What two temperature readings are required to use a manufacturer's charging chart?

To effectively use a manufacturer's charging chart, it is essential to know the indoor wet bulb temperature and the outdoor dry bulb temperature. The indoor wet bulb temperature is critical because it reflects the moisture content and temperature of the air entering the system, which significantly influences the efficiency of refrigeration and air conditioning operations. The outdoor dry bulb temperature provides a reference for the ambient conditions affecting the system's performance and allows the technician to determine the appropriate refrigerant charge needed for optimal operation.

By obtaining these two temperature readings, technicians can accurately assess and adjust the refrigerant charge to maintain efficient system performance in varying environmental conditions. This information is crucial for ensuring the system operates within its designed specifications and enhances energy efficiency while preventing potential refrigeration issues.