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Firman WH03662OF - 3650/4500W Dual Fuel Open Frame Inverter Generator

The Firman WH03662OF is a portable open frame dual fuel inverter generator with a rated wattage of 3,650 W and a starting wattage of 4,500 W.

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Description

Zoom on the Firman WH03662OF

In summary, the Firman WH03662OF is a portable inverter generator especially useful for:

  • RV travellers wishing to enhance their freedom and nomad lifestyle
  • People occasionally participating in sporting competitions, open-air performances and outdoor festivals
  • Homeowners in need of an emergency backup power for their essentials
  • Tailgating and campground aficionados with the desire of enjoying power anywhere they go

In the following paragraphs, we shall explore the power characteristics, available outlets, portability, and any additional features of the device, along with its emission compliance information.

Power & Run Time

The Firman WH03662OF in use

The Firman WH03662OF

The dual-fuel technology of the Firman WH03662OF allows for an output of 120V and provides superb power and versatility. If gasoline-powered, the device provides a running wattage of 3650W and a starting wattage of 4500W. If propane-powered, it gives 3300 rated watts and 4100 starting watts. Additionally, as the generator is parallel capable (parallel kit not included), it can be linked to a second unit for more power.

At a noise rating of 69 dBA (less noisy than a normal conversation), this inverter generator can be started via a conventional pull-start mechanism, or a convenient and easy-to-use electric starter (battery included).

With a fuel capacity of 6 gallons, the WH03662OF can operate for up to 25 hours using gasoline (fuel consumption around 0.24 GPH), or for up to 19 hours (on a 20 lbs tank - propane consumption around 0.25 GPH) using propane.

The WH03662OF produces a clean sine wave: thanks to a <3% Total Harmonic Distortion (THD), your sensitive electronics can be safely plugged in the AC outlets.

Outlets

The control panel provides the upcoming 4 AC outlets:

Duplex 120V 20A (5-20R)
120V 30A (L5-30R) receptacle
120V 50A (14-50R) receptacle

It also sports 3 DC outlets: there's two 5V USB ports (USB-A) with which you may charge electronics, for example mobile phones or tablets, conveniently and a 12V 8A (cigarette lighter style) receptacle with which you may charge your batteries with ease.

If you own an RV with a 50-amp service, you can consider this Firman unit as RV-ready, as it features a 14-50R outlet. Its L5-30R receptacle can also be used for a simple RV connection with the included L5-30P to TT-30R adaptor.

Important note: The 14-50R outlet is normally 120/240V. However, this unit does not produce 240V. This outlet is here for your convenience, but should only be used to power 120V appliances. In addition, since the generator provides a maximum of 3650 running watts, it will not be possible to draw the full 50 amps from the outlet.

Portability

The Firman WH03662OF has a conventional, open frame design, of the following dimensions: L24.5 x W24.1 x H23 in, which offers support and allows it to be raised above ground level. The device has been designed for tough environments and demanding outdoor use.

Even though this device may be technically portable (as in movable), manipulation and transportation without special equipment can be a challenge, as it weighs 119 pounds. Still, once it is on the ground, its set of wheels (⌀9") and its folding handle can easily solve the issue of low mobility and allow for easy relocation of the device.

Features

Panel of the Firman WH03662OF

The WH03662OF's control panel

To help you monitor the WH03662OF's status and activity, its control panel is equipped with a convenient meter, which displays voltage, frequency and lifetime hours.

In addition to this info, several light indicators serve to show you when the oil level is too low, the generator is overloaded and the generator is ready.

The inverter generator includes a built-in fuel gauge, a quick, easy and convenient method of checking the device’s gas level.

As for its security measures, the device features an overload protection (circuit breaker) and an automatic low oil shut-off, letting you use it with a peace of mind.

The WH03662OF also benefits from Firman’s CO Alert carbon monoxide shutdown, which automatically shuts down the engine when harmful levels of carbon monoxide accumulate around the generator or a CO Alert fault occurs. It’s a welcomed additional security feature, but don’t forget to always take your generator outside (opens in a new tab).

Apart from the typical documentation and an owner's manual (opens in a new tab), which lets you start it right away, the Firman WH03662OF also is packed along with the following accessories: oil, tool kit, propane hose, RV adapter, funnel and battery charging cables.

Emissions

The Firman WH03662OF is EPA-approved and CARB-compliant. Thus, selling and purchasing this generator is allowed in each of the 50 states, including California.

Moreover, it features a spark arrestor, which makes it suitable for use in forested areas.

The unit also meets the ANSI/PGMA G300-2018 safety and performance requirements.

The Firman WH03662OF versus other generators

The following charts are provided to give you an idea of how some of the key specs of the Firman WH03662OF compare to inverter generators of similar power (between 3500 and 4500 W).

  • As its dry weight is 119 pounds, the Firman WH03662OF is one of the heavier of the inverters which can generate 3500 to 4500 running watts. If you are concerned by weight, one of the champions in the above-mentioned power range is the WEN GN400i, with a dry weight of just 66.1 pounds.
  • This inverter generator, with its lowest possible noise rated at 69 dBA falls into the more noisy category, compared to other devices of a similar running wattage. If noise emissions are important to you, one of the least noisy generators of this power range is the Westinghouse iGen4500DF with only 52 dBA.
  • With a run time of up to 25 hours at 25% load, the WH03662OF has one of the highest run times, compared to its similarly powerful peers.
  • Even though run times are undoubtedly important, they are dependent on the fuel capacity to a large extent. For a more wholesome picture, we must take into consideration the fuel consumption of the generator. In fact, this inverter generator is not among the most fuel efficient, within the aforementioned wattage range : its estimated gasoline consumption at 25% load is around 0.24 GPH. If fuel consumption is your top priority, we suggest to check out the Champion 200988, which has a fuel consumption of only 0.16 GPH and thus, is one of the most efficient devices in our database.

Price comparison

As you can see from this interactive chart, when compared to other 3500-4500W dual fuel inverter generators, the Firman WH03662OF is on the expensive side of the price range.

While certainly not the cheapest of its kind, purchasing it would most likely also mean enjoying the reliability of a high-end product.

The bottom line

STRENGTHS:
  • CO Alert technology
  • Several accessories included
  • RV adapter included
  • Electric start
  • Parallel capable
  • Dual Fuel
  • Inverter
  • High run time
WEAKNESSES:
  • On the expensive side
  • No 240V output
  • No remote start
  • On the heavy side (119 lbs)
  • On the noisy side (69 dBA)
  • Low fuel efficiency

Do you own the Firman WH03662OF and agree (or disagree) with these strengths and weaknesses?

Let us know and write your own review.

Features and Specifications

General
InverterYes
PortableYes
Parallel capableYes, cable not included
RV readyNo
FuelDual Fuel (gasoline/propane)
Engine208 cc OHV 4-stroke
Starting systemRecoil, Electric
VoltageAC: 120V 60 Hz, DC: 12V
Power
 GasolinePropane
Running watts3,650 W3,300 W
Starting watts4,500 W4,100 W
Running amps30.4 amps27.5 amps
Peak amps37.5 amps34.2 amps
Run time @50% loadUnknownUnknown
Run time @25% load25 h19 h
Features
GFCI outletsNo
Covered outletsYes
Automatic Voltage RegulationInverter
AC outlets
  • 1x Duplex 120V 20A (5-20R)
  • 1x 120V 30A (L5-30R)
  • 1x 120V 50A (14-50R)
DC outlets2x 5V USB port (USB-A)
1x 12V 8A (cigarette lighter style)
Data centerVFT
IndicatorsLow oil, overload and output ready
Fuel tankSteel, 6 gal
Fuel gaugeYes
Misc
Weight119 lbs
Approx. dimensions (L x W x H)24.5 x 24.1 x 23 in
Noise (lower limit)69 dBA
THD< 3%
ComplianceCARB, EPA, ANSI/PGMA G300-2018
SecurityLow oil and overload protection, CO monitoring
Spark arrestorYes
NeutralFloating
Accessories includedOil, funnel, tool kit, propane hose, RV adapter, battery charging cables, battery, and wheel kit
Warranty3 years
SeriesWhisper, Hybrid
UPC840876136621

Unlike many websites, we did our best to research each of the specs above. That being said, we are not immune to making the occasional mistake or omission. Should you notice any missing or incorrect values, don't hesitate to suggest improvements so we can address the issue.

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About FIRMAN Power Equipment

Founded in 1999, Firman Power Equipment is a company with a short, but established history in the power equipment industry. Based in Arizona, the company offers an immense range of products, including power tools, automotive equipment, storage utilities, work wear, but most importantly, a wide selection of generators of all sizes, designs and outputs. Interestingly, Firman is a wholly owned subsidiary of the China National Machinery Industry Corporation - a somewhat well renowned company in China and acts as a de facto distributor of their products in the US.

Warranty Information

The Firman WH03662OF is covered under a warranty for up to 3 years. This warranty may be limited and may not cover all parts of the generator.
For more information about the warranty of Firman generators, please consult Firman's warranty policies (opens in a new tab). Alternatively, you can also contact their Customer Support: 1-844-FIRMAN1 (844-347-6261).

Questions & Answers

What can it power?
Examples of items that can be simultaneously powered.
The examples below are based on a maximum load of 80% and estimated wattages. For a more accurate estimation, use our wattage calculator.
ItemRunning WattsStarting Watts
At homeRefrigerator (energy star)1921192
Hair dryer18001900
Washing machine9001650
Cell phone charger2020
Total2912 W3912 W
For campingRadiant heater13001300
RV refrigerator180600
RV AC (11,000 BTU)10101600
Blender400850
Cell phone charger2020
Total2910 W3500 W
For workGrinder14002500
Demolition hammer12601260
Drain cleaner250250
Total2910 W4010 W

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