Keeps not with us

We had fire alarms "stuck" with this type of installation in several rooms at a smooth, coated non-woven wallpaper. In some rooms, the discs are simply fallen back from the ceiling. Some also the fire alarm itself separates from the adhesive layer of the disc. That's natürlcih great if it happens at night, and all are awakened by the blast, the cause of Feurmelder when he crashes to the ground. I can not understand if we did something Falch. Perhaps the magnet push should not be stuck on wallpaper, but only plastered ceiling. For our situation (smooth, coated non-woven wallpaper) this fixture is apparently not suitable. But praise for the Ei Electronics smoke detectors: You have survived all the case from the ceiling on a Lamminatboden healing.