Where must the sensor bulb on a TEV be installed on the suction line?

The correct placement for the sensor bulb of a thermostatic expansion valve (TEV) on the suction line is on the top of the line for lines smaller than 7/8 inches in diameter. This positioning is crucial because it ensures that the sensor bulb effectively senses the refrigerant's temperature and pressure conditions. By placing the bulb on the top of the suction line, it is less likely to be influenced by any refrigerant oil that may settle at the bottom, allowing for a more accurate reading of the vapor's temperature. This accuracy is vital for the TEV to respond properly to varying cooling demands and to maintain optimal system efficiency.

For lines larger than 7/8 inches, the guidelines may change, but for smaller lines, this specific placement targets the best performance of the TEV, preventing issues like underfeeding or overfeeding the evaporator due to incorrect sensor readings.