Where is the TXV sensing bulb never to be placed on the suction line?

The sensing bulb of a thermal expansion valve (TXV) plays a crucial role in regulating the flow of refrigerant through the system based on the temperature of the suction line. It is critical that the sensing bulb is placed correctly to ensure accurate temperature readings and proper system operation.

Placing the sensing bulb on the bottom of the suction line is not appropriate because this position can cause the bulb to be exposed to liquid refrigerant instead of the vapor that it needs to sense. The purpose of the sensing bulb is to detect the vapor temperature, which helps in adjusting the flow of refrigerant to maintain optimal cooling performance. When the bulb is positioned on the bottom of the suction line, it may not accurately represent the temperature of the refrigerant vapor, leading to improper system function, fluctuations in cooling performance, and potential system damage.

In contrast, placing the sensing bulb on the top, right side, or left side of the suction line allows it to accurately measure the vapor temperature, as these positions facilitate better exposure to the vapor phase of the refrigerant and avoid liquid refrigerant saturation. Therefore, avoiding placement on the bottom is essential for the reliable operation of the TXV and overall HVAC system efficiency.