I was wanting to check on the possible CO when using a ventless heater, so I checked it with my Gas detector. It is a $1700 Kit, and I just got it back from calibration, cot $350.00. Very accurate meter. It even checks the oxygen content in the air; which should be around 21% the 78% nitrogen. a small very small percentage of other gasses. I also checked it with a small meter I own.
I ran the heater (20,000 BTU) for 2 hours and checked the air for gasses. All OK.
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