Chimney suction dropped: what actually fixes it

A chimney that no longer pulls smoke is the single most common call we get, and in the large majority of cases the motor is fine. Grease is the culprit. Knowing which one you are dealing with saves you paying for a part you did not need.

Check this before you call anyone

Turn the chimney on at the highest speed and hold a thin strip of paper under the hood. If it is pulled up and held, the motor is still doing its job and the problem is airflow. If the strip barely moves and the chimney sounds quieter than it used to, the motor or capacitor is a real suspect.

Grease is almost always the answer

Cooking oil vapour condenses on every surface the air passes: the baffle or mesh filter first, then the fan blades, then the inside of the duct. Each layer narrows the path. A chimney can lose more than half its effective suction to a build-up you cannot see without opening it.

• Baffle filters look clean from below and are coated on the inner face
• Fan blades collect a sticky film that unbalances them and drops airflow
• The duct elbow just above the hood traps the most grease of any single point

Auto-clean does not solve this. The auto-clean cycle heats the oil collector so oil drains into the bowl. It does nothing for the filters, the blades or the duct.

When it really is the motor

A failing motor usually announces itself: a humming that does not spin up, a rattle that changes with speed, or a chimney that trips the MCB. A worn capacitor gives you a motor that starts only if you nudge the blades. Those are genuine repairs, and the part cost should be shown to you before it is fitted.

How often to clean

For a household cooking twice a day with regular Indian tempering, every three to four months. Deep-frying weekly pushes it closer to three. If oil has started dripping back down onto the hob, it is already well overdue.

What a proper service covers

• Filters removed, soaked and degreased rather than wiped
• Oil collector and hood interior cleaned
• Fan blades cleaned so they run balanced
• Suction measured before and after so the difference is not a matter of opinion
• Duct mouth checked, and the full duct cleared if the build-up warrants it

If the technician cannot tell you the before-and-after difference, you have no way to know whether you got what you paid for.