I have a heat alarm and 2 smoke alarms that are mains powered with battery backup and they are all interlinked.
We’ve had regular issues of them going off for apparently no reason but sometimes the next door neighbours alarm is also going off.
Could they accidentally be linked together?

I suppose our alarm could be picking up smoke from next door.

In a new build anything is possible!

I’ve seen the room thermostat wired to the hall lights before, and have also encountered wiring across properties in a particularly poor development.

Are they linked by actual wires or using the bluetooth function? With the bluetooth ones you programme them all at the same time to link them together but there is every chance a builder just did both houses at the same time to save time or accidentally put a detector up in the property that is actually set up to be linked next door.
I’m sure you could reprogramme them if required.

Edit, would mean if your neighbour burns toast and sets the alarm off it could also set yours off and it would look like it’s going off for no reason in your property.

We have them.

Wired together upstairs off the lighting circuit, then wireless from one to kitchen and garage.

You have an enrolement procedure on the wireless, set one as master and then add the others in. Its harder than it sounds as you only have a tiny LED for feedback.

Maybe your neighbours has been added in together by accident.

I would find the instructions for yours and start the process again.

Ours are blighted by random (once every 3mo) false alarms. Its very hard to find which is at fault – they flash red only on alarm – but the alarm doesn’t sound long enough to run round the house. Not funny at 4am.

I’m going to unlink them in the hope of finding the faulty one.

Is it a full alarm, or just the occasional beep?
Full alarm, then change your hallway alarm head. It is 99% the hallway that needs changing when random alarms go off.
Not really sure of the actual cause of it failing, but one theory is that the hallway gets the most traffic going past it, so picks up the most dust. Dust kills the sensors.
Occasional beep, but doenst happen in the daytime – change the battery. The early hours of the morning are the coldest times, and when the battery will be giving out the lowest power, so the alarm may be seeing a flat battery. Once it warms up, it thinks the battery is OK.

Thanks all. The house is 100 years old. We put the alarms in about 6 years ago but not at the same time as the neighbours so I’d be surprised if they were set up to link together. I don’t think they are Bluetooth, I think they are hardwired. Probably worth giving them all a good clean.
EDIT: it’s full alarm, usually at 10pm but sometimes only for 10seconds.