A hydronic water heating system for a defined area, the system comprising: a boiler assembly having a water input and a water output; a controller integrated within the boiler assembly and configured to regulate the heating of water from the water input to a temperature corresponding to a water temperature set point along a nonlinear output reset curve; and a user interface configured to receive a user-defined water temperature set point corresponding to a reference outdoor temperature, wherein the nonlinear output reset curve is generated in part based on the user-defined water temperature set point and comprises a first water temperature set point corresponding to a minimum outdoor temperature (Tout_min) with respect to the defined area, a second water temperature set point corresponding to a maximum outdoor temperature (Tout_max) for which heating is required in the defined area, and a plurality of water temperature set points between the first and second set points and corresponding to outdoor temperatures (Tout) between the minimum and maximum outdoor temperatures (Tout_min; Tout_max) with respect to the defined area; characterized in that the system further comprises a thermostat cycling feedback loop wherein the controller is further configured to dynamically adjust at least the first water temperature set point and the corresponding nonlinear output reset curve based on a thermostat cycling input. a boiler assembly having a water input and a water output; a controller integrated within the boiler assembly and configured to regulate the heating of water from the water input to a temperature corresponding to a water temperature set point along a nonlinear output reset curve; and a user interface configured to receive a user-defined water temperature set point corresponding to a reference outdoor temperature, wherein the nonlinear output reset curve is generated in part based on the user-defined water temperature set point and comprises a first water temperature set point corresponding to a minimum outdoor temperature (Tout_min) with respect to the defined area, a second water temperature set point corresponding to a maximum outdoor temperature (Tout_max) for which heating is required in the defined area, and a plurality of water temperature set points between the first and second set points and corresponding to outdoor temperatures (Tout) between the minimum and maximum outdoor temperatures (Tout_min; Tout_max) with respect to the defined area; a first water temperature set point corresponding to a minimum outdoor temperature (Tout_min) with respect to the defined area, a second water temperature set point corresponding to a maximum outdoor temperature (Tout_max) for which heating is required in the defined area, and a plurality of water temperature set points between the first and second set points and corresponding to outdoor temperatures (Tout) between the minimum and maximum outdoor temperatures (Tout_min; Tout_max) with respect to the defined area; characterized in that the system further comprises a thermostat cycling feedback loop wherein the controller is further configured to dynamically adjust at least the first water temperature set point and the corresponding nonlinear output reset curve based on a thermostat cycling input.