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I bought this unit for testing CO levels in Scuba tanks before diving them and used this unit less than 5 times. While the unit worked it was OK but would have variable readings with too much flow across the sensor. When I recently pulled the unit out of the case where I store it inside my house, it would not let me calibrate the unit. Upon further investigation the sensor has died on the unit after uses in 21 months and is now a paperweight. They state the sensor will last 2-4 years, but this one has seen minimal use and has already failed. The unit was not abused, I always stored it in a case and it last worked when I used it 6 months ago. Sensorcon states I can have it repaired for $60 since it is out of warranty. This one only lasted for 5 uses so I think I will take my money elsewhere.
This is the 2nd one I've purchased. Both times the product reached an above 30 ppm reading & both times I called the local gas company and they read 0 ppm all over my house, even while my Sensorcon maintained a 15-20 ppm reading after I had aired out my house for more than 2 hours. This is a false product. I even took it outside for a few hours and drove around & the readings even increased, out in broad daylight - it happened to be a hot day, so to my mind this product is nothing more than a glorified "heat sensor" - whether it detects CO to boot, I wouldn't bet on it.
It is not clear that this unit only works for 2 years, then it needs a calibration. That calibration make the unit good for 180 days beyond the 2years. The unit can be sent in for the calibration for $40. If you include shipping, then you could potentially get it calibrated twice -- but now you have spend just as much money as buying a new one that is good for two years. So, basically, unless you have a calibration gas handy to do the calibration yourself, this unit is only practical for two years.
This thing is mediocre at best. If you are looking for an accurate reader and for a company that answers phone calls, this is not the product to buy. You can get a used CO detector that is much more reliable for about the same price.
Bought from Amazon, thinking this meter would be good to have from time to time in my home tool kit (HVAC testing and automobiles). Unfortunately, the manual of this tool indicates it will reach end of life (EOL) after 2 years (plus 180 days longer if the meter is calibrated). I have attached a photo of the relevant page of the manual to my review. This is an expensive device for only 2 years of use (or 2.5 years if you pay to calibrate it). Perhaps that makes sense for a professional HVAC tech, but certainly not for a home user. This meter is designed, it seems, for daily use by a professional. For that purpose, I expect it is fine and the built quality is sturdy. For a home user, I would not recommend it to others.