Early warning signs you should never ignore

Carbon monoxide is stealthy, but your home and your body often send signals long before a crisis.

• Visible soot or scorch marks near the furnace, water heater or around a fireplace insert.
• Persistent headaches, dizziness or nausea that improve when you step outside.
• Frequent short-cycling (the furnace turns on and off rapidly), which can mean airflow or safety-control problems.
• A “hot” or metallic smell during operation that you’ve never noticed before.
• Yellow, flickering flames in a gas appliance that should have steady blue flames (appliances vary – don’t disassemble anything yourself).
  

If any of these show up, don’t try to diagnose the appliance with DIY videos. Call a specialist. A trained technician can check combustion, draft, venting, heat exchangers, safety switches and controls quickly and safely.

What to do if the CO alarm sounds (step-by-step)

1. Get fresh air first.
   Move everyone outdoors or to an area with open windows and doors. Don’t stop to “look around” or gather belongings.
2. Call for help from outside.
   Use your phone once you’re in fresh air. If anyone feels unwell, call emergency services.
3. Do not re-enter until professionals say it’s safe.
   Even if the alarm stops, CO could still be present. Let a qualified technician or first responder check levels and equipment.
4. Schedule a full inspection of all fuel-burning appliances and vents.
   Ask for a written summary of findings and what was corrected.

Pro tip: Replace the detector after a confirmed alarm event if the manufacturer recommends it or if the unit is near its end-of-life. They’re inexpensive insurance.

Heat pumps, all-electric homes and what “lower risk” really means

If your home uses an electric heat pump for heating, you don’t generate CO to heat the house. That’s a big safety advantage. But many all-electric homes still keep a gas range or gas fireplace and garages remain a risk if a vehicle idles inside. Keep detectors anyway. They protect you from sources you might not think about – like a visiting relative warming up a car in the garage on a chilly morning.

The garage rule everyone forgets

Never run a vehicle in an attached garage – even with the garage door open. Cold mornings tempt people to “warm up the car.” CO builds in the garage and seeps into the house through tiny air leaks, door gaps and wall penetrations. Start the car, back it out immediately and let it warm up outside.

Similarly, never use an oven to heat the home and never run fuel-burning space heaters indoors unless the device is designed and listed for indoor use with proper ventilation (most aren’t). If you’re uncertain, don’t use it – call a specialist for safe alternatives.

Annual professional maintenance: what you should expect them to check

A good winter or pre-winter visit for fuel-burning equipment should include:

• Visual inspection of heat exchanger areas (or appropriate testing methods) for cracks or corrosion.
• Combustion and draft checks to ensure flue gases are leaving the home properly.
• Safety controls verification (limit switches, pressure switches, flame sensors).
• Vent system inspection for obstructions, loose joints or improper slopes.
• Airflow checks (filter condition, blower wheel cleanliness, duct restrictions).
• Operational test to confirm stable ignition, flame characteristics and temperature rise within manufacturer specs.

Ask the technician to walk you through what they found. A few minutes of explanation makes you a more confident homeowner. If something is out of range, have them show you in simple terms. You’re not learning to repair furnaces; you’re learning to recognize when to call quickly next time.If your contractor can’t explain findings in plain English, get a second opinion. A clear conversation is part of safe operation.