This is just a quick comment on CO (carbon monoxide) detectors; more general comment will follow when time allows:
The sensor in a CO detector has a limited life and modern non-rechargeable lithium batteries will last about as long (FIVE years odd), in a CO detector. Therefore, current UK practice is for CO detectors to contain a non-replaceable battery which is "armed" by the installer by removing a tab. Once it starts chirping, the whole module needs to be replaced for the sake of the sensor as well as the battery, and the old one recycled. Once the replacement unit is armed and installed, it's best to open the old unit and cut ONE of the battery wires or it will go on chirping in the recycling bin for days or even weeks. The battery is effectively used to time the life of the sensor and most current non-rechargeable lithium batteries are pretty safe compared to the rechargeable kind. Test kits are available to check that CO sensors are working and this might require periodic access. The rest of the detector tests itself every couple of minutes and a tiny LED should flash green every couple of minutes.
Any SMOKE detector in a multiple-occupancy building which isn't connected to the fire alarm system in some way needs to be treated with a modicum of suspicion. CO detectors are usually only mandatory in rooms actually containing a gas-fired appliance.
This is just a quick comment on CO (carbon monoxide) detectors; more general comment will follow when time allows:
The sensor in a CO detector has a limited life and modern non-rechargeable lithium batteries will last about as long (FIVE years odd), in a CO detector. Therefore, current UK practice is for CO detectors to contain a non-replaceable battery which is "armed" by the installer by removing a tab. Once it starts chirping, the whole module needs to be replaced for the sake of the sensor as well as the battery, and the old one recycled. Once the replacement unit is armed and installed, it's best to open the old unit and cut ONE of the battery wires or it will go on chirping in the recycling bin for days or even weeks. The battery is effectively used to time the life of the sensor and most current non-rechargeable lithium batteries are pretty safe compared to the rechargeable kind. Test kits are available to check that CO sensors are working and this might require periodic access. The rest of the detector tests itself every couple of minutes and a tiny LED should flash green every couple of minutes.
Any SMOKE detector in a multiple-occupancy building which isn't connected to the fire alarm system in some way needs to be treated with a modicum of suspicion. CO detectors are usually only mandatory in rooms actually containing a gas-fired appliance.