Smoke alarms went off but no obvious reason.

[DtPeabodysLoosePants]

Wtf! Our 3 smoke alarms which are wired into the mains just suddenly went off. Ds and I were upstairs and I'd only just gone up after closing up the bottom two floors for the night (we are both feeling a bit bleurgh so going to bed). I've come down and nothing obvious as to why they have gone off. Batteries are all ok and recently tested. Any ideas as to why it's happened?

Are they also co2 detectors?

No, just smoke.

Ours sometimes do that too, DH thinks it could be spiders crawling over them.

Mine sometimes go off due to a change in atmospheric pressure, wired in ones too, google it it is a thing.

Ours used to do this all the time until we took the covers off, hoovered them out and now they're fine

I also find if the house gets too cold in the winter, they go off a lot then too

Sniff the lightbulbs. One of ours went ping and produced smoke.

Have you hoovered them recently?

I'll hoover them all today. Thank you. Scared me and the small one! They are all in the hall and on the two landings and all doors were closed so really odd. I have a nose like a bloodhound according to my dad so would have smelt even a whiff of smoke. Really odd.