A popping sound and then a flame – let’s make gas furnace backfires a thing of the past.
Boom said the furnace. A gas furnace backfire can deliver a scare, conjuring up involuntary images of explosions and destroyed homes. Backfiring is unlikely to blow your furnace into smithereens – but that doesn’t mean you shouldn’t take backfiring seriously.
If your gas furnace backfires you should address the problem as soon as possible. Leaving a malfunctioning furnace untreated means risking:
- Release of toxic soot into your living space (and perhaps carbon monoxide!)
- Significant damage to your heating system
- Repair costs that might not by covered by insurance
Here’s the good news. All three – damage to your health, home, and wallet – can be avoided. Discover what to do when you have a gas furnace backfire, which is sometimes called a blowback or puffback.
We list the 5 common causes of a gas furnace backfire and how to solve them, as well as how to diagnose and prevent backfires, when to replace your furnace, and when to call in the professionals.
Read on to find out all about gas furnace backfires and how to keep your property and health safe.
[Do you suspect toxic soot to leak from your gas furnace? Call Lux Restoration for professional HVAC inspection to keep your home or commercial property safe and free from damage.]
What is a gas furnace backfire and how dangerous is it?
A natural gas furnace backfire occurs when unburned gas accumulates in the furnace and suddenly ignites, causing a small explosion or loud noise. This can happen due to issues like delayed ignition or a malfunctioning gas valve. Backfires can cause all kinds of damage to your gas furnace, property, and health:
- A backfire causes internal damage to your furnace components, like to the heat exchanger, blower motor, burners, and ignition system
- The explosion forces soot and smoke through the HVAC-system and into your living space, causing damage to property, belongings, and health
- In rare cases, a backfire can cause a fire – especially if there are gas line leaks or if flammable materials are near the furnace
- Damage to the heat exchanger or other elements can lead to carbon monoxide leaks, which are extremely dangerous and potentially fatal
From 2017 to 2019 (the most recent period for which data are complete), there were an estimated 21 CO-related deaths annually associated with gas furnaces and boilers. For the 20-year period, 2000 through 2019, these equipment caused a total of 539 deaths from CO poisoning, data from the Federal Register shows.
Even if there’s no apparent damage or health risk, backfires can reduce the efficiency of your furnace, leading to higher energy costs.
But enough to sound the alarm. Let’s look at common causes for gas furnace backfires, and how to fix and prevent them.
5 common causes and fixes of gas furnaces backfires
With more Americans relying on natural gas or propane to stay warm through winter, many properties are at risk of a malfunctioning gas furnace. About half of households use gas appliances for heat and hot water, according to data from the Census Bureau.
On top of that, the number of high-efficiency natural gas furnaces installed by consumers has increased a lot in recent years, the American Gas Association observed.
Source: American Gas Association (AGA)
While gas furnace backfires can be alarming, understanding what can cause that popping sound can help you fix the problem. So what causes a gas furnace to backfire?
1. Delayed Ignition
The delayed ignition of a gas furnace occurs when gas builds up in the combustion chamber before you’re igniting the gas. Why does this happen? When the accumulated gas finally ignites a small explosion is created and causes backfire.
Dirty or faulty igniters, weak pilot lights, or improper gas pressure are often the cause of ignition backfires in high efficiency gas furnaces.
How to fix a delayed ignition:
To fix this type of furnace malfunction, have a professional HVAC technician clean or replace the igniter, adjust the pilot light, and check gas pressure.
Regular maintenance easily prevents this issue by ensuring all components are clean and functioning correctly.
2. Dirty burners
Dirty burners are another common cause for your natural gas furnace backfiring. This happens over time as burners gather dirt, dust, and debris.
Dirty burners then lead to uneven gas distribution and incomplete combustion. The result is gas buildup and backfires.
How to fix dirty burners:
You should clean your burners thoroughly or have a professional do it for you. Regular maintenance keeps burners free from debris. If the burners are severely corroded you might want to replace them.
3. Incorrect gas-to-air ratio
If the ratio of gas and air during combustion is incorrect it leads to incomplete combustion and subsequent backfiring. An improper gas-to-air ratio can be caused by issues with the gas valve, air intake, or exhaust system.
How to fix an incorrect gas-to-air ratio:
If you suspect the gas-to-air ratio of your gas furnace to be off, a HVAC professional should adjust the gas valve and check the air intake and exhaust systems. They may have to clean or repair these components to ensure proper airflow and gas distribution.
4. Cracked Heat Exchanger
The cause of your gas furnace backfiring could be your heat exchanger. When this element is cracked, gasses mix improperly and lead to backfires. Cracked heat exchangers present a big risk as they can result in carbon monoxide leaks.
How to fix a cracked heat exchanger:
A cracked heat exchanger likely requires replacement of the entire gas furnace. This is no regular HVAC maintenance and will require professional help due to the difficulty and safety hazards involved.
5. Ventilation problems
Poor ventilation of your gas furnace and HVAC-system is another possible cause of backfires.
This can be due to blocked flues, damaged vent exhaust pipes, hoses, or bad airflow in the furnace area.
Improper ventilation can also cause mold problems.
How to fix ventilation problems:
You can improve ventilation of your HVAC system and furnace by clearing any blockages in the flue and vent pipes. Make sure that the furnace runs smoothly and with adequate ventilation. If the issue persists, ask a professional to redesign the ventilation system and improve airflow.
Doing DIY fixes vs calling the professionals
If you notice that your gas furnace backfires, here are some steps to take and troubleshoot the issue yourself:
- Check the air filter: A clogged filter can cause airflow problems. Replace if dirty.
- Inspect visible components: Look for obvious signs of damage or debris.
- Ensure all vents and registers are open and the airflow is unobstructed.
- Verify that thermostat settings are correct.
Gone through all steps? Start up your gas furnace and see if the problem is gone. If you suspect the backfiring persists, stop and call a professional. If you smell gas, hear persistent unusual noises, or see visible damage, it’s best to immediately turn off the furnace and contact an HVAC expert.
Why call a professional? Having an expert address gas furnace issues ensures:
- Safety. Gas furnaces are complex systems and have dangerous components.
- Expertise. HVAC experts have the knowledge, experience, and tools to correctly diagnose technical issues.
- Warranty protection. DIY repairs might void your insurance and/or furnace warranty.
At Lux Restoration, we understand the importance of a well-maintained heating system. Our team of certified HVAC professionals is equipped to handle all your gas furnace needs, from routine maintenance to emergency repairs and fire damage restoration. We’re committed to ensuring your home stays safe and comfortable throughout the year.
During a professional inspection, you can expect:
- An examination of all furnace components
- Testing of gas pressure and electrical connections
- Inspection of the heat exchanger for cracks or damage
- Cleaning or replacement of key components as needed
- Calibration of the system for optimal performance
Our surface extends beyond gas furnace maintenance. We also inspect your property for toxic soot and damage if we suspect a backfiring gas furnace to have caused either.
Preventing future backfires
Gas furnaces have surprisingly high failure rates at 80% for filter failure and 50% for sensors and ignitors, heating specialist Christianson Heating found. Such failures can lead to backfiring furnaces.
That’s why the Consumer Product Safety Commission recommends homeowners “Have a professional inspect all fuel-burning heating systems, including furnaces, boilers, fireplaces, wood stoves, water heaters, chimneys, flues and vents each year.”
So what to do to prevent gas furnace backfire? Below are some steps you can take to maintain your gas furnace and reduce the risk of backfires:
- Replace filters regularly: Change your furnace filter every 1-3 months, depending on usage and air quality in your home.
- Keep the area around your furnace clean: Make sure the space around your furnace is free from clutter and combustible materials.
- Maintain proper ventilation: Ensure all vents and flues are clear of obstructions to allow proper airflow and exhaust.
- Install carbon monoxide detectors: Place CO detectors on every floor of your home, especially near sleeping areas.
- Pay attention to unusual sounds or smells: If you notice popping sounds, strange noises, or odors coming from your furnace, shut it off immediately and call a professional.
- Upgrade older systems: If your furnace is more than 15 years old, you could consider replacing it with a newer, more efficient model with advanced safety features.
By following these preventive measures, you can significantly reduce the risk of gas furnace backfires and ensure the safety and comfort of your home. However, even with diligent maintenance, issues can still arise.
That’s why it’s crucial to plan annual inspections. As recommended by the Consumer Product Safety Commission, have a certified HVAC technician inspect your furnace annually before the heating season begins.
At Lux Restoration, we understand the importance of a well-maintained heating system. Our team of certified HVAC professionals is equipped to handle all your gas furnace needs, from routine maintenance to emergency repairs. We’re committed to ensuring your home or commercial property stays safe and comfortable throughout the year.
[Don’t wait for a backfire to occur – take action now. Contact Lux Restoration today to schedule your professional gas furnace inspection and maintenance.]