Floor heating has been used for thousands of years, and essentially consists of a heat generation system and a heat distribution system with heat transfer through the floor. Modern studies for low energy buildings focus on taking advantage of water with low thermal value (lukewarm, 30-35 C), which necessitates reducing heat transfer coefficients in the system. Modern control systems allow for reducing the temperature when (part of) the building is unused, but require heating system with low heat capacity to be efficient. This implies using above-floor systems, i.e., inserting pipes in the underlayment between the subfloor (e.g., chipboard) and the floor covering (parquet, etc.).

In this paper, a heated water tank model as in Johansen et al. (2019) is modified/improved, and is extended with a water distribution system for floor heating. In comparison with the model in Lie et al. (2014), the solar heating element is excluded and the heated tank model is improved. Also, the model of the distribution system and the floor heating is improved. The developed model is compared with experimental data from Johansen et al. (2019), and the effect of the water recycling is analyzed wrt. its effect on the dynamics.