When Calgary’s winter temperatures plummet below freezing, your furnace becomes the lifeline of your home. Yet many homeowners panic at the first sign of heating trouble and immediately reach for the phone. While some furnace issues require professional expertise, others can be resolved with simple troubleshooting steps that take just minutes.
Understanding common furnace problems—and which ones you can safely address yourself—can save you time, money, and the frustration of sitting in a cold house while waiting for an emergency service call. Before you schedule that expensive appointment, run through these seven diagnostic checks that many Calgary homeowners can handle independently.
1. Check Your Thermostat Settings (The Most Common Culprit)
This might sound obvious, but countless furnace repair calls result from simple thermostat issues. Start by verifying that your thermostat is set to “Heat” mode rather than “Cool” or “Off.” Next, compare the thermostat’s set temperature against your home’s actual temperature—boost the setting at least three degrees higher than the current reading to trigger the furnace.
If your thermostat is battery-operated, replace the batteries even if they seem fine. Dead or dying batteries frequently prevent your system from communicating with your furnace, leaving your home without heat. This single troubleshooting step resolves approximately 30% of residential furnace complaints in Calgary during winter.
2. Verify Your Furnace Has Power
Before assuming your furnace is broken, check whether it’s receiving power. Look for a power switch directly on the furnace unit—these switches can accidentally get flipped off during cleaning or maintenance. Additionally, modern furnaces have a safety switch inside the service panel that automatically cuts power when the door opens.
Next, inspect your electrical panel’s circuit breaker. If the furnace breaker sits in the middle or “Off” position, flip it to “Off” first, then back to “On.” If the breaker trips immediately, this indicates a potentially serious electrical problem requiring professional attention. However, if it stays in the “On” position after resetting, your furnace should resume normal operation.
3. Replace Your Furnace Filter
A clogged furnace filter represents the most ignored yet most effective maintenance task you can perform. When dust and debris accumulate over time, airflow becomes restricted, causing your furnace to work harder and potentially overheat or shut down.
Check your filter monthly during heating season, especially if you have pets or live in a dusty environment. Most standard filters require replacement every 60 to 90 days, though high-efficiency filters may last up to six months. Replacing your filter is inexpensive—typically $15 to $30—yet prevents numerous heating problems and improves energy efficiency throughout your home.
4. Open All Vents and Registers
Sometimes the problem isn’t your furnace at all—it’s blocked airflow. Walk through your home and verify that all supply and return vents are fully open. Check for furniture, storage boxes, curtains, or other items blocking air circulation. In Calgary homes with basements, ensure return air vents near furnaces aren’t covered by boxes or stored items.
Additionally, make sure your furnace’s intake and exhaust vents on exterior walls aren’t blocked by snow, ice, or debris. During Calgary’s harsh winters, snow accumulation can completely obstruct these vents, preventing proper airflow and triggering furnace shutdowns.
5. Listen for Specific Sounds Indicating the Problem
Your furnace communicates problems through its sounds. If you hear continuous clicking when attempting ignition, the ignition system isn’t firing—this requires professional repair. However, occasional clicking during startup is normal.
Banging, rattling, or clanging noises often indicate loose ductwork or equipment inside your furnace—problems you can sometimes address by securing visible loose components. Screeching sounds typically signal a damaged blower motor or pulley, requiring professional replacement. Humming that gradually increases in volume suggests electrical or motor problems. Document what you hear and report it to your technician for faster diagnostics.
6. Test Your Pilot Light (For Older Furnaces)
If your furnace is older and still uses a pilot light rather than electronic ignition, you can safely relight it following your furnace manual’s instructions. However, if the pilot light repeatedly goes out or won’t stay lit, this indicates a deeper problem requiring professional service.
Modern furnaces use hot surface ignitors or spark ignition systems that glow red when functioning properly. If you notice the ignitor isn’t glowing, the heating element has cracked and needs replacement—a technician’s job.
7. Inspect Your Condensate Drain Line
Modern high-efficiency furnaces produce condensation that drains through a condensate line to prevent water damage. If this line becomes clogged with dust or debris, the furnace shuts down automatically as a safety feature. Locate your condensate drain line (usually a plastic pipe near your furnace) and verify it’s not blocked.
If you find debris, gently flush the line with distilled water. Ensure the line slopes toward the drain and isn’t kinked or compressed. Many Calgary homeowners prevent this problem by scheduling professional furnace maintenance annually before winter arrives, which includes flushing condensate lines as part of routine service.
When to Stop Troubleshooting and Call the Experts
If you’ve worked through these seven checks and your furnace still isn’t producing heat, or if you smell gas, hear strange sounds, or suspect safety issues, contact a professional immediately. Gas leaks, electrical problems, and heat exchanger failures require certified technicians with specialized equipment.
Shift Heating & Cooling’s experienced technicians are available 24/7 throughout Calgary and surrounding areas to diagnose and repair furnace problems that exceed DIY troubleshooting. Many issues resolved through basic troubleshooting can be prevented entirely with seasonal maintenance—a small investment that keeps your furnace running reliably through Calgary’s long winters.
