Midway into my first winter with an Enviro Boston 1700 insert. I have an IR thermometer and get very different temps if I aim at the door, the outside top, or the top of the stove itself, where the air blows out. If I aim at the top of the "inner box" (where the air blows out) an inch or two left or right is 50 degrees different. Could anyone with this insert give me some advice on where to measure the temp?