How Do I Know If My Furnace Is Overheating? Need To Know

Rima Chatterjee

In this blog post, we will know in detail the causes of overheating of furnaces.

What Is Furnace Overheating?

Closing of furnace vents is one of the major causes of furnace overheating and it creates certain problems such as leaks, clogs in the components of furnace.

How Do I Know If My Furnace Is Overheating

Warning Signs of Furnace Overheating

Gas leaks and carbon monoxide exposure can be serious risks caused by furnace overheating.

Here are the main warning signs to be looked for furnace overheating:

  • Unusual smells like rotten eggs or sulfur can be due to gas leaks.
  • Strange noises hissing, popping or banging could mean air flow problems.
  • Flu-like symptoms nausea, dizziness, headaches or breathing difficulties could be carbon monoxide poisoning.
  • A malfunctioning furnace even if it looks ok could indicate an underlying problem.

If you spot any of these warning signs, contact professionals immediately to keep your family safe.

Possible Causes of Furnace Overheating

A furnace is vital for any home heating system. Be aware of any signs of overheating. Possible causes:

  • Dirty air filters will always restricts airflow
  • Clogs in fuel lines affects heat distribution
  • Cracks or leaks in ductwork allow gasses or chemicals to escape
  • Insufficient preventative maintenance reduces furnace performance and increases risk of overheating
  • Faulty heat exchanger distributes heated air throughout homes. A faulty one is dangerous.

What to Do if Your Furnace is Overheating?

If your furnace is overheating, it can be a stressful and daunting situation for any homeowner. 

Here’s a guide to help out:

  1. Shut off the gas supply and electricity  to avoid further damage and risk of fire.
  2. Contact a certified HVAC technician to assess and fix the issue safely and efficiently.
  3. Look out for any bad smells, hissing noises, or excessive heat  coming from your furnace.
  4. Keep everyone including pets away from the furnace until professionals arrive.
  5. Check all gas lines leading into your home and examine house plants’ soil.
  6. If you smell gas or suspect CO poisoning symptoms like dizziness or nausea – evacuate immediately and contact local authorities.

Factors to Consider for Furnace Maintenance

Ensuring furnace safety is essential for homeowners. Good maintenance can prevent problems that risk health and safety. 

Here’s what to keep in mind:

Regular maintenanceGet a professional HVAC technician to inspect your furnace every season for safer operation and longer life.
Warning signsWatch out for symptoms like nausea, dizziness and breathing trouble in family membersAlso, the smell of rotten eggs or sulfur in the house signals a gas leak.
Call for helpIf you hear a hissing noise, call the Fire Department or Gas Company. Do not investigate it yourself as this may involve risks like carbon monoxide exposure.
Use detectorsAlways have Carbon Monoxide detectors installed in homes using Gas Furnaces or other Gas Supply appliances.
Safeguard against fire hazardsCheck for worn cracks on heat exchangers which can burn hazardous carbon deposits inside them. Be sure the ductwork is intact with sealed joints.

Factors to Consider for Furnace Safety

To stay safe:

  • Install Carbon Monoxide Detectors and Smoke Alarms and test them monthly.
  • Keep plants one meter away from furnaces.
  • If you smell gas, turn off any open flames, contact the Gas Company and leave the house.
  • Get a HVAC technician to inspect and maintain your furnace annually.
  • Check for loose connections in the gas lines or soil covering plant roots around the gas supply line. 

Importance of Furnace Safety and Maintenance 

Maintaining furnace safety is essential for health and safety of family, pets, and property

Neglecting it can lead to gas leaks and carbon monoxide poisoning, which has severe health risks. 

Signs include,

  • Breathing issues
  • Dizziness
  • Nausea
  • Eye irritation

Gas furnace maintenance should be done yearly by HVAC professionals. Homeowners should also inspect them for signs of wear and check the ductwork.

Using a furnace safely is key. Follow manufacturers’ instructions and call an expert for any unusual sound or hissing.

Gas companies offer leak checks and gas detectors to alert homeowners. A rotten egg smell may indicate a gas leak, call your local utility company or fire department immediately.

Houseplants can also detect gas leaks. Monitor plant health to prevent any issues with fumes from a malfunctioning furnace.

What prevents a furnace from overheating?

Open the vents of the thermostat and turn off the thermostat to prevent the furnace from overheating.


Preventing the overheating of the furnace must be done in order to avoid the hazards. The warning signs must be checked and the guidance to treat the overheating of the furnace should be done by contacting the pro.

About the author

Debarghya Roy: A heating systems author, Passionate about energy efficiency and sustainability, Sharing insights and empowering readers through informative blog articles.