Infrared thermometer failure

[diulin]

A few days ago, right after changing its 9v battery, my Zoto IR thermometer started reading way below the actual temperature. I know this, because I can point it at my woodstove, and it reads around 155 to 160 degrees Farenheidt. Point it at cooler things and the temperature does go down from there, but I haven't checked to see if there are temperatures at which it is accurate. There's nothing at all wrong with the display, but it is just obviously giving me the wrong temperature (by a lot). Has anyone else had this experience or have any suggestions for fixing it?

Thanks.

[david s]

Have you checked to see if it’s set on C rather than F. It may have switched by default when you changed the battery.

IR thermometers only read the surface temperature so can be quite misleading. The temperature of the surface will be markedly higher than the centre of the brick or refractory. If shooting a temperature in my oven when it’s really cranking , at the crown my IR gun will usually read ERR meaning it’s beyond its range. Similarly the floor temperature can vary considerably from front to back and from side to side. A far more reliable method is the burning away of the black soot which occurs at around 300C.

[diulin]

Have you checked to see if it’s set on C rather than F. It may have switched by default when you changed the battery.

IR thermometers only read the surface temperature so can be quite misleading. The temperature of the surface will be markedly higher than the centre of the brick or refractory. If shooting a temperature in my oven when it’s really cranking , at the crown my IR gun will usually read ERR meaning it’s beyond its range. Similarly the floor temperature can vary considerably from front to back and from side to side. A far more reliable method is the burning away of the black soot which occurs at around 300C.

Thanks for the suggestions. Yes, my first thought was that it was reading in C, not F. But I checked that. And I've tried various surfaces. I don't have any way of measuring their precise temperature, but I know they are way above what the thermometer is reading. If the display on the thermometer were flickering or there were any other signs decline in its function, I'd figure it was just bad. The fact that it acts like everything is fine is what makes me wonder if it just needs to be reset, recalibrated, or something.