A 20 ton package unit is a type of air conditioning system that is typically used in commercial buildings. It is a self-contained unit that is installed on the roof of the building and is used to provide air conditioning and heating to the building. The package unit consists of a condenser, an evaporator, a compressor, and a fan. The condenser is responsible for cooling the air that is drawn in from outside and then passing it through the evaporator, which removes the humidity from the air. The compressor then compresses the air and sends it to the fan, which then pushes the air through the ducts and into the building. The package unit is designed to be energy efficient and cost effective, as it requires minimal maintenance and is relatively easy to install. It is also designed to be durable and reliable, as it is designed to withstand the elements and provide years of reliable service.