An experimentally-validated novel three-fluid fin-and-tube heat exchanger (TriCoil™) is proposed for water-based thermal energy storage integration with ducted split systems (DSS) for residential heating and air-conditioning applications. TriCoil™ was modeled and simulated considering three circuitry layouts. The simulations showed that the capacity of the considered coils varied from around 4.5 to 13 kW depending on the operational mode and circuitry layout. With the capacity range of the considered coils, TriCoil™ can be a replacement to an A-shape indoor coil of DSS considering its dimensions with respect to its capacity. Also, fin density and thickness effects on TriCoil™ were investigated to improve its performance. For charging TES mode, the capacity increases by around 95% by increasing the Fin-Tube Ratio by 11%. For modes other than the charging mode, the change in the capacity mostly follows the trend of the air-side effectiveness when changing fin density and fin thickness; the capacity is more responsive to increasing fin density than increasing fin thickness. The TriCoil™ model was validated experimentally for different operational modes, and the average mean absolute error (normalized bias error) among different operational modes compared to the experimental data was 1.3% (0.17%) for the R410A side, 4.2% (-3.03%) for the water side, and 1.4% (-0.03%) for the air side.