Generally the performance of the thermostatic expansion valve depends upon the correct location of the thermal bulb. This should be clamped firmly to a horizontal section of the suction line near to the evaporator outlet if possible, and preferably within the refrigerated space. The entire length of the bulb should make good thermal contact with the pipework, as illustrated in Figure 18.
The location of the bulb relative to the diameter of the tubing is also important. It must never be located on the underside of the pipework, where it will register false temperatures because of the presence of oil in the pipework.