The 2020 ASHRAE Handbook—HVAC Systems and Equipment discusses various systems and the equipment (components or assemblies) that comprise them and describes features and differences. This information helps system designers and operators in selecting and using equipment. Major sections discuss air-conditioning and heating systems; equipment and components for air handling, heating, cooling, and general application; packaged, unitary, and split-system equipment; and general systems. This volume is published as a bound print volume, in PDF format, and online, in two editions: one using inch-pound (I-P) units of measurement, the other using the International System of Units (SI).