Air-cooled vs liquid-cooled generators

Air-cooled generators come with engines that use fans to force air across the engine for cooling, while liquid-cooled generators use enclosed radiator systems for cooling, similar to an automobile. Generally, liquid-cooled engines are used on larger kW generators due to the larger engines required for the higher power output.

Air-cooled generators

Air-cooled units use internal fans to force air across the different parts of the generator. This keeps the generator from overheating. 

Wattages

7.5kW, 10kW, 14kW, 18kW, 22kW, 24kW, 26kW, and 28kW

Benefits

• Size - Air-cooled generators are smaller than liquid-cooled generators.
• Weight - Air-cooled generators are lighter than liquid-cooled models.
• Placement - Air-cooled generators are more flexible regarding installation locations and are quicker to install.
• Fuel efficiency - Generac's air-cooled generators are more fuel efficient than liquid-cooled models.
• Price - Generac's air-cooled generators are less expensive than liquid-cooled models.
• Bundles - Can come prepackaged with an automatic transfer switch.
• Wind rating - 150 mph wind rating (180 mph for PowerPact).

Liquid-cooled generators

Liquid-cooled units include a radiator and water pump. The pump distributes coolant to the engine. The heat of the engine is transferred to the coolant, which flows into the radiator where it’s cooled by air.

Wattages

22kW, 25kW, 27kW, 30kW, 32kW, 36kW, 38kW, 45kW, 48kW, 60kW, 80kW, 100kW, 130kW and 150 kW.

Benefits

• 3-phase power options - Liquid-cooled generators can provide three alternating currents for more reliable power delivery: What's the Difference Between Single-Phase and 3-Phase Power?
• Power - Generac's liquid-cooled generators have larger engines and alternators resulting in more power capacity than air-cooled models. This additional power is often required by commercial applications, although liquid-cooled generators can also be used for residential applications.
• Superior cooling - When temps climb over 120⁰ F, air-cooled units can overheat and shut down.
• Fuel - Liquid-cooled generators have three fuel options: Liquid propane, natural gas, or diesel. 

Additional differences

• Liquid-cooled generators are not packaged with transfer switch options
• Liquid-cooled generators have a 12-minute exercise cycle by default. A dealer can extend this up to 60 minutes.
• Liquid-cooled generators do not have status LEDs
• Liquid-cooled generators must be mounted on a concrete slab
• Liquid-cooled generators do not have wind ratings