A winter storm knocks out your power. Now what? Will your furnace still keep you warm?
It’s a common question — and an important one. Whether you have a gas furnace or an electric system, it’s critical to understand how power outages affect heating so you’re not left in the cold when it matters most.
Let’s unpack how gas and electric furnaces respond during an outage, what misconceptions homeowners often have, and what you can do to prepare.
Why Power Reliability Matters More Than Ever
Power outages are becoming more frequent and severe. From ice storms in Texas to wildfires in California, extreme weather and aging infrastructure are straining the grid across North America.
For homeowners, this isn't just a lights-off inconvenience — it's a heating emergency, especially in colder regions where pipes can freeze in a matter of hours.
The type of furnace you choose can influence your home's resilience during blackouts — but perhaps not in the way many people assume.
What Happens to Electric Furnaces During an Outage?
Total Shutdown
Electric furnaces rely entirely on the electrical grid to function. When the power goes out:
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The heating elements stop working
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The blower fan shuts down
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Even the thermostat may go dark, depending on its power source
If you’re using an electric resistance system or an all-electric heat pump, your home will lose heat as soon as the power goes out. Unlike some gas appliances (like a gravity-fed water heater), there’s no partial functionality — the system is completely offline.
Recovery When Power Returns
Once the power comes back, systems often resume normal operation. But there can be hiccups:
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Smart thermostats may need to reconnect or reboot
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Systems without surge protection are vulnerable to power surges
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You might need to manually reset your breaker or thermostat settings
Consumer Reports recommends checking your HVAC system after any outage, especially if it tripped a breaker or you notice strange behavior.
What About Gas Furnaces? Don’t They Work Without Electricity?
This is one of the most common homeowner misconceptions.
Modern Gas Furnaces Still Need Power
Even though gas furnaces burn natural gas, almost all models made in the past 20 years still require electricity for:
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Blower motors (to push warm air through your ducts)
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Electronic ignition (no more pilot lights in most systems)
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Control boards and safety sensors
So unless your gas furnace is an older model with a standing pilot light and no electronic controls (very rare in 2025), it will also shut down during an outage.
As HVAC.com explains, electricity powers the essential components of even the most efficient gas systems.
Misunderstanding the “Gas Advantage”
Many people assume gas = independence from the grid. In reality, gas heating systems are just as grid-dependent as electric ones when it comes to operation — the difference lies in how backup power solutions interact with them.
Backup Power Options: How to Stay Warm During an Outage
If your furnace (gas or electric) needs electricity, the question becomes: how can you keep it running during a power outage?
Whole-Home Generators
These systems automatically detect outages and restore power within seconds. A properly sized generator can:
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Power your furnace, lights, refrigerator, and other essentials
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Run for days on natural gas or propane
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Cost more upfront but provide long-term peace of mind
According to the National Renewable Energy Laboratory, whole-home generators are ideal for homes in outage-prone areas or with critical systems like medical devices.
Portable Generators
A more affordable option, but with caveats:
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Must be manually started and connected
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Can only power select circuits, so you need a transfer switch for HVAC use
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Safety concerns: must be used outside only, with proper ventilation
Most portable generators in the 5,000–7,500-watt range can handle essentials like a gas furnace, but you'll want to verify the wattage and startup load of your unit. Home Depot’s generator sizing guide offers a helpful breakdown to make sure you’re choosing the right backup solution.
Battery Backup Systems
These are gaining popularity, especially when paired with solar panels. While most can't power a whole furnace for long, they’re useful for:
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Keeping your thermostat and control board alive
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Running a ductless mini-split (if you have one) in “low” mode
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Silent operation, no fuel required
Battery backups are best for short outages or supplementing other systems.
How to Prepare Your Furnace for a Power Outage
You can’t control when the power goes out — but you can control how prepared your system is.
Pre-Outage Tips
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Install surge protection on your furnace circuit
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Keep a battery-powered thermostat or power bank ready
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Know how to reset your furnace once power returns
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If you have a generator, test it seasonally and keep fuel on hand
During an Outage
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Keep doors closed to retain heat
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Open cabinet doors under sinks to help prevent pipe freeze
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Layer up and monitor indoor temperature if the outage lasts more than a few hours
So, Which Furnace Type Handles Power Outages Better?
Truthfully? Neither system works well without electricity — unless you’ve prepared a backup power solution.
That said:
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Gas furnaces use less electricity, so they’re easier to run off a portable generator
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Electric systems (especially heat pumps) may be better paired with solar + battery backup
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Older gas systems with standing pilots may run during outages — but they’re becoming obsolete
If grid reliability is a concern where you live, backup planning is more important than the furnace type itself.
Final Thoughts: Plan for the Worst, Heat with Confidence
The takeaway is clear: whether you heat your home with gas or electric, power outages will impact both systems.
To stay warm during blackouts:
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Understand how your specific system works
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Invest in a backup solution that matches your fuel type and budget
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Practice basic outage prep every season
Curious how your furnace choice affects other areas of homeownership, like resale or energy efficiency? Check out our full guide: Gas vs. Electric Furnaces: Which is Better?
👉 Or read next: Home Resale Value: Does Your Furnace Type Matter?
Alex Lane
Your Home Comfort Advocate
