Understanding the fundamental equations used in HVAC and refrigeration systems is crucial for accurate design, troubleshooting, and maintenance. Key calculations often involve thermodynamic principles such as the ideal gas law, specific heat capacities, and enthalpy changes. For instance, calculating the cooling load requires understanding both sensible and latent heat transfers, which can be expressed through equations involving temperature differences and moisture content. Another vital aspect is the calculation of compressor work, which can be estimated using thermodynamic equations derived from the refrigeration cycle. The Coefficient of Performance (COP) is also a frequently used metric, defined as the ratio of cooling or heating provided to the energy consumed. Accurate determination of these parameters ensures system efficiency and optimal operation. Additionally, psychrometric calculations are integral to HVAC systems, involving the relationship between air temperature, humidity, and enthalpy. Equations such as the ones used to determine the humidity ratio or dew point are essential tools for professionals working in system design and air-quality control. Mastery of these equations enables technicians to properly size components, select appropriate refrigerants, and troubleshoot system issues effectively.