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A dual fuel standby generator lets you run on either natural gas or propane, which matters when one supply is interrupted, rationed or simply unavailable during a storm. Most buyers want a unit that starts automatically during an outage, carries enough output for the circuits they care about, and runs at a noise level their neighbors and their own household can live with. This list is built from manufacturer specifications, brand reputation and the patterns owners commonly report about installation, fuel flexibility and service. We have not tested these units ourselves, so treat the specs as manufacturer-stated figures and confirm them against the current data sheet before you buy.
Our Top Picks
Quick Comparison
| Product | Best for | Key feature |
|---|---|---|
| Generac Guardian Series 22kW | Full-home backup in a mid-size house | Automatic transfer and wide product line |
| Generac Generac Home Standby 14kW | Essential circuits in a smaller home | Lower output with dual fuel capability |
| Kohler 20RESCL | Owners who want a heavy-duty, long-life unit | Engine built for frequent use |
| Kohler 24RESCL | Larger homes with high starting loads | Higher output for central air and well pumps |
| Cummins Onan 22RESA | Buyers who prioritize quiet operation | Low-speed design for reduced noise |
| Briggs & Stratton 40kW Standby | Larger properties needing substantial power | High output for whole-house loads |
| Champion 13000-Watt Standby | Budget-minded buyers with modest loads | Entry-level standby option |
| Generac 26kW Dual Fuel Standby | Rural homes with mixed fuel access | Strong output for larger households |
Generac Guardian Series 22kW
This is a common choice for homeowners who want whole-house coverage in a mid-size home and prefer a brand with a broad dealer and service network. It suits people who plan to have an installer size the unit to their load calculation.
Key specs
- Rated output of 22 kW on natural gas and propane (manufacturer-stated)
- Automatic transfer switch integration
- Air-cooled, enclosed weatherproof housing
- Designed for permanent outdoor pad mounting
Pros
- Wide installer and service availability
- Automatic start and transfer during outages
- Dual fuel operation gives flexibility when one supply fails
Cons
- Noise at full load is noticeable close to the unit
- Installation cost depends heavily on transfer switch and gas line work
Generac Home Standby 14kW
A smaller-output unit aimed at households that only need essential circuits such as refrigeration, lighting, furnace blower and a few outlets. It fits condos, smaller single-family homes and buyers who want to keep the installation footprint modest.
Key specs
- Rated output around 14 kW (manufacturer-stated)
- Dual fuel capable with natural gas or propane
- Automatic exercise cycle for routine self-checks
- Weather-resistant enclosure for outdoor installation
Pros
- Lower output means a smaller, less intrusive installation
- Automatic exercise cycles help the engine stay ready
- Good fit for essential-load backup
Cons
- Not enough capacity for large central air systems in many homes
- Requires careful load planning to avoid overloading
Kohler 20RESCL
Kohler is widely known for engine durability, and this model suits owners who expect frequent outages or want a unit they can run for long stretches. It is a reasonable pick for rural properties where service calls take longer.
Key specs
- Rated output of about 20 kW (manufacturer-stated)
- Dual fuel operation on natural gas and LP
- Air-cooled engine in an enclosed housing
- Compatible with automatic transfer switches
Pros
- Strong reputation for engine longevity
- Good output for whole-home essentials
- Dual fuel flexibility for mixed supply situations
Cons
- Installed price and required accessories add complexity
- Service depends on local Kohler-authorized dealers
Kohler 24RESCL
A step up in output for households with larger loads such as central air, electric water heaters and well pumps running together. It suits larger homes where the 20 kW class would be marginal after a load calculation.
Key specs
- Rated output of about 24 kW (manufacturer-stated)
- Dual fuel capable on natural gas and propane
- Enclosed, weather-resistant housing
- Automatic transfer compatible
Pros
- Higher capacity for demanding whole-home loads
- Durable engine design owners often praise for reliability
- Fuel flexibility helps during supply disruptions
Cons
- Larger footprint and heavier unit need a stable pad
- Higher output usually means more noise under load
Cummins Onan 22RESA
Onan units are known for relatively low operating noise, which makes this model a good consideration for homeowners with close neighbors or noise-sensitive households. It fits buyers who value quiet operation as much as capacity.
Key specs
- Rated output of around 22 kW (manufacturer-stated)
- Dual fuel capable on natural gas and LP
- Designed with noise-conscious enclosure and engine speed settings
- Automatic transfer switch compatible
Pros
- Generally regarded as one of the quieter standby options
- Solid output for whole-home backup
- Good match for noise-sensitive neighborhoods
Cons
- Dealer network is smaller than the largest competitors
- Parts and service may take longer to arrange in some areas
Briggs & Stratton 40kW Standby
A high-output unit for large properties, workshops or homes with substantial electrical demand. It is best suited to buyers who have had a detailed load analysis and expect heavy continuous use.
Key specs
- Rated output around 40 kW (manufacturer-stated)
- Designed for natural gas and propane operation
- Enclosed outdoor housing with weather protection
- Requires professional sizing and installation
Pros
- Large capacity covers most residential whole-house loads
- Suitable for properties with multiple high-draw appliances
- Robust build for heavy use
Cons
- Much larger and louder at full load than smaller units
- Likely oversized for average homes, adding unnecessary cost
Champion 13000-Watt Standby
A budget-minded option for buyers with modest backup needs, such as refrigeration, a furnace blower and some lighting. It is a sensible starting point when the goal is covering essentials rather than running the whole house.
Key specs
- Rated output around 13,000 watts (manufacturer-stated)
- Dual fuel capable on natural gas and propane
- Automatic start features on compatible configurations
- Outdoor enclosure for permanent installation
Pros
- Budget-friendly entry into standby power
- Covers essential loads in smaller homes
- Dual fuel gives backup fuel options
Cons
- Not suitable for central air or large electric heat
- Smaller brand service footprint in some regions
Generac 26kW Dual Fuel Standby
A larger Generac option for households that need more headroom, especially in rural areas where propane is the backup fuel of choice. It suits homes with well pumps, multiple HVAC zones and a desire for extra margin.
Key specs
- Rated output around 26 kW (manufacturer-stated)
- Dual fuel operation on natural gas and propane
- Automatic transfer switch integration
- Weatherproof enclosure for outdoor mounting
Pros
- Extra capacity for demanding whole-home loads
- Wide dealer and parts availability
- Good fuel flexibility for rural properties
Cons
- Full-load noise can carry to neighboring properties
- Requires adequate clearance and a suitable pad for safe placement
Buying Guide
Selection criteria
A dual fuel standby generator is a permanent installation, so the decision rests on four things: how much power you need, which fuel supplies you can rely on, how much noise you can accept, and how well the unit will be serviced over its life. Start with a load calculation from a licensed installer rather than a guess, because an undersized unit will trip or stall, while an oversized one adds cost and noise without benefit.
Important features
- Automatic transfer switch compatibility for hands-off outage response
- Dual fuel capability so you can switch between natural gas and propane
- Weather-resistant enclosure rated for outdoor pad mounting
- Automatic exercise cycles that keep the engine and battery ready
- Engine reputation and local service availability
Specs to check
- Rated output in kW, confirmed against your load calculation
- Fuel consumption figures for natural gas and LP at 50 and 100 percent load
- Noise rating in dBA at a stated distance, usually 23 feet (7 meters)
- Required clearances to walls, windows, vents and property lines
- Warranty length and what it requires for maintenance records
Noise figures from manufacturers are often measured under lab conditions. For how to read them and compare fairly, see Generator Decibel Ratings Explained: What dBA Numbers Mean and How to Compare Generator Noise Ratings Fairly.
Choosing by need
- Essential circuits only: a smaller unit in the 13 to 14 kW class is usually enough.
- Whole-home with central air: plan for the 20 to 26 kW range, depending on the load calculation.
- Large property or heavy loads: consider the 40 kW class, but only with a professional sizing study.
- Noise-sensitive neighborhood: prioritize the lowest-rated dBA unit that meets your load and plan placement carefully.
Placement affects what you hear as much as the rating does. See Where to Place a Generator for Less Noise and Safe Exhaust and Sound Barriers for Generators: Placement, Materials and Clearance before finalizing your pad location.
Things to watch out for
- Do not size by advertised peak watts alone; match rated kW to your calculated load.
- Confirm that your gas line can supply enough flow for the unit at full load.
- Check local code requirements for permits, setbacks and inspections.
- Plan for vibration; mounting and pads matter. See Reducing Generator Vibration Noise: Pads, Mounts and Surfaces.
- Never run any generator indoors or in an attached garage, because exhaust carbon monoxide can be lethal.
Installation involves gas, electrical and building code work. Consult a licensed electrician, a qualified gas fitter and your local building department before purchase or installation.
FAQ
What does dual fuel mean on a standby generator?
Dual fuel means the engine can run on either natural gas or liquid propane (LP). Many owners use natural gas as the primary fuel and keep propane as a backup, or the reverse, depending on which supply is more dependable where they live.
Is natural gas or propane better for a standby generator?
Natural gas offers a continuous supply through the utility line, but it can fail in a major outage. Propane is stored on site, which helps during disruptions, but tank levels must be maintained. Many people choose dual fuel so they are not dependent on only one source.
How big a standby generator do I need for a house?
Size depends on the total of the loads you choose to back up. A licensed installer should perform a load calculation that includes starting surges from motors such as central air compressors and well pumps. Smaller homes covering essentials may need around 13 to 14 kW, while whole-home backup often falls in the 20 to 26 kW range.
How loud is a standby generator?
Manufacturers typically publish noise ratings in dBA at about 23 feet. Full-load operation is louder than idle or light load, and placement, enclosure design and surfaces around the unit all change what neighbors hear. Compare figures measured at the same distance and conditions.
Do standby generators need regular maintenance?
Yes. Oil changes, air filter checks, spark plug service and battery inspection are part of routine care, and many manufacturers recommend periodic professional inspections. Keeping the unit serviced also helps it start reliably during an outage.
Can a dual fuel standby generator be installed without a professional?
Generally no. Permanent installation involves gas connections, transfer switch wiring and code-compliant placement. Hire licensed professionals and check local permit requirements before work begins.
Does a standby generator run automatically during an outage?
Standby units are designed to detect a utility outage through an automatic transfer switch, start, and transfer the load without manual action. Many units also run scheduled self-tests, though the test schedule and noise level should be confirmed for your model.
Conclusion
For smaller homes that only need essential circuits, a 13 to 14 kW class unit such as the Champion 13000-Watt Standby or the Generac Home Standby 14kW is a practical place to start. Mid-size homes with central air generally fit the 20 to 24 kW range, where the Generac Guardian Series 22kW, Kohler 20RESCL, Kohler 24RESCL and Cummins Onan 22RESA are reasonable candidates; buyers who weigh noise heavily may lean toward the Onan. Larger properties or homes with heavy continuous loads should look at the Generac 26kW Dual Fuel Standby or the Briggs & Stratton 40kW Standby after a professional load study. Whatever you choose, confirm the specifications with the manufacturer, base your decision on a load calculation, and have a licensed installer handle the gas, electrical and code requirements.
