Dual Sensor Smoke and Fire Alarm, and Why They Are The Best

(Don’t let this happen)

Most so called smoke and fire alarms (smoke detectors) out there are NOT dual sensor. Most of them have a single “ionization” detector that detects flame.

The thing is…it’s usually not the fire that will kill you, it’s the smoke and it’s deadly component carbon monoxide that will end your life.

Here’s what you need to know:

The single sensor “Ionization” types rarely detect the smoke particles that will likely end your life before the fire itself does – particularly if it’s a slow smoldering fire while you’re sleeping. “Photoelectric” detectors however will detect these smoke particles and alert you – which is why you need a dual-sensor smoke detector for ultimate safety.

According to a career firefighter, “If you are sleeping, by the time the ionization sensor detects the actual flames, the smoke and the CO will most likely have already gotten to you and you will be dead”.

That’s why it’s so VERY VERY important to have a dual-sensor smoke detector.

I have installed the following two types of smoke detectors which I believe are among the best out there. These are dual sensor and are designed to alert you to both smoldering low-flame fires and high intensity rapid flame fires.


Battery Powered ‘stand-alone’ Smoke Detector

First Alert Dual Sensor Battery-Powered Smoke and Fire Alarm


‘Hardwired’ (with battery backup) Smoke Detector

These are used for homes with internal wiring (power) for smoke detectors.
First Alert Dual Sensor ‘Hardwire’ Smoke Alarm with Battery Backup

This detector will protect you 100% from fire related death/injury if used properly and placed correctly in your home.

It is important that you have the proper placement for your smoke alarms. Install your alarms at least 20 feet from appliances like furnaces and ovens, which produce combustion particles. Smoke alarms should be at least 10 feet from high humidity areas like showers and laundry rooms, and at least 3 feet from heat/AC vents. Be sure to install a smoke alarm in each bedroom, one at the top of each stairwell, and one on every level.

One way to remember to replace the battery is every time you switch the clock during daylight savings time or any time the detector chirps.

Always look for a photoelectric-ionization detector and buy one. I just replaced ALL the smoke detectors in my house because they had gone beyond their shelf life.

Did you know that smoke detectors have a limited life of 8 to 10 years?

Also make sure to have a B-C extinguisher on hand near the kitchen to put out kitchen grease fires which are the number-one cause of residential structure fires.

Hopefully you can put a small one out, but if you discharge the entire extinguisher and the fire is not out…evacuate the house immediately and make sure you or someone called 911!

Here’s how to put out a grease fire.


  1. Good Info Ken.
    If I might add a thing or two?

    (1 If you have a “craw-space” or basement under your home, put one or two under there, A lot of fires start there first than BURST into the house fast fast fast, even faster than you can run/get out of the house.. I have seen homes where the fire started in the basement and the house almost exploded as it spread upstairs.

    (2 Even though it’s not recommended also install one in the furnace room, in the kitchen, and every other room, not just the bedrooms and hallways/stairs.

    (3 Install a Carbon Dioxide Detector next to every “smoke/fire” detector. I don’t like the “combo” detectors.

    (4 Test your detectors every three months (no more that six months)with smoke/flame/CO. you can even have the fire department test them for you if needed.

    (5 As Ken mentioned replace the batteries once a year, use the old batteries in something else to use them up, ALWAYS put fresh/new batteries in the detectors.

    (6 As Preppers we don’t like the .gov in our homes, but have the FD come by and take a look at your detectors, get recommendations, most of the FD I know could care less about if you have “stuff” stored, but they will help you in case of fire prevention or an actual fire.

    Fire/Smoke/CO is not something you want to mess with, save your life and your family, do it right.

    1. First, I think you should do a bit more research. CO detectors should not be put next to smoke detectors. CO don’t rise like smoke.

      Second, you have to be realisitc. Who is really going to test their detector every 3 months or 6 months? Replace the batteries every year? You are asking for too much. There are a crapload of things that must be done around the house. Add this to your day job.

      Finally, the main blog is incorrect as well. Dual sensors have been found to be worse than photoelectric alone. This is because manufacturers will actually desensitize both sensors because they found that they trigger too easily which end up with people just pulling the batteries or turning them off. Just get a photoelectric sensor alone. If you have the extra dough, get a separate ionization sensor that isn’t close to the kitchen but I don’t think it’s worth the extra cost and aggravation.

      1. I have utilized dual sensor detectors for years… without issue. When you choose to eliminate a sensor because you may get false alarm is short sighted with regards to safety.

  2. The problem is the damned things keep making noise for no good reason. My only interaction with smoke/fire/CO2 detectors is trying to get them to shut up and buying batteries for them. I removed the one in my motorhome because I couldn’t make it stop tweeting every few seconds. I just removed the battery yesterday from the one in the house for the same reason. I have never had the damned things work correctly (i.e. alertme to a fire) but I have had them work incorrectly for 30 years or so.

    By the way motor homes (and probably trailers too) have a propane detector in them as well. They are somewhere near the stove/oven at floor level. Five years ago one of these went bad. I had no idea what was wrong, the fridge didn’t work, the stove didn’t work. So I brought it to an RV place and for a mere $100 they removed the shutoff valve thus disabling the propane detection system BUT allowing me to use propane.

    In general too many of the things designed to “protect” us seem to work the other way around. I begged the dealer to remove the smart key system from my new jeep when I bought it. Can’t do it, they say. So I’ve got a $80 key to start the jeep with and if it goes bad or I lose it then it will cost me $80 to buy a new one and about a week to get it from the factory. WHY??? So that no one can steal the frigging Jeep!! It’s not like I live in Baltimore. No one where I live steals cars but I had to pay extra for a anti-theft system I didn’t even want.

    I purchased a audio recording program for my laptop from the internet. It only cost $$30 but it was cool and would record any audio that played on the laptop. When I bought the new laptop I moved the program and tried to reboot the audio program and it won’t work. It’s a one time install thing. I have to buy it again. Why?? Because they built in an anti-pirate feature. They screwed their customers to make sure non-customers didn’t screw them.

    Then there is the stupid alarm/beeper that goes off if my seat belt isn’t on. I wear my seat-belt 100% of the time. But if you don’t get the damned thing on before you start the car the damned beeper starts making noise. Why?? I’m 71 years old, certainly old enough to make my own decisions. Why does my damned car have to beep at me?

    I’m mad as hell and I’m not gonna take it no more.

  3. I don’t have a dual sensor but I do have one of each type mounted side by side.

    1. That is smart, and good that you knew about both types of detectors. Hopefully others will discover this too, and upgrade…

    2. I use 9V lithium batteries for A/C backup. And I do have the smoke/CO units. a CO detector in the hall is pretty useless if the bedroom door is closed.

      I use the aerosol foam fire cans from Lowe’s. The dry chemical units cause a huge mess, and I am told the agent is corrosive. I wish my electric range had knobs in front like my BIL’s gas stove. Then I wouldn’t have to reach over a fire to deny that fire more heat.

      Now that I am thinking of it, I will test one of these foam cans on the fire bowl outside to verify effectiveness.

  4. I did not know this about smoke alarms, maybe you just saved my families lives . Great information, thank you.

  5. I have a hardwired super sensitive carbon monoxide detector in my furnace/laundry room and a super sensitive smoke alarm 4 feet away in my living room. Pain in the ass for both of them going off when I broil steak or let the dogs in from the laundry room where the wood smoke rolls in from a downdraft from the chimney outside. I Had the furnace and wood stove inspected, it’s good. The locations are in the best spots for the detectors and the wood stove is in the best spot to distribute the heat. It is the direction the house is facing for wind drafts. You don’t know the problem until you install the wood stove and chimney. Just have to live with it going off all hours of the night when the stove is being used, or turn the house around!

    1. @ Star
      You supply the dinner and I’ll bring a few of my buddies over to spin the house a good 90° :-)
      Smokes going off in the middle of the night is absolutely NO FUN at all.

  6. Make absolutely sure that your “dual” sensor alarm is NOT a CO + smoke detector. If placed high, by the time the CO fills high enough to set it off, you will be dead. If placed low, by the time the smoke fills low enough to reach it, you will be dead. Put independent CO detectors as low as you can get them, and independent smoke detectors as high as you can get them.

    Signed, daughter of a VFF

    1. That’s exactly what I do. I have separate carbon monoxide detectors, plugged in at ordinary outlet level, approximately 18 inches above the floor.

      [ Read: Carbon Monoxide Poisoning – Do You Have These Symptoms? ]

      Also, to be clear, when I say “dual sensor” smoke alarms up in the article, I’m not talking about one with a CO detector. Rather, I’m talking about a smoke alarm that has two sensing methods built-in, as described above.

      [ Read: Do Smoke Detectors Expire – Why – and What’s the Shelf Life? ]

    2. Thanks for posting this. I use a Buddy heater in the winter when it gets in the teens and lower. I got a co detector when recommended by someone here on this list but it was way to high on the wall. I also remember all the places it said to not put it- outside walls, near furnace or kitchen. I have a small manufactured home and was running out of places to put it. Wound up on a living room wall close to the heater but much to high!

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