Gas Furnace Repair

Gas furnace safety is something Bay Area homeowners should never take lightly — and it's the category where we see the most dangerous DIY repair attempts. A cracked heat exchanger can leak carbon monoxide into your living space with no visible warning signs, and we've detected dangerously elevated CO levels in Bay Area homes where furnaces appeared to be "working fine" aside from a faint, unusual smell. The Bay Area's seismic activity adds another safety layer. Earthquake shut-off valves on gas furnaces trip during even minor tremors along the Hayward and Calaveras faults. After a valve trips, it must be properly inspected and reset — never just forced back open. Our technicians perform gas leak detection and pressure testing on every furnace reset, ensuring your system is safe before restoring heat. Bay Area furnaces typically run October through March, with heaviest use during the December–February cold snaps when overnight temperatures in San Jose drop into the low 40s. Systems that sit idle for 7+ months can develop issues that only appear when the heat kicks on: flame sensors coated with oxidation from humid summer air, blower capacitors weakened by months of disuse, and thermocouple drift from thermal cycling. Furnace troubleshooting guide: ✓ No heat at all → check thermostat batteries and settings first; then check whether the pilot light or hot surface igniter is functioning. ✓ Furnace cycles on/off rapidly → dirty flame sensor (the #1 furnace repair we perform — a 10-minute fix). ✓ Blowing cold air → limit switch tripped due to overheating, often from a clogged filter. ✓ Banging noise on startup → delayed ignition from dirty burners; gas accumulates before igniting with a "boom." ✓ Yellow pilot flame → incomplete combustion, potential CO hazard; call immediately. ✓ Burning smell on first use of season → dust burn-off is normal for first 10 minutes; if it persists, shut down and call us.