Overview#
The Cummins RS25 is a 25 kW liquid-cooled residential standby generator from the QuietConnect RS Series. It marks the transition from the air-cooled RS13A/RS17A/RS20A platform to the liquid-cooled 2.4-liter inline 4-cylinder engine that powers the RS25 through RS40 models. The liquid-cooled design provides better thermal management, longer engine life, and more consistent power output under sustained load.
The RS25 runs on natural gas or propane vapor (field selectable at installation) at 1,800 rpm and produces 69 dB(A) at 23 feet with the Sound Level 1 aluminum enclosure. The enclosure is wind-rated to 180 mph per ASCE 7-10. The unit is equipped for cold weather starts down to -40 F when outfitted with the factory-installed coolant heater and crankcase vent heater.
At 1,109 lbs and 72 x 34 x 45.5 inches, the RS25 requires a larger pad and more structural support than the air-cooled models. PowerCommand 1.1 controls provide electronic governing, self-diagnostics, automatic exercise scheduling, and remote monitoring capability with optional WiFi accessories.
Technical Specifications#
| Parameter | Value |
|---|---|
| Standby Rating | 25 kW |
| Voltage (1-phase) | 120/240V |
| Voltage (3-phase) | 120/208V, 277/480V |
| Frequency | 60 Hz |
| Engine Displacement | 2.4 L |
| Cylinders | 4 (inline) |
| Aspiration | Naturally aspirated |
| Rated Speed | 1,800 rpm |
| Cooling | Liquid-cooled |
| Controller | PowerCommand 1.1 |
| Sound Level | 69 dB(A) at 23 ft (7 m) |
| Dimensions (L x W x H) | 72.0 x 34.0 x 45.5 in |
| Weight | 1,109 lbs |
| Wind Rating | 180 mph (ASCE 7-10) |
| Cold Weather | -40 F (with factory accessories) |
Our Service Experience#
The RS25 is the entry point for liquid-cooled residential generators in the Cummins lineup. The 2.4L engine is compact and reliable, but it adds coolant system maintenance that the air-cooled models do not require. The factory-installed coolant heater must be plugged in at all times -- it keeps the engine block warm for fast starting and prevents condensation damage during extended standby periods.
Service intervals are longer than the air-cooled models: oil change at 500 hours or annually, air filter at 500 hours, spark plugs at 1,000 hours. The coolant should be tested annually and replaced per Cummins specifications (typically every 2-3 years or when antifreeze protection degrades).
Battery condition remains the most common service issue. We recommend weekly exercise and annual battery load testing. The PowerCommand 1.1 controller makes diagnostics straightforward -- fault codes, runtime hours, and exercise history are all accessible from the front panel display.
Frequently Asked Questions#
What is the standby rating of the RS25? 25 kW at 120/240V single phase (104 amps on both fuels) or 120/208V three phase. The rating is identical for natural gas and propane vapor.
How does the RS25 compare to the RS20A? The RS25 is a liquid-cooled unit with a 2.4L inline-4 at 1,800 rpm, while the RS20A is air-cooled with a 999 cc V-twin at 3,600 rpm. The RS25 delivers 25% more power, runs at half the engine speed (longer engine life), and provides better thermal management. The trade-off is higher weight (1,109 vs 531 lbs), larger footprint, and coolant system maintenance.
What is the warranty on the RS25? 2-year limited warranty from Cummins. Extended options available up to 10 years.
