What Size Generator To Run A Furnace? (Complete Guide 2023)
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When a power outage occurs, keeping your furnace running is essential for your comfort and safety.
However, not all generators are created equal, and choosing the right size generator to power your furnace can be a bit confusing.
In this article, we’ll guide you through the process of determining the wattage requirement of your furnace and selecting the appropriate generator size to ensure that your home stays warm and cozy during a power outage.
What Size Generator To Run A Furnace?
The size of the generator to run a furnace depends on the wattage requirement of the furnace, ranging from 1,000-20,000 watts. As a general rule, a generator with a capacity of at least 5,000 watts is usually sufficient to run a furnace.
Here is a chart that outlines recommended generator sizes for running a furnace:
| Furnace Wattage | Minimum Generator Size | Average Generator Size | Large Generator Size |
|---|---|---|---|
| Up to 500 watts | 1,000-2,000 watts | 2,000-3,000 watts | 3,000-5,000 watts |
| 500-1,000 watts | 2,000-3,000 watts | 3,000-5,000 watts | 5,000-7,000 watts |
| 1,000-2,000 watts | 3,000-5,000 watts | 5,000-7,000 watts | 7,000-10,000 watts |
| 2,000-4,000 watts | 5,000-7,000 watts | 7,000-10,000 watts | 10,000-12,000 watts |
| 4,000+ watts | 10,000-12,000 watts | 12,000-15,000 watts | 15,000-20,000 watts |
Recommended Generator To Run A Furnace
- 3000 watts – CRAFTSMAN C0010030 Gas-Powered Generator
- 5500 watts – maXpeedingrods 86lbs Inverter Generator
- 8700 watts – Champion Power Equipment 100520 Open Frame Inverter
- 10,000 watts – DuroMax XP10000EH Dual Fuel Portable Generator
- 15,000 watts – Westinghouse Home Backup Portable Generator
Determining How Many Watts Does a Furnace Use?
Choosing the Right Generator Size for Your Furnace
To ensure that your furnace runs efficiently, it’s essential to choose the right generator size. One of the most critical factors to consider is wattage.
Calculating the Required Watts for Your Furnace
Most home furnaces use 3500 to 5000 watts of energy, which translates into 20 amps at 240 volts or 12 amps at a 120-volt circuit.
You can determine the required watts for your furnace by checking the user manual.
Calculating Required Watts Using Volts and Amps
The user manual may include the model number and either input voltage or output voltage. Using this information, you can calculate the required watts for your furnace.
The formula is: Volts x Amps = watts. For example, if your furnace has a 20 amp draw and runs on 240 volts, then the required watts will be:
240V x 20A = 4800Watts.
Calculating Required Amps for Your Generator
In this case, if your furnace uses 12 amps per 120-volt circuit, you will require 250-300 amps at 240V or 167 amps at 120V.
It means a generator that can produce 300 amps or higher will be the right option to go for.
Types Of Generators For Running The Furnace
Generators that can run a furnace are:
Gasoline Generators
It’s the most compact and cheapest type of generator that also produces less power compared to its other counterparts.
But when it comes to choosing the smallest generator, make sure it can produce enough power to keep the furnace running.
Natural Gas Generators
This natural gas generator is the best choice for the furnace.
This type of generator doesn’t need to be refueled frequently while producing greater wattage than gasoline or diesel models.
It does, however, cost a considerably higher price.
The power output of a natural gas generator ranges from 5000 to 30,000 watts, making it perfect for covering all requirements.
Diesel Generators
This diesel generator is also a popular option for running furnaces.
This type of generator is broadly available and able to produce the same power as natural gas generators while coming at a relatively lower cost.
The power output of the diesel generator ranges from 7000 to 45,000 watts, making it suitable for running furnaces and other appliances at the same time.
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A few safety tips to follow to survive a winter power outage for a generator
If you have a gasoline generator, then the best suggestion for you is to place it outside.
You should also offer a shelter for the generator that is well ventilated and has a fire-resistant coating.
Using a generator will be a safer way to operate a furnace only if you take the necessary precautions.
The following are a few safety guidelines to follow during a winter power outage:
Stay away from the gas
If you inhale, the generator can produce carbon monoxide gas, which can cause serious damage if you inhale.
This is safe to use even if placed in a well-ventilated room, keeping the doors and windows open.
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Use a carbon monoxide detector
Use a carbon monoxide monitor while operating a generator to prevent the gas from getting into your home.
It’s also recommended to place the generator at a safe distance from the house.
Get extra fuel
If you don’t have a power outage problem, get some propane or gasoline to be prepared.
Charge batteries
If you have a solar generator, always keep it charged and store it properly, so you can use it whenever you need it.
Use the right size cord
Use good quality and outdoor safe cord that can properly carry the wattage from the generator to the furnace without getting burned.
Keep the generator parallel
Keeping the generator in parallel will give a power boost that helps run multiple appliances along with the furnace.
Best Generator To Run Furnace
1. A-iPower AP1500i 1500 Watt Portable Inverter Generator Gas Powered
- Produces 1500 starting watts with 1200 running watts of clean and safe power for sensitive electronics, such as phones, televisions, laptops, and other electronics.
- Complete with A-iPower’s “Low idle” technology for an extended run time of 4 hours at 100% load and 6.5 hours at 50% load.
- Equipped with a low oil alert light and low oil automatic shutdown, helping keep your generator performing year after year.
- Powerful 79cc OHV 4-Stroke engine provides an abundant power supply yet runs at a super quiet operation of only 52 decibels.
- Light weight and compact at only 46 pounds, making your tailgate or camping experience as smooth as possible.
Looking for a reliable generator to run your furnace or other sensitive electronics during a power outage or while on the road? Look no further than the A-IPower AP1500i Portable Inverter Generator.
With 1500 starting watts and 1200 running watts of clean and safe power, this gas-powered generator is perfect for use in your home, RV, or during emergencies.
You’ll be able to power your furnace, phones, laptops, televisions, and other electronics with ease, without worrying about damaging them.
One of the standout features of this generator is its “Low idle” technology, which allows for an extended run time of up to 4 hours at 100% load and 6.5 hours at 50% load.
This means you’ll be able to keep your power supply going for longer, even when you need to run it at full capacity.
And don’t worry about running out of oil – the AP1500i has a low oil alert light and automatic shutdown feature, so you’ll always know when it’s time to top up or change the oil. This will help keep your generator running smoothly year after year.
Despite its powerful 79cc OHV 4-Stroke engine, the AP1500i runs at a super quiet operation of only 52 decibels.
You won’t have to worry about disturbing your neighbors or fellow campers while you enjoy your tailgate or camping experience.
Plus, at only 46 pounds, this generator is light weight and compact, making it easy to transport and store when not in use.
Overall, the A-IPower AP1500i Portable Inverter Generator is a reliable and versatile option for anyone in need of a generator to run their furnace or other sensitive electronics. With its extended run time, low oil alert, and quiet operation, you can rest easy knowing that you’ll have power when you need it most.
2. Craftsman 3000i Inverter 50 St/CSA
- Built in Handle – Easy mobility; carry with one hand
- Steady power – Our technology makes safe, clean power for your electronics
- Easy start – Start/Stop/Choke dial makes starting quick and easy
- Boost of Power – 50 percent more starting capacity allows you to do more with a smaller product
- Ultra Quiet Design with High Performance – Perfect for camping and tailgating
One of the standout features of this generator is its built-in handle, which makes it incredibly easy to move around.
You can even carry it with just one hand! Plus, with its steady power output, you can rest assured that your electronics will be safe and sound while it’s running.
Starting the Craftsman 3000i Inverter is a breeze, thanks to its Start/Stop/Choke dial.
And even though it’s a smaller product, it packs a punch with 50 percent more starting capacity, giving you a boost of power to handle all your needs.
If you’re worried about noise levels, don’t be. The Craftsman 3000i Inverter is designed with an ultra-quiet engine that won’t disturb your camping or tailgating experience.
But just because it’s quiet doesn’t mean it skimps on performance. This generator can handle all your power needs with ease.
Overall, the Craftsman 3000i Inverter is an excellent choice for anyone looking for a reliable and efficient generator.
Its easy mobility, steady power, and quiet operation make it perfect for a variety of applications, from powering your furnace to keeping your electronics charged while on the go. Give it a try and see for yourself!
3. maXpeedingrods 5500W Inverter Generator
- [Multi-Purpose Power Supply]Rated power 5000W, maximum power 5500W, basically can meet the larger power appliances (such as conventional power tool). Under power outage scenarios, it can basically provide continuous power supply for small and medium-sized households
- [Easy Start] Recoil Start and Eletric Start are configured in two starting modes, electric start is easy to operate and can be started successfully at once. recoil start can be used as an alternative starting method to recharge the built-in battery for electric start when it runs out of power.
- [Clear Digital Display]The panel is equipped with a digital display screen to monitor the data and feedback information in real time. It helps you clearly understand the fuel condition, usage, power generation status and generator condition.
- [Power More Appliances]With 2*120V 20A, 1*120V 30A, 1*120V/240V 30A dual voltage plug (can be directly connected to 220V and 240V appliances), 2*USB port to solve the output needs of conventional appliances. Large panel with many interfaces, can supply power to a larger number of appliances simultaneously without transfer switch
- [Compact Design]Makes it lighter weight in the 5KW and higher power band, and 25% weight reduction on the basis of the previous generation MXR5500, with a net weight of only 86lbs, a significant increase in portability. The longest side is 21.7 inches, making it smaller and more convenient to store when not in use.
- [Brand Warranty]Maxpeedingrods warrants all the inverter generators against defects in workmanship under normal use for a period of 2 years from the date of retail purchase by the original end-user purchaser (“Warranty Period”), and free lifetime technical support and customer service.
The maXpeedingrods 5500W Inverter Generator is easy to start with two starting modes, Recoil Start and Electric Start.
The electric start is especially user-friendly and can be started successfully at once, while the recoil start can be used as an alternative starting method to recharge the built-in battery for the electric start when it runs out of power.
The generator’s panel is equipped with a clear digital display screen that monitors the data and feedback information in real time.
This feature helps you understand the fuel condition, usage, power generation status, and generator condition.
With multiple output interfaces, including 2120V 20A, 1120V 30A, 1120V/240V 30A dual voltage plug, and 2USB ports, this generator can power more appliances simultaneously without a transfer switch.
The maXpeedingrods 5500W Inverter Generator has a compact design, making it lighter weight and more portable than other generators in its class.
It weighs only 86lbs, and its longest side is 21.7 inches, making it easy to store when not in use.
Finally, the maXpeedingrods 5500W Inverter Generator comes with a 2-year warranty against defects in workmanship under normal use and free lifetime technical support and customer service.
So, you can purchase this generator with confidence, knowing that it will be backed by excellent customer service.
4. CPE 100520 DH Series Open Frame Inverter
- Advanced Open Frame Inverter Design: 30% quieter and 25% lighter than a traditional Champion 7000-watt generator, plus this inverter only produces Clean Power, and Economy Mode saves fuel
- Electric Start: The convenient electric push-button start includes a battery
- Quiet Technology and Extended Run Time: 72 dBA is great for your next project or home backup, with 8750 starting watts and 7000 running watts for up to 10. 5 hours run time on gasoline
- Intelligauge: Monitor voltage, frequency and operating hours with ease.Use a damp cloth to clean exterior surfaces of the generator
- Champion Support: Includes 3-year limited with FREE lifetime technical support from dedicated experts
CPE 100520 DH series advanced inverter design is not only 30% quieter and 25% lighter than traditional generators, but it also produces clean power and has an Economy Mode to save fuel.
With an electric push-button start and a battery included, starting up your furnace during a power outage has never been easier.
Plus, the Quiet Technology and Extended Run Time of up to 10.5 hours on gasoline ensure that you can stay warm and cozy without any interruptions.
The Intelligauge feature allows for easy monitoring of voltage, frequency, and operating hours, while the generator’s exterior surfaces can easily be cleaned with a damp cloth.
And with Champion Support, you can rest assured that you’ll have access to dedicated experts for free lifetime technical support.
5. DuroMax XP10000EH Dual Fuel Portable Generator
- Plenty of Power – With 10,000 starting watts and 8,000 running watts, this unit can handle heavy loads from lights and a refrigerator to a home air conditioner and high amperage power tools
- Dual Fuel Technology – This generator runs on gasoline or propane, giving you the freedom and flexibility of fuel choice
- Powerful Engine – The DuroMax 439cc OHV engine is a workhorse that provides plenty of power to handle multiple jobs, from powering high voltage appliances to heavy duty power tools
- Idle Control – Lowers the RPMs of the generator when not in use, saving fuel and reducing noise. Ideal on job sites where power is used intermittently
- MX2 Technology – Get the maximum power from each of the 120-volt receptacles. Choose between operating the generator at both 120V and 240V simultaneously, or at 120V only with full power. Ideal for usage with RVs
The DuroMax XP10000EH Dual Fuel Portable Generator could be the perfect solution for you to run a furnace. This powerful generator can handle heavy loads with its 10,000 starting watts and 8,000 running watts.
One of the standout features of the DuroMax XP10000EH is its dual fuel technology. You can use either gasoline or propane as fuel, giving you the flexibility to choose the option that suits you best.
The generator’s powerful 439cc OHV engine is designed to handle multiple jobs, from powering high-voltage appliances to heavy-duty power tools.
The DuroMax XP10000EH also has Idle Control, which lowers the RPMs of the generator when not in use, saving fuel and reducing noise.
This feature is particularly useful on job sites where power is used intermittently. The MX2 Technology allows you to get maximum power from each of the 120-volt receptacles, making it ideal for usage with RVs.
Whether you need a reliable backup power source for your home or RV, the DuroMax XP10000EH is an excellent choice.
With its impressive power output, dual fuel technology, and efficient design, this generator is a solid investment for anyone in need of a dependable power source.
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FAQs About Right Size Generator To Run Furnace
How Much Wattage Is Required To Run A Home Furnace?
A home furnace is typically a light-duty appliance that doesn’t need much wattage to keep running.
Most gas-fired furnaces require around 600 watts of electricity to keep running.
Can A 2000 Watt Generator Run A Furnace?
A 2000-watt generator is powerful enough to run an oil or natural gas furnace.
The starting wattage of these furnaces is 1600 watts, and the running wattage is 600 watts.
A 2000-watt generator, on the other hand, is capable of running multiple lights, a radiant heater, and a couple of fans.
What Is The Quietest Generator For A Furnace?
When choosing a generator for a furnace or other appliance, the sound level is an important factor, especially for a sensitive family or neighbor.
The YAMAHA EF2000iSv2 Gas Powered Portable Inverter will be the right option to keep the environment calm while getting the job done.
Will a 3500 watt generator run a furnace?
A 3500 watt generator can certainly run a furnace, provided the furnace is not too large or power-hungry.
Can I power my furnace with a generator?
The answer to this question depends on the size of your furnace. If you have a small furnace, then you may be able to use a portable generator to power it.
However, if you have a large furnace, then you will need a larger generator to power it.
Will a 1000W generator run a gas furnace?
No, a 1000 watt generator is not enough to run a gas furnace. The starting wattage for most furnaces is between 2000 and 3000 watts.
Will a 5000 watt generator run a furnace?
Yes, a 5000 watt generator will run a furnace.
Can a 6500 watt generator run a furnace?
A 6500 watt generator can indeed run a furnace, however, it is not recommended to do so for extended periods of time.
It is best to use a generator that is specifically designed to power a furnace, such as a standby generator.
How many watts does a furnace draw?
It depends on the type and size of the furnace. Generally speaking, most furnaces will require between 3000-4000 watts to operate.
If you have a larger or more powerful furnace, it may require up to 6000 watts.
Will a 5500 watt generator run my furnace?
In general, a 5500 watt generator should be able to power a furnace without any problems.
Will a 4000 watt generator run a furnace?
If you have a 4000 watt generator, you should be able to run a furnace without any issues.
Final words
Whether you want to be prepared for a harsh winter or a power outage, a generator is an all-in-one solution.
Throughout the guide, we have explained what size generator to run the furnace and offered some ideas for determining your own.
Hopefully, getting the right size generator for the furnace will be a straightforward task for you, so you can enjoy warm air on those cold days.
