Mash Tun

[Kev888]

I see focus have buy 1 get one free on this:
http://www.focusdiy.co.uk/SpaceBlanket1 ... on_lagging
Do you reckon that would do a good insulation job or is the matting type better?

Not sure exactly what the matting in this thread is, but generaly closed cell foam such as armaflex or quality sleeping mats give quite a lot more insulation than fiber glass or rockwool for the same thickness - the space blanket is probably a cheaper way of doing it but you'd need it to be much thicker. I used about 5 layers of sleeping mat which added up to about 40mm; the space blanket would have been several inches thick for equivalent performance - but it would work just as well if you did that.

Cheers
Kev

[JontyR]

I'd be tempted to check if the space blanket is loose fibres encapuslated within a sealed cover. If that's the case then it would make cutting it to fit round taps etc a pain as you'd have to re-seal it to keep the insulation in. I personally chose matting as it is easy to cut to fit around virtually anything.

[NewPeculier]

Could I put a bend in the outlet pipe (running it lower than the base of the MT) so that I can run off directly to the boiler or is it better to use tubing I can take off and clean separately?

[haz66]

Could I put a bend in the outlet pipe (running it lower than the base of the MT) so that I can run off directly to the boiler or is it better to use tubing I can take off and clean separately?

Quite a lot of people do do that so yeah whatever you feel best with.

[jmc]

I started to insulate my Tun today - staplefordbill, I'm going to use duct tape for a johnny cash style finish rather than the standard shiny

I'm using cable matting for insulation, I ordered a 20m x 13mmx 550mm roll so hopefully I should have enough.

Hi JontyR
I really like the insulation material you used.

I'm really disappointed with heat loss in my coolbox mashtun so I'd like to add some insulation.
Mine's an Igloo Marine 52 coolbox ~ 49L


When I looked for cable matting the only one I found with your specification wasthis one at over £137!

Hopefully you got yours a lot cheaper. Could you please tell us where you sourced the insulation?
TIA John

[sladeywadey]

I have the same coolbox and I suffer from heat loss too. I never found a resolution to this despite preheating with near boiling water for half hour before mashing, using foil on top of the mash etc. I'm ditching the coolbox to summer party duties! I'm considering making my own out of a Young's 27L fermenter..

[Blackaddler]

You might find that the heat loss is due to the lid not seating properly. [Maybe the sides of the Igloo bulge slightly?]
This was the case when my 66L Coleman was nearly full.

The solution was easy enough. I just put a pallet strap around it, and ratcheted the lid down tight. [A piece of wood might be required along the side to bring it back into shape, depending on the type of strap.]

For extra insulation, I also place the coolbox on a wooden board covered with a towel, and then cover the whole lot with a old duvet [£1 from a charity shop].

Sorted.

[jmc]

Thanks for suggestion Blackaddler.

Unfortunately I just think coolbox insulation it was quoted as having was exagerated.

I must admit its large for the 5 gal brews I do so its normally half full,
but I preheat and place it on a 4 layers of thermal-board (on a wooden board), place 4 layers of thermal board on lid, then wrap in sections of hot-water cylinder insulation all strapped together with bungy ropes.
With all that last mash reduced from 67C to 59C in 90 mins.
(Garage was about 5C at the time though.)

When insulation was removed sides and base felt warm so heat leaking through mash tun walls.
I don't think lid is a bad fit, as there is no condensation in insulation wrapping.

I''ve done 15 AG batches since I started AG last June and to be honest they have been very tasty, but I think I need more control so I'm hoping some closed-cell type matting would give better insulation
ATB John

[Kev888]

I'm hoping some closed-cell type matting would give better insulation

I don't know what that particular coolbox has in it but they're often polystyrene (sometimes the lid is just air), and hot water cylinder jackets are typically stuffed with fibreglass. Closed cell foam insulation like armaflex or good quality sleeping mats, or rigid stuff like kingspan & celotex, are much better (two/three times) better insulators for a given thickness.

Sadly they're many more times expensive too, but if the budget stretches you can of course add as much thickness as you want if you make it yourself. I've got nearly 40mm of closed cell foam around my MT and 25mm of celotex top and bottom (go outdoors had a great offer on their sleeping mats last year), it loses less than a degreeC in 90mins - though to be fair thats with 10kg grain bills so the extra mass helps as well.

But as mentioned above, if there is a gap for vapour to escape around the lid a lot of heat can escape that way too.

Cheers
Kev

[Blackaddler]

Unfortunately I just think coolbox insulation it was quoted as having was exagerated.

With all that extra insulation, it sounds like you might be right...

[JontyR]

Hi JontyR
I really like the insulation material you used.

I'm really disappointed with heat loss in my coolbox mashtun so I'd like to add some insulation.
Mine's an Igloo Marine 52 coolbox ~ 49L


When I looked for cable matting the only one I found with your specification wasthis one at over £137!

Hopefully you got yours a lot cheaper. Could you please tell us where you sourced the insulation?
TIA John

Hi John,

I'm afraid that's not a bad price for it! We buy direct from the manufacturer and get it only slightly cheaper. The stuff I used was some surplus to requirements matting that had been kicking around for ages.

[jmc]

You might find that the heat loss is due to the lid not seating properly. [Maybe the sides of the Igloo bulge slightly?]
This was the case when my 66L Coleman was nearly full.

The solution was easy enough. I just put a pallet strap around it, and ratcheted the lid down tight. [A piece of wood might be required along the side to bring it back into shape, depending on the type of strap.]

Hi Blackaddler

I had a change of heart and thought it would be a good idea to first take your advice and try to minimise any heat loss due to a poor-fitting lid.

I'd thought lid was OK, but on closer examination I think it may have warped after 11 AG brews.

This week I bought a cheap racket strap from ebay for under £2.50 inc postage, and it seems to close the lid quite a bit.

Picture of coolbox mashtun before tightening strap:


Gap - before:


Gap - after (about 2-3 mm less):


Proof of the pudding will be revealed on this weekend's brew.

Thanks again for all the advice.
ATB John

[danbrew]

I must admit its large for the 5 gal brews I do so its normally half full,

This could also be adding to your problems and a cheap and effective solution is to make a fitted 'cushion' out of bubble wrap that can sit on top of your mash and fill out the dead space somewhat. Better still make a slab of camping mat foam which will sit neatly on top of the mash(this is what I use though I'm a bit worried about it eventually getting mouldy/ manky).

If you fold the bubble wrap in such a way that it could 'float' on the surface of the mash then cleaning it down afterwards could be a lot easier than if you let the mash get in amongst the layers of polythene. With my camping mat slab I use a sheet of polythene to stop it getting too wet - though there's no avoiding the steam...

Be sure to increase strike temp a degree to account for having to heat this space filler - but it should make a difference to overall heat loss.

[Blackaddler]

Proof of the pudding will be revealed on this weekend's brew.

Something else I've since found... If you locate the ratchet on the front side, just below the lid, it will pull the side in more, and you don't need a stiffener.

A couple of other things that I do...

...weigh out the ingredients into the mashtun the day before brewing, and leave it indoors overnight, to warm up...

...on brewday, underlet [so much easier and quicker than doughing in] and stir until the temperature evens out.

My last 2 mashes [10kg and 14kg] have had no loss in temperature over 90mins, despite the almost freezing weather.
In fact, I noticed an very slight rise in temperature!

[boingy]

I'm not keen on the bubble wrap in the mash idea - not exactly food grade.

The root cause of your problem is that the coolbox is just too big for your batch size.
Next time try using a thinner mix so that the tun is fuller. That will give you a bigger thermal mass and also reduce the heat-sapping air space above it.