it did it the other day (I now realise that's what it was. I remember hearing the noise and couldn't place it but this time I'm sure). Ive checked the booklet and there is a trouble shooting page but it doesn't mention just two beeps. Any ideas what it could be? It's a Kidde Fyrnetics one. TIA
Ive just managed to get hold of DH at work. Apparently they are mains ones but with battery backup. There's no light on the unit at all though. We have one on every floor and none of them are have a light on of any sort. The power everywhere else in the house is fine and I've just checked the fuses and they don't have their own one as far as I can see.