[Howto] Xiaomi Mijia Honeywell Smoke Detector clean

Suddenly my 1 month old smoke detector from Xiaomi Mijia Honeywell sounded, 5:30u in the morning. All the programmed lights in the house went on.

No smoke, no fire, nothing, false alarm.

I removed the battery from the smoke detector to kill the 80 dB siren and went back to bed.

A few days later, I was still getting a smoke warning when I reinstalled the battery, unable to reset the smoke condition.

Today I read about it’s a photoelectric smoke detector, not a radioactive thing :radioactive:. So I decided to open it, to clean the “light chamber” (dark room) where light reflected by the smoke illuminate the photoelectric cell.

First I removed the cover from the bottom. 3 clips around the bottom hold it together. In the middle is a round black button that can be lifted. Notice the arrows :arrow_right: that mark the notches. I cleaned the light chamber and the cover with clean air.

With the white cover removed I noticed that the center of the white cover can be removed with a small lefthand twist. That gives access to the same light chamber cover.

After reassembling the false alarm is gone.

I will try it with some cigarette smoke to test it later on.

nice post ! helpful

Link to the DH:

A little bit of info, if you or anyone is a smoker, most smoke detectors have a shorter life span than otherwise. When smoking was allowed in office buildings my company had a contract to replace the smoke detectors as they failed. In one building which was 55 floors my crew replaced 215 units in one year. After when smoking was banned we replaced only 50 that next year, and most were in the lavatories, as people went in there to smoke. The following year when the smoking bans became more enforced by company fire marshal’s that number wnet to five. So if you smoke plan on cleaning or replacing often.

Hi @joelw135,

No smoker here in the house, but you are right about nicotine. Amazing what it does with your lungs, ceiling and the mounted equipment there. When white becomes yellow it is nicotine.

Also when smoking was banned in airplanes, it was good for everything.

Once I opened a photocell smoke detector in a B747, there was a small fly in the detector causing a fault (dual system), no fire alarm.

Grtn Ben

Part of my job was before we installed the building automation systems in AC and heating ducts we had to clean areas surrounding the sensors. The orange brown liquid that was produced when plain water was applied was awful smelling and just disgusting. We wore rubber gloves, and face masks. The Tin Knockers (People that install and modify ductwork) all hated removing and working on buildings during the smoking years. Even the smokers hated working on this stuff. I installed the first paper tape building automation system in 1974 and back then smoking was still going on, and the tapes would get gunked up and sticky when the maintenance staff would go and smoke in the tape reader room as it was cool compared to the un air conditioned areas they worked in. We finally had to relocate the reader and all the 250 pair cables to another secure area. My boss loved that as he made a huge amount on that. I was called at 1:00AM while at home to fix the system (before it was relocated) I drove over an hour got there to find the tape was stuck together on the reel from the Nicotine. I had to remove the tape and create a new one, which took about four hours of typing the codes out of a binder. Then clean the reader another hour, just in time for the start of the day. I spent another four hours duplicating the tape to lock away for safekeeping. When the building manager found out what had happened over night he authorized the 300,000 dollars to relocate the equipment to another floor. We worked nights and ran a redundant system so the system was working during the move. A number of the maintenance staff were fired for unlocking and smoking in there.