Can You Run A Furnace With A Generator?

Power outages during the winter season will put you in the unpleasant situation of dealing with the excess cold. I know you don’t want to deal with this awful situation. And if you are confused about connecting the furnace with the generator or not, this article is for you.

You could run the furnace with a generator if your generator is 2500 watts or more. You should also install a transfer switch to power the furnace when the electricity shuts off. Following the safety precautions, you can also run a gas furnace with a generator with enough wattage of 1500 watts.

In this article, I will help you understand the wattage requirement of the generator to run a furnace. You will also know the safety precautions to undertake while running the furnace with the generator. So, keep reading.

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Can you plug a furnace into a generator?

As a furnace is essential to keep your home warm, bad weather during snowstorms causes a power outage.

You can use the generator at such times to keep your furnace running. 

Using a generator with enough wattage to power your furnace is always recommended.

You should install a transfer switch to power the furnace with the generator.

It is better to hire a professional instead of you doing this job. 

Calculating the power wattage needed to run your furnace during a power outage would be best. 

If you connect only the furnace to the generator, you don’t need a high-wattage generator. 

If you plan to run all your appliances with the generator, you must calculate the wattage needed to run all the appliances and install a generator accordingly.

Mostly horsepower of the furnace fan determines the power the generator needs to run the particular furnace. 

Let’s assume you have a gas furnace; it usually comes with a quarter-horsepower fan or the half-horsepower fan. 

In the case of a quarter horsepower fan, your generator needs 1600 wattage to start the furnace.

And once it starts running, it will consume 600 watts to continue running. 

And if your furnace has a half horsepower fan, your generator needs to be capable of handling two hundred watts while the furnace is starting and up to nine hundred watts to run it continuously. 

Generally, high-wattage generators come with 5000 watts which would be an ample amount to power up the furnace. 

You can also choose to have a small generator only to power up the furnace during a power outage, in case you want it to be portable and noise free.

Is it safe to run a furnace with a generator?

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It is not so dangerous to plug the generator into the furnace if you follow all the safety precautions. 

While the generator is running, keeping it outdoors is the first safety measure you have to take.

Because it produces hazardous chemicals while functioning, affecting the people’s health in the near environment. 

Most people think it is safe to keep the generator indoors if the windows are wide open to give enough ventilation.

And it is not true; even with enough ventilation, the hazardous gasses released by the generators are not good to inhale. 

With that said, keeping the generator outdoors also requires some safety precautions. 

While installing the generators outdoors, ensure to install the carbon monoxide detector device to sense any hazardous gasses entering your home.

It is advised to keep the generator far away from your house rather than keeping it close. 

You have to ensure the safety measures depend on the type of generators you use. 

Let’s say you use a fuel-consuming generator, and then there will be extra fuel to fill it back into the generator.

Keep that away from the generator to prevent fire hazards. 

There are battery-charged generators; in this case, you must check the battery power to keep it charged for running them when needed.

Don’t let them be devoid of charge, putting them in a terrible situation during a power outage. 

As already discussed, calculate the watts required to run your furnace. 

And install the generator according to your furnace’s and other appliances’ power consumption. 

If you overload your generator with more appliances that require high watts, there are chances of burning and fire.

What size of generator do I need to run my furnace?

To know the exact power wattage of the generator required to power your furnace, you have to do a calculation as mentioned below. 

Begin calculating by adding the starting and the running wattage of your furnace’s electronic and electrical components. 

The calculation will result in the number; the formula to determine the generator’s size is 1.2 multiplied by the wattage of the furnace.

Include the wattage required by all the appliances. 

The transformer, heating element, control board, blower fan, and electronics are the components of the furnace which need the power to operate. 

The heating element and the blower fan consumes high wattage of current.

The other components require fewer watts than the healing element and the blower fan. 

To give you an idea, the heating element of the 4kw needs 4-kilo wattage. 

However, if your furnace requires 20 kW, you must install a generator of 20,000 watts. 

Let’s say you have a gas furnace; in that case, it needs a power supply to these parts: Igniter, lights, sensors, inducer motor, blower fan, and control board.

In these parts of the furnace, the blower fan requires high watts.

A control board and the inducer motor also require significant watts. 

In contrast, lights and sensors don’t need much electricity to function. 

Calculating the blower fan’s wattage requirement in the gas furnace is important. 

The easiest method of calculating the watts required by the furnace is to check the user handbook to see its voltage requirement. 

Using this information, you can calculate the watts required. 

You can calculate the watts required by multiplying the voltage and amperage of the furnace.

Watts=volt multiplied by amperage. 

Let’s take the amperage of your furnace as 10 amps, with 120 volts.

Then the wattage required is 1200 watts. 

Calculate accordingly and install the generator of specific requirements.

The best generator to run a furnace

So far, I have researched and encountered the best generator to run the furnace, and I am sharing the same with you. 

Best generator to run a furnace:

Westinghouse iGen2200 furnace generator

It has a wireless connection option, highly portable with a kick start Device. 

This generator can be controlled by a remote up to 80 feet from the generator. 

It also lasts for 12 hours, provided fuel is full. 

It is less noisy than other generators as it is designed with a steel frame. 

To be specific, it produces noise levels only up to 68 dBa. 

In addition to a furnace, you can operate other applications like television, power tools, and sump pump. 

An oil shortage sensor is also designed to inform you when to fill and stop the device.

It comes with a three-year guarantee.

Beneficially, it has a water-resisting capability.

Honda EU 1000S inverter generator

This generation is the result of the incorporation of advanced technology; it is less noisy and will operate without hassle.

It would be the best choice because it enables you to plug in an air conditioner rather than other home appliances. 

It will work for 8 to 20 hours, depending on the low and high load of the generator.

Its feature of advanced inverter technology powers all the appliances efficiently and prevents the appliance from any damage.

You can extend this generator up to 6000 watts by connecting it with another generator in a parallel position.

It will automatically switch off the engine with the indicator of low oil level if the oil in the generator is insufficient. 

As it comes in a compact outlook, you can easily move it wherever you want.

Firman 3000 Watt generator

It comes with wheels to facilitate easy movement.

It also has a handle to give a grip while moving this 98-pound generator. 

It also runs for ten hours with an engine of 1.8-gallon fuel storage capacity. 

It has a control panel which is a new feature, making it stand out from the crowd. 

Another unique feature of this generator is that it has a cover over lights, sockets, and light indicators, which would keep the dirt away from accumulating. 

And it doesn’t stop here; along with this generator, they supply wrench, oil, and the funnel. 

It supplies efficient electricity with 3% THD with an eco-mode to further increase its efficiency.

Predator 3500 Inverter generator

The predator generator has an excellent capacity for running for 12 hours to withstand the constant power outage. 

It is a compatible device easy for motorhome movement. 

It also has a 30 amp RV adaptor, so you don’t have to worry about installing it with the outlet. 

And the automatic turn-off option when there is low fuel makes it impressive. 

The indicator lights are efficient in warning of overload, which would save you from hazards. 

With a noise level of 57 decibels, it is very quiet not to annoy you and your neighbors.

Will a 3500-watt generator run a furnace?

As already discussed, an electric furnace requires a thousand to two thousand watts.

A 3500-watt generator would be enough if you planned to run only a furnace with it. 

If you want to run the house with a 3500-watt generator, it cannot withstand the voltage of all home appliances. 

In such a case, you must plan to install another generator or replace the existing 3500-watt generator with the 5000 watts high-wattage generator.

Furnace maintenance tips to save yourself from winter

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It is terrible to imagine dealing with a faulty furnace during winter. 

Giving enough attention to furnace maintenance is essential to avoid faults and failures during the winter. 

Here are some of the maintenance tips you have to prioritize: 

  • Examine the thermostat of your furnace. Check if dirt and dust are accumulating on the thermostat. Clean it once in a while to keep the furnace efficient. If the thermostat becomes faulty, it will be hard for your furnace to regulate the temperature.
  • Air filters are essential to prevent airborne diseases and allergens from creeping into the air. So it is crucial to change it regularly. If you haven’t bothered to change the air filters even after dirt accumulation, it will affect your furnace as it works overtime to pressurize on that dirt to wipe off.
  • The tension belts in your furnace wear out over time. If you find your furnace producing wired noise, it should be because of this belt. In this case, replace the belt yourself or seek help from professionals.
  • Check the vents regularly. Clean them before they are over accumulated with dirt and debris. If these vents are clogged, it will cause carbon monoxide toxication. 
  • Ensure that the blower motor of the furnace is functioning well. If you are noticing the noise while the blower motor is running, it may be because of a faulty blower’s motor or wheel. You must consult the technician to find the cause and fix the issue with the blower motor. Fix it as the technician suggests instead of deciding on your own. 
  • Clean the heating elements and the ducts at the beginning of every season.

Final thoughts

Running a furnace with a generator is safe if you install a generator with enough wattage to support the voltage requirement. You will have serious damage and hazards if you ignore the importance of choosing a generator with the right power wattage to run a furnace.

Cleaning the furnace regularly to wipe off all the dirt and dust is important to maintain efficiency. Calculate the wattage required to run the furnace by following the steps mentioned in the article. 

A gas furnace requires less power than an electric furnace. You can choose a generator according to the type of furnace you have. Follow all the maintenance tips required to increase the efficiency of your furnace.

Reference: Gas Furnace: Energy Consumption, Energy use calculator.

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Arthur Smith

Howdy! I am Arthur Smith, an electrical engineer who is extremely passionate about electronics. I have lived in different parts of the US and currently reside in Wisconsin. I am one of those rare children who knew what he wanted to study and do in life right from the start. I was a curious child who wanted to know how switches work and how the AC works, and I would always observe my dad whenever he would handle the wires and fix things around the house. I currently work as an electrical engineer at a reputed company and write for this blog. And I read loads of books or play video games in my free time.

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