Detailed analysis of thermographic data for 440 km (250 miles) of district heating networks demonstrates that there is a strong connection between the condition of the heating culvert and the radiative surface temperature and surface temperature pattern. Provided the thermogram has a good geometric image it is possible to make an accurate determination of the position and extension of the damage of the culvert. However, to get this results one got to know what infrared system to use for a specific application, how to operate it, and during what weather conditions. In this paper is presented a project aiming at developing operational routines, and determining operational advantages and limitations for airborne and groundbased thermography for district heating applications. A comparison is made of the information content of thermograms from an airborne longwave infrared line-scanner, helicopterborne and groundbased mobile longvawe Thermovision. Thermal registration was performed repeatedly, for the same investigation area, during similar weather conditions. Evaluation of operational advantages and limitations for the different systems used was performed according to (a) an indicating method (qualitative), mainly pointing out areas with undefined damage of culverts, and (b) an analysis method (quantitative) , which gives temperature classified data for determing the condition of the network studied.