The cooling method of an air compressor affects installation cost, energy use and maintenance. Air-cooled machines are simpler and dominate the small and medium range, while water-cooled machines remain common in large plants and hot environments.
Air-cooled compressors
Air-cooled machines reject heat through a fan and radiator, needing no cooling water. They are easy to install, but the rejected heat must be ventilated from the room. In hot climates or poorly ventilated spaces, they run hotter and use more energy.
Water-cooled compressors
Water-cooled machines transfer heat to a cooling water loop, which is more effective and quieter, and the heat can be recovered more easily. They need a water supply, treatment and a cooling tower or chiller, adding installation and maintenance cost.
How to decide
Choose air cooling for most installations under roughly 100 kW with adequate ventilation. Choose water cooling for large machines, high ambient temperature, limited airflow, or when heat recovery to a water loop is valuable. Always weigh the running cost of the cooling system against the simpler air-cooled alternative.