Assessing safety of "underfloor heating" systems
Interest in underfloor heating systems has been increasing steadily. The structures based on film heating elements are of particular importance among these systems, as they can adjust their resistance depending on the temperature. In this paper, the operating conditions of underfloor heating systems are investigated, and a methodology for assessing their safety under various operating conditions is developed. Currently, in order to obtain licensing for the "underfloor heating" systems, they are examined by standard methods. Applying new technologies for assessing the safety of these systems requires novel approaches that imply conditions close to actual operation. The authors assembled a testing stand with a polymer heating element on a thermal insulation cover, closed with linoleum. Laboratory research was carried out using the TPM 138 "OVEN" device, which recorded the temperature throughout the entire volume of the stand. The research results on the distribution of temperature fields recorded by the device during the extreme operation of the "underfloor heating" system are as follows. A dangerous situation is set, which can lead to a fire when the surface is covered with polyester batting material and exposed to additional mechanical stimuli. It was also found that, with insufficient heat transfer, electrical insulation was violated, leading to electric shock. Currently, self-regulating polymer heating elements should be used under additional control, avoiding extreme operation modes. Experiments demonstrated that it is necessary to develop guidelines for services, installation and operation of such systems.