Experimental study on thermal performance of roof and floor capillary radiant heating systems

Abstract This research picks up the bedroom and study of a residential building in Chengdu as the research object. The temperature variations in the supply water of the room, the surface temperature of roof and floor, and the indoor air is analysed when the capillary ends were located on the roof and the floor respectively. Furthermore, the internal mechanism of the different heating environments of the two heating modes is revealed by analysing the heat flux density. The results show that: under the same water supply temperature and flow rate, the thermal response time of the roof radiant heating is shorter and the stability of the surface temperature of the floor radiant heating is better due to the different thickness of the capillary network. The floor heating room has more uniform distribution and better comfort. The heat transfer characteristics of the roof and floor surface are different, and the variation of the radiation and convection heat transfer amount are also different. The heat flux density of the roof increases faster and the maximum value can be reached in only 60 minutes, while the floor needs 156 minutes. The roof heating is about 4.36% higher than the floor heating in the proportion of radiation heat exchange. Thus, roof radiant heating is preferred for intermittent heating. This paper provides a reference when designing the end of the residential heating systems.