Last updated: March 2026

RS20A

Power: 20kW LP / 18kW NG
Installed Cost: $11,000–$16,000
Noise: 65 dB
Weight: 531 lbs
Warranty: 5 years
Fuel: Dual-fuel (NG/LP)

Best for: 2,500–3,000 sq ft where noise matters. Quietest 20kW available. Built-in load management.

The RS20A is the top of Cummins' residential line. At 65 dB across all operating modes, it's quieter than anything else at this output. With built-in load management, it handles loads that would normally require a 24–26kW from competitors. Cummins claims it can start a 5-ton AC under full pre-load.

What This Generator Keeps Running

3-4 ton AC (Cummins claims 5-ton startup with load management), electric water heater (load-managed), refrigerator, freezer, furnace, sump/well pump, all lighting, home office.

Limitations: 20kW is the ceiling for Cummins residential. If your loads exceed it, you need a different brand.

What It Actually Costs

Unit price

$5,804

Installed

$11,000–$16,000

RS20AC bundle at $6,833 includes 200A ATS: $146 less than the Generac 22kW + ATS at $6,979, with load management included.

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How Loud Is It?

65 dB always. During a multi-day outage, 2 dB quieter than Generac 22kW (67) and 4 dB quieter than Kohler 20RCA at full speed (69).

How Big Is It?

Same compact Cummins footprint. 531 lbs gen only, 596 lbs with ATS bundle.

Maintenance

Same engine as RS13A and RS17A. Same service, same parts, same cost.

Pros & Cons

What's good

✓Quietest 20kW available: 65 dB in all modes
✓Built-in load management (4 appliances) punches above its weight
✓5-ton AC startup claim (manufacturer-stated, not independently verified)
✓Smallest footprint at this output
✓Four purchase configurations (standard/extreme, with/without ATS)
✓Clean recall record
✓Remote start/stop via Cloud Connect

What's not

✗20kW is the ceiling: need more and Cummins can't help
✗18 kW on NG: only QuietConnect model with derating
✗Dealer network still growing in some regions
✗Service call prepayment ($1,200) reported
✗Cloud Connect cloud outages
✗5-ton AC claim not independently verified

Frequently Asked Questions

Can the Cummins 20kW really start a 5-ton AC?▾

Cummins claims it can using built-in load management to shed other loads during compressor startup. We haven't independently verified this. Have your installer confirm with your specific AC system.

Cummins RS20A vs Generac 22kW?▾

Cummins: quieter (65 vs 67 dB), smaller, built-in load management, clean recall record. Generac: 2 more kW on propane, 1.5 more on NG, larger dealer network. Cummins is $1,000 less installed.

What's the difference between all the RS20A variants?▾

RS20A: gen only, standard cold (0°F). RS20AC: gen + 200A ATS. RS20AE: gen only, extreme cold (-40°F). RS20ACE: gen + ATS + extreme cold. Pick based on whether you need the ATS bundled and your climate.

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