I use a 70 qt Coleman with CPVC manifold. During mashes, I have noticed at times that my temp readings are multiple degrees different throughout the cooler. The manifold gets in the way of stirring up the grain which likely contributes to variant temps. Any ideas on improving this issue?
I stir throughout mash-in, which is about 2-3 minutes, and another 2-3 minutes afterward. That generally gets me within 1°C throughout the grain bed.
Do you put water or grain in first? Water first might help as it will get the cooler walls and manifold at the right temp before adding grain. The grain tends to float a bit too, so it won’t get down into the manifold until it is wet (and warmed).
I agree with Sean. I keep stirring until I get the same temp reading no matter where in the tun I check.
he must have a orange cooler…
When using my cooler (round, orange) I preheat a bit with some hot tap water and then add the strike water, then the grain. Like Denny I stir until the temp stabilizes. After that I’ll stir about every 15 minutes and add hot water if I lose temp from said stirring. Stirring seems to help the efficiency a bit as well.
When using my direct-fired stainless tun with RIMS, I also stir until the temp is stable and then let the RIMS system keep it there, but still give a full stir about every 15 minutes.
I stir well in the begining then every 15-20 minutes. I use a round “yellow” cooler and take my temps at the top. I loose 1-2 degrees depending how long I mash.
Blue coolers spawn their own 152 degree mash water
Thanks everyone
My cooler is round and blue. 
I stir three times during the 75 minute mash and don’t worry about it otherwise. If the temp is close enough, it’s good enough. It’s always within 1-2F anyway.
40 quart marine cooler (white and rectangular) works best for my 5 gallon batches. Stir down to temp, usually about 2-3 minutes; most of the water added first, then grain and stir a minute or so, then more water, keep stirring until temps are uniform and at desired temp. YMTMV (your mash tun may vary)… 