A lot of hard- wired systems have connecting wires between fire alarms, so that if one goes off with an alarm, they all go off. I take the point that your middle one does not go off, so it may not be entirely straightforward.

If the upstairs and downstairs alarms are connected, then only one of them needs to be activated for them both to sound; therefore only one of them is ‘wrong’. Another possibility is that it’s the centre one which is wrong and setting the other two off.

Even mains- powered ones often have a battery back- up inside each alarm, I wonder if yours do.

I would suggest testing each alarm individually first, if possible, by pressing the test button on each.

The other thing is whether opening all the windows and doors upstairs, middle and downstairs, stops them from going off. Smoke is easily diffused around a home, even between floors, and it only takes a tiny amount of smoke to set an alarm off.

If you have a faulty alarm which is hyper- sensitive to the point of going off when there is no smoke around, then the radio-active smoke sensor inside the alarm has probably gone wrong, and the whole alarm will need to be replaced, (and the new one connected into the ‘one off – all off’ system wires in the ceiling rose).

They can be disconnected individually by removing the wires in their ceiling rose, but you would need expert help with this now by law. Hope it doesn’t come to this.

Hope this is of some help. Belliger
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