I have received the VisorTech photoelectric smoke alarms for free as part of a product testing of testberichte.reviews. Included in the package: 4 Smoke detectors 1 manual 4 x mounting screws 4 additional batteries CR-V9 In some states, it is now compulsory to have smoke detectors in the house. I live in Berlin and with us, it is not mandatory, but is definitely coming soon. Then I pre-empted the laws Thanks to the tests. The smoke detectors are white and have a test button and an indicator light. Despite the additional Batteries contained in the smoke detector itself already. One can put into operation the smoke detector quickly. Simply the pocket on back open (turn) and unpack and connect the battery. Then turn the cap up again and press the test button and already sounded the alarm, which is very loud with 85 dB. The battery keeps the manufacturer a year before they must be replaced. The warning light indicates when the battery becomes weak, to be replaced in time. The smoke detectors are maintenance-free and are, once they have been attached, ready for action. They can screw it by clicking on the back of the alarm first anschraubt the cover and then the other part of the smoke detector is up turning back. But there is also the possibility to get to magnets are glued in advance, then you can remove the smoke detector fast times. But if that holds, I do not know. I think screwing on the ceiling is more secure. At the ceiling because smoke rises upwards known. I have my smoke detector in the bedroom and hallway Worse mounted as the living room has a kitchen and therefore a false alarm could be triggered. While cooking can while burning ever smoke rising and therefore you should when alarm is triggered, to ascertain whether in fact there is a fire. The fire department can cause costs nothing call. Not the fire is actually dangerous, but the smoke. More people die of the smoke inhalation than burning them. Especially in sleep you realize something is not. The smoke detector works with photoelectric detection. The works by the scattered light method. In smoke detector itself a beam of light is sent into a sensor chamber. Because clean air does not reflect light, the beam always strikes the same place. This light beam is interrupted by smoke, lands at a different location and then triggers the alarm. A safe procedure and so I give full marks. I also find the value for money in a set of 4 absolutely fine and therefore recommend this Rauchmelderset very happy to help.
