Strategies for flow rate balancing in radiant floor heating systems

Flow rate balancing makes it possible to provide each zone with a design flow rate and to meet the heating load in a radiant floor heating system. Even though the control device of the heating system works well, insufficient water flow rates can degrade control performance and thermal comfort. The water flow rate should be adjusted appropriately to cope with the heating load of each zone. This study analyzes the effect of flow rate balancing upon indoor climate and thermal comfort in a radiant floor heating system through field survey and computer simulations. The results indicate that an increase in the dwelling floor area coincides with a more excessive uneven distribution of flow rate. As the gross floor area of the sample houses increases, the necessity of flow rate balancing for each zone becomes more crucial. An analysis was performed for additional hydraulic problems caused by hydronic devices such as header, valve, etc., and possible strategies to maintain the optimal flow-rate inside the pipes in a radiant floor heating system were suggested. Under part-load conditions the use of a dynamic balancing valve is a more effective method to prevent a cavitation as it reduces the pressure drop across a balancing valve.