Thermographic inspection of district heating networks using an infrared camera has been practiced for more than 45 years – with handheld camera or the camera mounted on top of a car. Typically, such methods cover only 50-70% of the network. Areas with limited or no accessibility are not registered. Often it is in such areas the district heathing companies struggle to locate leaks and other damages. During the past ten years, thermal camera technology has undergone an astonishing development. Weight and size have been reduced dramatically, and it is now possible to mount a high-quality thermal camera under a drone, so 100% coverage of the network can be achieved.