Cummins RS20A 20kW Air-Cooled Generator Review

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The consumer has many buying choices when shopping for a home standby generator, including offerings from Generac, Kohler, GE, Briggs & Stratton, Cummins, and more.  The selection process can be daunting for the uninitiated.

Generac’s impressive marketing and vast dealer network factors heavily in the firm’s longstanding domination of the residential market for standby power.  In recent years, other viable contenders have been growing market share with an impressive line of generators causing consumers to pause and consider Generac’s competition.

Today’s article focuses on one such competitor in the air-cooled generator arena, the RS20A from Cummins Power Generation.  Before we begin dissecting the features and benefits of this impressive 20kW air-cooled generator, let’s take a brief look at the company.

Cummins Power Generation has a long history in creating innovation from its beginning in the 1920s with David Onan’s invention of the TENLITE generator to today’s impressive lineup of power generation products in residential, industrial, mobile, and marine applications.  Today, Cummins Power Generation is a division of Cummins, Inc., a world leader in the design and manufacture of diesel engines, where its gaseous and diesel generators are distributed in over 190 countries to markets including data centers, health care facilities, commercial office buildings, and hospitals. 

Every year, Builder magazine surveys over 3,000 U.S. homebuilders on the best performing builder products and in each of the past four years has awarded Cummins with the Brand Leader award. 

With that introduction, let’s take a close look at the Cummins RS20A air-cooled generator.

Innovative Design

The image below depicts a creative design and engineering achievement from Cummins that combines an aesthetically pleasing enclosure with ease of service and installation.  The ingenious design also factors into why the Cummins RS20A is the quietest 20kW air-cooled generator on the market.

While competitors manufacture steel and aluminum housings, every Cummins RS20A generator will come with a thick 11-gauge aluminum enclosure with resilient architectural grade powder coat paint, making it an ideal housing choice in every application, including coastal areas.

Ventilation and engine cooling is, perhaps, the most inventive element with the added bonus of very quiet operation.  Most competitors have side-mounted vents for air intake and exhaust.  Step to the side of a competitive unit while it is in operation, and you’ll notice a marked increase in noise levels.  Not the case with the Cummins RS20A

Low Noise Output

Notice from the picture above how ventilation through the lid wraps all the way around the lid, pointing engine noise down and not out.  A large automotive grade corrosion resistant muffler design also helps keep noise levels low in all directions around the generator.  In fact, the Cummins RS20A’s sound output of 62dB(A) is the lowest in the industry.        

Most manufacturers measure sound output when standing 23-feet away, directly in front of the unit.  Step to the side of one of these competitor units, and listen as sound levels increase markedly.  No wonder competitors use only one microphone to measure sound!  Cummins does it different at its Acoustical Testing Center in Fridley, Minnesota where eight (8) microphones are placed around the generator.  Because there are no side-mounted vents on the Cummins RS20A generator, sound output levels is the same (62 decibels) in all directions. 

Hearing is believing, so listen to this brief sound persuader video on the Cummins RS20A:

Cummins 20kw Generator - RS20A Sound Test from Buckeye Power Systems on Vimeo.


Low Carbon Emissions

Read the small print in some competitor descriptions and you’ll note the unit is “Not for sale in California or Massachusetts.”  That’s because emission certifications do not meet the stringent requirements from these two states.  However, unlike the competition, every Cummins RS20A is U.S. EPA and CARB Emissions Certified and available for sale in all 50 states.  

Cummins Engineered Alternator

The alternator is a component seldom considered by most consumers.  But the alternator is where the real work gets done with standby generators and, while some competitors use alternators made in China, Cummins designs, engineers, and manufactures its own alternators and electronic controls right here in the U.S.A. 

More Flexibility with Periodic Exercise Routines

Automatic standby generators are programmed to perform a periodic exercise routine that typically lasts 10-20 minutes.  The Cummins RS20A can be programmed to perform this exercise on a weekly, bi-weekly, or monthly basis.  Most manufacturers offer only a weekly exercise routine.  We program our RS20A installations to perform a monthly exercise, saving consumers considerably on fuel expense and wear and tear.


We’ve been an authorized dealer for Cummins Power Generation products for three years and we give Cummins high marks for consistent, reliable power.  Perhaps that’s why Cummins uses its trademark protected slogan, “Performance you rely on.™”   Simply put, Cummins manufactures a quality product with excellent reliability and backed by a 5-year, 2000-hour limited warranty.

Cummins recommends the Cold-Weather equipped version for areas of the country where temperatures routinely falls below 0 degrees.  The Warm-Weather version is, generally, recommended for areas south of the Mason Dixon line.

The Bottom-line

Buckeye Power Systems is proud to recommend the Cummins RS20A air-cooled generator as your best solution for reliable standby power.  We offer cold-weather equipped versions as well as warm-weather versions at a price that can’t be beat anywhere.  Period.