What the physical model calculates Electrical power heats the water Thermal mass slows down temperature changes Heat loss increases with the temperature difference to ambient Hot water draw-off is replaced by colder inlet water The thermostat uses hysteresis to switch the heater on and off dT/dt = (P_eff - Q_loss + Q_flow) / (m · c)Q_flow = m_dot · c · (T_inlet - T_water) P_eff = eff. heater power, Q_loss = heat loss, Q_flow = inlet flow heat, m = water mass, m_dot = inlet mass flow, c = water specific heat
Key message Physical models are interpretable, robust, and trusted — but only as accurate as their assumptions. Simulation self-check: running