The five main procedures in HVAC are: 1) Heating – This involves the use of a furnace, boiler, or heat pump to provide warmth to a space. 2) Ventilation – This involves the use of fans, ducts, and other equipment to provide fresh air to a space. 3) Air Conditioning – This involves the use of an air conditioner to cool a space. 4) Humidification – This involves the use of a humidifier to add moisture to a space. 5) Filtration – This involves the use of filters to remove dust, pollen, and other airborne particles from a space. Each of these procedures is essential for providing a comfortable and healthy environment in any space.