Fortunately I know there aren't any discarded ones around. The only room where that was a possibility I ruled out during last night's wander round the house listening.
Looking like it is probably the battery backup then. Obviously the most likely candidate is the one over the stairs that is awkward to get to. I assume I should turn off the power to them before fiddling.
Fortunately I know there aren't any discarded ones around. The only room where that was a possibility I ruled out during last night's wander round the house listening.
Looking like it is probably the battery backup then. Obviously the most likely candidate is the one over the stairs that is awkward to get to. I assume I should turn off the power to them before fiddling.