What are the most reliable hardwired smoke alarms?

[Del91574]

Ionization detectors in a residence are a recipe for false alarms....think of what causes an ion detector to alarm: products of combustion....what generates it? Cooking, and other similar activities.
 
There has been a long time debate in the industry for which detection criteria is better for which application and which is faster; there is no silver bullet. Ion or PE with thermals or without (I don't like using PE's without thermals if I can help it).

I'm not touching the inherent long discussion regarding the installation of 120V detectors and their interconnection to a FACP and the inherent issues and false sense of security. There's a reason why they can't be used and supervised, the voltage separation issue and wiring methods that negate the ability to supervise the loop on the 120V side of the detection circuit, especially with the normal wiring methods and cabling that is installed. While it may seem outwardly simple to accomplish, once the engineering and electrical theories and applications are put into closer scrutiny, it's no surprise that it hasn't been done yet and why doing such is not listed by UL and others.

 

[emjackson]

We have a Dual Sensor (photoelectric and  ionization) fire alaram as it quickly respond to fire with active flames as well smoldering.

 

[ano]

If you have a choice of more "regular" smoke alarms, or a less number of "super" smoke alarms, I'd go for more units of the "regular" version. All UL smoke alarms have to meet certain standards, so I wouldn't pay a whole lot more for better ones. A dual sensor alarm more likely uses the dual sensors for false alarm prevention (both sensors need to detect smaoke to alarm) than to add sensativity.  As DELInstallations says, ionization can cause many false alarms.  
 
TYPICALLY ionization alarms are used for local alarms in the house to alert you early, but with the negative of having to deal with some false alarms. Photoelectric alarms are used when they have to be 100% correct because the fire department is on the way. Both types have uses, only its different uses.

 

[Del91574]

I'm going to one-up this.....if mission critical is the need or desire, the facts are you're not going to be using an analog standard detector, you're going to need to migrate into an intelligent device and related hardware. SS has had multi-criteria detectors out for a few years and they work beautifully in locations where you CAN'T have a false but conventional type PE or ion heads will false. Even an intelligent panel with % of alarm values and criteria will smooth the majority of the applications out there.
 
The problem is people are not going to spend the $ for a panel that costs close to what their entire install does even if the panel can do smart tandem ring, logic and/or smoke/co/therm off a single detector.
 
Remember, while it's not the popular view, people are gawking at spending around $40-50 per I4 detector at trade cost, let alone $200 for a multi-criteria and $2K+ for a intelligent panel.

 

[emjackson]

Regular maintainanece is must for fire alrams otherwise this can lead to a major incident. We have suffered similar kind of fire damage loss due to euipment failure.

 

[OldTimer]

A couple of points to ponder:
AHJ = Authority having jurisdiction
Start with you local code inforcement office. They should be able to tell you what codes have been adopted in your area or send you to who has authority. Electrical, building, or fire department...
Smoke detection
Ionization detectors can miss a slow smoldering fire.
Photo electric detectors can miss fast burning fires (Most have heat detectors)
Proper placement is a must. Learn about dead air spaces and out of path areas before ever recommending the placement of life safety devices.
110v w/batt ion (or sometimes PE) detectors are early warning detectors. Burnt toast should sound them. Ion detectors use a radioactive magnet to detect air born particals. cooking fish or fatty meat will set them off.
Early warning detectors are not allowed to activate automatic notification to the fire department.
System detectors are not early warning. They are designed to detect for a predetermined amount before tripping. They are designed and approved for activating automatic notification to the fire department.
Dual ion and PE detectors active an alarm if either sensor is triped.
So, you want to know the best way to go: system detectors or 110 ion detectors???
In my opinion, you need both.
Take the basic 2 story 3 bedrom.
110's top of stairwells and on each floor...
System detectors top of stairwells and on each floor. In every sleeping area. 135` fixed temp heat detectors in Attic furnace rooms garages and above sources of ignition, and any inclosed areas housing elect, equipment.
Audability has to be 100%. It should yell "FIRE". We don't need people hiding under the bed because they heard a siren. All sounders and wire should be aproved for fire alarm use. We don't want them to melt near the ceiling the one time you needed them or have them short out the system...
Of course the use of 110 ions in the sleeping areas is fine. Just not my recommendation.
OK, Let's talk CO detectors:
CO detectors rely on shape changes that take place to synthetic human tissue. The synthetic tissue has a life expectancy of 4 to 7 years. If the detector doesn't show a dead date then it is already dead (made before dead dates were required). Before disposing of it, take a hammer and smash it so it doesn't end up back in service. Most proffesional CO detectors have a replaceable sensor unit.
CO is a toxic gas that will build up in the body. It diplaces oxigen in your blood. It can run from a slow build up at low levels to a fast build up at high levels. Some people are more sensitive then others. Some get head ackes, some just become drowsy and pass out, but everybody can be over come by CO.
Getting someone effected out side in to fresh air asap is most urgent!
Driving them down the highway with all the windows open for an hour is a very good way to get it out of their system. AND YES calling 911....
So where does it come from and how does it move around?
CO is a product of combustion when fuel is burnned. An appliance that burns gas expells CO. If it is not vented propperly, wind blows down the vent... it will float in the house. CO is heavier than air, but in a heated condition it is lighter and will rise until cooled. Then it will sink. It will penitrate through sheetrock. That is why attached garages have to have 100% plastic vapor barrier between the sheet rock and the living areas.
There has been a lot of wars about placement and writing generic codes, so please use common sense. When code calls for the ceiling near the sleeping area (hallway) please place it clear of the landing but not after the HAVC intake. You want to be btween the source of the CO and the return duct...
I perfer wall mounting of CO detectors in these areas because if the air is hot near the ceiling then the CO gasses may never reach the detector! The ceiling becomes a dead air spot.
In sleeping areas the best place is a foot above bed hight. This didn't make code mostly because every sleeping may not end up with a bed in it...
Because CO can displace the air from the floor upward or from near the ceiling downward the detector would wake someone on the bed before over coming them. Personally I hate the thought of the detector on the ceiling activating long after the person on the bed has already surcomed to the CO.
When protecting an are with a source of CO (gas cook top, furnace, gas water heater...) you want to use the ceiling.
My guess is that if we went into a house owned by any of those that sat through these wars we would at least find a CO detector in their basement at about 2 feet off the floor.
Now for sensetivity. CO amounts of 35ppm over an extended time can poison someone. Code for the lowest sensitivity is 70ppm. So if you have occupants that don't ever leave the house, then don't count on the detectors 100%. Specially in months that the house is closed up (heat or AC). 
System sensor smoke detectors are my favorite. Low bug probems. High immunity to dirt. Low false alarms. More than likely to activate when they die instead of just going to sleep. And I've installed and serviced thousands of them.
Funny, but the earlist modle smoke detectors I ever worked on consisted of one transistor and one PE emitor on refector. Can't recall the mfr? They worked. We replaced them due to cell phones tripping them...LOL
Properly installed fire detection saves lives!
 
 
 

 

 

[Del91574]

@ Old
 
A lot of your information is incorrect or out of date. I'm only going to point out a few key points as many statements are misleading. Let me know if you want specific building code, NICET or NFPA references to further your knowledge from what was commonly assumed in the past.
 
Dead air space in relative terms of detector location has been proven otherwise and NFPA has changed the requirements for the 4-12" rule or 3' from a peak rules that used to be prevalent. Heat detectors can't be blanket statement of 135 or 194 for X or Y. You need to consider the highest ambient and go 15 degrees above that. 135 will trip in an attic space (not if, but when).
 
There are 4 types of CO detector elements and they perform differently and have different operating characteristics, not the single that you're referencing. There are primarily 2 used (out of the 3 most common) used in the alarm industry. Yes, there is a service life, however they vary significantly.

To treat CO poisoning, usually if there's enough exposure to generate an reaction, it's not drive with windows open, it's get the person to a hospital for hyperbaric treatment. (I commonly work at one of the top 5 trauma hospitals in the US on their security and fire systems and have seen these cases a little too often).
 
CO is approximately the same density as normal air, so placement of detectors would follow the location of smoke detectors, however there is no limit either high or low, and factually, the main reason why the mounting height is put in the specification is to limit physical damage and/or access to a hush feature (straight from the manufacturer's engineers). Some of your statements are clearly representing local building codes and conditions in your area, but there is no national or code mandate to install continuous plastic vapor barrier when an attached garage exists. The only building code mandate is the thickness of the sheetrock (fire code) and the joints must be at least 2 coats to help with both fire and the spread of gasses.