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expired Posted by TattyBear | Staff • Oct 9, 2023
expired Posted by TattyBear | Staff • Oct 9, 2023

First Alert CO605 Plug-In Carbon Monoxide Detector w/ Battery Backup

$16

$47

65% off
Amazon
38 Comments 15,177 Views
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Deal Details
Amazon has First Alert CO605 Plug-In Carbon Monoxide Detector with Battery Backup (White) on sale for $16.45. Shipping is free w/ Prime or on $25+ or $35+ orders (minimum requirement varies by location)

Thanks to Deal Hunter TattyBear for finding this deal.

Product Details:
  • Loud 85-decibel alarm sounds when CO levels are elevated
  • Equipped with end of life signal chirp, so you know when it's time to replace the unit for safety
  • Single test/silence button
  • Features an advanced electrochemical carbon monoxide sensor that accurately detects carbon monoxide levels, no matter where the detector is placed in the room

Editor's Notes

  • About this deal:
    • Our research indicates that this deal is $6.04 less (27% savings) than the next best available price from a reputable merchant with prices starting from $22.49 at the time of this posting.
  • About this product:
    • 7 year limited warranty
    • 4.7 out of 5 stars rating at Amazon based on over 16,300 customer reviews
  • About this store:
  • Additional Note:
    • Please refer to the Forum Thread for additional discussion regarding this deal.

Original Post

Product Info
Community Notes
About the Poster
Deal Details
Product Info
Community Notes
About the Poster
Amazon has First Alert CO605 Plug-In Carbon Monoxide Detector with Battery Backup (White) on sale for $16.45. Shipping is free w/ Prime or on $25+ or $35+ orders (minimum requirement varies by location)

Thanks to Deal Hunter TattyBear for finding this deal.

Product Details:
  • Loud 85-decibel alarm sounds when CO levels are elevated
  • Equipped with end of life signal chirp, so you know when it's time to replace the unit for safety
  • Single test/silence button
  • Features an advanced electrochemical carbon monoxide sensor that accurately detects carbon monoxide levels, no matter where the detector is placed in the room

Editor's Notes

  • About this deal:
    • Our research indicates that this deal is $6.04 less (27% savings) than the next best available price from a reputable merchant with prices starting from $22.49 at the time of this posting.
  • About this product:
    • 7 year limited warranty
    • 4.7 out of 5 stars rating at Amazon based on over 16,300 customer reviews
  • About this store:
  • Additional Note:
    • Please refer to the Forum Thread for additional discussion regarding this deal.

Original Post

Community Voting

Deal Score
+55
Good Deal
Visit Amazon

Price Intelligence

Model: First Alert CO605 Plug-In Carbon Monoxide Detector with Battery Backup , White

Deal History 

Sort: Most Recent
Post Date Sold By Sale Price Activity
01/02/25Amazon$18
1
10/10/22Amazon$18
1
10/08/22Amazon$18
0

Current Prices

Sort: Lowest to Highest | Last Updated 6/18/2025, 10:28 AM
Sold By Sale Price
Amazon$27.99
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Top Comments

These aren't for the ceiling, they plug into an outlet. Good for an older home that doesn't have hard wired detectors. Or if you just want to add an extra detector in a specific area for peace of mind. And finally if you already have good smoke detectors that aren't dual and just need to add a CO. Sometimes it's beneficial to have a CO at a different level too. CO can be high/middle/low in a room, it's almost neutral with air density.

37 Comments

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Oct 9, 2023
593 Posts
Joined Jan 2011
Oct 9, 2023
apkesh
Oct 9, 2023
593 Posts
This is a great deal. Got 3 for each floor of the home. I am surprised this hasn't gotten more up votes.
3
Oct 9, 2023
4,806 Posts
Joined Aug 2011
Oct 9, 2023
AllyFrizzle
Oct 9, 2023
4,806 Posts
Great price. Thanks for sharing.
Oct 9, 2023
3,885 Posts
Joined Jul 2012
Oct 9, 2023
desynergy
Oct 9, 2023
3,885 Posts
These look like the ones our fire department gives out, when they have any on hand. They always have free smoke detectors, but always out of the carbon monoxide detectors.
1
Oct 9, 2023
3,290 Posts
Joined May 2004
Oct 9, 2023
starfoxinstinct
Oct 9, 2023
3,290 Posts
What's the benefit of this over buying a combo fire and CO alarm? Seems like if you just sprung for a combo instead of one of each, you'd pay the same in the end and take up less ceiling.
Pro
Oct 9, 2023
1,149 Posts
Joined Jan 2009
Oct 9, 2023
Devaney1984
Pro
Oct 9, 2023
1,149 Posts
almost just bought 3, then double checked my smoke alarms and they double as CO detectors...if you have the first alerts that costco was selling a while back you should be covered
Oct 9, 2023
114 Posts
Joined Feb 2014
Oct 9, 2023
ScottF9329
Oct 9, 2023
114 Posts
Quote from starfoxinstinct :
What's the benefit of this over buying a combo fire and CO alarm? Seems like if you just sprung for a combo instead of one of each, you'd pay the same in the end and take up less ceiling.
These aren't for the ceiling, they plug into an outlet. Good for an older home that doesn't have hard wired detectors. Or if you just want to add an extra detector in a specific area for peace of mind. And finally if you already have good smoke detectors that aren't dual and just need to add a CO. Sometimes it's beneficial to have a CO at a different level too. CO can be high/middle/low in a room, it's almost neutral with air density.
Oct 9, 2023
3,290 Posts
Joined May 2004
Oct 9, 2023
starfoxinstinct
Oct 9, 2023
3,290 Posts
Quote from ScottF9329 :
These aren't for the ceiling, they plug into an outlet. Good for an older home that doesn't have hard wired detectors. Or if you just want to add an extra detector in a specific area for peace of mind. And finally if you already have good smoke detectors that aren't dual and just need to add a CO. Sometimes it's beneficial to have a CO at a different level too. CO can be high/middle/low in a room, it's almost neutral with air density.
Thank you!

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Pro
Oct 9, 2023
1,991 Posts
Joined Nov 2006
Oct 9, 2023
BossNog
Pro
Oct 9, 2023
1,991 Posts
Wow! These used to be $19 regular price. Guess I need to stock up on a few
1
Oct 9, 2023
139 Posts
Joined Jul 2013
Oct 9, 2023
SpinD
Oct 9, 2023
139 Posts
Quote from ScottF9329 :
These aren't for the ceiling, they plug into an outlet. Good for an older home that doesn't have hard wired detectors. Or if you just want to add an extra detector in a specific area for peace of mind. And finally if you already have good smoke detectors that aren't dual and just need to add a CO. Sometimes it's beneficial to have a CO at a different level too. CO can be high/middle/low in a room, it's almost neutral with air density.
Good advice, with one correction: CO is heavier than air. So, for a CO-only detector, it's better to have them lower. Smoke, on the other hand, generally rises with heat from a fire, so fire/smoke detectors should be near the ceiling. The instructions with the purchased unit will provide guidance. Overall, the benefits of a detector far outweigh these differences, so a Combo detector is still a good choice.
Last edited by SpinD October 9, 2023 at 01:35 PM.
Oct 9, 2023
698 Posts
Joined Oct 2014
Oct 9, 2023
turboc20
Oct 9, 2023
698 Posts
Quote from SpinD :
Good advice, with one correction: CO is heavier than air. So, for a CO-only detector, it's better to have them lower. Smoke, on the other hand, generally rises with heat from a fire, so fire/smoke detectors should be near the ceiling. The instructions with the purchased unit will provide guidance. Overall, the benefits of a detector far outweigh these differences, so a Combo detector is still a good choice.
You must have a poor grade in Chemistry.
CO is 28 and air is roughly 29 (mixture of O2 which is 32 and N2 which is 28).
So CO is slightly lighter than air.
Oct 9, 2023
114 Posts
Joined Nov 2014
Oct 9, 2023
mcdalgun
Oct 9, 2023
114 Posts
is it free voltage?
Oct 9, 2023
126 Posts
Joined Jan 2014
Oct 9, 2023
ImAPoetAndIKnowIt
Oct 9, 2023
126 Posts
Quote from turboc20 :
You must have a poor grade in Chemistry.
CO is 28 and air is roughly 29 (mixture of O2 which is 32 and N2 which is 28).
So CO is slightly lighter than air.
Yeah, if his theory was correct, all the oxygen would be in two feet next to the floor and we would suffocate if we were sitting or standing. And if we wanted a boost in oxygen, we would lie on the floor. Drive a stake through this BS.
1
Oct 9, 2023
92 Posts
Joined Sep 2011
Oct 9, 2023
BREEZEL1
Oct 9, 2023
92 Posts
In case you are interested-
Before you buy: Illinois Smoke Alarm Law- Effective January 1, 2023
The updated law requires Illinois residents to replace their old smoke alarms with the type that has a long-term,
"10-year sealed battery." This would apply to residents that are still using alarms with removable batteries or alarms that are not hardwire.
1
Oct 9, 2023
3,885 Posts
Joined Jul 2012
Oct 9, 2023
desynergy
Oct 9, 2023
3,885 Posts
Quote from Devaney1984 :
almost just bought 3, then double checked my smoke alarms and they double as CO detectors...if you have the first alerts that costco was selling a while back you should be covered
It depends where your smoke detectors are mounted. The CO2 part are very sensitive. If it's within so many feet of a ceiling fan blowing air around, air outlets/vents, fresh air returns, window air conditioner, an open window, etc, they're next to useless. If any air is moving, it's not going to detect CO2. (The owners manuals will usually tell you this). When they built my house, they placed most of our detectors in the worst spots for CO2 detection. You really want to place these behind a cabinet or some type of structure that keeps the air calm (5 feet? 10 feet?) surrounding it.
1

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Oct 9, 2023
698 Posts
Joined Oct 2014
Oct 9, 2023
turboc20
Oct 9, 2023
698 Posts
Quote from ImAPoetAndIKnowIt :
Yeah, if his theory was correct, all the oxygen would be in two feet next to the floor and we would suffocate if we were sitting or standing. And if we wanted a boost in oxygen, we would lie on the floor. Drive a stake through this BS.
My post was about "light" vs "heavy", in other words, density. That is not just theory that is REAL.

You were talking about heavier gas concentrating in lower layer which I didn't say that.

The air does not split in layers because O2 and N2 are already thoroughly mixed together. If you simply release new O2 in room, guess what, it will initially lay on floor.

And come to the case of CO. It will be newly released into air by combustion so it will initially be floating high on ceiling because:
1. it's lighter
2. it comes from combustion with higher temperature.

Sure eventually it will be mixed with air and everywhere but that doesn't matter any more.
Last edited by turboc20 October 9, 2023 at 02:27 PM.

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