Calgary winters are no joke, and your furnace becomes the most important appliance in the house. The good news? Many furnace issues are common and fixable, once you know what to look for.
In this guide, we’ll cover the top seven furnace problems we see in Calgary homes, explain what’s usually causing them, and give you tips on what you can try yourself before calling in a professional furnace repair.
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Why Calgary Winters Are Tough on Furnaces
In Calgary, your furnace often runs from late September to early May. That’s months of near-constant demand in a dry, frigid environment. Frequent freeze-thaw cycles, older duct systems in established communities like Brentwood or Bowness, and hard water buildup (for hydronic systems) can all wear down components faster.
This is why knowing the early signs of trouble and staying ahead of them can save you from costly emergency calls.
Problem #1: Furnace Isn’t Turning On
Check the thermostat: Sometimes the issue is as simple as dead batteries or a setting that’s been accidentally bumped to “cool” instead of “heat.”
Inspect the circuit breaker: Your furnace might have tripped the breaker. Flip it off and back on once. If it keeps tripping, you need an electrician or HVAC tech.
Call a technician: If nothing turns on (no fan, no click, no lights), your furnace may have a safety lockout, failed ignitor, or board issue.
Problem #2: Furnace Blowing Cold Air
Dirty air filters: Restricted airflow can cause the furnace to overheat and shut down the burner, leaving just the fan blowing cool air.
Pilot light or ignition issue: In gas furnaces, a weak or failed ignition source won’t allow the burners to fire properly.
Overheating issues: If your furnace keeps overheating due to blocked vents or poor airflow, it may enter “cool-down mode,” where it blows cold air until it resets.
Problem #3: Weak or No Airflow
Blower motor issues: A failing blower motor can result in very weak or no airflow, even if the burners are producing heat.
Clogged ducts or vents: If registers are closed or ducts are full of debris, airflow can’t circulate well.
Dirty or broken fan blades: Dust buildup or fan damage can slow the system down significantly.
Problem #4: Frequent Cycling On and Off
Thermostat issues: Poor placement (e.g., near a drafty window) or calibration issues can cause the system to short-cycle.
Airflow restriction: Dirty filters, blocked vents, or undersized ductwork can cause quick overheating and shut-off.
Faulty limit switch: This component monitors the heat exchanger temperature. If it’s malfunctioning, the furnace may shut off too early or too often.
Problem #5: Unusual Noises (Banging, Rattling, Screeching)
Loose parts or ducts: Banging or rattling usually means something’s come loose, blower housing, access panels, or ductwork.
Worn motor bearings: Screeching sounds could mean your blower motor needs lubrication or replacement.
Cracked heat exchanger: This is serious. So, if you hear loud pops or booming, shut off the furnace and call a pro immediately. It could indicate gas buildup or combustion issues.
Problem #6: Higher Energy Bills with No Comfort Gains
Dirty burners or filters: Poor combustion or restricted airflow makes the furnace work harder than it should. Additionally, older furnaces (15+ years) can lose 20–30% efficiency, even with maintenance.
Problem #7: Pilot Light or Ignition Problems
Bad thermocouple: This safety device shuts off gas flow if the pilot light goes out. If it’s faulty, the system won’t stay lit.
Dirty flame sensor: A common issue in Calgary homes. If the sensor is corroded or dusty, it may fail to detect flame and shut down gas flow.
Weak gas supply: Low pressure or a partially closed gas valve can prevent ignition.
Preventive Maintenance Tips to Avoid Furnace Problems
Staying ahead of the issues plaguing your installed furnace can extend your system’s lifespan and help you avoid costly emergency repairs. Start by replacing your furnace filters every 1 to 3 months, especially during Calgary’s peak heating season, so your system can breathe easily. Schedule annual furnace tune-ups to catch small problems before they turn into major breakdowns. Make sure your home’s supply and return vents are clean and free from obstructions to maintain proper airflow. Finally, consider installing a smart thermostat to optimize comfort, reduce runtime, and boost overall efficiency.
FAQs About Furnace Problems in Calgary
Why is my furnace running but not heating?
This often points to a clogged filter, malfunctioning ignitor, or extinguished pilot light. In Calgary’s cold snaps, even a small issue can stop the heat. If airflow seems fine but the air stays cold, it’s time to call a licensed technician.
How do I fix my furnace that keeps shutting off?
Start by replacing your air filter and checking the thermostat settings. If it keeps short cycling, the problem may involve poor airflow, a dirty flame sensor, or a faulty limit switch, best handled by a pro.
What is the most common furnace repair?
Blower motor failures, ignitor issues, and dirty flame sensors top the list. These parts work overtime in Calgary winters, and regular maintenance can prevent most of these mid-season breakdowns.
Is it safe to reset my furnace?
Yes, if you follow your furnace’s manual and only do it once. Multiple resets mean a deeper issue, like a failing safety switch or ignition fault. In that case, shut it off and call a technician.
When should I call a furnace technician?
If you notice no heat, burning smells, loud bangs, or cold spots, and your system is over 15 years old, it’s best to get it checked before winter makes the problem worse.
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