431neb]

 

[TSMill]

I use polytuf Eva closed cell foam from bunnings. It has a diamond plate surface and I've glued 2 layers with the textured surface outwards. This gives a small air gap against the vessel which may aid insulation.

 

[Adr_0]

I use polytuf Eva closed cell foam from bunnings. It has a diamond plate surface and I've glued 2 layers with the textured surface outwards. This gives a small air gap against the vessel which may aid insulation.

Should do the trick, I'm going to do exactly that on the top 1/2-2/3 of my MLT and kettle. Just watch the air gaps on your MLT.

I'm getting all giddy at this thread! (chemical engineer)

 

[emnpaul]

431neb, do you work in the rail industry by any chance?

I have the same insulation around my keggle, held in place semi-permanently with a tripple layer of duct tape. It does the job really well. My boil temp went from 96.8 to 101.2 with that addition alone and ramp times cut by heaps. It's good stuff.

Edit: Not sure where you'd go to actually buy some. It was given to me by a mate that builds train cabs. I think he said it was R6 Dacron.

 

[431neb]

I don't use it for the boil as you can probably see emnpaul. I use an over the side electric element to get my uninsulated keggle up to the boil and a 3 ring burner after that... but to the point, the insulation is simply polyester wall batts. It's a common alternative to glass wool batts like pink batts and the yellow (bradford?) glass wool batts.

From memory, I lost 10 degrees that day but my mash time was 6 hours or so. Next time I will use some foil house wrap / sarking as well to see if that radiant heat barrier makes much difference.

 

[aaronpetersen]

I agonised for a while on whether it should face shiny side in or out. I went with it facing out. No idea if i was right or wrong,

I've also been wondering whether insulation should be shiny side in or out. I went for shiny side in as I reasoned that it would reflect the radiant heat back towards the pot.
Does anyone actually know which is right?

 

[technobabble66]

Supposedly the shiny surface reflects radiant heat, & needs an air gap (facing the heat source) to do that. If it's in contact with a solid or liquid, then the reflection stuff doesn't really occur and the heat is just conducted through. That's the basic theory.
How that applies here, i wasn't sure. The shiny surface is textured, so maybe there's a moderate number of little air pockets to allow the reflection to occur from that side. Otherwise, the same kinda applies to the foam side - tiny pockets of air trapped in the foam against the shiny inner surface.
I went with the idea that both might be similarly valid, such that the shiny effect is somewhat compromised anyway and only works a bit, and decided that the shiny side on display would be a better finish to keep clean, etc (& look shiny!).
No-one at Clarke Rubber had a clue (including the manager/owner).

I've already cut mine to fit, so i now can't be bothered to try to do a temp comparison on shiny side out compared to shiny side in...

Maybe best to do 2 layers - inner facing in, outer facing out.

 

[user 25501]

Thanks for all the input.

I'll try the "ghetto" method first brew with my camp mattress's. Then may upgrade as you suggested with a double layer of 10mm formshield.

I can't find any more info on Airflex Nitrile Rubber. That's what the guy(s) use at beer belly and it looks slick too.

 

[slash22000]

All this talk of insulation has got me thinking about insulating my BIAB urn again.

Anybody have any tips for insulation that I can cut to fit sight tubes, handles, etc?

 

[keifer33]

I went with the silver insulation from Clark Rubber for my last two brew rigs. Its pretty easy to cut out the necessary parts and hold it on with a few straps.

 

[Adr_0]

I've also been wondering whether insulation should be shiny side in or out. I went for shiny side in as I reasoned that it would reflect the radiant heat back towards the pot.
Does anyone actually know which is right?

It should be shiny side out, particularly if the rest of it is foam or something with good conductive resistance (low thermal conductivity). By the time your temperature drops going through the insulation the surface temperature on the outside of the insulation won't be very high and you won't get a hell of a lot of heat loss from radiation, but anything you DO have will be reduced to very little when you have the shiny side out and every little bit helps.

If you have the other side out, it probably radiates heat a lot better than something shiny, so increases heat loss. And the only benefit of the insulation on the middle is the conductive resistance the shiny stuff offers, which probably isn't that flash (probably actually has high thermal conductivity).

But the best reason of all - never mind heat transfer fundamentals - is that it looks heaps blingier with the shiny side out.

Just some rough numbers, comparing my stainless mash tun (0.4m diameter, 0.6m high and ~1m2 of surface area) the heat loss from radiation from the bare metal at 50°C was about 140-150W. With 75L of water that means I would be losing at least 1.5°C per hour. At 65°C it was 250W, or about 3°C per hour.

With a product with an emissivity of 0.03 (i.e. shiny insulation stuff) that goes down to about 7W, or insignificant. The air/foam on the middle reduces the surface tempearture a bit (because heat doesn't get out as easily) and then the shiny surface poorly radiates it so it reduces heat loss in two ways and is theoretically 0.3°C per hour. Actual measurements are about 0.5°C per hour.

EDIT: Note that white is just as good as shiny, believe it or not