Carbon Monoxide Detectors, Portable CO Detector with Temperature Sensor ＆ LCD Backlight Screen, Handheld Carbon Monoxide Meter Tester 0-1000PPM Range, Indoor/Oudoor (Includes Battery x3)

Works fast, it's accurate.

machine payed for itself -would have cost me a service call at the furnace company @ 150

I liked the size and basic design of the unit. Backlit display was easy to read.The problem I had is that most of the time, the reading was 0 ppm. This is my first CO meter, but I was having trouble believing the zero number, especially when in the vicinity of flame sources such as burning candles. To get substantial CO readings, I had to fire up my charcoal grill. I also found running a gasoline engine in an enclosed space would get a reading.The readings at the low end of the range seemed to be erratic and/or non-linear. I might see a reading of 10, which would drop to 0 a second later, and then back to 10 after another second. I understand the sensor has a slow response time, but I would have expected more gradual changes in the readings.The sensor supposedly has a 3-year lifetime. I would not buy this unit next time.

There were comments stating that the detector did't work despite it being exposed to some combustible source. well, I was starting to feel the same way. However after removing the top part( please be carefull doing so). While starting my car one morning, I heard a beeping and I was thinking it was comming from the car, but I looked in my pocket and found the CO detector going crazy with readings 70s,30s and so forth. It sounds off even when the most minutest co particles emited into the air. This gadget really works.

Overall, I'm impressed with the quality of this $40 carbon monoxide meter. Well worth the expenditure to check for appliance leaks in the house, as well as the cabin of my vehicles.The instructions are not clear on the calibration time, as many questioners noted. When first turned on, the digital screen will display "120", and begin to count down each second, until 2 minutes later, the display will automatically change to the sampling mode. The 120 second calibration mode can be interrupted at any time by pressing the “ON” button, and will revert to the sampling mode. The instruction sheet lists a 60 second response time; the data sheet for the Nemoto NAP-505 sensor lists a 30 second response time. The response time varies with temperature, and increases with colder temperatures. Your choice if you want to wait the full 2 minutes.The instructions indicate a typical sensor life of 3 years, while the data sheet for the NAP-505 sensor lists an expected life of 7 years. The electrolyte used in the sensor is hygroscopic, and will attract water will degrade the device. Store the CO meter in a low humidity environment, to achieve the expected life.The CO meter in the sampling mode with backlight off, draws about 8 mA. The 750 mAh AAA Eneloops I use (to avoid parasitic cell corrosion/leakage) will therefore power the unit for probably 75-100 hours of realistic “ON” time. I’m satisfied with that amount of operating time….more than I need.I have no way to test the ppm accuracy of the meter, other than to approach the exhaust pipe of my car. The CO concentration does increase the close I come to the pipe. I don’t have a standard gas bottle. The NAP-505 is a quality Japanese sensor, so I’m inclined to trust the accuracy. My gross test on my car shows that the meter does work.It’s great that a product used for safety checks, is available at such a reasonable price. I’d buy this CO meter again.