What is the first step in the sequence of events when commissioning an EPR?

The first step in the sequence of events when commissioning an Electronic Expansion Valve (EPR) is to open the EPR fully. This step is crucial because it allows the refrigerant to flow through the system unimpeded, facilitating a stable starting condition to observe system behavior. Opening the valve fully ensures that you start the commissioning process with maximal flow, which helps in diagnosing and setting the rest of the system parameters under actual operating conditions.

By doing this, the technician can assess whether the system operates effectively and can effectively register the refrigerant flow and temperatures throughout the system. This initial action sets a foundation for subsequent steps like adjusting the EPR setting and fine-tuning the system to achieve optimal performance based on the design specifications. Overall, opening the EPR fully is an essential part of understanding the system's behavior before making further adjustments.