A Study on Heating Characteristics of The Combined Radiant Floor Heating & Cooling System with Uneven Tubing

When a radiant floor system is use for both heating and cooling, a primary problem exits due to the tube spacing of floor heat exchanger needed in summer not matching that in winter. To solve it, this paper took an office building as research object, a non-uniform tubing floor radiant system had been developed to meet the different requirement of load in summer or winter correspondingly, and provided a new attempt for the combination of radiant heating and cooling. The field measurement of a non-uniform tubing radiant floor heating system had been carried on, the rules of temperature changes of floor surface, interior surface of building envelope and indoor air had been analyzed, the thermal comfort and PMV in this room had been calculated. The result of measurement indicates that the horizontal air temperature differences are within +/- 0.3 degrees C and have no adverse influence on thermal comfort, though the maximum floor surface temperature difference shifting from 4.2 degrees C to 4.7 degrees C with a non-uniform tubing, and the PMV of room varied from -1.8 to 1.5 during the whole testing time. The hours during which PMV was less than -1 account for 15% of whole testing time, happened in night when the room wasn't in use. A conclusion can be drawn that this system can satisfied the requirement of thermal comfort during the heating period.