Application of phase change material (PCM) floor in a solar water heating system can greatly enhance the floor's energy storage capacity, and thus space for water tank is saved and heat loss at night is effectively avoided. This study put forward a new PCM floor including capillary plaits and macro-packaged PCM layer, and investigated the heat storage and releasing process with experimental and simulation method. Accelerated thermal cycle was used to test the characteristic of PCM, and a mathematical model was established for heat transfer analysis. Thermal characteristic of the PCM floor was tested under stable operation condition. The result reveals the new PCM floor is able to release 37677.6 kJ heat for 16 h in the pump-off period in a room of 11.02 m(2) and that account for 47.7% of energy supplied by solar water. The comparison between PCM room and ordinary room shows latent heat storage by capric acid is much more suitable and useful than sensible heat storage by concrete within the floor. Two influencing factors of PCM floor were analyzed by validated mathematical model. The research shows that the designed PCM floor is capable of achieving large-span intermittent heating and lower thermal conductivity for the decoration material is helpful for adjusting the floor surface temperature in the present design. (C) 2014 Elsevier Ltd. All rights reserved.