How To Power Furnace With Generator

How to Power Furnace With Generator

Power outages can be quite inconvenient, especially during the colder months when you heavily rely on your furnace to keep your home warm and comfortable. However, if you have a backup generator, you can still power your furnace and ensure that you and your family stay warm even when the grid goes down. In this article, we will guide you through the steps on how to power your furnace with a generator.

1. Choose the Right Generator

The first step in powering your furnace with a generator is to choose the right generator. It’s important to select a generator that has enough wattage capacity to handle the power requirements of your furnace. Most furnaces require between 500 to 1500 watts to operate, depending on their size and efficiency. Check the furnace’s manual or the nameplate on the unit to determine its power consumption.

Tip: It’s always better to have a generator with a higher wattage capacity than your furnace’s requirement to accommodate any potential power surges or additional appliances you may want to power during an outage.

2. Find the Furnace Circuit Breaker

Locate the circuit breaker that controls your furnace. In most cases, it will be labeled “furnace” or “HVAC” on your home’s electrical panel. Switch off this circuit breaker to disconnect the furnace from the main electrical supply.

3. Prepare the Generator

Next, you need to prepare your generator for use. Make sure it is placed in a well-ventilated area outside your home to avoid the risk of carbon monoxide poisoning. Check the oil and fuel levels, and if necessary, fill them up. Start the generator following the manufacturer’s instructions.

4. Connect the Generator to Your Furnace

Now it’s time to connect your generator to the furnace. Locate the furnace’s power cable and unplug it from the electrical outlet. Connect the male end of a heavy-duty, outdoor-rated extension cord to the furnace’s power cable. Plug the female end of the extension cord into one of the generator’s available power outlets.

Note: Ensure that the extension cord you use is rated to handle the wattage of both the generator and the furnace. Using an undersized cord can lead to overheating and potential fire hazards.

5. Restore Power to the Furnace

With the generator running and the furnace connected, go back to the electrical panel and switch on the circuit breaker for the furnace. This will restore power to the furnace, and it should start running as normal.

Important: Keep an eye on the generator’s fuel levels and periodically refuel it as needed. Also, ensure that the generator is never operated indoors or in close proximity to doors, windows, or vents to prevent carbon monoxide buildup.

Frequently Asked Questions On How To Power Furnace With Generator

How Do I Connect A Generator To My Furnace?

To connect a generator to your furnace, you’ll need a transfer switch and an appropriate power cord. Follow the manufacturer’s instructions and consult a professional if needed.

What Size Generator Do I Need To Power My Furnace?

The size of the generator you’ll need to power your furnace depends on the furnace’s power requirements. Consult the furnace’s manual or a professional for accurate sizing information.

Can I Run My Furnace On A Portable Generator?

Yes, you can run your furnace on a portable generator, but make sure it has sufficient wattage capacity and is connected properly using a transfer switch.

Will A Generator Damage My Furnace?

No, a properly connected and sized generator should not damage your furnace. However, it’s important to follow safety guidelines and consult a professional to avoid any potential risks.


Powering your furnace with a generator can provide you with peace of mind during power outages, ensuring that you can stay warm and comfortable in your home. Remember to always prioritize safety when working with generators and follow the manufacturer’s instructions carefully. By choosing the right generator, properly connecting it to your furnace, and ensuring proper ventilation, you can effectively power your furnace and weather any power outage without sacrificing your comfort.

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