A 4 pipe fan coil unit is a type of heating and cooling system that is typically used in commercial buildings. It consists of two separate coils, one for heating and one for cooling, connected to four separate pipes. The four pipes are connected to a fan that circulates air through the coils, providing heating or cooling depending on the temperature setting. The fan coil unit is an efficient and cost-effective way to heat and cool a building, as it requires no additional equipment such as a furnace or air conditioner. It is also relatively easy to install and maintain, making it a popular choice for many commercial buildings. The fan coil unit is an important part of any HVAC system, as it helps to maintain a comfortable temperature throughout the building.