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Propane gives you less power. Here is how much
Updated
Propane stores for years and does not gum up a carburetor. That makes it a great outage fuel. But it holds less energy than gasoline, so the same engine makes fewer watts on it. Some listings print the propane numbers. Some only print the gasoline ones.
The drop on the models we checked
| Generator | Running watts, gas | Running watts, propane | Drop |
|---|---|---|---|
| Westinghouse WGen9500DF | 9,500 | 8,500 | 11% |
| Westinghouse WGen5300DFcv | 5,300 | 4,800 | 9% |
| Champion 4000-Watt Dual Fuel | 3,000 | 2,700 | 10% |
| Westinghouse iGen5000DF | 3,900 | Not on the listing we read | Check the manual |
So plan on about 10 percent less. If the calculator says you need 2,900 running watts and you want to run on propane, the Champion's 2,700 propane watts will not cover it, even though its 3,000 gasoline watts would.
How to read a runtime claim
Every listing says "up to" some number of hours. Makers usually measure that at a light load, often a quarter or half of rated power. The listings we read did not state the load next to the claim. Run the generator harder and the hours fall fast.
| Generator | Maker claim | Tank | Works out to |
|---|---|---|---|
| WGen9500DF | Up to 12 hours | 6.6 gal | 0.55 gal per hour |
| WGen5300DFcv | Up to 14.5 hours | 4.7 gal | 0.32 gal per hour |
| iGen5000DF | Up to 18 hours | 3.4 gal | 0.19 gal per hour |
| Champion 4000-Watt | Up to 10 hours | 1.54 gal | 0.15 gal per hour |
| WEN 56235i | 10 hours (spec table) | 1 gal | 0.1 gal per hour |
Treat those as best-case fuel use at a light load. For a multi-day outage at a heavier load, plan on more fuel than the table suggests. The Champion listing also claims up to 25 hours on propane. The part we read did not say what size propane tank that assumes.
Gas or propane: which to keep on hand
- Propane keeps for years in the tank and is easy to store. You give up about 10 percent of your watts.
- Gasoline gives full power, but it goes stale in months. Use fuel stabilizer, rotate it through your car, and run the carburetor dry before storage. The WEN 56235i has a fuel shutoff made for that.
- A dual-fuel unit lets you keep both. Many owners store propane for the outage and use gasoline only when they need every watt.
Store all fuel outside your living space, away from the generator while it runs, and let the engine cool before you refuel.
Safety first, every time
- Carbon monoxide kills. Never run a generator indoors, in a garage, in a shed or on a porch, even with the door open. Keep it at least 20 feet from the house. Point the exhaust away from windows, doors and vents. Put battery CO alarms inside your home.
- Never backfeed. Do not plug a generator into a wall outlet or dryer outlet. It can kill a utility worker or a neighbor and can start a fire. To power home circuits you need a transfer switch or an interlock kit, installed by a licensed electrician.
- Without that, run heavy-duty outdoor extension cords from the generator straight to each appliance.
- Let the engine cool before you refuel. Store fuel outside the house.