On a stove well warmed for 2 hours ran a fire on medium high with a crystal clear window no visible smoke from 10 feet away, I have a window that i can see the top of the chimney, and window full of fire I can not get over 325 that seems a bit odd to me. I have to say i bought 2 from a big box store as suggested to compare one to another and the other was broken and would not go over straight down 6 o'clock. Thermometer is 18 inches from stove. What i really do not get is when it reads 150F and I wet a finger and touch it to the flue pipe it sizzles very loud. What gives here other than the temperature is just plain wrong.