Last night, I learned how important it is to consider the distance-spot ratio when using my temp gun. I use a Etekcity Lasergrip 774 Infrared Thermometer. Last night, I was checking my temps and noticed that my hotspot was about five degrees cooler than I like it. I knew I hadn't changed the thermostat setting, so I wondered if my RHP was failing or if it was just the change in seasons. I went over to the enclosure to raise the thermostat setting and took one more reading. It was seven degrees warmer than the previous reading!
I tested it and noticed that the further back I stood, the cooler the reading. Then, I remembered seeing the diagram below and decided to re-read the instructions. I thought the temp gun took the temperature of the spot where the laser hits. Turns out the temp gun takes the temperature of the area around the spot and that area grows larger the further away you are.
So, if like me you tend to skim instructions and you're, thus, unaware of the distance-spot ratio, beware. Your temp gun's readings can mislead you if you don't use it properly.