Predictive Maintenance of District Heating Networks: A Comprehensive Review of Methods and Challenges

District heating is one of the main strategies for providing heat supply for buildings in cold climate countries. However, large parts of the current prefabricated pipes of these networks are reaching the end of their technical service life. Replacing these pipes is a time-consuming procedure and requires huge investments. Predictive Maintenance (PdM) is a promising strategy to deal with these situations and to optimize and prioritize maintenance activities. This paper surveys different PdM approaches considering difficulties in implementing PdMs in district heating networks (DHNs) compared with other energy sectors. It demonstrates that the PdM methodology is unique for each DHN according to the distinctive characteristics, environmental factors, heating resource type, available data, equipment, and other factors. To the best of the authors’ knowledge, this paper presents the first comprehensive review focused on various aspects of PdM strategies developed for DHNs, including data analytics, prediction models, and integrated technologies to facilitate the implementation of these strategies in DHNs. A thorough discussion on state-of-the-art technologies and real-world challenges for implementing PdM is presented, and potential research avenues are provided.