Furnace Won't Turn On Without Power? Here's the Fix

It can be incredibly frustrating when your furnace suddenly stops working, especially in the dead of winter when you desperately need it for heat. And one of the most common culprits behind furnace failure? A lack of power.

Your furnace relies on electricity to run components like the blower motor, circuit board, sensors, and relays. So when the power cuts out, safety features kick in to prevent potentially dangerous operation during an outage. But that doesn't make dealing with a freezing cold house any easier!

Don't worry - in most cases, you can get your furnace going again after the power returns. You just need to troubleshoot the right issues. This guide will cover everything you need to safely restore power and heat.

Why Your Furnace Needs Electricity to Operate

Today's furnaces do more than just blow hot air - they rely on electrical parts to function properly:

• The blower motor requires electricity to spin the fan and circulate warm air.
• The circuit board controls temperature, timers, sensors and more to regulate furnace operation.
• Relays, switches , and other components also need power to trigger system actions.

Without electricity, these crucial components can't activate your furnace heating cycle, leaving you powerless against the cold.

What Happens When the Power Goes Out?

Furnaces have a built-in safety system to prevent dangerous operation when the power fails. When an outage strikes:

• The safety system kicks in and automatically shuts off your furnace.
• This prevents risks like gas leaks , fire hazards , and carbon monoxide poisoning .
• You'll need to rely on backup heating sources like a fireplace or space heaters.

Safety is the top priority here - you should never tamper with or override this protection system. Operation without electricity can have catastrophic consequences.

Instead, troubleshoot why your furnace won't restart after power returns. The issue typically boils down to a few key problems.

Getting Your Furnace Working After an Outage

Inspecting Your Thermostat

Issues with your thermostat are one of the most common reasons a furnace won't turn back on.

Start by checking the thermostat thoroughly:

• Ensure batteries are installed and functional.
• Flip modes between heat/AC - is anything displayed?
• Adjust temperature higher - does it trigger heating?

If the thermostat shows no signs of power, seems faulty, or won't activate heating, it likely got damaged or reset during the outage. You may need a replacement.

Checking Power Switches

Another quick thing to check - make sure your furnace's power switch is actually turned on!

Most furnaces have an external power switch mounted nearby or inside a control panel. When power cuts out, all switches can reset to "off".

• Locate the furnace power switch and flip it "on" if needed.
• Also verify your main circuit breaker or fuse box didn't trip.

It seems simple, but furnaces with a flipped "off" switch won't restart without a manual reboot.

Reigniting the Pilot Light

For gas furnaces, an outage may extinguish its pilot light - the small flame that ignites the burners.

If your gas furnace won't restart, confirm that the pilot light is still lit. If not:

• Use the unit's built-in ignitor to manually relight it.
• Refer to your specific furnace's lighting instructions if needed.

With the pilot light reignited, the furnace should fire back up to supply heat.

When to Call in a Professional

If you've checked the thermostat, switches, and pilot - and your furnace still lacks power - it's time to call in backup.

Contact an HVAC technician right away if:

• Basic troubleshooting fails to restore operation.
• You smell gas or suspect a leak.
• The furnace makes unusual noises when trying to start.
• Temperature control problems continue.

A qualified professional can investigate more complex electrical issues, avoiding extensive repairs down the road.

Preventing Future Furnace Power Loss Issues

To help avoid repeated power-related failures, consider proactively upgrading your furnace's resiliency.

Getting a Backup Generator

Since power outages can happen anytime, installing a backup generator prepares you for the worst:

• Automatically provides electricity when the grid fails.
• Keeps your furnace operational until utility power returns.

Backup generators prevent dropping temperatures from leaving you out in the cold next outage.

Installing Surge Protectors

Electrical surges during storms can damage the sensitive circuit boards in HVAC systems.

Adding power surge protectors safeguards your furnace:

• Absorbs harmful voltage spikes.
• Prevents component frying and failure points.

Surge protectors provide an extra defense to keep systems running smoothly.

Upgrading to a Dual-Fuel System

• Combines electric heat and gas/propane heating.
• Automatically switches when one fuel source is disrupted.

Dual-fuel configurations continue heating evenly despite losing one power source. The flexibility lets you ride out electrical issues and stay comfortable.

Losing heat right when you need it most is incredibly stressful. But there are steps you can take to get your furnace running again:

• Never override safety features during an outage - it puts you at risk.
• Attempt basic fixes like checking the thermostat before calling pros.
• Consider preventative upgrades to improve electrical reliability.

Restoring steady operation after losing furnace power prevents extensive repairs down the road. And more importantly, it keeps you warm when winter weather strikes its worst!