SMART HOME BUTLER · KITCHEN
The extractor speeds up when the smoke does
Not just on and off. More smoke means more speed, less smoke means less, and it keeps running for a few minutes after the hob goes off to clear what is left.
Cooking smoke is not just a smell, it is something you breathe
Stir-frying produces a lot of PM2.5 — fine particles small enough to reach deep into the lungs. A single round of high-heat frying can push kitchen PM2.5 to ten times its usual level, and it does not politely stay in the kitchen. It drifts to the living room and into the bedrooms.
Everyone has an extractor hood. The problem is how it gets used. Most people either run it flat out the whole time, or flick it to low and start cooking, then switch it off the moment they are done. None of those is right: full speed is loud and wasteful, low speed cannot keep up, and switching off immediately leaves the last of the smoke circulating through the house.
Let the system watch the actual air and all three problems go away.
It responds to the numbers in the air, not to your hand
With an air quality sensor in the kitchen, the system knows the PM2.5 level every minute. As the level rises it turns the fan up; as it falls it turns the fan down. That clears the smoke without running at full roar the entire time.
What happened in those thirty minutes
- 0 min
Prep
PM2.5 at 12, the air is clean. The extractor is off and the kitchen is quiet.
- 5 min
Pan and oil go on
The level passes 35 and the fan starts on low. There is only a faint smell at this point, so low is enough and it stays quiet.
- 7 min
Fish goes in
The level passes 80 and it steps to medium. This is the moment a person would normally reach over and press the button — the system just gets there first.
- 11 min
The worst of it
Past 150, so full speed. These are the minutes that need the most extraction, and also the minutes when your hands are fullest.
- 19 min
Off the heat, levels dropping
The fan steps back to medium and then to low. It does not sit at full speed doing nothing.
- From 23 min
Still running after the hob is off
This is the part most people skip. Switching off the hob does not mean the air is clean — the remaining smoke is still circulating. The system runs on at low for five more minutes and clears it before stopping.
Four things it takes care of
Health
PM2.5 reaching deep into the lungs is real harm. Whoever cooks most often takes the brunt of it, which makes this a good job to hand to a machine.
Quiet
No need to run flat out throughout. Full speed only during the few genuinely smoky minutes; the rest of the time it works softly.
Cleanliness
Smoke stops drifting onto the sofa and curtains. With less greasy film, furniture and walls are far easier to keep clean.
Running cost
High when needed, low when not, off when done. Over a year that adds up against leaving it on full throughout.
Different cooking, different thresholds
| What you are cooking | Low | Med | High | Why |
|---|---|---|---|---|
| Stir-frying, high heat | 30 | 70 | 130 | Smoke arrives fast and hard, so drop all three and start earlier |
| Pan-frying fish or steak | 35 | 80 | 150 | The general case. Most homes can use this set as-is |
| Simmering and soups | 50 | 110 | 200 | Mostly steam rather than smoke — too sensitive and it runs for nothing |
| Air fryer, oven | 40 | 90 | 160 | Almost nothing early, then a sudden burst, so keep the middle threshold tight |
| Open-plan kitchen | 25 | 60 | 120 | No wall in the way, so extraction has to start sooner or it goes straight into the living room |
What you need to have
Home Assistant calls every device an "entity". The brand and model do not matter — what matters is the category it falls into.
| What it does | Category in the system | Essential? |
|---|---|---|
| Measure PM2.5 | sensor | Yes |
| Extractor hood | fan, or a switch | Yes |
| Measure carbon monoxide | sensor | Recommended |
| Make-up air fan at a window | fan or switch | Nice to have |
| Receive alerts | notify (phone app) | Recommended |
How the whole thing works
Use the ready-made decision, do not build one
The hub ships with 22 tested automation blueprints. Think of a blueprint as a fill-in-the-blanks form: the structure is done, you supply the content. This one uses greenhouse, which exists to handle "when this number passes that, do this". Three speeds means three rules, each filled in once.
| Field | What it means | Suggested |
|---|---|---|
| Which number to watch | The kitchen PM2.5 sensor | — |
| Act above | One threshold per rule | 35 / 80 / 150 |
| Step back below | A little under the start value, to stop it flapping | 25 / 60 / 120 |
| What to control | The extractor, set to the matching speed | — |
| Notifications | Not needed here, but essential on the CO rule | CO only |
Two optional additions
| If you want | Blueprint | What it does |
|---|---|---|
| Carbon monoxide alarm | A second greenhouse | CO above the safe level means full extraction and an immediate alert. This has nothing to do with smoke — it is an independent safety rule, and not one to switch off because it is noisy |
| Unattended hob reminder | entity_state_trigger_notify | Messages you if the extractor stays at full speed beyond a set time, which usually means the hob is on and nobody is in the kitchen |
Just say the word
None of the above needs clicking through by hand. The WOOWTECH hub ships with HA-MCP, which lets AI connect straight into your system, build the thing, and then check for itself that it really runs.
Prompts you can copy straight across
Every block below is meant to be copied whole, and the button on the right does it for you. Pick whichever one is closest to what you want — you do not need all five.
Connect the kitchen extractor hood to the air quality sensor so it picks its own speed from the PM2.5 reading: low when there is a little smoke, medium once it builds, full when it gets really sharp, and back down again as the air clears. Start by finding which of my devices you can use, read the names back to me, and only build it once I say yes.
Set up the kitchen extractor hood to change speed automatically from PM2.5. Use one of the ready-made blueprints already on the hub rather than writing config yourself. First find the kitchen air quality sensor and the extractor hood and read them back to me. If the hood only appears as on and off, wrap it into a fan with three speeds before you go any further. Use 35 for low, 80 for medium and 150 for full. On the way back down use 25, 60 and 120 instead, so the numbers for going up and coming down are spread apart and the speed does not flap when the reading sits near a threshold. When it drops under 25, do not stop straight away — keep running at low for 5 more minutes to clear what is left, then switch off. Add one separate carbon monoxide rule as well: above 35 ppm, full extraction plus an immediate alert to my phone. That one is a safety rule, so give it no schedule and no other conditions. Do not notify me about ordinary speed changes; just get on with it quietly. Once it is built, test it yourself, confirm it really runs, and then tell me which devices you used.
My kitchen is open-plan — there is no wall between the hob and the living room, so smoke drifts straight out. Build the same three-speed setup, but shift the whole set of thresholds down: 25 for low, 60 for medium, 120 for full, so it starts pulling earlier. Move the step-back numbers down to match, keeping them apart from the numbers that switch it up. Make the run-on after cooking longer too: low speed for 8 minutes. If there is an air quality sensor in the living room as well, tell me afterwards whether its readings come down with it.
The extractor hood speed rules you set up for me start too late when I stir-fry. Drop the first threshold from 35 to 30 and the second from 80 to 70. Leave the full-speed step and the run-on time exactly as they are. When you are done, tell me which rules you touched and what all three thresholds are now.
I am standing in the kitchen right now, so run all three hood speeds for me one after another while I watch. Take it to the lowest step and hold ten seconds, then jump to medium for ten seconds, then push it to full for ten seconds, and send a phone notification on every change so I know which step it is on. Once the three are done, hand it back to automatic instead of leaving the hood stuck at full. If a step sends the message but the hood does not actually react, say which step it was and do not smooth it over.
Common questions
Where should the sensor go?
The speed keeps hopping around
It runs at full speed while I am making soup, and it is loud
The extractor is running but levels will not drop
The readings look too high across the board
Do I have to rebuild it to change the thresholds?
A month from now
The sofa and curtains no longer smell of cooking, and the kitchen walls are noticeably less greasy. You have stopped freeing up a hand mid-cook to reach for the hood.
The part you will appreciate most is those five minutes after you finish — you are already sitting at the table while it quietly clears the last of the smoke.