Compare Generators Side-by-Side
Select up to 4 generators to compare specs, power output, noise levels, runtime and more. Your compare URL is shareable.
- Firman H03655
- Generac #8251 GP2500i
Quick charts
Each chart uses its own Y-axis scale (so numbers are comparable within a chart).
Running watts
W
Starting watts
W
Noise
dB
Runtime @50%
h
Running watts by fuel
Shows how output changes across gasoline/propane/natural gas (when available).
| Specification | Firman H03655 | Generac #8251 GP2500i |
|---|---|---|
| General | ||
| Product type | Generator | Generator |
| Fuel | Dual-Fuel | Gasoline |
| Inverter | No | Yes |
| Parallel capable | No | Yes |
| RV ready | Yes | No |
| Running watts | Winner: Winner: 3650 W | 2200 W |
| Starting watts | Winner: Winner: 4550 W | 2500 W |
| Noise (lower limit) | Winner: Winner: 67 dB | 0 dB |
| Weight | 112 lbs | Winner: Winner: 48 lbs |
| Run time @50% load | Winner: Winner: 14 h | 4.5 h |
| Run time @25% load | Not available | 8 h |
| Fuel tank | 5 gal | 1 gal |
| Fuel gauge | Yes | No |
| Approx. dimensions (L × W × H) | 25.7 x 21.8 x 21.6 | 19.7 x 11.4 x 17.9 |
| Electrical | ||
| Voltage (AC) | 120V 60 Hz | 120 |
| Voltage (DC) | Not available | 12 |
| GFCI outlets | No | No |
| Covered outlets | Yes | Yes |
| Automatic Voltage Regulation | Yes | Yes |
| THD | 25 % | Not available |
| Engine | ||
| Engine | 208 cc OHV 4-stroke, cast iron sleeve | 98 cc OHV 4-stroke |
| Alternator | Not available | Not available |
| Starting system | Recoil | Recoil |
| Warranty | ||
| Warranty | 3 years | 3 years |
| Power by fuel | ||
| Gasoline | Not available | Not available |
| Running watts | 3650 W | 2200 W |
| Starting watts | 4550 W | 2500 W |
| Running amps (120V) | Not available | Not available |
| Running amps (240V) | Not available | Not available |
| Peak amps (120V) | Not available | Not available |
| Peak amps (240V) | Not available | Not available |
| Run time @50% load | 14 h | 4.5 h |
| Run time @25% load | Not available | 8 h |
| Propane | Not available | Not available |
| Running watts | 3300 W | Not available |
| Starting watts | 4100 W | Not available |
| Running amps (120V) | Not available | Not available |
| Running amps (240V) | Not available | Not available |
| Peak amps (120V) | Not available | Not available |
| Peak amps (240V) | Not available | Not available |
| Run time @50% load | Not available | Not available |
| Run time @25% load | Not available | Not available |
| Other | ||
| Data center | Not available | Not available |
| Indicators | false | true |
| Compliance | EPA, ANSI/PGMA G300-2023 | EPA, ANSI/PGMA G300-2023 |
| Security | Not available | Not available |
| Spark arrestor | Yes | Yes |
| Neutral | Floating | Not available |
| UPC | 840876136553 | 696471003946 |
| Core / High-priority specs | ||
| Running Watts (Gasoline) | 3650 | 2200 |
| Running Watts (Propane) | 3300 | Not available |
| Starting Watts (Gasoline) | 4550 | 2500 |
| Starting Watts (Propane) | 4100 | Not available |
| Runtime @ 50% Load (Gasoline) | 14 | 4.5 |
| Runtime @ 25% Load (Gasoline) | Not available | 8 |
| AC Outlet Types | 1x Duplex 120V 20A (5-20R); 1x 120V 30A (L5-30R); 1x 120V 30A (TT-30R) | 1x Duplex 120V 20A (5-20R) |
| Electrical & power | ||
| Frequency | 60 | 60 |
| Engine & construction | ||
| Engine Type | 208 cc OHV 4-stroke, cast iron sleeve | 98 cc OHV 4-stroke |
| Engine Displacement | 208 | 98 |
| Cylinder Sleeve | cast iron sleeve | Not available |
| Engine Oil Type | Not available | 10W-30 |
| Runtime & fuel system | ||
| Runtime @ 25% Load (Gasoline) | Not available | 8 |
| Runtime @ 50% Load (Gasoline) | 14 | 4.5 |
| Safety & compliance | ||
| Overload Protection System | Low oil and overload protection | Low oil and overload protection |
| Low Oil Protection | Yes | Yes |
| Carbon Monoxide Monitoring | Yes | Yes |
| Included equipment | ||
| Starting Components | Oil, funnel, tool kit, propane hose, and wheel kit | Recoil |
| Included Accessories | Oil, funnel, tool kit, propane hose, and wheel kit | Oil, funnel, tool kit, and battery charging cables |
| Warranty & identification | ||
| Residential Warranty | 3 | Not available |
| Commercial Warranty | 3 | 3 |
| Part Number | Not available | 82512 |
| Additional specs | ||
| Summary | The Firman H03655 is a 3,650-watt dual-fuel generator built around a 208 cc OHV 4-stroke engine with a cast iron sleeve. Running on gasoline, it delivers 4,550 starting watts and 3,650 running watts. Switch to propane and output drops to 4,100 starting watts and 3,300 running watts. This power level runs a refrigerator, microwave, window air conditioner, or multiple power tools simultaneously. The dual-fuel flexibility means you can operate on whichever fuel is available, a practical advantage during extended outages or when propane storage is more convenient than gasoline.
At 67 dB at quarter load, the H03655 operates quietly enough for residential neighborhoods without disturbing neighbors. The 5-gallon tank delivers 14 hours of runtime at 50 percent load on gasoline, translating to roughly one full day of moderate use before refueling. The RV-ready configuration and included wheel kit position this unit as a go-anywhere power source for camping, job sites, and home backup scenarios. | The Generac GP2500i is a 2200-watt inverter generator built for portable backup power and recreational use. At 48 pounds, it moves easily between campsites, job sites, and emergency situations. The inverter technology means laptops, phones, and sensitive tools run safely because the power output stays stable. This unit runs on gasoline and delivers 2500 starting watts, so it can handle the initial surge when motors kick on. |
- Most PowerfulFirman H036553650W running
- QuietestFirman H0365567 dB
- Longest RuntimeFirman H0365514h at 50% load
Where to buy
Prices can change. We update these automatically.
Firman H03655
Store links
No links yet.
Generac #8251 GP2500i
Store links
No links yet.
Disclosure: Some links may be affiliate links. Specs and comparisons are never hidden.