Review on High-Precision Handheld Carbon Monoxide Meter | Portable CO Detector | CO Gas Leak Detector and Monitor Tester (1000ppm) by Mike Rogers

I have never had a portable air tester. I had an odor in my home that I thought might be due to my central air filter not being changed in a long time due to pandemic restrictions, so I called the HVAC company to have the filter replaced. The guy who showed up was testing my rooftop HVAC unit after hanging something similar to this test unit, orange and black, on one of my room's air vents. The device emitted a continuous tone. The device hanging in the room next to the ventilation began to beep faster and faster. When he came down he said the heat exchanger had cracked resulting in carbon monoxide pollution and said I needed a new air conditioner. He told me what his company would install for $10,000-$14,000 or more and was ready to go. I told him I will take care of it, he said don't use heat and it was summer so I don't need heat. After he left I wanted to get a manual tester like his. The brand he used was listed on Revain, but the reviewers said this one was just as good, so I went with that one. Since my central heating is off, I assume the tester is accurate if it doesn't detect carbon monoxide, while the other said to set it to maximum with the heating on. Since then it has been switched off. I really like this tester because I'm not familiar with setting up devices and this one was easy and always turns on unlike the portable AQ tester I got that says the battery is low after 3 months , charge immediately and no matter how long it takes to charge, it still gets the same message and is useless. I will use this brand for any other testers I need.