Tri-Fuel Generators: Gasoline vs Propane vs Natural Gas & Are They Worth It?

What Is a Tri-Fuel Generator?

A tri-fuel generator is designed to run on three fuels:

1. gasoline
2. propane/LPG
3. natural gas

Current portable examples use a fuel selector and appropriate hoses/regulators to switch between supported fuels.

Champion's current 201438 includes both:

• propane hose
• 25-foot natural-gas hose

and supports all three fuels from the factory.

FIRMAN similarly sells current tri-fuel models ranging from smaller 4,000W-class units through larger 9,200W gasoline-running-output equipment.

Why Tri-Fuel Is So Useful for Home Backup

The key advantage is not merely convenience.

It is supply redundancy.

During an extended outage:

Natural Gas

Use utility-fed gas while service remains available.

No:

• gasoline cans
• propane cylinder swapping
• repeated refuelling

Propane

Use fuel stored before the event.

Useful when:

• gas utility is unavailable
• you want a known reserve
• gasoline availability is poor

Gasoline

Use the fuel that often provides the generator's highest electrical output.

That gives you three distinct failure modes instead of one.

For an emergency-backup machine, that has real value.

Gasoline vs Propane vs Natural Gas Output

This is the most important table on the page.

Current examples:

Champion's current ratings are manufacturer-published at 10,000/9,000/8,000 running watts.

Westinghouse's WGen11500TFc manual lists 11,500W gasoline, 10,500W propane and 9,500W natural-gas continuous output.

FIRMAN's current T09275 drops from 9,200W gasoline to 6,900W natural gas - a 2,300W reduction.

That is why "tri-fuel" alone tells you almost nothing about usable home-backup capacity.

Why Does Natural Gas Usually Produce Less Power?

Gasoline, propane and natural gas have different energy and fuel-delivery characteristics.

The engine therefore may not produce identical maximum output across all three fuels.

For the buyer, the practical conclusion is simple:

natural gas is usually the convenience fuel, not the maximum-output fuel.

Gasoline often wins raw output.

Propane usually sits between the two.

How Much Power Do You Lose on Natural Gas?

It varies materially by generator.

Champion 201438

Gasoline:

10,000W

Natural gas:

8,000W

Reduction:

2,000W / 20%

Westinghouse WGen11500TFc

Gasoline:

11,500W

Natural gas:

9,500W

Reduction:

2,000W / about 17%.

FIRMAN T07573

Gasoline:

7,500W

Natural gas:

5,500W

Reduction:

2,000W / about 27%.

FIRMAN T09275

Gasoline:

9,200W

Natural gas:

6,900W

Reduction:

2,300W / 25%.

That is enough to completely change which household loads fit.

Size the Generator From Natural-Gas Output if NG Is Your Main Fuel

Suppose your calculated backup load is:

8.5 kW

You buy a generator marketed around:

10,000 watts

Sounds fine.

But your intended fuel is natural gas.

Champion 201438:

8,000W NG

Now it is too small for an 8.5 kW continuous requirement.

On gasoline:

10,000W

it fits.

This is why you should use our generator size calculator and compare the result against each fuel rating separately.

What Size Tri-Fuel Generator Do I Need?

For home backup, I would broadly investigate:

But again:

use the NG number if NG is the primary fuel.

A "9,200W" tri-fuel generator could become a 6,900W machine when connected to natural gas.

Best Tri-Fuel Size for Home Backup

For serious panel-connected manual backup, the sweet spot is generally:

roughly 8-10+ kW continuous output on the fuel you actually intend to use.

That means you may need a machine advertised above 10 kW if natural gas is the plan.

The Westinghouse WGen11500TFc is strong here because even after NG derating it still provides:

9,500W continuous on natural gas.

That is substantially more useful than a machine whose NG rating falls into the 5-7 kW range.

Tri-Fuel Generator + Generator Interlock

For a house, this is probably the strongest tri-fuel architecture:

tri-fuel generator → 30A/50A inlet → approved panel interlock → manual load management

You get:

• utility natural gas when available
• propane backup
• gasoline backup
• hard-wired household circuits
• existing electrical panel
• far lower cost than permanent standby

See our generator interlock kit guide.

Tri-Fuel Generator + Manual Transfer Switch

A manual transfer switch works too.

It can be preferable where:

• interlock is unavailable for the panel
• fixed critical loads are preferred
• electrical architecture favours separate transfer equipment

See our generator transfer switch guide.

Is Tri-Fuel Good for Whole-House Backup?

Yes - with realistic expectations.

A large 120/240V tri-fuel generator can supply many household circuits.

But "whole house" does not mean:

everything on simultaneously.

You still have a limited generator.

For example, Champion's 201438 provides on natural gas:

8,000W continuous

or about:

33.1 amps at 240V.

That can power a lot.

It does not reproduce a 200A utility service.

Can a Tri-Fuel Generator Run Central AC?

Some can.

The important inputs are:

• 240V capability
• compressor starting load
• running load
• other simultaneous household demand
• fuel-specific generator output

A large Westinghouse-class tri-fuel unit may support some central AC systems, particularly with sensible load management or an appropriate soft-start device.

But test the actual AC requirements.

Do not buy from tonnage alone.

Can a Tri-Fuel Generator Run a Well Pump?

Yes, with adequate:

• 240V output where required
• running wattage
• motor starting capability

This is one reason I favour large 120/240V tri-fuel machines for rural or well-served properties.

Can a Tri-Fuel Generator Run a Furnace?

Usually, if it is a gas furnace whose electrical demand is primarily:

• blower
• ignition
• controls

That is a relatively modest load compared with electric resistance heating.

A tri-fuel machine using the home's natural gas can therefore power the electrical side of a gas heating system while both systems use the same utility fuel infrastructure.

Natural Gas Is the Convenience Fuel

This is where tri-fuel earns its money.

A suitable NG connection can remove:

• carrying gasoline
• repeated fuel-can refills
• swapping propane cylinders

during an outage.

If the generator is outside, connected safely, and the home's gas supply remains available, you can potentially operate for prolonged periods without touching liquid fuel.

That is a massive quality-of-life improvement versus gasoline-only portable backup.

But Natural Gas Is Still a Utility

Do not confuse convenience with independence.

If the gas utility is interrupted:

your NG option disappears.

That is exactly why propane and gasoline remain useful.

Tri-fuel is compelling because each fuel covers weaknesses in the others.

Propane Is the Stored-Fuel Middle Ground

Propane gives you:

• onsite stored fuel
• easier long-term storage than gasoline
• less fuel-system degradation concern than stale gasoline
• higher output than NG on many models

It usually produces less output than gasoline, but often more than natural gas.

Example:

Champion 201438:

• gasoline: 10,000W
• propane: 9,000W
• NG: 8,000W.

Propane literally sits in the middle.

Gasoline Is the Maximum-Power Option

When you need every available watt:

gasoline usually wins.

That can matter temporarily when starting:

• AC
• well pump
• large appliance

or carrying heavier household loads.

You can therefore use natural gas for routine outage operation and retain gasoline as a higher-output fallback.

That is far more useful than treating fuel selection as a permanent brand identity.

Tri-Fuel vs Dual-Fuel

This is the key buying decision.

Buy Dual-Fuel When:

• property has no NG
• natural gas will never be used
• dual-fuel unit is materially cheaper
• propane already gives you the redundancy you need

Buy Tri-Fuel When:

• property already has NG
• suitable NG connection is practical
• multi-day outages are a real concern
• you want maximum fuel redundancy

For a home already connected to natural gas:

tri-fuel usually wins.

For an off-gas home:

dual-fuel may be all you need.

See our dual-fuel generator guide.

How Much More Is Tri-Fuel Worth?

I would not pay an unlimited premium for the third fuel.

Compare the closest dual-fuel and tri-fuel models on:

• gasoline output
• propane output
• NG output
• outlet configuration
• electric start
• warranty
• price

Then ask:

"What am I actually paying for natural-gas capability?"

If the answer is $100-$200 and you have NG at the property, that can be excellent value.

If the tri-fuel machine costs $800 more while delivering worse output and you barely lose power, the economics are weaker.

Tri-Fuel vs Gasoline-Only

Tri-fuel is generally a much stronger emergency-preparedness product.

Gasoline-only means your outage plan depends on:

• stored gasoline
• fuel rotation
• petrol stations
• manual refuelling

Tri-fuel gives you two additional supply routes.

Unless price/output makes the gasoline-only machine materially better, I would take the redundancy.

Tri-Fuel vs Natural-Gas Standby Generator

This is manual vs automatic backup.

Tri-Fuel Portable

Wins on:

• upfront cost
• fuel flexibility
• mobility
• easy replacement

NG Standby

Wins on:

• automatic start
• automatic transfer
• permanent installation
• unattended operation
• larger residential ecosystem

If you're frequently away from home, tri-fuel's manual nature matters.

The generator cannot roll itself outside and connect the inlet.

Tri-Fuel vs Propane Standby Generator

Same principle.

Propane standby gives:

• automatic operation
• permanent storage
• seamless transfer

Tri-fuel portable gives:

• much lower capital cost
• three fuel choices
• mobility

Your willingness to operate the system manually decides much of the comparison.

Tri-Fuel Inverter Generators

Tri-fuel is no longer limited to conventional open-frame equipment.

FIRMAN's current WT06073 is a tri-fuel inverter generator rated at:

• 6,000W running gasoline
• 5,400W propane
• 4,500W natural gas

with:

• 120/240V output
• less than 3% THD
• electric start
• parallel capability
• 50A outlet
• 67 dB at quarter load

and a current listed price around $1,999.99.

That creates an interesting premium category:

quiet-ish inverter architecture + home-panel voltage + three fuels.

Is a Tri-Fuel Inverter Worth It?

Yes when you want:

• lower noise
• sensitive-electronics output
• 120/240V
• multiple fuels
• moderate home backup

But look at the NG derating.

The FIRMAN WT06073 falls from:

6,000W gasoline

to:

4,500W natural gas.

If you need 5.5 kW continuously on NG, the expensive tri-fuel inverter still does not solve your problem.

Best Tri-Fuel Generator for High-Capacity Home Backup

From the current examples we've researched, the Westinghouse WGen11500TFc remains the strongest high-output configuration for broad home backup.

Current manufacturer manual data gives:

• 11,500W gasoline
• 10,500W propane
• 9,500W natural gas
• 14,500/13,500/12,000W peak respectively
• 120/240V output
• 9.5-gallon gasoline tank.

That 9.5 kW NG rating is the important number.

It keeps the generator in serious home-backup territory even on its weakest fuel.

Champion 201438 Tri-Fuel

Champion's current 201438 is another strong option:

• 10,000W gasoline
• 9,000W propane
• 8,000W natural gas
• electric + recoil start
• 120/240V
• L14-30R
• 14-50R
• 25-foot NG hose
• propane hose
• CO Shield
• 3-year limited warranty
• lifetime technical support.

It runs:

• 8 hours gasoline at 50% load
• 3 hours on a 20 lb propane cylinder at 50% load.

That is a solid home-backup package.

FIRMAN Tri-Fuel Generators

FIRMAN currently offers several relevant configurations.

T04073

• 4,000W gas
• 3,600W propane
• 3,200W NG
• 120/240V
• electric start
• $1,099.99 current listed price.

T07573

• 7,500W gas
• 6,750W propane
• 5,500W NG
• 120/240V
• L14-30R
• 14-50R
• current listed price around $1,349.99.

T09275

• 9,200W gas
• 8,300W propane
• 6,900W NG
• 120/240V
• 30A and 50A outputs.

FIRMAN's range illustrates why you need to compare NG output carefully rather than assuming the largest gasoline model automatically remains the strongest NG value.

Tri-Fuel Generator Runtime on Gasoline

Champion 201438:

• 7.7-gallon tank
• 8 hours at 50% load.

FIRMAN runtime varies by model and tank size.

The T07571/T07573 family uses an 8-gallon tank and advertises up to 12 hours at 25% load.

Remember:

25% and 50% runtime numbers cannot be compared directly.

Tri-Fuel Runtime on Propane

Champion 201438:

• about 3 hours at 50% load
• using a standard 20 lb propane cylinder.

That is not much long-outage autonomy.

If propane is intended to carry a house for days, a larger approved propane supply deserves investigation.

Tri-Fuel Runtime on Natural Gas

Natural gas does not have a tank-style runtime when connected to a utility gas supply.

The practical runtime is limited by:

• continued gas service
• adequate pressure
• generator maintenance
• mechanical operation

That is exactly why NG is attractive for long outages.

It also means you need to confirm the fuel connection is actually capable of delivering full generator demand.

Does a Portable Tri-Fuel Generator Need a Dedicated Natural-Gas Line?

Potentially.

Do not assume an existing barbecue outlet can supply a 500cc generator at full demand.

Fuel delivery depends on:

• pipe size
• length
• pressure
• meter/regulator capacity
• other gas appliances
• generator requirement

A machine can run under light load and still be fuel-starved when household electrical demand rises.

Have the fuel system sized properly.

Natural-Gas Hose Length Matters

Champion supplies a 25-foot NG hose with the 201438.

Do not simply extend that hose indefinitely with random additional fittings because you want the generator farther away.

Fuel pressure/drop and manufacturer requirements matter.

Generator placement also needs to satisfy carbon-monoxide safety.

Solve both constraints properly.

Can You Connect a Tri-Fuel Generator to the House Gas Meter?

Through a correctly designed and approved connection, potentially yes.

But the generator is not simply connected "to the meter."

A suitable system needs:

• correct pressure
• shutoff
• approved connection
• correct piping/hose
• sufficient gas capacity

Use a qualified gas professional where required.

What If Natural Gas Goes Out?

Switch to one of the other fuels according to the generator's approved procedure.

That is the entire tri-fuel thesis.

If:

NG fails

you retain:

propane + gasoline

If:

gasoline stations are shut

you retain:

NG + propane

If:

propane delivery becomes difficult

you retain:

NG + gasoline

No individual fuel is invulnerable.

The diversity is the value.

Can You Switch Fuels While the Generator Is Running?

This is model-specific.

Some fuel-selector systems are designed to support switching under defined conditions.

Others may require shutdown or a specific procedure.

Do not assume the word "tri-fuel" means:

turn the dial whenever you fancy.

Read the actual operating manual.

Tri-Fuel Generator Noise

Large conventional tri-fuel generators are not quiet.

Champion publishes approximately:

74 dB(A)

for its 201438.

FIRMAN's T07571 similarly lists:

74 dB at quarter load.

If noise matters, tri-fuel inverter models such as the FIRMAN WT06073 become more interesting at around 67 dB quarter load, but you give up substantial capacity on NG.

Tri-Fuel Generator Weight

High-output tri-fuel units are heavy.

Champion 201438:

231 lb.

FIRMAN T07571:

213 lb.

So "portable" means:

wheeled and movable

not:

easy to carry.

Plan the storage and deployment route in advance.

Electric Start Matters

For a 200+ lb high-output backup generator, electric start is worth having.

Champion's 201438 includes:

• battery
• electric start
• recoil backup.

That is the setup I prefer.

Battery starting for convenience.

Recoil for redundancy.

Tri-Fuel Generator Maintenance

Three fuels do not mean three engines.

Normal engine maintenance still includes:

• oil
• air filter
• spark plug
• valve checks where applicable
• starter battery
• fuel-system inspection

You additionally need to keep:

• propane hose/regulator
• NG hose/fittings
• gasoline system

in usable condition.

More fuel options create more flexibility.

They also create more equipment to inspect.

Gasoline Storage Still Needs Managing

Buying tri-fuel does not fix stale gasoline if you leave petrol sitting in the carburettor/tank for years.

The advantage is that you can reduce how often gasoline is needed.

Natural gas or propane can become the normal exercise/outage fuel where the manufacturer permits that operation.

Follow the model's storage procedure.

Can You Run a Tri-Fuel Generator Under a Carport?

Do not assume it is safe simply because it is technically outdoors.

Portable-generator placement needs sufficient distance from:

• doors
• windows
• vents
• occupied structures

and must follow current manufacturer and safety guidance.

The generator needs weather protection without trapping exhaust.

Tri-Fuel Generator for Hurricanes

Excellent category.

A hurricane can disrupt:

• grid electricity
• petrol stations
• roads
• delivery systems
• sometimes natural-gas infrastructure

Tri-fuel gives you three supply paths.

For a home already served by NG, it is arguably the strongest portable hurricane-generator configuration.

Tri-Fuel Generator for Winter Storms

Also excellent.

You can:

• use NG for routine operation
• keep propane stored
• retain gasoline for maximum output/fallback

Cold-weather factors still include:

• starter battery
• oil
• propane vaporisation
• natural-gas pressure

Fuel diversity does not remove weather engineering.

Tri-Fuel Generator for Rural Homes

If there is no NG service:

tri-fuel loses part of its value.

You effectively own a dual-fuel generator with an unused third capability.

For a rural off-gas property, I would generally compare:

• dual-fuel generator
• propane standby
• diesel

before automatically paying extra for tri-fuel.

Tri-Fuel Generator for Natural-Gas Homes

This is the killer use case.

You get:

NG convenience

plus:

propane storage

plus:

gasoline maximum output

For manual home backup, that is a very strong fuel architecture.

Tri-Fuel Portable vs Whole-House Standby

If the homeowner can afford the standby system and wants:

• automatic power
• no manual setup
• unattended operation

standby still wins.

If they want:

• lower capital cost
• fuel diversity
• occasional backup

tri-fuel portable wins the economics.

This is not really a generator-quality comparison.

It is a labour vs capital comparison.

Is Tri-Fuel Worth It for RV Use?

Potentially, but natural-gas availability is usually less useful on the road.

For RV owners, gasoline + propane may already cover most practical situations.

Tri-fuel makes more sense when the generator also serves as home emergency backup.

What Is the Best Tri-Fuel Generator?

There is no universal winner.

Our current use-case calls are:

Best for Maximum Home-Backup Output

Westinghouse WGen11500TFc

because the current NG rating remains a strong 9,500W while gasoline reaches 11,500W.

Strong All-Round Alternative

Champion 201438

at 10,000 / 9,000 / 8,000 running watts with both hoses included and 120/240V home-backup outputs.

Best if You Want Inverter Architecture

FIRMAN WT06073

with 6,000 / 5,400 / 4,500W fuel-specific ratings, less than 3% THD and 120/240V output.

Smaller Home/Jobsite Option

FIRMAN T04073

at 4,000 / 3,600 / 3,200W.

Questions to Ask Before Buying a Tri-Fuel Generator

1. What are the running watts on gasoline?
2. What are the running watts on propane?
3. What are the running watts on natural gas?
4. What is the starting output on each fuel?
5. Is it 120/240V?
6. Does it have L14-30R?
7. Does it have 14-50R?
8. Is electric start included?
9. Are NG and propane hoses included?
10. What NG pressure/supply does it require?
11. How long is the supplied NG hose?
12. What is gasoline runtime at a stated load?
13. What is propane runtime on the supplied/reference cylinder?
14. Can it connect to larger propane storage?
15. Can fuel be switched while running?
16. How much more does it cost than the closest dual-fuel model?

The answer to #16 tells you whether the third fuel is good economics.