My Gas Furnace Won’t Ignite

At John Nugent & Sons, we frequently get calls from residents across Northern Virginia, including Fairfax, Arlington, and Reston, reporting that their gas furnaces won’t ignite.

We would love to help you in the moments when your furnace doesn’t turn on. Contact us online to speak to a member of our team.

7 Reasons Your Gas Furnace Won’t Ignite

1. Tripped Circuit Breaker

If the blower motor in your furnace causes a power overload, it may trip the circuit breaker. This prevents the motor from running and stops the burners from firing. Check your electrical panel and reset the breaker if necessary. If the problem persists, it could indicate a more serious electrical issue that requires professional attention.

2. Broken Electronic Ignition System

This is one of the most common malfunctions in modern gas furnaces. The electronic ignition system is responsible for lighting the gas when your furnace calls for heat. If it’s faulty, your furnace won’t ignite. While this is typically a quick fix for an experienced HVAC technician, it’s not a DIY job due to the complexities of the system and the potential safety hazards involved.

3. Dirty or Rusty Burners

Over time, burners can accumulate grime, dust, or rust, which can obstruct the flow of gas and cut off the oxygen supply necessary for ignition. This buildup can prevent the burners from lighting properly or cause them to produce an uneven flame.

Regular maintenance can prevent this issue, but if you’re already having problems, a thorough cleaning by a professional may be necessary.

4. Open Safety Switch

Furnaces have various safety switches that prevent operation under dangerous conditions. If any of these switches are open, the burners won’t turn on. This could be due to a variety of issues, from a clogged flue to a faulty limit switch. An HVAC technician can run diagnostic tests to identify the specific problem and restore your furnace to safe operation.

5. Dirty Air Filter

One of the simplest yet often overlooked causes of furnace problems is a clogged air filter. A dirty filter restricts airflow, which can cause the furnace to overheat and shut down as a safety precaution. It can also lead to inefficient operation and increased energy bills.

Regularly changing your air filter (typically every one to three months) can prevent this issue and improve your furnace’s overall performance.

6. Broken Flame Sensor

The flame sensor is a crucial safety component that detects whether the burners are lit. If it’s broken or malfunctioning, it may fail to detect the flame and shut off the gas supply as a precaution, even if the burners are actually lit. This can result in your furnace starting the ignition process but failing to stay lit.

While cleaning the flame sensor can sometimes resolve the issue, a broken sensor will need to be replaced by a professional.

7. Strong Draft

Surprisingly, a strong draft can prevent your furnace from igniting or staying lit. Modern furnaces are sensitive to pressure changes, and a strong draft can disrupt the delicate balance needed for proper combustion. This is particularly common in homes with fireplaces or in areas prone to high winds.

If you notice your furnace having trouble on windy days, this could be the culprit. Solutions may include adjusting dampers, sealing air leaks, or installing draft-inducing equipment.

If you have any issues turning on your furnace, contact our trusted HVAC experts. We’ll send a technician out to check your furnace.

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Call Us at 703.291.1926

DIY Gas Furnace Fixes

A DIY project shouldn’t be confusing, so the heating and cooling experts at John Nugent & Sons have created simple directions to fix the furnace issue yourself.

Follow these steps to fix a gas furnace that won’t ignite:

• Ensure the furnace filter is clean — if not, replace the dirty filter with a clean one. Also, check that the power to the furnace is on. Last, make sure the gas supply to the furnace is open.
• If your gas furnace initiates the start cycle but doesn’t fire up, it’s likely because of a faulty, damaged, or dirty ignitor/sensor. This is a very common problem — you can try to clean the sensor and replace the ignitor. It’s possible for a flame sensor to go bad; but more often than not, it’s not broken, just dirty from carbon buildup.
• A flame sensor is an important component of a furnace that’s responsible for igniting and maintaining the flame within the furnace. A flame sensor failure is pretty common due to the buildup of materials and particles in the confined area. To clean the flame sensor, start by making sure your furnace is off — use the switch on the unit or cut the power source at the breaker box. Next, locate the flame sensor. It’s the metal rod in the direct path of the burner with a wire attached to it. If possible, remove the sensor by removing the screws and pulling the wire off. Clean the surface of the sensor by wiping it with either sandpaper or steel wool. Once clean, reinstall the flame sensor directly back into the location from which it was removed.
• A gas furnace ignitor is used to start the furnace. It uses an electric current and filament to ignite. Make sure your furnace is turned off before you attempt to replace the ignitor. Now, locate the ignitor — it’s usually near the center of the burners. Then, unscrew it from its place. It’s important that you take note of the location of the ignitor so you won’t have any trouble fitting in the new one. You’ll now have to position a new ignitor and screw it in place.

If you have any questions about the steps outlined above, call the professionals at John Nugent & Sons. You’ve got questions, we’ve got answers. When it comes to tackling common furnace problems, we’re the experts.

Call John Nugent & Sons today or contact us online for professional furnace help.

Furnace Repairs in Northern Virginia

If you’ve followed these steps and your gas furnace still won’t ignite, you’ll likely need a furnace repair or replacement. And, if needed, John Nugent & Sons offers additional furnace maintenance through our service contracts.

Worst-case scenario, we can also help you with furnace replacement in Fairfax, VA. Take preventative measures this winter and give John Nugent & Sons a call to help you when your gas furnace isn’t working properly.

Call us to schedule a service appointment for furnace replacement or other services.