⚡ Firman Generator Propane Runtime Calculator
Calculate exactly how long your Firman generator will run on any propane tank size at any load level
| Tank Name | Usable Propane (lbs) | Gallons (approx) | Total BTU Available | Liters (approx) |
|---|---|---|---|---|
| 20 lb Cylinder | 17 lbs | 4.0 gal | 366,900 BTU | 15.1 L |
| 33 lb Cylinder | 28 lbs | 6.6 gal | 604,500 BTU | 25.0 L |
| 40 lb Cylinder | 34 lbs | 8.0 gal | 734,100 BTU | 30.3 L |
| 100 lb Cylinder | 85 lbs | 20.1 gal | 1,835,200 BTU | 76.0 L |
| 500 Gallon Tank | 1,693 lbs | 400 gal | 36,600,800 BTU | 1,514 L |
| 1000 Gallon Tank | 3,386 lbs | 800 gal | 73,201,600 BTU | 3,028 L |
| Model (Watts) | 25% Load | 50% Load | 75% Load | 100% Load | Tank Size |
|---|---|---|---|---|---|
| W03083 (3000W) | ~13.4 hrs | ~7.1 hrs | ~4.9 hrs | ~3.7 hrs | 20 lb |
| W06573 (6500W) | ~6.8 hrs | ~3.6 hrs | ~2.5 hrs | ~1.9 hrs | 20 lb |
| P08003 (8000W) | ~5.5 hrs | ~2.9 hrs | ~2.0 hrs | ~1.5 hrs | 20 lb |
| T07571 (7500W) | ~5.9 hrs | ~3.1 hrs | ~2.1 hrs | ~1.6 hrs | 20 lb |
| W03083 (3000W) | ~66.8 hrs | ~35.3 hrs | ~24.3 hrs | ~18.3 hrs | 100 lb |
| W06573 (6500W) | ~34.0 hrs | ~18.0 hrs | ~12.3 hrs | ~9.3 hrs | 100 lb |
| P08003 (8000W) | ~27.5 hrs | ~14.5 hrs | ~10.0 hrs | ~7.5 hrs | 100 lb |
| Firman Model | Rated Watts | BTU/hr @ 100% | lbs/hr @ 50% Load | Gal/hr @ 50% Load |
|---|---|---|---|---|
| W03083 | 3,000W | 22,000 | 0.51 | 0.12 |
| H03652 | 3,650W | 24,000 | 0.56 | 0.13 |
| W06573 | 6,500W | 43,000 | 0.99 | 0.24 |
| T07571 | 7,500W | 49,000 | 1.13 | 0.27 |
| P08003 | 8,000W | 54,000 | 1.25 | 0.30 |
| W09561 | 9,500W | 63,000 | 1.46 | 0.35 |
Propane generators became the mainstream choice for folks that need back-up energy, whether at home or during trips. They last through almost every weather that one can imagine and truly need only a bit of attention. Here what truly impresses about Propane: it can stay in stored tanks for years without loss.
On the other hand, gasoline becomes thick clogs the lines and seems to always work against your interest. Moreover, Propane burns more cleanly, which certainly does not hurt.
Propane Generators: The Good and the Bad
But there is a catch. The energy density of Propane simply does not match that of gasoline. If you use Propane, you will have to burn around 20 to 25 percent more fuel to reach the same result.
Also the produced power suffers, and that is clearly visible. Take a sample with one model: it reaches 11 200 peak watts on gasoline, but on Propane it falls to 11 000 peak watts. Similarly happens with the steady power, that sinks from around 9 500 to 8 500 watts.
The most common home backup generators that run on Propane use between half and one full gallon each hour. For bigger devices that jumps to two or three gallons each hour. Many home owners tie their Firman Generator to a tank of 500 gallons Propane, but recall that such tanks only fill to 80 percent for safety.
The point is that if you already have a big tank for home heating, then Propane generators clearly seem much more practical.
Now these days dual fuel systems (even third versions) are very common. One can switch between gasoline and Propane as needed, and some types include also natural gas. The most common flexible units do that quite well.
Even so there is one trouble: engines on Propane can be hard to start. Quite a few folks had to pull the string many times before it starts.
Cold weather creates problems for Propane in small tanks. When the temperature drops, the pressure in the tanks goes down, which sometimes causes freezing and stopping during the generator work under load. Bigger systems escape that bye pulling liquid Propane directly from the tank, instead of waiting for steam.
Swapping the fuel tanks is truly easy with Propane. Turn one, attach the next, and done, no spill, no mess. I truly like this.
Class B and C RV generators on Propane that give around 3 kilowatts are popular with travelers. The only doubts of some come from the high use of fuel and the trouble finding refill spots during travel.
Propane generators give you full control, unlike those on natural gas that connect directly to the city net. Even so that duty has two sides, you must yourself store the fuel. The advantage?
Propane does not go bad like gasoline, so unless you run the generatormonthly, keeping Propane simply is the simpler and reliable way.
