Generator to Run Furnace

Last Update: February 24, 2023
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This is our review of the best generator to run furnace in 2023.

If you want to keep your family warm and secure this winter, you may wonder what size generator you'll need to power the furnace.

A portable generator is an essential piece of equipment to have on hand if you reside in, or are visiting, an area with frequent power outages. In the event of a blackout, a portable generator can be used to power an electric furnace and keep the house toasty.

Many older furnaces are not intended to function with a portable generator, but some modern furnaces can. Even if your heater isn't movable, you can still use a generator to keep your house toasty during a blackout.  

We found that WEN 56380i Super Quiet 3800-Watt generator is the best to run the furnace in 2023.

But every home has unique needs. So I've also reviewed the best 5 generators in every category.

Let's get started.

Generator to Run Furnace

Best Generator To Run Furnace

Here is the detailed summary of top picked best generator to run furnace.

The WEN 3800 Watt Inverter can power even the most delicate devices with a total harmonic distortion of less than 1.2 percent when compared to a pure sine wave.

With its digital screen, you can quickly access any data you might require. Keep an eye on things like power output, fuel level, and how long the engine can operate.

The spark arrestor in our TT-30R outlet makes it legal to use in all national parks and forests while still providing up to 28 amps of quiet electricity.

The WEN 3800 Watt Inverter Generator's compact size, built-in wheels, and folding handle make it easy to move and store.

Even with the heat blowing, the capacity never surpassed the 20% level, and that was with me hooking up my refrigerator, gas furnace and blower, a couple of televisions, internet, lights, etc. 

Sufficient energy for all of your requirements during the cold season. 

This is our best pick generator to run furnace.

Specification for WEN 3800 Watt Inverter Generator

  • Running Wattage: 3400W
  • Starting Wattage: 3800W
  • Run Time:  8.5 Hours (on 50% load)
  • Fuel Tank Size: 2.2 Gallons
  • Noise Level: 51 dBA (from 22 feet)

Your purchase of Champion Power Equipment 200988 4500-Watt will be backed by Champion Support's three-year limited warranty and our support center network's 24/7/365 availability for FREE.

You can link up to two inverters together to boost output using the Parallel Kit (sold separately) and the included standard 50-amp RV outlet. Easy to carry thanks to the foldable design and indestructible tires.

With 4500 beginning watts, 3500 running watts, up to 14 hours run time, and 3150 running watts, up to 21 hours on propane, the Extended Run Time 61 dBA is perfect for recreational vehicles, tailgating, and camping.

Real-time monitoring of voltage, frequency, and working hours are provided by Economy Mode, and the EZ Start Dial makes starting the machine a breeze.

Since its running output (what it can consistently handle) is only 3150 watts or 26 amps, this can power your refrigerator, furnace fan, some lights, a TV, or a small window AC without the rest of the house's electrical appliances.

It is incredibly economical to operate because of its compact dimension.

Specification for Champion Power Equipment 200988 4500-Watt Generator

  • Running Wattage: 4500W
  • Starting Wattage: 3150W
  • Run Time: 14 hours on gas and 22 hours on propane (25% load)
  • Fuel Tank Size: 2.3 Gallon (Gasoline)
  • Noise Level: 61 dBA (from 22 feet)

If you need a backup power source for your residence, look no further than the Westinghouse WGen9500 Portable Generator, which has 12 500 peak watts and 9 500 running watts. 

Its heavy-duty 457cc 4-Stroke OHV Westinghouse Engine can operate for up to 12 hours on a single tank of gas. This generator's remote start key fob and push-button electric start make remote lighting a breeze. 

The User-friendly control panel highlights the unit's Transfer Switch Ready L14-30R and larger 14-50R outlets, which can power multiple large items at once with a single cable hookup, including an air conditioner, refrigerator, sump pump, lights, and an entertainment center. 

In order to keep you up-to-date with real-time data and routine upkeep, the VFT Data Center shows you data on volt output, frequency, and lifetime hours. The sturdy, never-flat wheels, foam grip handle, and lift bracket make it easy to move from place to place, allowing you to power your home, travel trailer, or work location quickly and easily. 

The generator can be easily started and stopped with the press of a button, thanks to the inclusion of an electronic start system. 

The air-cooled overhead valve construction of the 457cc Westinghouse engine allows for cooler, more fuel-efficient operation, while the cast iron cylinder sleeve ensures years of dependable use. 

In the event that low oil is discovered, the engine will shut down automatically to prevent damage. All required pollution levels are achieved, as set by the EPA and CARB. Also coverage for Labor and Components for Three Years and a Widespread System of Support

Specification for Westinghouse 12500 Watt Portable generator

  • Running Wattage: 9500W
  • Starting Wattage: 12500W
  • Run Time: 12 hours
  • Fuel Tank Size: 6.6 Gallon (Gasoline)

In the Eco-Mode, WEN 56225i generator's motor will automatically change its fuel consumption to maximize fuel economy, thereby extending the generator's run time and engine life.

Silent operation (only 53 decibels) means it won't disrupt your space where power is required the least.

Connect two inverter generators together via the WEN 56421 Parallel Connection Kit for a combined output of more than 2250 volts.

The WEN 2250W Inverter Generator has a gasoline shutoff feature as well. This function cuts gasoline to the generator, causing it to run until all of the gas in the carburetor has been used up before powering down. This prevents the buildup and obstructions produced by stale fuel inside the carburetor, requiring less servicing and extending the life of the device.

The WEN 2250 Watt Inverter is extremely portable thanks to its lightweight construction (it only weighs 48.5 pounds) and integrated carrying handle.

Using the WEN 56421 Parallel Connection Kit, you can easily connect two WEN inverter generators together to share power. Built-in overload protection and indicator lights join low-oil and low-fuel automatic shutdown to keep your generator and your devices secure from harm.

This would be perfect for running your furnace and some accompanying LED lights.

Specification for WEN 56225i Generator

  • Running Wattage: 1800W
  • Starting Wattage: 2250W
  • Run Time: 6 hours (on 50% load)
  • Fuel Tank Size: 1 Gallon (Gasoline)
  • Noise Level: 53 dBA

With its ability to run on both gasoline and liquid propane, the Champion Power Equipment 201052 3800-Watt Dual Fuel Portable Generator is a good choice for those in need of a portable power source. 

The electronic start is battery-operated and features Cold Start Technology for easy ignition even when temperatures are low. Start using your Dual-Fuel generator immediately with either gasoline or propane, thanks to our unique fuel selector switch. 

The 224cc Champion engine runs on gasoline, producing 4750 starting watts and 3800 running watts; at 50% load, it can operate for 14 hours on a full barrel of fuel. 

With a 20-pound propane tank, it can operate for 10.5 hours at 50% load, producing 4275 starting watts and 3420 running watts. This unit has a Volt Guard built-in surge protector that prevents overloads and keeps your equipment secure, and it only makes as much noise as a vacuum from 23 feet away (68 dBA).

There are multiple power receptacles, including a 120V 30A RV (TT-30R), a 120V 30A locking outlet (L5-30R), and two 120V 20A household outlets (5-20R). 

It is also  EPA  and CARB-compliant generator, as it is backed by a 3-year limited warranty and FREE lifetime technical assistance provided by Champion Support and our nationwide network of service centers.

Specification for Champion Power Equipment 201052 Generator

  • Running Wattage: 3,800W
  • Starting Wattage: 4750W
  • Run Time: 14 hours on Gas, 10.5 hours on propane
  • Fuel Tank Size: 4.7 Gallon
  • Noise Level: 68 dBA

Generator to Run Furnace - User Guide

If you would like to heat your home with gas, and most people do because it's so readily available, you'll need a gas heater. A furnace burns the gas, and the heated air is blown around the house by a fan.

Ratings for gas furnaces include both their highest BTU input and their efficiency at converting fuel into heat (British Thermal Units). Gas furnaces with an AFUE (Annual Fuel Utilization Efficiency) rating of 97% or greater are the most efficient models available. In simple words, 97% of the fuel is converted into heat for the house, while the remaining 3% is wasted in the form of smoke and draughts.

A gas furnace's capacity is also crucial. If the furnace is too tiny, it will have to work harder than necessary to heat the house, and its performance will suffer as a result. However, a heater that is too big will waste energy by turning it on and off too frequently.

Generator to Run Furnace - User Guide

How Big Generator do you need to Power a Furnace?

Choosing a furnace generator requires careful consideration of several variables. It's important to consider the furnace's starting and running watts, as well as the power needs of any other machines that may be on at the same time.

A gas furnace can be powered by a generator producing only 2,000 watts. Electrical and gas heating systems have distinct power draws in actual use.

In contrast to an electric furnace, gas heaters have a low power consumption. Only the blower engine, draught inducer motor, and control board require electricity. However, electric furnaces can't function without a constant supply of energy.  

How to Figure Out How Much Electricity a Furnace Needs?

First, you'll need to know how many volts, amps, watts, or horsepower your furnace's parts use. Check the owner's manual, the stickers on your furnace, or the labels on the electrical parts. Then you can use this watt-volt-amp calculator to figure out how much power it needs.

The most important part of a gas furnace is the motor for the blower fan. To get the wattage, multiply the voltage by the amperage. The rated or running watts is the value you'll get.

The starting watts will be between two and three times this number. In the same way, if you know both the voltage and the wattage, you can divide the watts by the volts to find the amperage.

How to Pick a Generator to Power Your Furnace?

Here are a few things to consider when choosing a generator to power a furnace. Essential things to think about are:

  • The size of the furnace.
  • The type of fuel it uses.
  • The weather where the furnace will be used.

Size of the Furnace

When choosing a generator, the most important thing to consider is the furnace's size. About 50,000 BTUs is the average for a home furnace. But furnaces can be anywhere from 25,000 BTUs to more than 100,000 BTUs. Also important is the type of fuel that the furnace uses. Most homes have natural gas furnaces. But Oil and propane furnaces are also used.


It is another important thing to think about. It is important to consider the climate where the furnace will be used. Furnaces are made to work within a certain temperature range. A high-capacity generator may be required if the furnace is used in a very cold winter.

Furnace Wattage

A 3500-watt generator can power a furnace, but this is not recommended. The furnace will put a lot of stress on the generator, which wasn't made to handle that load.

A 4000-watt generator can run a furnace. But the time the generator can run will depend on the size and type of furnace. If the furnace is electric, the generator will need to be able to give it enough power to keep running.

FAQs About Right Size Generator To Run Furnace

Generator to Run Furnace - FAQ

Could a generator power your furnace?

There are two types of generators that can power a gas furnace: portable 

and permanent. Even though permanent generator installations are preferable for heating a house, portable generators are a viable alternative. 

If you need to run your furnace, it's important to get a generator with enough wattage. These are your most cost-effective choices in the event of a power outage, but they also tend to be the most elaborate. Here are some suggestions for using portable engines with heating systems.

A portable generator can be connected to a standard electrical socket by using a special adapter. Make sure the plug is connected to the generator and not the gas heater, though, if you plan on using both appliances at the same time. 

The generator needs to be located outside the home, away from any walls, and out of reach of any curious youngsters. Another crucial consideration when using a generator with your furnace is to hook it up using an extension cable of sufficient quality and stipulate that it be used with your specific model of furnace. If you don't, you might start a fire or get shocked by electricity.


Can I Use a Generator Without Worrying About Damaging My Furnace?

Perhaps you're concerned that using a generator will ruin your heating system. A 3500-watt generator will be adequate to power your home's furnace and other minor appliances. The use of a generator with a greater power output could be required for high-efficacy heating systems. In some cases, surge safety is helpful for high-efficiency devices. Unless you want to spend money on two generators, one of which would have to power the furnace.

Keep the generator outside if you need to use it. People in the building, particularly those near windows, are at risk from the generators' toxic exhaust fumes. Use only high-quality, manufacturer-recommended extension cables with your furnace. An electrical fire or shock could result from a power cable being installed improperly. Finally, it's critical to always double-check area regulations for safety measures

Is It Risky to Use a Generator with a Gas Furnace?

As long as you take the standard precautions when operating a generator, using one to power your gas furnace is perfectly secure. A generator should always be operated in a well-ventilated outdoor area.

If your home relies on a generator for heating and cooling, and you also have a lot of other items that need to be connected to it, you might want to invest in two. The first one can power your home's utilities, while the second can power your heating system. Because of this, your house will be safe from damage caused by the generator overworking itself.

Can a 2000-watt generator power a furnace?

A 2000-watt generator can power a furnace that uses oil or natural gas.

The wattage of these furnaces is 1600 watts when they first turn on and 600 watts when they are running.

On the other hand, if you go higher than a 2000-watt generator that can, that will be beneficial.


As long as you take the standard safety measures when using a generator and give it a demonstration run beforehand, you should be able to safely power your gas furnace with a generator. To power and operate the gas furnace, you will also need a generator of sufficient size, as well as the necessary accessories, such as power cables and fuel.

We found that WEN 56380i Super Quiet 3800-Watt generator is the best to run the furnace in 2023.

Generator to Run Furnace-Summary

If you're in need of a generator to power your gas furnace, you can find many suitable choices available, including portable and inexpensive models. In case you lose power again, and it's during a cold spell or other inclement weather, having a generator to power your gas heater will be critical.

Hope this guide generator to run furnace will help you to decide your best generator.