Why Is My Furnace Loud at Startup — Normal vs Problem Sounds

Published: July 23, 2026 — BC Wide Home Services Ltd, doing business as BC Wide Heating & Air Conditioning — Greater Vancouver, BC

Normal Startup Sounds

A soft whoosh when the burners ignite (gas igniting), a gentle hum from the inducer motor spinning up, a low rumble as the blower motor starts, and metal pinging from ductwork expanding as it heats. These are normal and should not be loud or alarming.

Concerning Startup Noises

Loud bang at ignition — delayed ignition (gas accumulates before lighting). Loud screech — inducer motor bearings failing. Heavy thud — blower wheel unbalanced or motor mount loose. Grinding — blower motor bearings worn. Loud hum with no spin — failed capacitor. These indicate problems needing service.

When to Call for Service

Call for service if: the startup noise is significantly louder than it used to be, the noise persists throughout the heating cycle (not just at startup), you hear grinding or metal-on-metal sounds, or the noise is accompanied by the furnace not working properly. Most startup noise issues are diagnosed and repaired quickly.

Related Services

Safety Reminder

If you smell gas, suspect carbon monoxide or believe there is an immediate danger, leave the property and contact emergency services or the appropriate gas emergency authority. Do not remain inside — exit the building immediately and call for help from outside.