Turn on the range hood automatically when you start cooking

The idea

Having the range hood or exhaust fan switch on by itself as smoke, steam, or cooking odours build up, and switch off again once the air clears, means nobody has to remember to operate a separate control with their hands full of a hot pan.

What you'll need

• An air-quality, smoke, or humidity sensor positioned near the cooktop, capable of detecting steam or smoke levels or a rapid rise in particulates.
• A smart switch or smart plug on the range hood or exhaust fan, if it isn't already a networked appliance.
• Optionally, a stove-on signal (a knob sensor or a power-monitoring plug on the stove) as an earlier, more proactive trigger than waiting for smoke or steam to actually build up.

How the automation works

Same trigger, condition, action pattern as the rest of this series, with a choice of two triggers:

• Trigger (reactive): the air-quality or smoke sensor detects levels above a set threshold.
• Trigger (proactive): a stove-on signal fires the hood immediately when cooking starts, rather than waiting for smoke or steam to build up first, closer to how a person would actually use the hood.
• Action (on): turn the range hood or exhaust fan on, scaling fan speed to the reading's severity if your hood supports variable speed.
• Action (off): once the reading drops back under the threshold for a sustained period (a few minutes, to avoid the fan cycling repeatedly), turn the hood back off.

Common mistakes to avoid

• No sustained-clear condition on the off trigger. Without requiring the reading to stay clear for a couple of minutes, the fan can cycle on and off repeatedly as levels fluctuate near the threshold.
• Sensor placed too close to the cooktop. This can fire the hood on completely normal, low-smoke cooking like a gentle simmer.
• Sensor placed too far away. A sensor mounted away from the cooking area can be slow to react to an actual spike, defeating the point of automatic activation.
• Relying only on the reactive trigger. Some cooking produces strong odours with very little visible smoke or steam. A proactive stove-on trigger tends to cover this better than a pure air-quality threshold.

Variations worth trying

This automation's often paired with opening a window automatically, or activating a separate ventilation fan, as an extra response alongside the range hood. Don't rely on this sensor for gas safety though: the particulate or VOC sensor used here doesn't detect carbon monoxide or a gas leak, that needs a dedicated, purpose-built detector with its own certified sensor. If you want gas-leak alerts as part of the same automation system, add one as a separate device with its own higher-urgency response, rather than assuming your air-quality sensor already covers it.