Intermittent heating performance of different terminals in hot summer and cold winter zone in China based on field test

With the increasing demand for winter indoor thermal comfort, increasingly many residents in the hot summer and cold winter zones in China have begun to take various intermittent heating measures. Different heating terminals show dissimilar intermittent heating performances, including heating capacity and thermal response speed, which further influence the indoor thermal environment and energy performance. To achieve a comprehensive understanding of different heating terminals, field tests and comparative experiments were conducted in this research. Three typical heating terminals, a fan coil, radiant floor, and radiator, were chosen as the research objects, and their thermal performances were evaluated in terms of the actual energy utilization rate, thermal response speed, and temperature distribution by comparative analysis. The results showed that the fan coil had the best intermittency, with a start-up time that was only 15.2% of that required for floor heating. However, the fan coil environment showed significant stratification, and the vertical temperature difference was six times larger than that of the radiant floor in the comparative experiments. This phenomenon was amplified by the variation of thermal load in the field test. The vertical temperature difference of the air conditioner was the largest and stable at 9-10 degrees C, while the radiator and radiant floor were only 0-1 degrees C. Moreover, the intermittency differed by height. The combination of field tests and experiments provided full and accurate comparative results for these three typical terminals. Quantitative analysis demonstrated that it is difficult for these three terminals to achieve both thermal comfort and energy savings with intermittent heating. Therefore, the study results provide valuable reference information for the chosen heating terminals in hot summer and cold winter zones and specify the optimal direction and index for intermittent heating.