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Select up to 4 generators to compare specs, power output, noise levels, runtime and more. Your compare URL is shareable.

  • Firman WH03662OF
  • Generac #8947 iQ5200DF
  • Model WH03662OF
    Model WH03662OF

    Firman 3,650W Dual-Fuel Generator

    3650W
    Running
    69 dB
    Noise
    View details
  • Model #8947 iQ5200DF
    Model #8947 iQ5200DF

    Generac 3,900W Dual-Fuel Generator

    3900W
    Running
    0 dB
    Noise
    View details
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).
Generator Specifications Comparison
SpecificationFirman WH03662OFGenerac #8947 iQ5200DF
General
Product type
Generator
Generator
Fuel
Dual-Fuel
Dual-Fuel
InverterYesYes
Parallel capableYesYes
RV readyYesNo
Running watts
3650 W
Winner: Winner: 3900 W
Starting watts
4500 W
Winner: Winner: 5200 W
Noise (lower limit)
Winner: Winner: 69 dB
0 dB
Weight
119 lbs
Winner: Winner: 107 lbs
Run time @50% load
Not available
Winner: Winner: 9 h
Run time @25% load
25 h
15 h
Fuel tank
6 gal
3.2 gal
Fuel gaugeYesNo
Approx. dimensions (L × W × H)
24.5 x 24.1 x 23
24.6 x 20.3 x 22.5
Electrical
Voltage (AC)
120
120
Voltage (DC)
12
5
GFCI outletsNoYes
Covered outletsYesYes
Automatic Voltage RegulationYesYes
THD
<3% %
<3% %
Engine
Engine
208 cc OHV 4-stroke, cast iron sleeve
223 cc OHV 4-stroke
Alternator
Not available
Not available
Starting system
Recoil, Electric
Recoil, Electric
Warranty
Warranty
3 years
3 years
Power by fuel
GasolineNot availableNot available
Running watts
3650 W
3900 W
Starting watts
4500 W
5200 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
Not available
9 h
Run time @25% load
25 h
15 h
PropaneNot availableNot available
Running watts
3300 W
3500 W
Starting watts
4100 W
4700 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
Not available
11 h
Run time @25% load
19 h
20 h
Other
Data center
Not available
Not available
Indicators
true
false
Compliance
CARB, EPA, ANSI/PGMA G300-2023
CARB, EPA, ANSI/PGMA G300-2023
Security
Not available
Not available
Spark arrestorYesYes
Neutral
Floating
true
UPC
840876136621
696471104509
Core / High-priority specs
Running Watts (Gasoline)
3650
3900
Running Watts (Propane)
3300
3500
Starting Watts (Gasoline)
4500
5200
Starting Watts (Propane)
4100
4700
Runtime @ 50% Load (Gasoline)
Not available
9
Runtime @ 50% Load (Propane)
Not available
11
Runtime @ 25% Load (Gasoline)
25
15
Runtime @ 25% Load (Propane)
19
20
AC Outlet Types
1x Duplex 120V 20A (5-20R); 1x 120V 30A (L5-30R); 1x 120V 50A (14-50R)
2x Duplex 120V 20A (5-20R) GFCI; 1x 120V 30A (L5-30R)
Electrical & power
Frequency
60
60
Engine & construction
Engine Type
OHV 4-stroke
OHV 4-stroke
Engine Displacement
208
223
Engine Oil Type
Not available
10W-30 / SAE 30
Runtime & fuel system
Runtime @ 25% Load (Gasoline)
25
15
Runtime @ 50% Load (Gasoline)
Not available
9
Runtime @ 50% Load (Propane)
Not available
11
Safety & compliance
Overload Protection System
Not available
Low oil and overload protection, CO monitoring
Low Oil ProtectionYesYes
Carbon Monoxide MonitoringYesYes
Included equipment
Starting Components
Not available
Oil, funnel, tool kit, propane hose, and battery
Included Accessories
Oil, funnel, tool kit, propane hose, RV adapter, battery charging cables, battery, and wheel kit
Oil, funnel, tool kit, propane hose, and battery
Warranty & identification
Commercial Warranty
3
Not available
Part Number
Not available
8947, 8945
Additional specs
Summary
The Firman WH03662OF is a 3,650-watt dual-fuel inverter generator built for both home backup and job site work. On gasoline, it delivers 4,500 starting watts and 3,650 running watts. On propane, output drops to 4,100 starting and 3,300 running watts. This wattage range powers most household appliances, mid-size power tools, and multiple devices simultaneously. The dual-fuel option gives users flexibility during fuel shortages or when propane's longer shelf life matters. Because the WH03662OF runs at 69 dBA, placement within 20 to 30 feet of living spaces remains practical for residential use. The inverter produces less than 3% THD, which protects laptops, TVs, and other sensitive electronics from voltage spikes. A 6-gallon tank delivers 25 hours of runtime at 25% load on gasoline and 19 hours on propane. At 50% load, runtime drops to zero hours, meaning users refuel frequently under moderate-to-heavy demand.
The Generac iQ5200DF is a 3,900-watt dual-fuel inverter generator that bridges emergency home backup and recreational use. At this output level, it powers essential circuits like refrigerators, sump pumps, and window air conditioners simultaneously, but not a full house or central HVAC. The dual-fuel design lets owners switch between gasoline and propane based on availability, a genuine advantage when supply chains break down during extended outages. Because the iQ5200DF produces electronically regulated current with less than 3% THD, laptops, flat-screen TVs, CPAP machines, and smart home devices run safely without voltage-related risk.
  • Most Powerful
    Generac #8947 iQ5200DF
    3900W running
  • Quietest
    Firman WH03662OF
    69 dB
  • Longest Runtime
    Generac #8947 iQ5200DF
    9h at 50% load
Where to buy
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Firman WH03662OF
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Generac #8947 iQ5200DF
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