HVAC studies range in scale from single components (such as a radiator) to large and complicated systems (such as a climate control system for a large building).
Physical processes that are commonly modeled in HVAC simulations include:
Buoyancy
Thermal radiation
Conjugate heat transfer (CHT) between fluids and solids.
Typical HVAC systems include the following components:
Heating/cooling units such as furnaces, heaters, air conditioners, and radiators
Fans/pumps
Thermostats.