What device is essential for controlling temperature in a hydronic system?

The thermostat is essential for controlling temperature in a hydronic system because it serves as the primary device for monitoring and regulating the temperature of the water circulating within the system. By sensing the temperature of the water and the space that needs to be heated or cooled, the thermostat can signal the boiler or heating source to either increase or decrease the temperature accordingly. This creates a balanced and comfortable indoor environment while ensuring efficient operation of the heating system.

The other devices have important functions in a hydronic system, but they do not actively control the temperature. A pressure gauge measures the pressure within the system, which is crucial for ensuring safe operation but does not influence temperature control. A flow meter is used to measure the flow rate of the water in the system, helping maintain proper circulation but again, does not regulate temperature. A heat exchanger facilitates the transfer of heat between two fluids, but it relies on an external control mechanism, such as a thermostat, to ensure the desired temperature is maintained. Thus, the thermostat plays a critical role in managing the overall thermal comfort provided by the hydronic system.