Over the past week there's been a constant high pitched sound in our dining room (and no, its not the kids!). Really uncomfortable: can't stay in the room for long. Also difficult to locate the exact source of the sound because of its pitch.

Having tried to rule out everything else, we think it might be the alarm sensor that is making the noise. The sensor is part of a Securit 800L system, coming up 3 years old.

Has anyone come across this as a fault and could give some advice?

Many thanks!

Are you sure its a sensor and not a speaker?

Battery dying on an old cordless phone?

I've had that one on callout, they swore blind it was from the alarm.

Edited February 3, 200521 yr by breff

Can't say as I've ever heard a PIR making a noise, (other than Optex ones clicking!) . I'd put money on it being anything but the PIR, assuming it is just a PIR. Is there a speaker in there somewhere, some people hide them in voids, or a faulty heating pump, that's another one where the sound travels quite well.

same as all the others, the sensor shouldn't make a noise like that. We are talking about a movement sensor aren't we? Not the extension speaker/ sounder?

have you looked at smoke detctors/alarms........... telephone system..... television/ video equipment .............. have you ever had tinitus?

Is the pitch very high if so it could be the relay in the PIR acting as a Piezo. Does the PIR light stay on continuously. I have come across this noise before but not with a PIR but with a Reed relay.

Edited February 3, 200521 yr by smart1

Have you got smoke detectors?

Have you ever changed the batteries?

or the thermostatic valve on a radiator?!

Go to the main fuse board and switch off the power for a couple of minutes?

Does it stop? what else happens?