# Need new CO Alarm



## Ultrarunner2017 (Oct 1, 2008)

Hi;
I have two CO alarms that are at their end-of-life. One of them emitted the telltale 3 short beeps every minute and displayed 'Err' on the display. Both units are more than 5 years old.


So, I'm about to take off for my local HD store and pick up two new ones.
But as I always do, I read up on which ones are good, and which to avoid. But after reading many reviews (including Consumer Reports), I am less confident about which ones to buy and where to buy them. Reviews on Amazon and HD are pretty much useless it seems, so I come here.


I would prefer the 10-yr Lithium battery option, but have read that some units purchased on Amazon (don't know about HD or Lowes) are old stock, and may not provide the life expectancy indicated.


There is a good deal at HD on a 2-pack of this one:
https://www.homedepot.com/p/Kidde-Battery-Operated-Carbon-Monoxide-Alarm-2-Pack-21025792/202805170


But I hesitate to buy a unit which states in its description that the battery needs to be replaced every 6mos. I have never needed to replace the batteries in any CO or smoke alarm more than once per year.


My next question is whether or not to get a unit with digital readout of CO level.
I would think that if any unit alarms, you leave the house (without opening doors/windows) and call 9-1-1 and have the FD come with their professional sensors.


OTOH, would a unit with a digital display show levels that won't cause an alarm? If that is the case, then perhaps it is worthwhile.
Either way, the price difference between units with and without isn't great (and in one case I found the one with the display to be less expensive).


So, which units in the under $50 price range are most reliable, and which stores are most likely to sell me a unit that hasn't been sitting on the shelf for a few years?
Of course, if I buy locally (not on Amazon), I can always return it to the store if I find that it is more than a few months old.


Thanks for your help


FW


Edit: It appears that more than one Kidde model indicates that the batteries need to be replaced every 6 mos. I suppose this is typical of (non-Lithium) battery operation?


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## Gregsoldtruck79 (Dec 21, 2017)

I have had the one in the pic now for 3 years. I keep it plugged in to a wall outlet so the backup batteries never get used. I have not changed them in two years now. 

I like the ability at any time to press the button on the top right and get the latest high CO PPM reading. The button on the top left gives me the test/silence feature. I want to know when it alarms, what the CO PPM was when it tripped.


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## Ultrarunner2017 (Oct 1, 2008)

Thanks. That's actually the same unit I am replacing. I have the AC powered one in the basement where there is an outlet, but I also need a battery operated one for the upstairs hall - where there isn't an outlet.
I guess the fact that I've had good luck with the First Alert is a good enough reason to go to them again.


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## user_12345a (Nov 23, 2014)

Consumer monoxide alarms only go off due to short term exposure at 70ppm and when exposed to that level or greater for a minimum amount of time. By the time one has gone off, you've been poisoned.

The monoxide level could stay perpetually at 69 ppm, detected as low level chronic exposure and the alarm won't go off for up to a month.

"30 ppm for up to 30 days
70 ppm for up to 4 hours
150 ppm for up to 50 minutes
400 ppm for up to 15 minutes
Read more: http://www.greenbuildingadvisor.com...oxide-alarm-may-not-protect-you#ixzz5KEzheHtC 
Follow us: @gbadvisor on Twitter | GreenBuildingAdvisor on Facebook"

The ones with a display will start showing levels well below that, but probably not below 30.

To put this in perspective, the co in the exhaust of a properly tuned furnace or water heater could be 20ppm. 

It takes a very serious problem to get a ul approved monoxide alarm to trip.


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