So, I've been struggling to figure out mash temperature control for the last several brews. I bought a Thermapen One because I was questioning weather to believe the Foundry displayed temp or that of a cheap $15 temp probe stuck into the mash bed before and after stirring the mash. This cheap probe always measured 7 degrees less than the Foundry. Yesterday, before mashing in, The Foundry and Thermapen each measured the strike water temp exactly the same. Last time I posted this issue here, someone suggested raising and lowering the malt pipe a couple times during the mash, so I did that at the 20 minute and 40 minute mark. My desired mash temp was 153 and the Foundry read 153, but the Thermapen read a consistent 147 mash temp both before and sifter stirring. The only thing I noticed raising and lowering the malt pipe (and thus mixing in the outside water) did was cause the heating elements to turn on. When I saw how this was going to go, at the 30 minute mark, I raised the Foundry temp to 159 degrees, and at the 40 minute mark, the Thermapen measured the mash temp a consistent 153 for the rest of the mash. Please note: My grist weight was 12 lbs, I used the small ring adapter, I use 240 volts, I recirculate, and I stir the top third of the mash bed every 10 minutes for the first 40 minutes. I ended this brew at 80% efficiency, which I was very pleased with. .