It’s a cold winter night and you’ve just lost power. You trek down to the basement to check things out and realize your furnace isn’t running at all. Uh oh. Now you’re not only in the dark, but losing heat too. Don’t panic yet! There are several things you can try to get your furnace going again after an outage. And if that doesn’t work, it’s good to understand the common problems professionals may need to repair.
Let’s dive in so you can get your home warm once again.
Why the Furnace Stops Working During an Outage
To understand why your furnace cut off, it helps to first understand a bit about how it works normally…
Overview of Furnace Operation
Your furnace relies on electricity for several crucial functions:
- Powering the thermostat and control circuitry
- Running the blower to circulate heated air
- Activating the ignition sequence to light the gas burner
- Monitoring safety sensors so things shut off if problematic
So when an outage hits, the furnace components powering these electrical loads suddenly turn off. Even though it runs on gas, electricity is key for things to operate smoothly.
Gas Valve Closes
Here’s where the safety mechanisms kick in. There’s a gas valve controlling flow from the gas pipes into the furnace burner. When electricity ceases powering the valves and igniter, this valve automatically closes.
This shutdown is crucial to prevent raw gas accumulating in the chamber while the components meant to safely combust it are inactive. It’s a protective measure to avoid dangerous gas leaks or explosions.
So in summary – safety features detect the loss of power and cut off the gas supply accordingly. It’s frustrating to be without heat, but this failsafe makes good sense!
Getting the Furnace Running Again
Okay, now that we know why the furnace stopped working, how about getting heat flowing once more? Let’s walk through some basic steps to reboot after an outage. Often, the furnace will restart itself when conditions allow.
Try Reset Steps
First, go through a full reset sequence to see if that’s enough to jog your system awake again:
- Furnace Power Switch – Turn off/on
- Electrical Breakers – Reset to “Off” then “On”
- Thermostat System Switch – Set to “Off” then “On”
Allow 5-10 minutes after this reset sequence for the furnace to cycle back up after you restore power via breakers and switches. The automatic ignition may delay as self-checks run before allowing gas flow again.
Wait for Automatic Reset
If the power outage was brief, the furnace should restart by itself once electricity comes back on. Here’s what happens in that automatic sequence:
- Draft inducer fan starts up to prep the heat exchanger
- Hot surface ignitor warms until hot enough to light gas
- Gas valve permits gas flow to the burners
- Gas ignites from hot ignitor surface
- Flame sensor confirms ignition successful
- Blower fan starts circulating warmed air
This is basically like a computer booting up when you press restart. It may take 10-15 minutes to cycle through the ignition sequence before blowing nice hot air.
If you just went through a longer multi-hour outage, the delay may be on the longer side. Especially if neighboring homes are all simultaneously rebooting furnaces straining the grid.
Inspect Simple Problems
Before calling in the pros, inspect the furnace yourself for any of these basic issues after a power failure:
- Blown Fuse : Check the furnace fuse for continuity. Replace any blown fuses.
- Tripped Circuit Breaker : Ensure circuit breaker haven’t tripped off for any wired components.
- Thermostat Batteries : Electronic thermostats will drain batteries rapidly during an outage.
- Switch Positions : Verify all switches meant to be on are indeed in the “ON” position after the restart.
Replacing a bad fuse or repositioning an errant switch mid-cycle can often resolve problems. This prevents wasting money on unnecessary repairs down the line.
Consider Calling for Professional Help
While basic troubleshooting may get your furnace humming again, it’s prudent exercising caution if you notice any of the following after an extended outage:
- Burning or Metallic Smells
- Gas Odor
- Unusual Noises During Ignition
- Failed Auto Restarts Persisting
Damaged components like hot ignitors, bad valves, or blown fuses can cause issues only a technician can assess and replace. It’s not worth the risk fumbling with complex furnace guts without the proper electrical know-how.
Contact a reputable HVAC company if something seems off despite your best solo reboot efforts. Furnace repairs often ramp up coming out of storm seasons for good reason – finicky electronics and sustained outages don’t mix well!
Safety Concerns After Losing Power
In addition to just getting your furnace operational again, also be mindful of safety around gas appliances and electricals after an outage. Severe winter storms that cause extended power failures also mean increased risks if proper precautions aren’t taken.
Carbon Monoxide Hazards
Carbon monoxide (CO) is a dangerous byproduct of combustion with no visible signs. Proper venting removes it from your home so it doesn’t accumulate. But venting systems often rely on electricity to run properly with blowers evacuating exhaust outside.
Without power, ventilation can cut off allowing CO to leak back indoors. That’s why generators should always be placed outside with secured extension cords feeding appliance power inside.
Ensure your CO monitors have good batteries after an outage. Listen for their alarms, and call emergency services if they sound or you suspect CO presence.
Gas Line Issues
Earthquake safety valves are meant to automatically shut off gas lines into the home when excess flow is sensed. But they can also trip unnecessarily if debris shifts around lines during storms.
While rare, sometimes underground piping gets inadvertently damaged by tree roots or digging equipment. This also triggers excess flow valves to kill the gas feed. Call the utility company immediately if your appliance pilot lights persistently go out after an outage.
Electrical Problems
From lightning strikes to restore power spikes, outages put excess strain on electricals. Signs of trouble include:
- Frequently tripping breakers
- Flickering lights
- Burning smell from outlets
- Sparse appliance functionality
Damaged wiring or overloaded circuits mean an urgent electrician visit. Put safety first before claiming insurance or replacing damaged electronics.
Steps for a Complete Furnace Inspection
While some outages barely faze a sturdy furnace, others can tax components to their brink. Having an HVAC technician perform a thorough inspection is wise after extended multi-day events resulting in repeat failed start attempts.
Some key things they’ll assess include:
External Components
- Gas Line : Check piping and valves for leaks
- Venting : Confirm exhaust path isn’t obstructed
- Electrical : Assess condition of wiring connections
Internal Components
- Control Board : Diagnose any error codes
- Blower Motor : Test functionality moving air
- Burners : Inspect for cracked ceramic or debris
- Heat Exchanger : Look for corrosion and holes
Combustion Functionality
- Ignition Sequence : Watch startup from scratch
- Burner Flames : Check for proper shape/color
- Flame Sensor : Confirm it shuts off gas when inactive
Sometimes the minor replacement of a cracked ignitor or bad thermocouple sensor gets it humming again. Other times, entire control boards may need swapping out if lightning fried the electronics.
Let the technician make the full assessment rather than playing a guessing game and buying piecemeal parts. Identifying underlying causes versus just visible symptoms is their specialty.
Options if Repair Costs Too Much
Replacing an entire furnace outright is quite the financial burden if you weren’t budgeting for it. But repairs nearing 50% of the cost of a new unit means its prudent considering replacement.
Repair vs Replace Calculation
Have the technician assess:
- Age of existing unit
- Efficiency rating
- Itemized repair parts and labor
- Cost of warrantied modern replacement
- Potential rebates on qualifying models
Crunch the numbers to see if repairing an aging gas guzzler is worthwhile, or if investing in an updated energy-efficient model nets long term savings.
Alternate Heating Sources
In especially frigid temps if the furnace effort stretches, consider backup plans to avoid pipes freezing and provide some warmth such as:
- Space Heaters
- Fireplace
- Heated Blankets
- Staying Elsewhere Temporarily
Layer up the sweaters and thick socks if braving things out at home until central heat restores. Just take safety precautions with space heaters, generators, or DIY propane setups.
Insurance Claim Help
Double check your homeowners/renters policy for specifics on coverage for things like:
- Failure due to Power Surge Damage
- Lyability for Pipe Freezing and Water Damage
- Temporary Housing if Uninhabitable
Keep all technician diagnoses reports and appliance age documentation handy when filing claims. Photos of damage help too.
Losing heat on a cold night while also stuck in the dark definitely warrants some troubleshooting urgency and stress. But avoiding unsafe furnace restarts or ignoring subtle signs of big issues will only make matters worse.
Arm yourself with the proper outage response knowledge ahead of time before scrambling in frozen panic:
- Safely reset furnace switches/breakers to encourage self-restart
- Give time for ignition sequence reboots after extended outages
- Inspect for basic problems like blown fuses or dead thermostat batteries
- Call professional help immediately if you smell gas or anything burning
- Perform qualified maintenance checks after major storms
- Research backup plans if ill-timed full unit replacement necessitates
Take it slow and steady, prioritizing safety steps first. Protect people first, then property damage concerns next. Everything else heat and comfort-wise follows once assured your family and home avoid harm.
Stay warm friends! And rest easier knowing exactly what to do when the power and furnace cut off unexpectedly on the next nasty winter night.