Mash Tun Insulation.

[MCT]

So I'm thinking about ditching my 38L round eski in favour of a 50 keg style vessel for my mash tun. Simple reason is I am doing double batches and I don't have the room in the tun for a mash out. I'm using a 3 tier gravity fed system and batch sparging.
Just looking for a bit of advise on insulation for the tun. Alot of people on here seem to be using just a bit of camping mat duct taped around the outside of the keg which is fine, but I'm wondering what people are using for the top/lid? I'm guessing I'd lose a fair bit of heat if it's not insulated well.
I was thinking of just cutting out a circular 11" piece of styrofoam (that's how big the hole in the top of the keg is), but I'm not sure how much this will help as the heat will still just escape around the sides of the styrofoam.

Which leads me to my next question.

How paranoid should I be about maintaining a a consistent mash temp? Am I right in thinking that most of the conversions will be done in the first 15/20 mins?
I'm guessing that the thermal mass in the mash should keep the temps fairly steady for a little while. Does it really matter if I lose a 5 degrees over an hour?

OK, I'm overtired and ranting. Hope that makes sense.

 

[yardy]

I'm converting to the same setup, i've got a glass concave lid from a huge saucepan that i'm going to fill with styrofoam, got the lid from vinnies, blessem :icon_cheers:

Cheers

 

[white.grant]

How paranoid should I be about maintaining a a consistent mash temp? Am I right in thinking that most of the conversions will be done in the first 15/20 mins?
I'm guessing that the thermal mass in the mash should keep the temps fairly steady for a little while. Does it really matter if I lose a 5 degrees over an hour?

Hi MCT,

I think that with an uninsulated stainless vessel,you'll lose more heat from around the circumference of your mash bed faster and experience uneven conversion and reduced efficiency. The inner mass may stay closer to your temps, but the outer bits won't. The surface area of a 50L keg syle vessel is quite large so a large proportion of your mash will be potentially underutilised.

cheers

Grant

 

[reVoxAHB]

Alot of people on here seem to be using just a bit of camping mat duct taped around the outside of the keg which is fine

Yep. I use concrete expansion joining with duct tape. Works fine but the downside (to this or camping mat) is that it gets quite grubby after a few batches- grain, runnings, etc. get trapped between your insulation and the keg itself. Only way to get it off is to cut yer tape. So the tip would be to go with something that's removable for cleaning after every batch. I prefer expansion joining as it comes in strips and works nicely (and snugly) between the keg ridges whereas a camping mat sort of blanket covers everything. Probably splitting hairs between the two materials as I doubt it really matters. I've been thinking about building a keg wrap out of wetsuit material that zips off from side.

but I'm wondering what people are using for the top/lid?

I found an aluminim 10" pizza tray works perfectly as a lid. The edges of the tray are beveled up 2cm", so the tray can be pressed neatly into the hole and the bevel provides a nice seal. I chuck a beach towel on top of that which probably wouldn't be as effective as your idea of styrofoam. Good one. I used a kettle lid previous to that, but it sort of sat on top of everything and didn't "seal" well.

Which leads me to my next question.

How paranoid should I be about maintaining a a consistent mash temp? Am I right in thinking that most of the conversions will be done in the first 15/20 mins?
I'm guessing that the thermal mass in the mash should keep the temps fairly steady for a little while. Does it really matter if I lose a 5 degrees over an hour?

No need to be paranoid, but a consistent mash temp means you'll make consistent beer from batch to batch (if reproducing recipes). a 5 degree range can make all the difference between a dry beer and sweet beer, affect attenuation and more.

 

[seemax]

Agree with above, the keg is an excellent conductor of heat, therefore the heat will be lost from the bottom and sides, not so much the top. I would expect you would lose 2-3C, even more over a 60min mash and the temperature distribution will be uneven. Suggest you do regular stirs, say every 15mins. You might be able to find an old stock pot lid or similar (Kmart, BigW?) that will fit nicely on top, then just insulate that with styrofoam or more camping mat.
Having said all that, in the early days I did a few mashes in a stove pot and although I lost 5C the beer still turned out great!

 

[bouncingcastle]

I just made this exact jump. Went from an esky to a 50L SS keg. Had the exact same thoughts.

So what was the answer for me? Yoga. Yes yoga.. lol - a $30 yoga mat from clark rubber sorted me out. It's about an inch thick of closed cell foam and has a 2mm latex lining (don't know if that is good or bad )

Came with enough to insulate the bottom of the keg, the sides, the top and the top of my saucepan lid.

Covered the whole thing in waterproof tape to avoid the grubbyness and it is just the ducks nuts for me!

The results - surprising to say the least. With my esky I would move a degree or 2 over a 60 minute mash.

The keg - moved 0 degress over the 60 minute mash (in fact only moved 3 degress over 6 hours!)

I can take pics tonight if anybody is interested?

Chris.

 

[KHB]

I actually used carpet underlay i had lying around. Wont lose a degree over 90min mash, covered it all with duct tape and got an old saucepan lid to put on top with underlay too

 

[reVoxAHB]

I can take pics tonight if anybody is interested?

Chris.

pic it up bouncing. cheers,
reVox

 

[crells]

Does anyone every try single batches (20l) in the 50l tun. If so how does that turn out ?

 

[fraser_john]

I have been using a polyester roof insulation batt! I just tie it around the mash tun (keg) whilst mashing. It suffers the grubbiness thing though

I like the sound of the yoga matt and look forward to some pics.

 

[KHB]

i use mine for 23lt batches i made sure my thermometer was low enough so its no problem, the other thing i did was have it draining from the bottom much easier IMHO

 

[FNQ Bunyip]

My keg like tun is coverd with builders blanket, the stuff that gos under the iron on the roof , its got silver paper on one side and duck tape holds it all in place ... the benifits of doing a bit of casual work for a plumber, lol . maybe a 1 loss over 60min....

cheers

 

[porky]

My mash tun with its coat on. Made with two layers of 8mm thick dense foam with a layer of Al-foil between. Holds on with Velcro strip on left side so we can remove for cleaning tun.
Lid is large pot lid with Styrofoam in it. Holds 1 degree over 60 minutes with no trouble.
Works fine for single or double batches.
Thermometer is welded type with a half socket welded to the tun and a 8mm hole through. This way I have a 10mm piece of 1/2 inch silicone tube inside the socket and I only have to screw the thermometer in until it is snug and it doesn't leak. The piece of silicone seals it.
This way I can remove it as well when dumping grain and cleaning. No worries about breaking it.

 

[bouncingcastle]

As promised,

I took some photos last night of my mash tun.


Full Shot - Shows taping of mat onto the keg with waterproof tape

Top Insulation

Glass Lid Inverted

Lid Removed

Bottom Insulation

Picture of the yoga mat I used. the grey strip is latex... I couldn't find any information on latex's heat conduction properties, so I thought I would make that make contact with the steel and have the closed foam on the outside.

C&B

Chris.

 

[MCT]

As promised,

I took some photos last night of my mash tun.

View attachment 22313
Full Shot - Shows taping of mat onto the keg with waterproof tape
View attachment 22314
Top Insulation
View attachment 22315
Glass Lid Inverted
View attachment 22316
Lid Removed
View attachment 22317
Bottom Insulation
View attachment 22318
Picture of the yoga mat I used. the grey strip is latex... I couldn't find any information on latex's heat conduction properties, so I thought I would make that make contact with the steel and have the closed foam on the outside.

C&B

Chris.

Thanks for that mate, much appreciated.
You may see photo's of a very similar mash tun on these forums soon!