Is a cracked heat exchanger an emergency?

Yes, a cracked heat exchanger is a serious safety emergency and you should stop using your furnace immediately.

A cracked heat exchanger is one of the most dangerous furnace problems a homeowner can face. The heat exchanger is the component that separates combustion gases — including carbon monoxide (CO) — from the air that circulates through your home. When it cracks, those toxic gases can leak directly into your living space. Carbon monoxide is odourless and colourless, meaning you won't know you're being poisoned until symptoms appear: headaches, dizziness, nausea, or worse.

Turn your furnace off at the thermostat right now if a technician has told you your heat exchanger is cracked. Don't run it "just for a little while" to stay warm — even short exposure to elevated CO levels can be dangerous, especially for children, elderly family members, or anyone with respiratory conditions. Make sure your carbon monoxide detectors are working and check that everyone in the home feels well. If anyone is experiencing symptoms, leave the house and call 911.

Ottawa-specific context: Ottawa winters are brutal, and losing heat can feel like a crisis in itself — but a cracked heat exchanger makes running your furnace more dangerous than having no heat at all. Ottawa HVAC Pro technicians carry equipment to perform combustion analysis and CO testing to confirm a diagnosis, because unfortunately, a cracked heat exchanger is sometimes misdiagnosed. It's worth getting a second opinion before committing to a full furnace replacement, which is typically the required fix since heat exchangers generally cannot be repaired under TSSA guidelines.

Replacement costs for a furnace in Ottawa typically run $3,500 – $6,500 depending on efficiency rating, and a cracked heat exchanger on an older furnace usually means replacement is the right call anyway.

Your next steps: Turn off the furnace, ensure your CO alarms are functioning, and call a licensed HVAC technician today — this is not a "schedule it for next week" situation. Ottawa HVAC Pro offers emergency service for exactly this kind of urgent heating issue. For a free estimate on furnace replacement, reach out to us directly.