What Is a Air-Cooled vs. Liquid-Cooled?

Air-cooled generators use a fan to cool the engine and are the standard choice for most residential systems up to about 26 to 28 kW, depending on the brand (Generac's air-cooled line goes to 28 kW). They're less expensive and adequate for typical home backup needs. Liquid-cooled generators use a radiator-based cooling system similar to a car engine, allowing for larger capacity than air-cooled units, at a higher price point. Most whole-home residential installations use an air-cooled unit; liquid-cooled units become more common for larger homes or light-commercial applications.