Odd noises, a yellow pilot flame, uneven heat, or rising bills all signal furnace trouble, some, like a gas smell, are emergencies.
Your furnace sends warning signs before it fails:
- Noises: banging (metal expansion), squealing (worn blower belt), rattling (loose parts), rumbling (dirty burner).
- Uneven or weak heat: often clogged filters, duct damage, a bad thermostat, or a failing heat exchanger.
- Yellow pilot light: the flame should burn blue; yellow or orange means incomplete combustion and possible carbon monoxide, get it serviced immediately.
- Rising bills or short cycling: point to inefficiency, oversizing, or component failure.
- Odors: burning (dust/electrical), gas (emergency shut-off), musty (mold in ducts).
Furnaces 15+ years old are near end-of-life and best replaced before a winter breakdown.
