How Infrared Cameras Work
Infrared cameras translate the heat signature of objects into colors on a gradient scale, with higher temperatures appearing as lighter colors, and lower temperatures and wet areas appearing as darker colors. Thermal images show surface-heat variations, which is why an Infrared camera is such a diverse tool for home inspections. Abnormally hot electrical components and connections can be viewed during an electrical inspection. Areas of moisture that may lead to leak and structural damage can be located based on apparent temperature differences. Heat loss and air leakage in a home, even areas of insufficient insulation, can be pinpointed quickly using an infrared camera.
I currently use the FLIR E50 thermal imager.