I got a new MES 40 for Christmas, the Sam's model. The recommended breaking it in at the max. temp. 275 deg. for 3 hrs. I did this, and while I was doing I thought I would check the accuracy of the temperature. With the unit holding very nicely at 275 deg. I put my wife's oven themometer in on the to shelf it registered 250 deg. Then I placed the probe of my Thermopen through the vent and it registered 315 deg. I have checked my Thermopen in ice water and boiling water and it show to be accurate. I wonder how accurate it is at checking air temp. How do you know which is correct?