On a hydronic heater system, what control responds to a load change?

In a hydronic heating system, the control that responds to a load change is the flow switch. The flow switch detects the flow of water within the system and is instrumental in ensuring that the heating source, such as a boiler, operates efficiently and safely. When there is a change in the heating load—such as an increase in demand for heat—this can lead to a change in water flow rate. The flow switch will respond to these changes by either activating or deactivating the heating elements to maintain the desired water temperature and flow throughout the system.

This mechanism is essential, as it helps the system to react promptly to variations in heating demands, thereby ensuring optimal operation and energy efficiency. Without the proper function of the flow switch, the system might either overheat or fail to meet heating requirements adequately.

The other components, while important for the overall operation of the hydronic system, do not respond directly to load changes in the same manner. The low water cut-off is a safety device that prevents equipment damage by shutting off the burner in case the water level drops too low. The expansion tank absorbs excess pressure in the system due to thermal expansion of water but does not perceive load changes directly. The aquastat, while it does regulate the