Smoke Alarms - Ionization, Photoelectric, 120V Interconnect Advice - Page 1
Forum section: electronics / general

author: edy
author_rank: Super Contributor
timestamp: January 20, 2019, 07:24:24 pm
content: Hi everyone,I am overdue on replacing a pair of FireX Smoke alarms (Model G-6). One is on the main floor, one on the top floor. They were manufactured Spring/Summer 2007 and are recommended to be replaced by 2016! They both are 120V using the 3-prong plug and are supposed to interconnect.Now I went shopping around and could not find the exact same model in my local area, so I had to get Kidde brand. They also have 120V models with a similar 3-prong plug, I'm assuming the pin-outs are the same but the plug I already have wired up for the FireX may not fit the Kidde exactly. I will have to check. For sure the mounting plate doesn't so I will have to change the mounting plates.Anyways, my current FireX are both ionization type. I saw there is also photoelectric available. I did some research and ended up buying 1 photoelectric and 1 ionization, figuring that I would be covered better with both.... Now it's a matter of which to install where. Ionization on top floor, photoelectric on bottom, or vice versa?Lately we noticed the old Fire alarm was setting off way too easily when cooking in the kitchen. No smoke, just some strong smell or a bit of burning cheese would set it off. I figure these things fail by actually setting themselves OFF to be on the safe side. The radioactive material and plates get hindered by smoke particles, causing lower current, setting off alarm. If the actual material AGES and gets old, it will also result in lower current, or reduce the threshold needed to get under what is needed to trigger the alarm. So perhaps it was mainly due to the age of the alarm that was making it trigger too often when unnecessary?Either way, do I install the ionization alarm on the main floor where the kitchen is? That is most likely to set off a fast flaming fire causing what I assume the ionization alarm will trigger. Whereas should I install the photoelectric upstairs where the smoke is most likely to rise, and where a smoldering type fire is most likely to occur? Note that our electric clothes dryer is upstairs.... if something happens will it trigger fast enough? Note that both existing alarms were mounted actually exactly one above the other, mounted along the main central stair well of the house. It seems that whatever is on the bottom floor will quickly go vertically up the stair column and end up near the top alarm soon after it reaches the lower alarm anyways.Advice, ideas? Is having both types of alarms wise? Do I use ionization on bottom or top floor? What about the photoelectric? Do the pinouts typically match for different alarm companies since the connectors seem to be almost identical? Am I overthinking this? Thanks for any help you can provide.NOTE: Apparently FireX was bought by Kidde a few years ago. I found some old manuals to check and it seems like I am better to wire in new connectors as they won't attach reliably anyways to the new alarms, so the pin-out won't matter as I won't use the old connectors anyways:https://www.kidde.com/home-safety/en/us/support/help-center/browse-articles/articles/what_products_will_firex_alarms_interconnect_with_.aspxhttps://www.kidde.com/home-safety/en/us/support/help-center/browse-articles/articles/what_products_will_firex_alarms_interconnect_with_.aspx

author: Benta
author_rank: Super Contributor
timestamp: January 20, 2019, 07:47:39 pm
content: It depends on what kind of fire you expectThe "ionization" type, which incidentally does NOT detect ions, but aerosols, reacts best to open-flame fires, but is prone to false alarms. The optical type detects smoke particles and is more sensitive to ember fires.I mounted Kidde detectors in my house, but chose the combined optical/CO type.

author: nsrmagazin
author_rank: Regular Contributor
timestamp: January 20, 2019, 09:40:36 pm
content: What kind of smoke. The shop should be able to tell you, but now a days they all don't know and just speak or are just jackasses.

author: leeatljs
author_rank: Contributor
timestamp: January 21, 2019, 10:34:41 am
content: Both optical and ionization are good in a home environment. Personally I install optical ones since they are easier to dispose of. Both will work equally well at home, and both are good smoke detectors. The smoke will kill you before the fire does. If you can, install a couple more.

author: GigaJoe
author_rank: Frequent Contributor
timestamp: January 22, 2019, 07:02:03 pm
content: dont know where U live, but ontario for example req. CO alarm as well, in all living areas. combined alarm would be make sense.for a smoke one, (just a smoke) unit with 2 diff sensors (optic and ion) just a few buck more expensive. ( i see most devices are battery powered now )

author: Benta
author_rank: Super Contributor
timestamp: January 22, 2019, 07:25:52 pm
content: Quote from: GigaJoe on January 22, 2019, 07:02:03 pmWhy on earth would you want a combined optical/ionization detector? Smoke and CO combined make sense.

author: floobydust
author_rank: Super Contributor
timestamp: January 22, 2019, 07:52:54 pm
content: NFPA updatesNational Fire Alarm and Signaling Code NFPA 72,based on theirtask group research.Snippet from photoelectric verses ionization fire alarms, and dual alarms:"The analysis found that 'When the ionization alarm was the first to respond, the dual alarm configurations (from high to low sensor sensitivities) alarmed 89 s, 67 s, and 47 s, faster on average than the photoelectric alarm."When the photoelectric alarm was the first to respond, the dual alarm configurations (from high to low sensor sensitivities) responded 535 s, 523 s, and 518 s faster on average than the ionization alarm at the middle sensitivity setting." And "Over the sensitivity range examined in the NIST study, dual alarms exhibited almost no average decrease in alarm time compared to photoelectric alarms during initially smoldering fire scenarios, irrespective of the ionization sensor sensitivity (4 s to 3 s from high to low sensitivity settings). Dual alarms exhibited a pronounced average decrease in alarm times compared to photoelectric alarms for initially flaming fire scenarios (38 s to 29 s from high to low sensitivity settings). ""For the kitchen fires, the average decrease in alarm time was a strong function of ionization sensor sensitivity (197 s to 18 s from high to low sensitivity settings). For the fires with the bedroom door closed, dual alarms exhibited a sustained average decrease in alarm time compared to photoelectric alarms (103 s to 94 s from high to low sensitivity settings)."The task group report is saying dual smoke alarms can be quicker, more time 1-9 minutes is a big difference.