Abstract: According to the national carbon neutrality development strategy, the heating industry should accelerate its development towards intelligence. At present, building units have advantages such as low cost, advanced technology, and resource conservation, so building units are the inevitable trend for future development. In this article, the current situation of DFMEA (Design Failure Mode and Effects Analysis) theory both domestically and internationally is studied. Based on the DFMEA reliability design technology, the structure and function of building unit heat exchangers are analyzed, and the DFMEA is used to perform failure analysis, failure consequence analysis, and risk priority technology calculation on the heat exchangers of building units. Targeted improvement plans are proposed for the output results, and ultimately, the product quality, work efficiency, and safety are improved and guaranteed by avoiding failure mode risks through improvements.