From the hallway, a furnace that will not heat looks the same no matter what broke. Inside the cabinet, though, everything happens in a strict order: inducer on, pressure switch closed, igniter glowing, gas valve open, burners lit, flame proven, and finally the blower sending heat through the house. Diagnosis is mostly a matter of finding where that chain breaks. In Boston homes, it tends to be the same handful of culprits: a flame sensor coated in oxide, a hot surface igniter cracked by thermal cycling, a pressure switch held open by a tired inducer or a plugged condensate trap, or a control board with a burned relay.
Cooling trouble instead? See AC Repair.
Warning Signs for Furnace Repair
Catching these issues early helps you avoid costly problems. Watch for these telltale signs:
- A furnace that shuts off every few minutes before the house warms up
- Flames that start, last a few seconds, and go out again and again
- Yellow, wavering burner flames where they should be sharp blue
- Squealing or grinding from the blower compartment
- The igniter glows and clicks, yet no flame ever appears
- Water, rust stains, or black soot around the flue or cabinet
- A fan that keeps running while the registers blow cool air
- A bang or boom when the burners ignite late
Don't Wait for a Total Failure
Left unchecked, even a small fault or temperature swing often signals a system working its way toward a breakdown. If you notice any of these signs, call (857) 767-3237 for a prompt inspection.
