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Propane or dual fuel generator: who it’s for
Standby generator on propane or portable dual fuel: how long a 20 lb tank or a large tank lasts, power loss, storage, and who connects the gas in Québec.
In short
Two families: the standby generator on propane, fed by a large tank, and the portable dual fuel generator, which runs on gasoline or on a cylinder.
- A Generac standby generator requires a tank of at least 250 US gallons. Cylinders aren’t enough.
- On propane, the two Champion dual fuel portables cited lose about 10% of their output (manufacturer’s figures).
- The gas connection is done by a licensed gas contractor, not by the electrician.
- Cylinders are stored upright and outdoors, never in the garage or the shed, and are requalified every 10 years.
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Standby or portable dual fuel
“Propane generator” can mean two very different things: a standby generator connected to a large tank, or a portable that takes a cylinder. The equipment, the runtime and the rules aren’t the same.
| Standby propane generator | Portable dual fuel | |
|---|---|---|
| Fuel | Propane (or natural gas) | Gasoline or propane |
| Propane supply | Tank of at least 250 US gal (Generac) | 20 or 30 lb cylinder (Generac multi-fuel) |
| Starting | Automatic, with an automatic switch | On site, by you (recoil or electric start depending on the model), with a manual switch in general |
| Gas connection | By a licensed gas contractor | You screw on the cylinder |
Watch out for a trap: Generac’s multi-fuel portables are designed for 20 or 30 lb cylinders only. They don’t get connected to a large tank.
How long it runs
With a 20 lb cylinder, according to the manufacturer Champion’s figures:
- a 4,500 W dual fuel inverter generator runs about 25 hours at ¼ load;
- a 7,500 W dual fuel generator runs about 5.5 hours at 50% load.
In other words, for an outage of several days, plan on several cylinders, or a standby generator.
With a tank, a standby generator’s runtime depends on the size of the tank and the load. Generac’s spec sheets give the hourly consumption: for example, from 9.57 litres at half load to 14.77 litres at full load for the 22 kW model. Your propane supplier can calculate the runtime based on your tank. The details by model are in our guide on the automatic standby generator.
Power loss on propane
A dual fuel generator gives a little less output on propane than on gasoline. Champion’s spec sheets show it:
| Champion model | On gasoline (continuous) | On propane (continuous) |
|---|---|---|
| 4,500 W inverter, dual fuel | 3,250 W | 2,925 W |
| 7,500 W, dual fuel | 7,500 W | 6,750 W |
That’s about 10% less. If you size the generator according to what you want to power, do the calculation with the propane figure.
Want to connect a generator to the house?
We install the transfer switch and set with you the circuits to back up. The price is in writing before the work.
Send my quote requestPropane or natural gas, for a standby generator
A standby generator can also run on natural gas. It’s then supplied continuously by the natural gas network, with no tank to fill. Your address still has to be served: check with your natural gas distributor (Énergir, for example). On natural gas, the generator gives a little less output than on propane: Generac indicates a typical loss of 10 to 20%.
Who connects the gas
In Québec, the gas part of a standby generator is done by a contractor holding the appropriate licence from the Régie du bâtiment: subcategory 15.2 for natural gas, 15.6 for propane. The electrician doesn’t do the gas part: it’s done by a licensed gas contractor. We do all the electrical part: transfer switch, connection to the panel, backed-up circuits.
The Québec Construction Code also requires that the engine of a generator connected to gas be approved. For the full process of an installation, see installing a generator: how it goes and what it costs.
Cylinders: storage and safety
- Store cylinders upright, outdoors, in every season.
- Never in an enclosed place such as a shed or a garage.
- A cylinder must be requalified within 10 years of its manufacture or its last requalification. The Government of Québec recommends bringing any empty, defective or over-10-year-old cylinder back to a propane supplier.
And the portable generator itself, on propane as on gasoline: Health Canada says to place it at least 6 metres from any building, with the exhaust pointing away from doors and windows, and never to run it indoors, in the garage or in the shed. A standby generator follows the manufacturer’s and the Code’s clearances, which the electrician checks on site.
Frequently asked questions
How long does a 20 lb cylinder last?
It depends on the generator and the load. According to the manufacturer Champion, about 25 hours at ¼ load for its 4,500 W inverter model, and about 5.5 hours at 50% load for its 7,500 W model.
Propane or gasoline: which to choose?
Propane is stored outdoors in cylinders, but it gives about 10% less output on the Champion dual fuel portables cited. A dual fuel generator lets you keep both options.
Can a portable be connected to a large tank?
Not Generac’s multi-fuel portables: they are designed for 20 or 30 lb cylinders only. For another brand, follow the manufacturer’s manual. A standby generator, on the other hand, is connected to a tank by a gas contractor.
Who can connect propane to a standby generator?
A contractor holding the appropriate gas licence from the Régie du bâtiment (subcategory 15.6 for propane). The gas part is done by a licensed gas contractor; we do the electrical part.
Where should propane cylinders be stored?
Upright, outdoors, in every season. Never in a shed, a garage or another enclosed place.
Can a propane generator run in the garage?
No. Health Canada says never to run a combustion generator indoors, in the garage or in the shed, and to place it at least 6 metres from any building.
My cylinder is more than 10 years old: what do I do?
A cylinder must be requalified within 10 years of its manufacture or its last requalification. The Government of Québec recommends bringing it back to a propane supplier.
A generator to connect to the house?
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Sources
The figures and requirements cited in this guide come from the documents below, consulted on October 4, 2026.
- Health Canada, preventing carbon monoxide exposure
- Champion, 4,500 W dual fuel inverter generator
- Champion, 7,500 W dual fuel generator
- Generac, multi-fuel portables and cylinder size
- Generac, minimum tank size for a standby generator
- Generac, Guardian 20, 22 and 24 kW spec sheet
- Generac, owner’s manual (power loss on natural gas)
- Government of Québec, brief on gas licence subcategories (in French)
- Québec.ca, propane cylinder safety (in French)
- Federal Transportation of Dangerous Goods Regulations, section 1.50 (requalification)
- Énergir, natural gas generators
- LégisQuébec, Construction Code, Gas chapter (in French)