The three major parts of an HVAC (Heating, Ventilation, and Air Conditioning) system are:
Heating system: This part of the HVAC system is responsible for providing heat to the building. It can be powered by various sources such as natural gas, propane, electricity, or oil. The most common heating systems are furnaces, boilers, and heat pumps.
Ventilation system: The ventilation system is responsible for providing fresh air to the building and removing stale air. It includes components such as air ducts, air filters, and ventilation fans.
Air conditioning system: The air conditioning system is responsible for cooling and dehumidifying the air in the building. It can be a central air conditioning system or a split system with individual units for each room. The most common types of air conditioning systems are central air conditioners, heat pumps, and ductless mini-split systems.