smoke detector recommendations?

I have two smoke detectors in my house which are over 8 years old, plus one CO detector. Since the smoke detectors are near end of life, I'd like to improve the coverage. I also need new detectors in a mobile home that I rent out.
My ideal would be
-- tri-mode (photoelectric + ionization + carbon monoxide) -- interconnected (all sound when one trips) -- operate whether power is on or off -- loud
I realize that I probably can't have it all, so I'm looking for the best compromise. I haven't found any place with really comprehensive listings, especially any which make it easy to determine what models meet which of my criteria. Consumer Reports has good descriptions of the issues but analyzes very few models.
So I'm looking for advice both on what compromises are most reasonable, and on specific models (possibly multiple models in combination) which might implement that compromise. I appreciate resources as well as direct information.
Notes on each of my items:
I probably don't need to explain why I want tri-mode -- anyone not familiar with the types can easily google them. I'm willing to spring for multiple detectors if there are no satisfactory tri-mode detectors available. (I haven't found any tri-mode detectors in a single unit.)
The advantage of interconnection should be obvious. Same for loud.
I'm unsure whether I want AC powered or battery powered. AC powered work without needing to change batteries and have plenty of power for a loud alarm. Battery powered operate when the power is out; I don't know if any of these can be interconnected. I know there are some AC powered with battery backup, but then that's still a battery to monitor and replace.
The big question with respect to AC vs battery is which is more effective overall. Power isn't out very much, but it does go out. In the house it probably averages a few hours a year -- once it was out for 18 hours after a severe thunderstorm, but usually it's not more than an hour or two, and it goes for months with no interruption at all. The mobile home is in a rural area and outages can be longer; it was without power for 3-1/2 days after Hurricane Kate, about 25 years ago. But are there any common factors to fire and power outage? Anything about a power outage that makes fire more likely? (Using candles and kerosene lamps would seem a significant risk. I have battery operated lights instead.) Perhaps an electrical malfunction could start a fire but then trip the breaker powering the detectors before they sound the alarm? On the other side, weak batteries are an obvious risk, albeit one which regular testing ameliorates. So neither is perfect, but what are the probabilities of a multiple failure? That is, power outage plus fire, or battery failure plus fire, or alarm not loud enough plus fire, etc? Are there other common mode failures?
In the house, I can easily run AC wiring and/or interconnection wiring in the attic. In the mobile home, I might be able to run it above the ceiling, or I could gouge a trough in the ceiling tile or just run it along the upper corners -- the place doesn't look good enough for me to worry about the damage.
Edward
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wrote:

Get at least the AC/DC in your rental. If you only get the battery operated ones, the renters will take the batteries out to use in some gadget.
Hank
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The current NFPA requirements are that smokes be installed in every bedroom and one on every level, all interconnected, and have a back up power supply.
The NFPA has been struggling for years to figure out why people disable their smoke detectors. I think the answer is that when there is a failure at 3 AM, and every smoke in your house blows off, scaring the snot out of everyone in the house, the instinct is to rip them out of the ceiling. Personally, I don't like the idea of the interconnections, because you don't know where the potential fire is. If only the smoke that detects the fire went off, you'd have a better idea where to run to, or from. Just my 2 cents.
You don't have to monitor the smoke batteries, they all have a beep warning when they're low. I would use a Kidde combination smoke CO2, 120 volt with 9 volt battery. I've had the fewest failures with Kidde
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RBM wrote:

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People disable them because some are too damn sensitive. You want to be warned of a fire, not fried eggs and bacon.
--
LSMFT

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Speak for yourself. If there's fried eggs and bacon in the house, I damn sure want to be notified of it :)
nate
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<stuff snipped>

at
A safety feature isn't really a safety feature if it's so prone to falsing. Nasal Radiators I've known complained that during the Vietnam war, cockpit warning systems were often disabled for that very reason.

don't
That's precisely why I dislike them. I want to know where the trouble is so a small greasefire doesn't turn into a holocaust. I know the common wisdom is to run, run, run but I've lived through fires and what the fire didn't burn, the firemen drowned. If there's a chance I can put it out with one of the many fire extinguisher located around the house, I'm going to go for it. We have two smokes and one fire extinguisher in each room - a result of having lived through two fires. Of course, when you wake up and you can't see because the smoke is as thick as cotton, that's when it's time to trot, bwana. Same is true when your feet stick to the floor because the varnish has melted from the heat. No extinguisher is going to put that fire out.
-- Bobby G.
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The most effective (loud) smoke alarm I ever saw (heard?) was a Sears model AC alarm. The damn thing was so loud, it actually physically took me aback. No doubt it would literally blow one out of their bed, a good thing. ;)
OTOH, I can see the advantage of a battery alarm. I can't recommend any.
I will say this about CO2 detectors. The Kidde digital readout model I bought ($20) seems to be junk. Doesn't reset to zero, never reads anthing but "28", and never "alarms". I have a rock that works as effectively.
nb
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My loudest alarm is a small battery smoke detector that drive me and the cats crazy every time I burn the food. I also bought a small battery CO alarm for $20 and its not too good. Maybe its just slow to react. I was looking at a CO detector I bought on sale 3 years ago cheap. I'm reading the box and its got a battery backup, and the whole thing will not work if the battery is dead, even though its AC connected. I'm sure the unit is probably over the life of the lithium battery, maybe.
CO detectors are also a good backup smoke detector. They inherently detect a fire or smoke.
greg
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wrote:

Current code for new construction requires
- ac/dc power (hardwired with battery backup) - interconnected (all det's must sound when one goes into alarm) - smoke detectors located as follows: at least one on each level of house; one in each sleeping room, and one outside each sleeping room.
A nice enhancement would be if you could find a product that also has the option of having one detector with a form C relay contact so that if you have an alarm panel, then your alarm panel can report a fire as well as intrusion to your monitoring company with just a little more wiring.
I wouldn't necessarily use combo photo/ions everywhere because some areas might be prone to false alarms (you may find that by code you need one near your kitchen for example, where an ion wouldn't be appropriate.) The detector should be chosen with the area in which it's going to be installed considered.
When you're wiring up the smokes, you need to use 14/3 or 12/3 cable (as appropriate for the circuit) as the black and white wires are used as normal for 120VAC power and the red wire is used for the interconnect. So you may have to check your box fill if you are using shallow octagon boxes.
good luck
nate
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On 2/4/2011 1:03 AM, Edward Reid wrote:

I don't have specific recommendations by brand, but I suggest that you not buy a multimode unit. I did some research and the average life span of a CO monitor is 5 years, after that the sensor deteriorates. But the life span of a smoke detector is longer than that. So you need to replace the CO detector every 5 years, and if you have multimode you will have to replace the whole thing.
Bill
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Thanks for all the comments. As expected, no clear answers, but more ideas to think about.
Edward
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