What sensing element is used to control water temperature in a gas-fired hydronic heating system?

In a gas-fired hydronic heating system, the appropriate sensing element for controlling water temperature is the thermal sensing element. This type of sensor is designed to respond to temperature changes, allowing for precise regulation of water temperatures within the system.

Thermal sensors, often in the form of thermocouples or thermistors, can detect the temperature of the water and provide feedback to the system's control mechanism. This feedback ensures that the gas-fired system maintains the desired water temperature, optimizing efficiency and comfort. Maintaining the correct water temperature is crucial for both safety and system performance, influencing the overall heating efficiency.

The other types of sensors, such as level, pressure, and flow, serve distinct functions. Level sensors are designed to detect the amount of liquid in a tank, pressure sensors monitor the pressure levels within the system, and flow sensors measure the rate of water flow. While all these elements are important in HVAC systems, they do not have the specific function of directly controlling water temperature as thermal sensors do.