Chimney noise and vibration: what each sound is telling you

Chimney noise is unusually easy to diagnose because each fault makes its own sound. A rattle that comes and goes is loose sheet metal or a duct flap. A steady grinding or whining that rises with speed is a bearing. A hum with no spin is the capacitor or a seized wheel. And a low, heavy drone with visible shaking is almost always grease built up unevenly on the blower wheel.

Start by noting three things: when the noise appears (start-up, all the time, only at top speed), whether it changes with the speed setting, and whether you can feel vibration in the hood or the cabinet.

The heavy drone with vibration

This is the most common complaint and the least alarming one. The blower wheel is a small drum with many short blades. Grease lands on those blades unevenly, so the wheel goes out of balance and the whole unit shakes at speed. You will usually notice the suction has dropped at the same time.

A deep clean of the blower and motor fixes it. Left alone, the imbalance wears the motor bearings, and then you are replacing a part instead of paying for a clean.

A rattle or a clatter

Intermittent, often worse at one particular speed. Usual suspects, in order:

• The non-return flap at the duct outlet knocking against its frame.
• A filter not seated properly in its catch after a wash.
• A loose screw in the hood or a mounting bracket that has worked itself free.
• The duct clamp slipping, so a joint moves as air pressure changes.

Switch the chimney off, check the filters are properly latched, and look for anything obviously loose. Beyond that, the rattle is usually in the duct and needs someone up there.

A grinding or whining that tracks the speed

A whine that rises and falls exactly with the speed setting points at the motor bearings. Chimney motors run in hot, greasy air for years, and eventually the lubricant in the bearing gives up. Grinding is that same fault further along.

This is worth attending to early. A worn bearing that is caught in time is a straightforward part change; one that is ignored can take the motor with it.

A hum with no rotation, or a slow start

The blower tries to start and cannot. Two causes dominate: a failed run capacitor, and a wheel stuck by hardened grease. Nellore's evening voltage dips make a marginal capacitor look worse than it is — the unit starts fine in the morning and struggles at eight at night.

Switch it off at the socket and leave it off. Do not push the wheel to get it going.

A whistle or a rush of air

A high, thin whistle is usually air squeezing through a restriction: filters that need washing, a partly blocked duct, or a duct diameter that was reduced somewhere along the run at installation. If the whistle appeared after the monsoon, check the duct outlet for a nest or debris.

Sound-to-cause, quickly

What you hear	Usual cause
Heavy drone, hood vibrates	Grease-loaded blower wheel
Rattle at certain speeds	Duct flap, loose filter or fixing
Whine or grind, rises with speed	Motor bearings
Hum, fan does not turn	Capacitor or seized wheel
Whistle	Blocked filters or restricted duct
Buzz from the cabinet	Mounting has loosened

What you can safely check

Switch the chimney off at the socket or MCB and turn the gas off at the regulator. Then take the filters out and look and listen: refit them properly and see if the rattle goes. Look for loose screws on the hood. Check the duct outlet from outside if you can do it from a stable position.

Do not open the motor cover, do not spin the wheel by hand through the filter opening, and do not spray anything into the housing.

When to call

Any grinding, any hum without rotation, any burning smell, and any vibration strong enough to feel through the cabinet are jobs for a technician. A motor, fan and filter deep clean is ₹499 on our rate card, and that resolves the grease-imbalance cases outright. If a capacitor or bearing is the culprit, the part is charged at MRP and shown to you before it is fitted.