Where should the bulb of a TXV be attached during system maintenance?

The bulb of a TXV (Thermostatic Expansion Valve) should be attached to the outlet end of the coil during system maintenance. This location allows the bulb to effectively sense the temperature of the refrigerant leaving the evaporator. By being positioned here, the TXV can accurately control the flow of refrigerant into the evaporator based on the cooling demands of the system. Proper placement ensures that the valve opens and closes correctly to maintain the desired superheat level, optimizing system efficiency and preventing issues such as liquid refrigerant returning to the compressor.

Placing the bulb at the inlet end of the evaporator would not provide accurate readings of the refrigerant state after it has absorbed heat, leading to potential system malfunctions. Similarly, attaching it to the compressor discharge line would expose it to excessively high temperatures and pressures, which could result in improper function. Positioning the bulb on the receiver-drier would also be ineffective, as it is too far down the refrigerant circuit and does not allow for accurate monitoring of the evaporator's performance.