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  • Carbon Monoxide Tester detects and measures CO gas concentration
  • Backlit display with CO measurements from 0 - 1000 ppm
  • Carbon monoxide meter with audible and visual alarms
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Product Overview

The ET110 CO Detector is an easy-to-use meter that detects and measures concentration levels of carbon monoxide (ppm) and temperature (Fahrenheit/Celsius), making it the perfect choice for HVAC professionals. Features backlit LCD screen, warning indicator light, audible and visual alarms and multiple function buttons. Includes carrying pouch and 4xAAA batteries.
  • Easy-to-use carbon monoxide meter detects and measures concentration levels of carbon monoxide gas
  • Portable carbon monoxide detector with user protection and short-term exposure limit (STEL) alarm
  • Low level alarm (35 ppm) and high level alarm (200 ppm)
  • Audible and visual alarms
  • Backlit display with CO measurements (0 to 1000 ppm) and temperature (Farenheit and Celcius)
  • Auto-power off after 20 minutes of no usage helps conserve battery life
  • Includes carrying pouch and 4xAAA batteries
  • Meter is NOT intended for use as personal protection equipment



  • Shop all Klein Tools electrical meters here



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  • California residents

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Customer Reviews

  • 4.2
    out of 52 reviews
  • 76%recommend this product
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Showing 1-10 of 52 reviews
Great tool
[This review was collected as part of a promotion.] Bought this a couple months ago and use it often very pleased
by
    • Recommended
    Great for home, camper, RV safety and for pros on the job! These days you can't be too careful wi...
    Great for home, camper, RV safety and for pros on the job! These days you can't be too careful with Carbon Monoxide in the home or on the job. This handy tool will let you know when you have a leak and when the concentration is too high. WHAT YOU GET: CO meter, carrying case, 4 AAA batteries, manual. WHAT YOU NEED: Nothing, it's ready to go out of the box after battery install. USE: This can tool can read nearly any level of CO and alarm you when it's unsafe. Calibration is done by the tool on it's own. It has a nice backlight for dark spaces. Warnings are given by an audible tone and warning light. Turn on the device and it will set itself and start measuring CO on it's own. It will read the variable levels in PPM and high levels can be retrieved as needed. You can also hold a certain level on the screen by using the hold button to show a client. This will also tell you the ambient temperature. The sensor lasts 5 years and is replaceable. My mom's CO detector was giving odd chirps and we couldn't find the issue. It was not a full alarm, but the battery was fine. One use of this tool by the detector and her furnace and sure enough, the levels were fine and the cheap wall detector was defective. This gives peace of mind and helps solve problems. OVERALL: This is a great tool, it's hand sized, can be worked with gloves, can hold high and low levels and had a multi level alarm to let you know when it's safe or not. It's also durable, it is drop safe up to about 3 feet. I'd highly recommend it.
    by
    • Recommended
    3 found this review helpful
    a few things to know about the ET 110 , this is not a for personal use that is something to keep ...
    a few things to know about the ET 110 , this is not a for personal use that is something to keep on your body for CO monitoring. This tool is intended for checking spots, rooms etc where suspect CO contamination could be present. Next is this is a electrochemical sensor. Lifespan is about 5 years and replaceable . Batteries are required. Both the sensor and batteries have warning indicators. Operating range is 0-1000 ppm in a 32 to 122F temperature range. Operations are straightforward, On, calibrate and let it work. Response time is 1 minute for 90 percent reading. However you can watch this work in real-time lighting a match at close range ,it took seconds for it to start indicating CO ppm. There is a temperature readout along with alarms lights , speaker mute and max and average functions all enhance this meter. Added is also backlighting which is helpful in dark areas. And a short term exposure limit warning . Good size comes with a case and good instruction book. For me I wish there was a timer function but works well for it value.
    by
    • Recommended
    7 found this review helpful
    Not a tool that the average homeowner would use, but can be useful for the concerned individual (...
    Not a tool that the average homeowner would use, but can be useful for the concerned individual (home owner, renter, etc) or a professional. I learned after trying to use this some basic information on how fuels burn and what the resultant byproducts are is really important to using this and understanding the reading it is telling you. I have natural gas for cooking, domestic hot water and for hydronic heating. I thought that if I placed the sensor in the exhaust gas from my stove, water heater and boiler that it would read really high carbon monoxide numbers. But it didn't, which originally made me think something is wrong with the device. Turns out that a properly operating gas appliance that is burning cleanly does not produce carbon monoxide, it produces carbon dioxide and water vapor. The exhaust of a car is a similar situation if all the emission equipment is functioning properly and the car is running properly. What I did learn that I forgot from high school chemistry is that carbon monoxide is generally produced from combustion that is fuel rich or where the is not complete combustion of the fuel. So it was reassuring to know that the gas appliances in my home of functioning correctly and burning cleanly, but this not the proper tool to really use for this purpose. There are devices called combustion gas analyzers that are use for this. This device cannot work properly at elevated temperatures (Normal ambient temperatures is where this will work and work accurately). You can use this in addition to you carbon monoxide to help find where carbon monoxide is coming from. I suspect you could use to check if exhaust ducting is sealed (but this may not work if the device is burning cleanly). But if you do have a carbon monoxide issue you can tell the level of carbon monoxide to an accurate level. Overall the device works well and is easy to use, comes with a case and batteries. The screen can be back lighted. But the instructions should do a better job of explaining where carbon monoxide comes from and how to effectively use this tool.
    by
    • Recommended
    6 found this review helpful
    Great tool and accurate based on my tests. What I like: • I exposed the tool to high, moderate, a...
    Great tool and accurate based on my tests. What I like: • I exposed the tool to high, moderate, and no levels of carbon monoxide. Each time the device recognized the presence of carbon monoxide and it recognized it quickly. When I say ‘quickly’ I’m talking about 1-2 seconds which is pretty much immediately. I was very pleased and pleasantly surprised with its speed. • Easy to read and follow directions are included. A rare thing with tools of this nature. Nice work Klein. The tool itself is also very use to use and understand what it’s telling you. Perfect for a professional or a DIY’er. • Lightweight and fits in your hand nicely. It also has a clip for your pants, tool belt, etc. • The temperature is a nice addition and it’s accurate as well. I compared it to several gauges and each was within a degree. • Easy to read with included backlighting. • The visual and audio alarm worked quickly and turns off as soon as the gas levels drop. • A storage bag is included. • The price is very good for this item. What I don’t like: • It can be a bit slippery in your hands. Some rubber grips or some ribs in the plastic would be helpful. Overall, a really nice tool to have. It’s accurate and it’s fast. I fully recommend.
    by
    • Recommended
    3 found this review helpful
    It's an awesome tool I wish they had the battery...
    It's an awesome tool I wish they had the battery door so you can just slide it off and put the batteries in and then slide the battery door back on but they got these little tiny Phillips head screws that holds the the belt clip on and also pulls the battery back on after so many times or if you're tighten it too tight you could strip the you know the the screw hole but luckily mechanically inclined and so I know just how tight to put it just tight enough so that everything stays together
    by
    • Verified Purchase
    Klein used to be quality!
    Last straw. Probably not buying Klein again. Sometimes you dont get what you pay for! Temperature reads 5 degrees off! Thats pure crap. I can buy a thermometer from the dollar store and would be more accurate than this. (I did a thorough testing). Makes me wonder how accurate the carbon monoxide readings are!!! Yes if i hold it to my cars exhaust it alerts, but i wouldnt need it for this obvious reason!! Yikes. Was nice knowing tou Klein! So long!
    by
      Klein Tools
      Accurate and reliable tool that's not overly priced for the safety value that it brings to the work site
      by
      • Verified Purchase
      by
      • Verified Purchase
      No accurate measurement of CO
      I could never get a CO reading. Always read 000 ppm right next to my gas furnace flue. I called Klein customer service, and they recommended I test it over a gas stove. I did, and still got no reading after several attempts. I sent it back.
      by
        Showing 1-10 of 52 reviews