Portable Carbon Monoxide Detector with Backlit LCD, High-Accuracy Electrochemical CO Sensor with Audible Alarm for Home, Travel, and Professional Use (Complies with UL 2034 Standard)

I consider this instrument a "second opinion." I can not attest to any type of accuracy or reliability. There was a problem with certain model years of SUVs drawing in exhaust from the air pressure created behind and below the body of the car while moving. Some experts thought it was not adequately addressed by the automobile manufacturer. The manufacturer said they did everything necessary. Who is right. I bought one of these, and kept it with me a few times while driving. It did not detect elevated carbon monoxide. Not sure that proves anything, but if the detector had shown an excessive level of carbon monoxide, then I would have a reason to take the car in for repairs. Now I just use it any time I am using a non-vented heater. I recall the light planes I once flew, had simple CO detector cards in them. If it turned dark brown, you had a carbon monoxide problem. Not sure if those are still made, but they were simple and reliable.

I had a very bad problem with my Furnace filters always get covered with soot after a week of replacement , I got anxious and was about to call in a professional to make sure there is no Monoxide leak or if my furnace is not burning efficiently so I was doing my research and found out this precious tool that eased my anxiety about monoxide leak and found out that the culprit was the excessive usage of candles by my GF . We stopped using candles for a whole month and we never saw soot on a filter again .

I purchased this specifically to check my furnace, which was beginning to get pitted in the heater module, which can cause CO leakage. However, for this review, I just used my car's tailpipe to check operation. DESIGN: This is a very ergonomically designed handheld with a nice display and good ease of use, once you decipher the chinese-english manual. It takes three AAA batteries and has a belt clip in the rear. It does have the CE approval mark on the battery cover. RESPONSE TIME: The response time to get an accurate reading is 120 seconds. When you first turn on the unit, it begins a 120-second countdown before it goes to the main screen to let you know when the first valid reading is. This is a nice feature, and it is also nice that you can skip the delay and go straight to the reading by pressing the power button again. I think some of the people who claimed the unit didn't detect CO may have not read the manual. FUNCTIONALITY: It has everything you would need for a CO monitor. -- MODES: You can set it in MAX hold mode, which causes the unit to only update if a reading is higher than the last displayed reading. This is especially useful if you don't want to wait around for an intermittent CO source to turn on. For example, you could set this on the floor next to a gas furnace and go back and check it later. There is a HOLD mode to just keep the current displayed value on-screen, such as if you wanted to record the value in a logbook. When you press the MODE button from SCAN mode, you go to HOLD mode. The MIN mode operates like the MAX mode, although I don't think most users will have any use for it. We all want to know the MAX value, right? -- UNITS: You can read the units as PPM or umol/mol by pressing and holding the C/F button in SCAN mode. Default is PPM. -- AUTO OFF: By default, the unit remains on until you shut it off, but there is also an Auto Off mode that shuts it off after 30 minutes without a keypress. The manual is incorrect about how to change this. You need to press and hold the BACKLIGHT button while in SCAN mode, then press the button again to toggle the mode ON or OFF. Another press and hold gets you back to the main screen. A nice feature is that when it is turned on, a little clock icon will be shown on the display to let you know it is set. - ALARM LIMIT: You can change the limit at which the unit alarms by pressing and holding the MODE button while in SCAN mode. You then use the C/F button to move the cursor to different digits, and the BACKLIGHT button to change the value. You press and hold the MODE button again once the limit is set to return to the main screen. The default is 24 PPM, and you should not change this if you are using this to monitor CO while you are sleeping. Prolonged exposure above this limit is dangerous. I think the main reason to adjust this limit is if you are using the device to obtain readings you know are high, and you don't want the annoyance of an alarm condition. I do think the currently set limit should either always be displayed on the screen, or displayed each time the unit is powered on, since this is a safety setting. It is not, so it is a good idea to always verify the alarm threshold if you are using this for your personal protection. -- ALARM: When the set threshold is exceeded, the device will beep loudly and flash the backlight on and off. I tested this by putting the device near my tailpipe. It responded immediately with a reading above the threshold, and the CO level began to climb due to the sensor's response time. The 2nd photo shows the alarming unit. -- C/F: The unit displays the ambient temperature in degrees Celsius or Farenheit. You can toggle between units by pressing the C/F button from any displayed mode in the main screen. -- CO UNITS: You can display the CO units in PPM or umol/mol simply by pressing and holding the C/F button. Each press and hold toggles the unit display. This is not mentioned in the manual. -- BACKLIGHT: The BACKLIGHT button ( a bulb icon) turns the green backlight on and off. MANUAL: Poorly written by Chinese author who doesn't know English well. Sadly, this occurs all too often with products made in China. There is some missing information, and some outright incorrect information in the description of how to use the product. I am deducting one star strictly because of the user manual, and I think it is important to have a well-written user manual, especially for a safety device. See above for the correct way to perform the various functions. SERVICE LIFE: The manual states that the sensor is only good for three years. Be aware of this when you purchase it. If used infrequently, you may want to test it with a CO emission before relying on it for safety purposes. ---- RATINGS (5 is best) --- DESIGN: ***** FUNCTIONALITY: ***** CO DETECTION: ***** ALARM: ***** MANUAL: *** OVERALL RATING: **** Country of Manufacture: Chine

I recently had an incident where my gas stove activated my CO alarm but maintenance couldn't find any leaks. I got this device to monitor CO levels while using my stove before the alarm goes off again. I like that you can clip it to your belt and the interface is easy to use. Every now and then it'll pick up a larger pocket of carbon monoxide at 15ppm and the alert is loud. The only downside it is takes about 2 minutes to start up and configure itself.

Everybody should have some type of CO {carbon monoxide} detector. I bought this unit to check for CO that might exist in my house and shop. I really wanted to know if their were any PPM {part per million} detected. It is very easy to use. I wish it would default to degrees F instead of degrees C. It has a Alarm / buzzer if the CO is at 100ppm or more. This unit works as stated - I tested it while using kerosene heaters in the shop. I compare it to other CO detectors my 3 friends have and all readings were the same value, so I know it works. One important note, If this CO detector gets drop hard, I would replace it than chance it.

I bought two of these because of the video advertisment shown on this offer that shows the unit is able of displaying ppm readings in the single digits, and no mention of it not showing single digits in the description, on the packageing, or in the included instructions, but I do see youtube videos showing readings in the single digits. My Nighthawk co detector doesn't display 1-9 ppm readings; but they say that don't. It looks like more than one company is selling this AS8700A device and they are not all the same units. The alarm will go off at a single digit level if I set it at a single diget level and the ppm hits that level, but the ppm number will say 0 if it is not 10 or over 10 ppm. The co levels were within .25 of a percent difference from the two devices and the temperatures varied by 3 degrees. Don't know if this is new manufacturing standards, or if Cheffort was the wrong supplier to get it from. The device is still nice, but if I knew what I know now, I would have put the money twords something better. AFTER THE ALARM IS SET TO 9, IF IT DOESN'T TRIGGER THE ALARM TO START THEN RESET THE ALARM TO 8. KEEP GOING DOWN WITH THE ALARM RESETS TO SET THE ALARM LOWER AND YOU WILL EVENTUALLY FIND WHAT YOUR PPM READING IS.