Where is a high pressure limit control typically installed?

A high pressure limit control is generally installed in the compressor discharge line. This location is crucial because it allows the control to monitor the pressure levels of the refrigerant as it exits the compressor, where the highest pressures typically occur. If the pressure exceeds a predetermined limit, the control can deactivate the system or initiate other safety measures to prevent damage, such as system failure or hazardous conditions.

The compressor discharge line is a vital component in maintaining the overall safety and efficiency of the heat pump. By directly monitoring the highest pressure point, the control acts as a protective mechanism, ensuring that the system operates within safe parameters.

In contrast, placing a high pressure limit control in the suction line would not provide the necessary monitoring of discharge pressures, as that line contains refrigerant at lower pressures. Similarly, the evaporator coil, while important for the heat exchange process, does not handle the highest pressure within the system, making it an unsuitable location for the high pressure limit control. The thermostat unit is primarily designed for regulating temperature rather than pressure, further validating why it is not the correct installation point for high pressure limit controls.