Figure 1 shows a System 450 reset control system that uses an outdoor air temperature master sensor and a supply water temperature sensor configured to reset the boiler supply water temperature relative to the outdoor air temperature. This control system can also be configured to use the run-time balancing feature to equalize the time that each of the three boilers run.
Figure 1. Example System 450 reset control system for a three-stage boiler with or without
run-time balancing