Сan a Portable Generator Run a Furnace? – Techniques And Tricks

If you live in an area where power outages are common, or if you are planning to travel to an area where outages are likely, it is important to have a portable generator on hand. A portable generator can provide the power you need to run a furnace and keep your home warm during an outage.

While most furnaces will not run on a portable generator, some newer models are designed to do so. If your furnace is not designed to run on a portable generator, you can still use one to keep your home warm during an outage. There are a few different ways to do this.

What Is a Gas Furnace?


A gas furnace uses gas – usually natural gas – to heat air. The gas is burned in a furnace, and the hot air is circulated through the home using a blower.

Gas furnaces are rated by their efficiency in converting fuel to heat and their maximum input in BTUs (British Thermal Units). The most efficient gas furnaces have an AFUE (Annual Fuel Utilization Efficiency) rating of 97% or higher. This means that 97% of the fuel is used to heat the home, and the other 3% is lost up the chimney or through other inefficiencies.

The size of a gas furnace is also important. A too-small furnace will have to work harder to heat the home and will not be as efficient as a larger one. On the other hand, a too-large furnace will cycle on and off too frequently and will also not be as efficient.

When choosing a gas furnace, it is important to consider the unit’s size and efficiency rating. A unit that is too large or too small will not operate as efficiently as one that is the right size. An efficient unit will save money on fuel costs over the long run, even though it may cost more upfront.

Gas Furnace Wattage

Most gas furnaces have a wattage between 30,000 and 60,000 BTUs. The average home uses a furnace with a 40,000 BTU rating. Gas furnaces are classified by their BTU output and their energy efficiency. The higher the BTU output, the more heat the furnace can generate. The higher the energy efficiency, the more efficiently the furnace uses gas to generate heat.

Furance in the room

How to Choose a Generator to Run a Furance?

A few things to consider when selecting a generator to run a furnace. The size of the furnace, the type of fuel it uses, and the climate in which it will be used are all important factors.


The size of the furnace is the most important factor to consider when selecting a generator. The average home furnace is about 50,000 BTUs. However, furnaces can range in size from 25,000 to over 100,000 BTUs. The type of fuel the furnace uses is also an important factor. Natural gas furnaces are the most common, but oil and propane furnaces are also used.


The climate in which the furnace will be used is also an important factor to consider. Furnaces are designed to operate in a specific range of temperatures. A larger generator may be needed if the furnace will be used in an area with very cold winters.


  • A 3500-watt generator can run a furnace, but it is not recommended. The furnace will put a strain on the generator, and it is not designed to handle that kind of load.
  • A 4000-watt generator will run a furnace. However, the size and type of furnace will determine how long the generator can run. If the furnace is electric, the generator will need to be able to provide enough power to keep the furnace running.
  • A 5000-watt generator will run a furnace as long as the starting wattage of the furnace is less than 5000 watts.
  • A 5500-watt generator can run a gas furnace up to 60,000 BTUs.
  • A 6000-watt generator can run a furnace, but the furnace will not operate at full capacity.

How to Connect a Generator to the Gas Furnace?

Step 1: Prepare the generator for connection.

Turn off the generator’s main circuit breaker.

Remove the generator’s grounding rod from the ground.

Step 2: Prepare the furnace to plug in.

Step 3: Connect the generator to run the furnace.

Connect the generator’s output terminal to the gas furnace’s input terminal.

Step 4: Turn on the generator’s main circuit breaker.

Step 5: Test the connection by starting the gas furnace.

Black generator on the yard


If you have a generator that you would like to connect to your gas furnace, there are a few things that you need to do to make sure that the process is done safely. First, you need to make sure that the generator is properly grounded. This will help to prevent any electrical shocks that could occur. Next, you must connect the generator to the gas furnace using a gas line. Make sure that the connection is tight to prevent any gas leaks. Finally, you need to start the generator and let it run for a few minutes to ensure everything is working properly.

Frequently Asked Question

How Much Electricity Does a Gas Furnace Use Per Day?

A gas furnace uses about 40,000 BTUs per hour, about 11,000 watts. If a furnace runs 10 hours daily, that would be about 110 kilowatt hours (kWh). This is just an estimate because actual usage depends on the size and efficiency of the furnace, the climate, and how often the furnace cycles on and off.

Can I Plug My Gas Furnace into a Generator?

Yes, you can plug your gas furnace into a generator. However, you must ensure the generator is properly sized for the furnace. If the generator is too small, it will not be able to power the furnace. Also, read the furnace’s manual to see if it has special instructions for connecting to a generator.

Orange generator on the stand

Will the Portable Generator Damage My Furnace?

No, the portable generator will not damage your furnace. Your furnace is designed to run on electricity, so running it on a portable generator is not a problem. Running your furnace on a portable generator can be a good way to keep your home warm during a power outage.

Does a Gas Furnace Work Without Electricity?

No, a gas furnace will not work without electricity. The furnace needs electricity to ignite the gas and to run the blower. In case of a gas furnace power outage, the gas furnace needs to be connected to the portable generator.


As winter sets in, many people worry about keeping their homes warm. For some, this means firing up the furnace for the first time in months. But for others, it may mean using a portable generator to run their furnace.

Portable generators can be a great way to keep your furnace running during a power outage. They can also be used to supplement your home’s existing heating system. Either way, they can be a lifesaver during a cold snap.

Ronnie Collins

Ronnie Collins

I’m Ronnie Collins. I’ve been passionate about gardening and woodworking all my life and even earned an MS degree in Botany from the University of Maryland. I’ve been working at a gardening company for a while, so I know the ropes about a whole lot of dedicated equipment such as the table saw, track saw, lawnmowers, chainsaws, garden hoses, and much more.

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