A 4 pipe HVAC system is a type of heating, ventilation, and air conditioning system that uses four separate pipes to distribute heated and cooled air throughout a building. This type of system is typically used in large commercial buildings, as it allows for greater flexibility in controlling the temperature of different areas. With a 4 pipe system, one pipe supplies hot air to areas that need to be heated, while another pipe supplies cold air to areas that need to be cooled. Two additional pipes are used to return the air back to the HVAC unit. This type of system is more efficient than a two-pipe system, as it allows for more precise temperature control in different areas. Additionally, it can be more cost-effective in the long run, as it eliminates the need for multiple HVAC units. The 4 pipe system is a great choice for larger buildings that need to be able to control the temperature in different areas.