How Do I Know If My Furnace Is Leaking Gas? Essential Tips

As a homeowner, it’s essential to ensure your furnace is safe and efficient. Gas furnaces generate heat energy through combustion, then distribute it through ventilation pipes. Malfunctions in the venting system or leaks can release dangerous byproducts like carbon monoxide. 

Here’s a guide on how to detect a gas furnace leak and keep it safe.

How Do I Know If My Furnace Is Leaking Gas?

 How Do I Know If My Furnace Is Leaking Gas

If your furnace has a gas leak you’ll likely hear hissing or blowing noises from the furnace or its pipes. 

You may smell gas or spot physical damage on the metal vent piping. If any of these are present, turn off the furnace and call a professional.

Signs of Gas Leakage in Furnaces

To identify gas leakages in your furnace, you need to be aware of the warning signs

 Here are the five main warning signs of gas leakage.

Yellow Flames or Pilot Light

Gas leakage is a major no-no, especially when it comes to furnaces. Look out for yellow flames or pilot lights – that’s a sign. Blue flames mean there’s a balanced amount of gas and air. 

But, yellow flames indicate a gas leak and it must be fixed quickly. Incomplete combustion leads to a release of yucky carbon monoxide.

Stay alert to any signs of gas leakage in furnaces. Yellow flames suggest incomplete combustion and a big health hazard. 

Unusual Smells

When it comes to gas furnaces, strange smells can be a sign of a leak. If you smell anything unusual such as rotten eggs, sulfur, or musty odors, turn off the furnace immediately and call for help.

Not everyone can detect gas by smell. Things like age or health can affect it. That’s why carbon monoxide detectors are important to have in your home.

Schedule routine maintenance checks for your furnace and inspect it annually to prevent gas leaks

In case of a gas leak, open windows and doors to improve ventilation. Don’t switch on any electrical appliances or use matches. Call emergency services if needed.

Elevated Gas Bills

A sudden jump in gas bills should raise alarm bells for homeowners. Especially when their usage hasn’t changed. 

Soot Buildup

Soot buildup in furnaces is a sign of gas leakage. The black, powdery substance accumulates when gas doesn’t burn correctly. Not only is this inconvenient, but it also poses health risks and increases the chance of fires.

To prevent soot buildup, get your furnace serviced regularly by a professional. This will ensure that all components are working and that there are no carbon monoxide leaks. 

Physical Symptoms

Gas in your furnace is a major problem. Watch out for any physical symptoms like headaches, dizziness and nausea. If you feel these signs – especially with fatigue or disorientation – get out of your house! And contact a professional.

You may hear a hissing sound from the furnace. It could be working too hard, making loud noises. 

Rust or moisture around the furnace, or whistling sounds, could mean a gas line issue.

Causes of Gas Leaks in Furnaces

By exploring these sub-sections, you can learn about potential issues that may lead to gas leaks in your furnace and take appropriate actions to prevent them.

Malfunctioning Burners or Heat Exchangers

Gas leaks in furnaces can be caused by malfunctioning burners or heat exchangers. This is a serious issue that homeowners should be aware of, as it can lead to fire and carbon monoxide poisoning.

Let’s look at the types of malfunctions that can occur with burners and heat exchangers:

  • Dirty Burners – Clogged burners can cause incomplete combustion of gas.
  • Clogged Air Inlet – Not enough oxygen for complete combustion due to restricted air flow.
  • Cracked Heat Exchanger – Gas fumes escape due to cracks in the heat exchanger.
  • Overheated Heat Exchanger – Cracking & gas leaks due to overheating.

Homeowners should get regular furnace maintenance done by professionals to prevent these malfunctions. If there is a gas leak or any furnace malfunction, call a licensed technician immediately.

Cracked or Damaged Vent Pipe

Damaged vent pipes are a terrifyingly common cause of gas leaks in furnaces. Cracks, gaps, or any other damage can lead to dangerous gas exposure.

Debris and leaves can also block the pipe, causing poor furnace performance and air quality.

It’s hard to spot these issues since they’re often hidden away in walls or crawl spaces. But, regular inspections can help prevent them.

Improper Ventilation In Furnaces

Gas leaks in furnaces can be caused by inadequate ventilation. If airflow is weak, toxic gases like carbon monoxide may enter your home undetected

Flawed Installation Of Gas Furnace

Incorrectly installed furnaces can cause serious gas leaks. Experts must be consulted when installing to avoid severe consequences. 

Let’s check out the five most common mistakes made:

  1. Choosing the wrong location. This can lead to dangerous gas emissions.
  2. Using the wrong size. This can cause overheating or frequent cycling.
  3. Piping errors like torque or stress fractures. This can lead to gas leakage.
  4. Not securing the flue pipes. This can cause carbon monoxide to escape into the home.
  5. Ignoring safety protocols. This can lead to impaired performance or worse.

Preventing Gas Leaks in Furnaces

Gas furnaces are a common home heating option, but you must be sure your furnace isn’t leaking gas.  

  • Inspect the venting and flue gasses pipe to make sure. 
  • High efficiency furnaces have options for direct vent and PVC pipes to release outside. 
  • Check the heat exchanger for damage too. 
  • During installation, follow clearance rules. And make sure you do regular maintenance of the vent system.
  • The combustion process produces carbon monoxide and other byproducts that must be vented out of the house. 
  • Make sure there are proper ventilation pipes for combustion gasses. Also, use outdoor air as combustion air when installing a high efficiency furnace.

Regular Maintenance Of Gas Furnace

It’s essential to maintain furnaces to ward off gas leaks. Ignoring regular maintenance could have fatal results. 

Here are 3 basics for furnace maintenance:

  1. Change/clean the air filters every 1-3 months.
  2. Inspect the burners, pilot light, and flue vent regularly for gas leaks.
  3. Get professional tune-up services yearly to ensure smooth operation and adjust gas pressure.
  4. Regular maintenance is also key to avoiding problems and leaks. Have a licensed HVAC technician inspect your system every year.

Proper Ventilation and Vent Pipe Installation In Gas Furnace

Good ventilation and vent pipes installation is key for avoiding gas leaks in furnaces. You must plan and execute carefully for the safety of people and property. 

Here is a 5-Step Guide:

  1. Choose the best spot for the furnace. Check that it’s well-ventilated, away from combustibles and obeying local codes.
  2. Pick the correct type of vent pipe. PVC may not be suitable for high efficiency units running at higher temperatures as it could melt.
  3. Size the pipes right. This will provide enough air flow and eliminate harmful gasses. The inlet should be bigger than the outlet.
  4. Make sure all pipework connections are tight. This stops any hazardous gasses getting stuck.
  5. Get help from professionals. It involves technical work and can be dangerous without the right help.

Proper Combustion Of Air In Gas Furnace 

Airflow is key for a furnace to run safely and efficiently. Oxygen must get into the combustion chamber to burn fuel and produce heat. 

The right amount of air must be present for optimal combustion. When windows and doors are closed, airflow must not be blocked or it could cause gas leaks.

Blockages on vents or air intake can reduce airflow and cause combustion problems. Regular cleaning and inspection will help spot blockages and ensure good airflow.

Upgrading to High-Efficiency Furnace

Upgrading to a high-efficiency furnace can help reduce the chances of gas leaks and conserve energy.

Here are five advantages:

High-efficiency furnaces have an AFUE rating of at least 90%, compared to 70-80% for standard models. This means they use less fuel and save money on energy bills.
Carbon FootprintHigh-efficiency models emit fewer greenhouse gases. They’re more eco-friendly than older furnaces.
Air QualityA high-efficiency furnace can improve air quality in your home by reducing dust, pollen, and other contaminants.
ComfortYou’ll enjoy more consistent heating, leading to a more comfortable living space.
Longevity & ReliabilityHigh-efficiency furnaces have more durable components, leading to increased longevity.

What to Do in Case of Gas Leak?

To ensure your safety, it’s important to know what to do in case of a gas leak in your furnace. 

If you suspect a gas leak, you should immediately evacuate your home and call emergency services. 

Evacuate the House during gas leak

If there is a gas leak immediately evacuate the house.

  • Don’t touch electric switches or devices.
  • If possible, turn off the gas supply outside, but only if safe.
  • Alert your neighbors.
  • Do not try to locate the source of the leak yourself.
  • Call 911 or emergency services from a safe distance.
  • Wait for trained professionals to arrive before entering your home again.

Call Emergency Services during gas leak

If there is a gas leak, evacuate your house or other enclosed space. Then call emergency services. Provide precise details about your location and the leakage. 

Don’t try to fix it yourself if you’re not a specialist or utility worker. Wait for specially trained professionals who can take charge before things get worse. 

Calling emergency services is not an option. Don’t hesitate to reach out if you smell gas or see signs of a leak. 

Contact the Gas Company and HVAC Contractor during gas leak

Contact the gas company and HVAC contractor fast. Gas leaks can be a serious threat to you, your family, and your home. 

The gas company will send a technician to locate and fix the source. Your HVAC contractor can assess any damage and make repairs.

Never attempt to find or fix the leak yourself – it could be dangerous! Immediately evacuate your home if you suspect a gas leak. 

Don’t turn on any lights or appliances that may ignite the gas. Outside, use a mobile phone or neighbor’s phone to call an emergency number. Then, contact the gas company and HVAC contractor.


It’s worth taking the time to check your furnace. Gas leaks can be very dangerous. If you think there’s a leak from your gas furnace or flue pipe system, contact a manufacturer or certified HVAC professional right away. Don’t put yourself at risk, check your furnace today.