Different temps in converted cooler

I have a Coleman cooler (not the Xtreme - just a 48 Qt. Chest cooler) that I converted to a MLT. I now have 6 AG batches under my belt and am beginning to get more comfortable with the process.

The previous batches, I found a decent spot for my thermometer's probe so it wouldn't get wet, but wasn't touching the side of the cooler either. I used the same spot every batch. But this last one, out of curiousity, I moved the probe to a new spot. 10 degrees different.

I figured it was just a hot spot in the mash, so I stirred things up. Same result. From the front (where the spigot is) to the middle, there's a 10 degree differential. Then at the very back of the cooler it's about 5 degrees cooler again. I figure I'll just average the temperatures I'm getting, but I'd prefer to get correct readings. BTW, I confirmed the temps with my floating thermometer. Same thing.

Has anyone seen this? For those of you who use chest coolers, is this normal?

One last thing - last batch my efficiency went from an average of 73% to 82. I ran the grain through my LHBS's mill twice, and stirred the mash a bit trying to figure out the temps. I'm assuming it's the double milling, but won't figure that out until this weekend's batch. Either way, I'm pleased my efficiency's improving.

I get different temps depending on where I sample after a mash, but not a 10 degree variation. More like 1-2 degrees.

i'm with brokenbrew on this one. the same thing happens to me. i mix thoroughly but still end up with different hotspots. Difference in temp ranges from 4-8 degrees different. And I DO use an extreme cooler. my beer's been attenuated well, so i'm not overly concerned, but if there's a way to fix it, I'd like to hear it!

That seems like a lot of variation. The only things I can think of:

1) bad thermometer although you tested this with a backup
2) not enough stirring
3) bad insulation in the cooler?

You have to stir a lot and then let it settle for a few minutes - maybe 5 or so. Then maybe stir again

A lot of the liquid is trapped in the grain and it takes time for diffusion and temp exchange.

You should be able to get to a nearly isotropic, nearly time-invariant point inside a cooler.

I vote for stirring. I've been stirring just enough to get things mixed up well, but nothing after (until last weekend). I'll stir more and see if that fixes it.

Glad to hear I'm not alone.

How thick is your mash? I would think that a thicker mash would be slower to have its temperature equalize.

Synovia said:

How thick is your mash? I would think that a thicker mash would be slower to have its temperature equalize.

Click to expand...

That make sense. But - I mash at about 1-1/2 qts / lb. Seems pretty soupy to me.

I have found that you need to stir, wait, stir, wait...ok get it...surprisingly it takes a while to become thermally homogenic....whew!

I stir about every 20 minutes, but I have a directly fired tun. Insulation isn't as good as a cooler.

David.

I had this happen and finally realized I didnt have the cooler on a level surface. It was just enough for most of the water to sit on one end of the cooler.