5 Gal Igloo Cooler issues

So, been use a 5 gallon igloo cooler for my AG batches (6 so far) and I am pretty much unable to get consistent mash temps TOP to BOTTOM. I have no issues hitting my mash temp, but I can't get the mash temp's the same through the mash. Stirring doesn't seem to help much. I take the middle as my target and see +/-5 or so from that. I insulated the lid of the cooler with great stuff as well and normally stir for the first few min then zip tie the lid down tight.

I can only guess that my height to width ratio is way to big to allow for consistent temps with out re-circulating water. Is there any "truth" to this?

My typical Recipes are 10-11lb bills with 3.5-4 gallons of water. The Cooler is pre-heated with 200+ deg water for 15min prior and then stirred to cool down to strike.

My beers are turning out OK but it just bugs the crap out of me. Should I use a 10gallon cooler or go to a square one?

Which half is the cooler half? The top or bottom? I would imagine the top is cooler since every time you open the lid you are letting in cool air which cools the top of the mash.

Correct, top is cooler, however when I close it (Within min of mashing in and mixing) it remains consistently cooler through out the mash.

I even ziptie the lid down so its very sug and no steam escapes. I even shook it hard once to mix it up and the temp dropped up top afterwords.

I forget to mention that I use 2 digital thermometers ran through the sides of the cooler so the lid never removed after dough in and mixing. (One towards the bottom, other closer to the top.) The thermometers are perfectly matched as well.

The thicker the mash, the worse this temperature differential will be. The reason is that there is less of a convection current in the mash helping to even out the temperature. Have you tried thinning the mash with more water? This also has the benefit of making stirring easier. And when you stir, you really have to not only stir from side to side (or in circles), but from bottom to top. I think some people use a drill with one of those corkscrew-like attachments to achieve this goal. I stir every 15 minutes to prevent large temperature differentials in the mash too.

I also suppose you could fill up the tun as close to the top as possible to reduce headspace, or maybe cut a piece of foamboard to the exact size of the inside of the tun and lower it as close to the mash as you can. But, I have no idea how well this would actually work.

How often do you check the mash temperature? I'd recommend checking once after mashing in a stirring, then again right before the sparge. Other than that, just keep it closed. The temperature will equal out if the cooler is closed and it has a good seal. When I used my small 5g cooler, it held the heat better than my 10g.

TwoHeadsBrewing said:

How often do you check the mash temperature? I'd recommend checking once after mashing in a stirring, then again right before the sparge. Other than that, just keep it closed. The temperature will equal out if the cooler is closed and it has a good seal. When I used my small 5g cooler, it held the heat better than my 10g.

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The temp of the mash is monitored constantly via two digital thermometers ran through the side of the cooler I stir pretty hard when I first mash in top to bottom to make sure I don't have any dough balls. I wonder if the very close proximity of the position of the lower thermometer vs the bulk head of the valve are why it reads hot. Like the valve is heat soaked and just over heats that small area..... I will move it next batch and see what it does.

Those lids are bad, they do not have insulation in them. If you are wanting to improve the insulation use some "Great Stuff" Drill a hole or two and fill it with foam. You can also throw something like a hot pad or a seat cushion on top of it too.

GREAT STUFF?

How much air space do you have on your MLT when its full?

I hate having lots of air space over the top of the mash. One of the easiest ways to consume it is with plastic balls (Ping Pong) or using plastic bags stuffed with lots more bags (wal-mart type)

I use a 12 gallon and check the mash temp about 5 minutes after doughing it and thats it, unless I step mash.

I have both a 5 and 12 and think its inherit in the design of a 5 gal container. Its taller than high. I think the closer the height to width ratio is to one, the more uniform the temp will be. The grist to water ratio plays a part too.

What is you extract efficiency?

1:1 grist ration is ideal for temp but not for mash efficiency. I believe 1:1.5 is best for efficiency. Then batch sparge with 1:1.5

How often do you stir your mash?

I do it every 15 minutes.

200+ degree water to preheat? that seems like alot. Is it warping the plastic?

I preheat with 130 degree water, and my sparge water at 185 has even warped the cooler wall.